WorldWideScience

Sample records for polarization ray tracing

  1. Investigation of propagation algorithms for ray-tracing simulation of polarized neutrons

    DEFF Research Database (Denmark)

    Bergbäck Knudsen, Erik; Tranum-Rømer, A.; Willendrup, Peter Kjær

    2014-01-01

    Ray-tracing of polarized neutrons faces a challenge when the neutron propagates through an inhomogeneous magnetic field. This affects simulations of novel instruments using encoding of energy or angle into the neutron spin. We here present a new implementation of propagation of polarized neutrons...... within the McStas simulation package and show that it outperforms the de-facto standard method implemented in the NISP package by Seeger and Daemen. We include simulation of a simplified model of a spin-echo instrument, including a simple virtual experiment.......Ray-tracing of polarized neutrons faces a challenge when the neutron propagates through an inhomogeneous magnetic field. This affects simulations of novel instruments using encoding of energy or angle into the neutron spin. We here present a new implementation of propagation of polarized neutrons...

  2. A model of polarized-beam AGS in the ray-tracing code Zgoubi

    Energy Technology Data Exchange (ETDEWEB)

    Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ahrens, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Brown, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Dutheil, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Glenn, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Roser, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Shoefer, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tsoupas, N. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-07-12

    A model of the Alternating Gradient Synchrotron, based on the AGS snapramps, has been developed in the stepwise ray-tracing code Zgoubi. It has been used over the past 5 years in a number of accelerator studies aimed at enhancing RHIC proton beam polarization. It is also used to study and optimize proton and Helion beam polarization in view of future RHIC and eRHIC programs. The AGS model in Zgoubi is operational on-line via three different applications, ’ZgoubiFromSnaprampCmd’, ’AgsZgoubiModel’ and ’AgsModelViewer’, with the latter two essentially interfaces to the former which is the actual model ’engine’. All three commands are available from the controls system application launcher in the AGS ’StartUp’ menu, or from eponymous commands on shell terminals. Main aspects of the model and of its operation are presented in this technical note, brief excerpts from various studies performed so far are given for illustration, means and methods entering in ZgoubiFromSnaprampCmd are developed further in appendix.

  3. Anisotropic ray trace

    Science.gov (United States)

    Lam, Wai Sze Tiffany

    Optical components made of anisotropic materials, such as crystal polarizers and crystal waveplates, are widely used in many complex optical system, such as display systems, microlithography, biomedical imaging and many other optical systems, and induce more complex aberrations than optical components made of isotropic materials. The goal of this dissertation is to accurately simulate the performance of optical systems with anisotropic materials using polarization ray trace. This work extends the polarization ray tracing calculus to incorporate ray tracing through anisotropic materials, including uniaxial, biaxial and optically active materials. The 3D polarization ray tracing calculus is an invaluable tool for analyzing polarization properties of an optical system. The 3x3 polarization ray tracing P matrix developed for anisotropic ray trace assists tracking the 3D polarization transformations along a ray path with series of surfaces in an optical system. To better represent the anisotropic light-matter interactions, the definition of the P matrix is generalized to incorporate not only the polarization change at a refraction/reflection interface, but also the induced optical phase accumulation as light propagates through the anisotropic medium. This enables realistic modeling of crystalline polarization elements, such as crystal waveplates and crystal polarizers. The wavefront and polarization aberrations of these anisotropic components are more complex than those of isotropic optical components and can be evaluated from the resultant P matrix for each eigen-wavefront as well as for the overall image. One incident ray refracting or reflecting into an anisotropic medium produces two eigenpolarizations or eigenmodes propagating in different directions. The associated ray parameters of these modes necessary for the anisotropic ray trace are described in Chapter 2. The algorithms to calculate the P matrix from these ray parameters are described in Chapter 3 for

  4. Interactive Stable Ray Tracing

    DEFF Research Database (Denmark)

    Dal Corso, Alessandro; Salvi, Marco; Kolb, Craig

    2017-01-01

    Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-pr...

  5. RAY TRACING IMPLEMENTATION IN JAVA PROGRAMMING LANGUAGE

    Directory of Open Access Journals (Sweden)

    Aybars UĞUR

    2002-01-01

    Full Text Available In this paper realism in computer graphics and components providing realism are discussed at first. It is mentioned about illumination models, surface rendering methods and light sources for this aim. After that, ray tracing which is a technique for creating two dimensional image of a three-dimensional virtual environment is explained briefly. A simple ray tracing algorithm was given. "SahneIzle" which is a ray tracing program implemented in Java programming language which can be used on the internet is introduced. As a result, importance of network-centric ray tracing software is discussed.

  6. Reverse ray tracing for transformation optics.

    Science.gov (United States)

    Hu, Chia-Yu; Lin, Chun-Hung

    2015-06-29

    Ray tracing is an important technique for predicting optical system performance. In the field of transformation optics, the Hamiltonian equations of motion for ray tracing are well known. The numerical solutions to the Hamiltonian equations of motion are affected by the complexities of the inhomogeneous and anisotropic indices of the optical device. Based on our knowledge, no previous work has been conducted on ray tracing for transformation optics with extreme inhomogeneity and anisotropicity. In this study, we present the use of 3D reverse ray tracing in transformation optics. The reverse ray tracing is derived from Fermat's principle based on a sweeping method instead of finding the full solution to ordinary differential equations. The sweeping method is employed to obtain the eikonal function. The wave vectors are then obtained from the gradient of that eikonal function map in the transformed space to acquire the illuminance. Because only the rays in the points of interest have to be traced, the reverse ray tracing provides an efficient approach to investigate the illuminance of a system. This approach is useful in any form of transformation optics where the material property tensor is a symmetric positive definite matrix. The performance and analysis of three transformation optics with inhomogeneous and anisotropic indices are explored. The ray trajectories and illuminances in these demonstration cases are successfully solved by the proposed reverse ray tracing method.

  7. Analysis of trace element compositions in adhesive cloth tapes using high-energy x-ray fluorescence spectrometer with three-dimensional polarization optics for forensic discrimination

    International Nuclear Information System (INIS)

    Goto, Akiko; Hokura, Akiko; Nakai, Izumi

    2008-01-01

    The forensic discrimination of adhesive cloth tapes often used in crimes was developed using a high-energy energy-dispersive X-ray fluorescence spectrometer with 3-dimensional polarization optics. The best measurement condition for discrimination of the tape was as follows: secondary targets, Rh and Al 2 O 3 ; measurement time, 300 s for Rh and 600 s for Al 2 O 3 ; 14 elements (Ca, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Zr, Nb, Mo, Sb, Ba and Pb) were used for discrimination. It is found that the combined information of yarn density and the XRF peak intensity of the 14 elements successfully discriminated 29 out of 31 samples, of which 2 probably had the same origin. This technique is useful for forensic analysis, because it is nondestructive, rapid and easy. Therefore, it can be applied to actual forensic identification. (author)

  8. Backward ray tracing for ultrasonic imaging

    NARCIS (Netherlands)

    Breeuwer, R.

    1990-01-01

    Focused ultrasonic beams frequently pass one or more media interfaces, strongly affecting the ultrasonic beamshape and focusing. A computer program, based on backward ray tracing was developed to compute the shape of a corrected focusing mirror. This shape is verified with another program; then the

  9. Ray tracing in anisotropic media with singularities

    Czech Academy of Sciences Publication Activity Database

    Vavryčuk, Václav

    2001-01-01

    Roč. 145, č. 1 (2001), s. 265-276 ISSN 0956-540X R&D Projects: GA ČR GA205/00/1350 Institutional research plan: CEZ:AV0Z3012916 Keywords : anisotropic media * ray tracing * singularities Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.366, year: 2001

  10. RAY TRACING RENDER MENGGUNAKAN FRAGMENT ANTI ALIASING

    Directory of Open Access Journals (Sweden)

    Febriliyan Samopa

    2008-07-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Rendering is generating surface and three-dimensional effects on an object displayed on a monitor screen. Ray tracing as a rendering method that traces ray for each image pixel has a drawback, that is, aliasing (jaggies effect. There are some methods for executing anti aliasing. One of those methods is OGSS (Ordered Grid Super Sampling. OGSS is able to perform aliasing well. However, this method requires more computation time since sampling of all pixels in the image will be increased. Fragment Anti Aliasing (FAA is a new alternative method that can cope with the drawback. FAA will check the image when performing rendering to a scene. Jaggies effect is only happened at curve and gradient object. Therefore, only this part of object that will experience sampling magnification. After this sampling magnification and the pixel values are computed, then downsample is performed to retrieve the original pixel values. Experimental results show that the software can implement ray tracing well in order to form images, and it can implement FAA and OGSS technique to perform anti aliasing. In general, rendering using FAA is faster than using OGSS

  11. Ray tracing theory and mirage occurrence conditions.

    Science.gov (United States)

    Woyk, E

    1978-07-01

    The new ray tracing theory, deduced from geometrical optics and widely developed for radio propagation in cosmic atmospheres, is now applied to optics. This paper is confined to the duct mode propagation which represents a singularity. A narrow horizontal beam emitted inside the waveguide can propagate a long path around the earth with very good periodic focusing: the central circular path coincides with the stratification of the atmosphere while rays above or below it are more or less curved. Perfect symmetry is not needed; but two specific conditions must be satisfied, and their occurrence just coincides with conditions under which mirages occur: a quiet mirage with sharp contours, evidently not much affected by scatter, occurs only during a temperature inversion, above a large hot desert, above a hot rather convex asphalt road, or (under convenient conditions) above a quiet level sea, which means only when favorable conditions establish the very sporadically occurring waveguide. A density maximum need not occur at all.

  12. RayTrace: A Simplified Ray Tracing Software for use in AutoCad

    DEFF Research Database (Denmark)

    Reimann, Gregers Peter; Tang, C.K.

    2005-01-01

    A design aid tool for testing and development of daylighting systems was developed. A simplified ray tracing software was programmed in Lisp for AutoCad. Only fully specularly reflective, fully transparent and fully absorbant surfaces can be defined in the software. The software is therefore best...

  13. Ray tracing — computing the incomputable?

    Directory of Open Access Journals (Sweden)

    Ed Blakey

    2014-03-01

    Full Text Available We recall from previous work a model-independent framework of computational complexity theory. Notably for the present paper, the framework allows formalization of the issues of precision that present themselves when one considers physical, error-prone (especially analogue rather than digital computational systems. We take as a case study the ray-tracing problem, a Turing-machine-incomputable problem that can, in apparent violation of the Church-Turing thesis, nonetheless be said to be solved by certain optical computers; however, we apply the framework of complexity theory so as to formalize the intuition that the purported super-Turing power of these computers in fact vanishes once precision is properly considered.

  14. X-ray Fluorescence Method for Trace Analysis and Imaging

    OpenAIRE

    Hayakawa, Shinjiro

    2000-01-01

    X-ray fluorescence analysis has a long history as a conventional bulk elemental analysis with medium sensitivity. However, with the use of synchrotron radiation x-ray fluorescence method has become a unique analytical technique which can provide trace elemental information with the spatial resolution. To obtain quantitative information of trace elemental distribution by using the x-ray fluorescence method, theoretical description of x-ray fluorescence yield is described. Moreover, methods and...

  15. Use of X-Ray Fluorescence Spectrometry to Determine Trace ...

    African Journals Online (AJOL)

    This paper deals with application of X-ray fluorescence spectrometry for the detection of trace elements in graphic. An X-ray spectrometer was constructed and used to carry out measurements on graphite spheres impregnated with different chemical elements. The intensities of the lines of these trace elements, as function of ...

  16. High precision ray tracing in cylindrically symmetric electrostatics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards Jr, David, E-mail: dej122842@gmail.com

    2015-11-15

    Highlights: • High precision ray tracing is formulated using power series techniques. • Ray tracing is possible for fields generated by solution to laplace's equation. • Spatial and temporal orders of 4–10 are included. • Precisions in test geometries of hemispherical deflector analyzer of ∼10{sup −20} have been obtained. • This solution offers a considerable extension to the ray tracing accuracy over the current state of art. - Abstract: With the recent availability of a high order FDM solution to the curved boundary value problem, it is now possible to determine potentials in such geometries with considerably greater accuracy than had been available with the FDM method. In order for the algorithms used in the accurate potential calculations to be useful in ray tracing, an integration of those algorithms needs to be placed into the ray trace process itself. The object of this paper is to incorporate these algorithms into a solution of the equations of motion of the ray and, having done this, to demonstrate its efficacy. The algorithm incorporation has been accomplished by using power series techniques and the solution constructed has been tested by tracing the medial ray through concentric sphere geometries. The testing has indicated that precisions of ray calculations of 10{sup −20} are now possible. This solution offers a considerable extension to the ray tracing accuracy over the current state of art.

  17. Cosmic ray access at polar heliographic latitudes

    International Nuclear Information System (INIS)

    Voelk, H.J.

    1976-01-01

    Based on a modified WKB analysis of the interplanetary irregularity spectra, a discussion of the radial dependence of the radial cosmic ray diffusion coefficient at polar heliographic latitudes is presented. At l-AU radial distance the parameters are taken to equal those observed in the ecliptic. In the sense of a present best estimate it is argued that relativistic nuclei should have significantly easier access to 1 AU at the pole than in the ecliptic. The reverse may very well be true for the direct access of very low rigidity particles

  18. Geometry-invariant GRIN lens: finite ray tracing.

    Science.gov (United States)

    Bahrami, Mehdi; Goncharov, Alexander V

    2014-11-17

    The refractive index distribution of the geometry-invariant gradient refractive index lens (GIGL) model is derived as a function of Cartesian coordinates. The adjustable external geometry of the GIGL model aims to mimic the shape of the human and animal crystalline lens. The refractive index distribution is based on an adjustable power-law profile, which provides additional flexibility of the model. An analytical method for layer-by-layer finite ray tracing through the GIGL model is developed and used to calculate aberrations of the GIGL model. The result of the finite ray tracing aberrations of the GIGL model are compared to those obtained with paraxial ray tracing. The derived analytical expression for the refractive index distribution can be employed in the reconstruction processes of the eye using the conventional ray tracing methods. The layer-by-layer finite ray tracing approach would be an asset in ray tracing through a modified GIGL model, where the refractive index distribution cannot be described analytically. Using the layer-by-layer finite ray-tracing method, the potential of the GIGL model in representing continuous as well as shell-like layered structures is illustrated and the results for both cases are presented and analysed.

  19. Ray-traced Delays in the Atmosphere for Geodetic VLBI

    Science.gov (United States)

    Hofmeister, Armin; Böhm, Johannes

    2014-12-01

    The application of ray-traced slant path delays has the potential to enhance geodetic Very Long Baseline Interferometry (VLBI) analysis through improving the correction of the tropospheric effects on the observations. The utilization of directly estimated ray-traced slant path delays calculated from true meteorological data has the potential to overcome the shortcomings of the commonly used method of indirectly determined slant path delays via zenith delays mapped to the actual observation angle. Within our project RADIATE VLBI (Ray-traced Delays in the Atmosphere for geodetic VLBI) we are developing a new ray-tracing program for application in geodetic VLBI analysis. We introduce our project and present an overview of the current development status of our ray-tracer. In order to verify our results, we compare our ray-traced delays to results of a ray-tracer comparison campaign by Nafisi et al. (2012b), te{bib_Nafisi_2012b}. The RADIATE piecewise-linear solution for the slant total delay calculated from mapping factors at 5(°) elevation agrees with most of the other ray-tracers, with mean differences below 1 cm and standard deviations below 0.6 cm at the station Tsukuba and mean differences below 2.5 cm and standard deviations below 1 cm at the station Wettzell.

  20. Ray Tracing for Ocean Acoustic Tomography

    National Research Council Canada - National Science Library

    Dushaw, Brian

    1998-01-01

    .... The Numerical Recipes software package provided the basis for much of this computer code. The ray equations are reviewed, and ray equations that include the effects of ocean current are derived...

  1. Sensitivity of Gamma-Ray Detectors to Polarization

    OpenAIRE

    Yadigaroglu, I. -A.

    1996-01-01

    Previous studies have shown that the largest gamma-ray detector to date, EGRET, does not have useful polarization sensitivity. We have explored here some improved approaches to analyzing gamma-ray pair production events, leading to important gains in sensitivity to polarization. The performance of the next generation gamma-ray instrument GLAST is investigated using a detailed Monte Carlo simulation of the complete detector.

  2. Approximate P-wave ray tracing and dynamic ray tracing in weakly orthorhombic media of varying symmetry orientation

    KAUST Repository

    Masmoudi, Nabil

    2014-01-01

    We present an approximate, but efficient and sufficiently accurate P-wave ray tracing and dynamic ray tracing procedure for 3D inhomogeneous, weakly orthorhombic media with varying orientation of symmetry planes. In contrast to commonly used approaches, the orthorhombic symmetry is preserved at any point of the model. The model is described by six weak-anisotropy parameters and three Euler angles, which may vary arbitrarily, but smoothly, throughout the model. We use the procedure for the calculation of rays and corresponding two-point traveltimes in a VSP experiment in a part of the BP benchmark model generalized to orthorhombic symmetry.

  3. Implementation of Refined Ray Tracing inside a Space Module

    Directory of Open Access Journals (Sweden)

    Balamati Choudhury

    2012-08-01

    Full Text Available Modern space modules are susceptible to EM radiation from both external and internal sources within the space module. Since the EM waves for various operations are frequently in the high-frequency domain, asymptotic raytheoretic methods are often the most optimal choice for deterministic EM field analysis. In this work, surface modeling of a typical manned space module is done by hybridizing a finite segment of right circular cylinder and a general paraboloid of revolution (GPOR frustum. A transmitting source is placed inside the space module and test rays are launched from the transmitter. The rays are allowed to propagate inside the cavity. Unlike the available ray-tracing package, that use numerical search methods, a quasi-analytical ray-propagation model is developed to obtain the ray-path details inside the cavity which involves the ray-launching, ray-bunching, and an adaptive cube for ray-reception.

  4. Ray Tracing RF Field Prediction: An Unforgiving Validation

    Directory of Open Access Journals (Sweden)

    E. M. Vitucci

    2015-01-01

    Full Text Available The prediction of RF coverage in urban environments is now commonly considered a solved problem with tens of models proposed in the literature showing good performance against measurements. Among these, ray tracing is regarded as one of the most accurate ones available. In the present work, however, we show that a great deal of work is still needed to make ray tracing really unleash its potential in practical use. A very extensive validation of a state-of-the-art 3D ray tracing model is carried out through comparison with measurements in one of the most challenging environments: the city of San Francisco. Although the comparison is based on RF cellular coverage at 850 and 1900 MHz, a widely studied territory, very relevant sources of error and inaccuracy are identified in several cases along with possible solutions.

  5. Linear polarization observations of some X-ray sources

    International Nuclear Information System (INIS)

    Shakhovskoy, N.M.; Efimov, Yu.S.

    1975-01-01

    Multicolour linear polarization of optical radiation of the X-ray sources Sco X-1, Cyg X-2, Cyg X-1 and Her X-1 was measured at the Crimean Astrophysical Observatory in 1970-1973. These observations indicate that polarization of Sco X-1 in the ultraviolet, blue and red spectral regions appears to be variable. No statistically significant variations of polarization were found for the other three sources observed. (Auth.)

  6. Polarized gamma-rays with laser-Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Ohgaki, H.; Noguchi, T.; Sugiyama, S. [Electrotechnical Lab., Ibaraki (Japan)] [and others

    1995-12-31

    Polarized gamma-rays were generated through laser-Compton backscattering (LCS) of a conventional Nd:YAG laser with electrons circulating in the electron storage ring TERAS at Electrotechnical Laboratory. We measured the energy, the energy spread, and the yield of the gamma-rays to characterize our gamma-ray source. The gamma-ray energy can be varied by changing the energy of the electrons circulating the storage ring. In our case, the energy of electrons in the storage ring were varied its energy from 200 to 750 MeV. Consequently, we observed gamma-ray energies of 1 to 10 MeV with 1064 run laser photons. Furthermore, the gamma-ray energy was extended to 20 MeV by using the 2nd harmonic of the Nd:YAG laser. This shows a good agreement with theoretical calculation. The gamma-ray energy spread was also measured to be 1% FWHM for -1 MeV gamma-rays and to be 4% FWHM for 10 MeV gamma-rays with a narrow collimator that defined the scattering cone. The gamma-ray yield was 47.2 photons/mA/W/s. This value is consistent with a rough estimation of 59.5 photons/mA/W/s derived from theory. Furthermore, we tried to use these gamma-rays for a nuclear fluorescence experiment. If we use a polarized laser beam, we can easily obtain polarized gamma-rays. Elastically scattered photons from {sup 208} Pb were clearly measured with the linearly polarized gamma-rays, and we could assign the parity of J=1 states in the nucleus. We should emphasize that the polarized gamma-ray from LCS is quit useful in this field, because we can use highly, almost completely, polarized gamma-rays. We also use the LCS gamma-rays to measure the photon absorption coefficients. In near future, we will try to generate a circular polarized gamma-ray. We also have a plan to use an FEL, because it can produce intense laser photons in the same geometric configuration as the LCS facility.

  7. Calculation of a wave field from ray tracing

    Czech Academy of Sciences Publication Activity Database

    Cairns, R.A.; Fuchs, Vladimír

    2010-01-01

    Roč. 50, č. 9 (2010), 095001-095001 ISSN 0029-5515 Institutional research plan: CEZ:AV0Z20430508 Keywords : ray tracing * lower hybrid * wave Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.303, year: 2010 http://iopscience.iop.org/0029-5515/50/9/095001/

  8. Ray tracing and refraction in the modified US1976 atmosphere

    NARCIS (Netherlands)

    van der Werf, SY

    2003-01-01

    A new and flexible ray-tracing procedure for calculating astronomical refraction is outlined and applied to the US1976 standard atmosphere. This atmosphere is generalized to allow for a free choice of the temperature and pressure at sea level, and in this form it has been named the modified US1976

  9. Real time ray tracing of skeletal implicit surfaces

    DEFF Research Database (Denmark)

    Rouiller, Olivier; Bærentzen, Jakob Andreas

    Modeling and rendering in real time is usually done via rasterization of polygonal meshes. We present a method to model with skeletal implicit surfaces and an algorithm to ray trace these surfaces in real time in the GPU. Our skeletal representation of the surfaces allows to create smooth models...

  10. ARTEAM - Advanced ray tracing with earth atmospheric models

    NARCIS (Netherlands)

    Kunz, G.J.; Moerman, M.M.; Eijk, A.M.J. van

    2002-01-01

    The Advanced Ray Tracing with Earth Atmospheric Models (ARTEAM) aims at a description of the electro-optical propagation environment in the marine atmospheric surface layer. For given meteorological conditions, the model evaluates height- and range-resolved transmission losses, refraction and

  11. Polarization measurements of gamma ray bursts and axion like particles

    CERN Document Server

    Rubbia, André

    2008-01-01

    A polarized gamma ray emission spread over a sufficiently wide energy band from a strongly magnetized astrophysical object like gamma ray bursts (GRBs) offers an opportunity to test the hypothesis of axion like particles (ALPs). Based on evidences of polarized gamma ray emission detected in several gamma ray bursts we estimated the level of ALPs induced dichroism, which could take place in the magnetized fireball environment of a GRB. This allows to estimate the sensitivity of polarization measurements of GRBs to the ALP-photon coupling. This sensitivity $\\gag\\le 2.2\\cdot 10^{-11} {\\rm GeV^{-1}}$ calculated for the ALP mass $m_a=10^{-3}~{\\rm eV}$ and MeV energy spread of gamma ray emission is competitive with the sensitivity of CAST and becomes even stronger for lower ALPs masses.

  12. An improved MIMO-SAR simulator strategy with ray tracing

    Science.gov (United States)

    Xiang, Xingyu; Mo, Zijian; Wang, Zhonghai; Chen, Genshe; Pham, Khanh; Blasch, Erik

    2016-05-01

    High resolution and wide-swath imaging can be obtained by Multiple-Input Multiple-Output (MIMO) synthetic aperture radar (SAR) with the state of the art technologies. The time division multiple access (TDMA) MIMO SAR mimics the motion of the antenna of SAR systems by switching the array channels to transmit the radar signals at different time slots. In this paper, we develop a simulation tool with ray tracing techniques to retrieve high resolution and accurate SAR images for development of MIMO SAR imaging methods. Without loss of generality, in the proposed simulator, we apply a TDMA MIMO SAR system with 13 transmitting antennas and 8 receiving antennas, where all transmitting antennas share a single transmitter and the receiving antennas share a single receiver. By comparing with the normal simulation MIMO SAR strategies, the simulation image using ray tracing results validate that the proposed method provides more accurate and higher resolution SAR images.

  13. Parallel ray tracing for one-dimensional discrete ordinate computations

    International Nuclear Information System (INIS)

    Jarvis, R.D.; Nelson, P.

    1996-01-01

    The ray-tracing sweep in discrete-ordinates, spatially discrete numerical approximation methods applied to the linear, steady-state, plane-parallel, mono-energetic, azimuthally symmetric, neutral-particle transport equation can be reduced to a parallel prefix computation. In so doing, the often severe penalty in convergence rate of the source iteration, suffered by most current parallel algorithms using spatial domain decomposition, can be avoided while attaining parallelism in the spatial domain to whatever extent desired. In addition, the reduction implies parallel algorithm complexity limits for the ray-tracing sweep. The reduction applies to all closed, linear, one-cell functional (CLOF) spatial approximation methods, which encompasses most in current popular use. Scalability test results of an implementation of the algorithm on a 64-node nCube-2S hypercube-connected, message-passing, multi-computer are described. (author)

  14. Microwave transport in EBT distribution manifolds using Monte Carlo ray-tracing techniques

    International Nuclear Information System (INIS)

    Lillie, R.A.; White, T.L.; Gabriel, T.A.; Alsmiller, R.G. Jr.

    1983-01-01

    Ray tracing Monte Carlo calculations have been carried out using an existing Monte Carlo radiation transport code to obtain estimates of the microsave power exiting the torus coupling links in EPT microwave manifolds. The microwave power loss and polarization at surface reflections were accounted for by treating the microwaves as plane waves reflecting off plane surfaces. Agreement on the order of 10% was obtained between the measured and calculated output power distribution for an existing EBT-S toroidal manifold. A cost effective iterative procedure utilizing the Monte Carlo history data was implemented to predict design changes which could produce increased manifold efficiency and improved output power uniformity

  15. Ray Tracing Modelling of Reflector for Vertical Bifacial Panel

    DEFF Research Database (Denmark)

    Jakobsen, Michael Linde; Thorsteinsson, Sune; Poulsen, Peter Behrensdorff

    2016-01-01

    Bifacial solar panels have recently become a new attractive building block for PV systems. In this work we propose a reflector system for a vertical bifacial panel, and use ray tracing modelling to model the performance. Particularly, we investigate the impact of the reflector volume being filled...... with a refractive medium, and shows the refractive medium improves the reflector performance since it directs almost all the light incident on the incoming plane into the PV panel....

  16. Modeling of the luminescent concentrators by ray-tracing

    Energy Technology Data Exchange (ETDEWEB)

    Burgers, A.R.; Van Roosmalen, J.A.M.; Slooff, L.H.; Kinderman, R. [ECN Solar Energy, Petten (Netherlands)

    2005-06-01

    We have made luminescent concentrator devices by gluing multi-crystalline silicon solar cells to polymer plates containing fluorescent dyes. The devices have been characterised by optical reflection- and transmission measurements and with external quantum efficiency measurements. We have applied different mirror configurations to the devices to improve the external quantum efficiency. The measurements have been modelled with a ray-tracing simulation. The simulation allows us to analyse loss mechanisms in the device.

  17. Ray Tracing modelling of reflector for vertical bifacial panel

    DEFF Research Database (Denmark)

    Jakobsen, Michael Linde; Thorsteinsson, Sune; Poulsen, Peter Behrensdorff

    2016-01-01

    Bifacial solar panels have recently become a new attractive building block for PV systems. In this work we propose a reflector system for a vertical bifacial panel, and use ray tracing modelling to model the performance. Particularly, we investigate the impact of the reflector volume being filled...... with a refractive medium, and shows the refractive medium improves the reflector performance since it directs almost all the light incident on the incoming plane into the PV panel....

  18. Backscatter, anisotropy, and polarization of solar hard X-rays

    International Nuclear Information System (INIS)

    Bai, T.; Ramaty, R.

    1978-01-01

    Hard X-rays incident upon the photosphere with energies > or approx. =15 keV have high probabilities of backscatter due to Compton collisions with electrons. This effect has a strong influence on the spectrum, intensity, and polarization of solar hard X-rays - especially for anisotropic models in which the primary X-rays are emitted predominantly toward the photosphere. We have carried out a detailed study of X-ray backscatter, and we have investigated the interrelated problems of anisotropy, polarization, center-to-limb variation of the X-ray spectrum, and Compton backscatter in a coherent fashion. The results of this study are compared with observational data. Because of the large contribution from backscatter, for an anisotropic primary X-ray source which is due to bremsstrahlung of accelerated electrons moving predominantly down toward the photosphere, the observed X-ray flux around 30 keV does not depend significantly on the position of flare on the Sun. For such an anisotropic source, the X-ray spectrum observed in the 15-50 keV range becomes steeper with the increasing heliocentric angle of the flare. These results are compatible with the data. The degree of polarization of the sum of the primary and reflected X-rays with energies between about 15 and 30 keV can be very large for anisotropic primary X-ray sources, but it is less than about 4% for isotropic sources. We also discuss the characteristics of the brightness distribution of the X-ray albedo patch created by the Compton backscatter. The height and anisotropy of the primary hard X-ray source might be inferred from the study of the albedo patch

  19. Constraining axion by polarized prompt emission from gamma ray bursts

    CERN Document Server

    Rubbia, André

    2008-01-01

    A polarized gamma ray emission spread over a sufficiently wide energy band from a strongly magnetized astrophysical object like gamma ray bursts (GRBs) offers an opportunity to test the hypothesis of invisible axion. The axionic induced dichroism of gamma rays at different energies should cause a misalignment of the polarization plane for higher energy events relative to that one for lower energies events resulting in the loss of statistics needed to form a pattern of the polarization signal to be recognized in a detector. According to this, any evidence of polarized gamma rays coming from an object with extended magnetic field could be interpreted as a constraint on the existence of the invisible axion for a certain parameter range. Based on reports of polarized MeV emission detected in several GRBs we derive a constraint on the axion-photon coupling. This constraint $\\g_{a\\gamma\\gamma}\\le 2.2\\cdot 10^{-11} {\\rm GeV^{-1}}$ calculated for the axion mass $m_a=10^{-3} {\\rm eV}$ is competitive with the sensitivi...

  20. Dynamic ray tracing for modeling optical cell manipulation

    Science.gov (United States)

    Sraj, Ihab; Szatmary, Alex C.; Marr, David W. M.; Eggleton, Charles D.

    2010-01-01

    Current methods for predicting stress distribution on a cell surface due to optical trapping forces are based on a traditional ray optics scheme for fixed geometries. Cells are typically modeled as solid spheres as this facilitates optical force calculation. Under such applied forces however, real and non-rigid cells can deform, so assumptions inherent in traditional ray optics methods begin to break down. In this work, we implement a dynamic ray tracing technique to calculate the stress distribution on a deformable cell induced by optical trapping. Here, cells are modeled as three-dimensional elastic capsules with a discretized surface with associated hydrodynamic forces calculated using the Immersed Boundary Method. We use this approach to simulate the transient deformation of spherical, ellipsoidal and biconcave capsules due to external optical forces induced by a single diode bar optical trap for a range of optical powers. PMID:20721060

  1. Frontiers in imaging magnetism with polarized x-rays

    Directory of Open Access Journals (Sweden)

    Peter eFischer

    2015-01-01

    Full Text Available Although magnetic imaging with polarized x-rays is a rather young scientific discipline, the various types of established x-ray microscopes have already taken an important role in state-of-the-art characterization of the properties and behavior of spin textures in advanced materials. The opportunities ahead will be to obtain in a unique way indispensable multidimensional information of the structure, dynamics and composition of scientifically interesting and technologically relevant magnetic materials.

  2. X-ray trace element analysis with positive ion beams

    International Nuclear Information System (INIS)

    Davis, R.H.

    1973-01-01

    A new trace element analysis having the advantage that many elements may be detected in a single measurement, based on positive charged particle induced X-ray florescence and on the production of X-rays by heavy ions, is described. Because of the large cross-sections for the production of discrete X-ray and the low yield of continuum radiation, positive charged particle X-ray florescence is a competitive, fast, analytic tool. In the experiment a beam of positive charged particles from an accelerator was directed toward a target. X-rays induced by the bombardment were detected by a Si(Li) detector the ouput from which was amplified and sorted in a multichannel analyzer. For rapid data handling and analysis, the multichannel analyzer or ADC unit was connected to an on-line computer. A large variety of targets prepared in collaboration with the oceanographers have been studied and spectra obtained for different particles having the same velocity are presented to show that the yield of discrete X-rays increases at least as rapidly as Z 2 . While protons of several MeV appear to be already competitive further advantage may be gained by heavy ions at lower energies since the continuum is reduced while the peak ''signals'' retain strength due to the Z 2 dependence. (S.B.)

  3. Polarized Emission from Gamma-Ray Burst Jets

    Directory of Open Access Journals (Sweden)

    Shiho Kobayashi

    2017-11-01

    Full Text Available I review how polarization signals have been discussed in the research field of Gamma-Ray Bursts (GRBs. I mainly discuss two subjects in which polarimetry enables us to study the nature of relativistic jets. (1 Jet breaks: Gamma-ray bursts are produced in ultra-relativistic jets. Due to the relativistic beaming effect, the emission can be modeled in a spherical model at early times. However, as the jet gradually slows down, we begin to see the edge of the jet together with polarized signals at some point. (2 Optical flash: later time afterglow is known to be insensitive to the properties of the original ejecta from the GRB central engine. However, a short-lived, reverse shock emission would enable us to study the nature of of GRB jets. I also briefly discuss the recent detection of optical circular polarization in GRB afterglow.

  4. The elimination of ray tracing in Monte Carlo shielding programs

    International Nuclear Information System (INIS)

    Bendall, D.E.

    1988-01-01

    The MONK6 code has clearly demonstrated the advantages of hole tracking, which was devised by Woodcock et at. for use in criticality codes from earlier work by Von Neumann. Hole tracking eliminates ray tracing by introducing, for all materials present in the problem, a pseudo scattering reaction that forward scatters without energy loss. The cross section for this reaction is chosen so that the total cross sections for all the materials are equal at a given energy. By this means, tracking takes place with a constant total cross section everywhere, so there is now no need to ray trace. The present work extends hole tracking to shielding codes, where it functions in tandem with Russian roulette and splitting. An algorithm has been evolved and its performance is compared with the ray-tracking code McBEND. A disadvantage with hole tracking occurs when there is a wide variation in total cross section for materials present. As the tracking uses the total cross section of the material that has the maximum cross section, there can be a large number of pseudo collisions in the materials with low total cross sections. In extreme cases, the advantages of hole tracking can be lost by the by the extra time taken in servicing these pseudo collisions; however, techniques for eliminating this problem are under consideration

  5. Adaptive sample map for Monte Carlo ray tracing

    Science.gov (United States)

    Teng, Jun; Luo, Lixin; Chen, Zhibo

    2010-07-01

    Monte Carlo ray tracing algorithm is widely used by production quality renderers to generate synthesized images in films and TV programs. Noise artifact exists in synthetic images generated by Monte Carlo ray tracing methods. In this paper, a novel noise artifact detection and noise level representation method is proposed. We first apply discrete wavelet transform (DWT) on a synthetic image; the high frequency sub-bands of the DWT result encode the noise information. The sub-bands coefficients are then combined to generate a noise level description of the synthetic image, which is called noise map in the paper. This noise map is then subdivided into blocks for robust noise level metric calculation. Increasing the samples per pixel in Monte Carlo ray tracer can reduce the noise of a synthetic image to visually unnoticeable level. A noise-to-sample number mapping algorithm is thus performed on each block of the noise map, higher noise value is mapped to larger sample number, and lower noise value is mapped to smaller sample number, the result of mapping is called sample map. Each pixel in a sample map can be used by Monte Carlo ray tracer to reduce the noise level in the corresponding block of pixels in a synthetic image. However, this block based scheme produces blocky artifact as appeared in video and image compression algorithms. We use Gaussian filter to smooth the sample map, the result is adaptive sample map (ASP). ASP serves two purposes in rendering process; its statistics information can be used as noise level metric in synthetic image, and it can also be used by a Monte Carlo ray tracer to refine the synthetic image adaptively in order to reduce the noise to unnoticeable level but with less rendering time than the brute force method.

  6. An implementation of ray tracing algorithm for the multiprocessor machines

    Directory of Open Access Journals (Sweden)

    Samardžić Aleksandar B.

    2006-01-01

    Full Text Available Ray Tracing is an algorithm for generating photo-realistic pictures of the 3D scenes, given scene description, lighting condition and viewing parameters as inputs. The algorithm is inherently convenient for parallelization and the simplest parallelization scheme is for the shared-memory parallel machines (multiprocessors. This paper presents two implementations of the algorithm developed by the authors for alike machines, one using the POSIX threads API and another one using the OpenMP API. The paper also presents results of rendering some test scenes using these implementations and discusses our parallel algorithm version efficiency.

  7. Ray tracing for inhomogeneous media applied to the human eye

    Science.gov (United States)

    Diaz-Gonzalez, G.; Iturbe-Castillo, M. D.; Juarez-Salazar, R.

    2017-08-01

    Inhomogeneous or gradient index media exhibit a refractive index varying with the position. This kind of media are very interesting because they can be found in both synthetic as well as real life optical devices such as the human lens. In this work we present the development of a computational tool for ray tracing in refractive optical systems. Particularly, the human eye is used as the optical system under study. An inhomogeneous medium with similar characteristics to the human lens is introduced and modeled by the so-called slices method. The useful of our proposal is illustrated by several graphical results.

  8. Photorealistic ray tracing to visualize automobile side mirror reflective scenes.

    Science.gov (United States)

    Lee, Hocheol; Kim, Kyuman; Lee, Gang; Lee, Sungkoo; Kim, Jingu

    2014-10-20

    We describe an interactive visualization procedure for determining the optimal surface of a special automobile side mirror, thereby removing the blind spot, without the need for feedback from the error-prone manufacturing process. If the horizontally progressive curvature distributions are set to the semi-mathematical expression for a free-form surface, the surface point set can then be derived through numerical integration. This is then converted to a NURBS surface while retaining the surface curvature. Then, reflective scenes from the driving environment can be virtually realized using photorealistic ray tracing, in order to evaluate how these reflected images would appear to drivers.

  9. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism.

    Science.gov (United States)

    Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J; Mancuso, Christopher A; Hogle, Craig W; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L; Dorney, Kevin M; Chen, Cong; Shpyrko, Oleg G; Fullerton, Eric E; Cohen, Oren; Oppeneer, Peter M; Milošević, Dejan B; Becker, Andreas; Jaroń-Becker, Agnieszka A; Popmintchev, Tenio; Murnane, Margaret M; Kapteyn, Henry C

    2015-11-17

    We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

  10. STATISTICAL PROPERTIES OF GAMMA-RAY BURST POLARIZATION

    International Nuclear Information System (INIS)

    Toma, Kenji; Sakamoto, Takanori; Hill, Joanne E.; Zhang, Bing; McConnell, Mark L.; Bloser, Peter F.; Yamazaki, Ryo; Ioka, Kunihito; Nakamura, Takashi

    2009-01-01

    The emission mechanism and the origin and structure of magnetic fields in gamma-ray burst (GRB) jets are among the most important open questions concerning the nature of the central engine of GRBs. In spite of extensive observational efforts, these questions remain to be answered and are difficult or even impossible to infer with the spectral and light-curve information currently collected. Polarization measurements will lead to unambiguous answers to several of these questions. Recent developments in X-ray and γ-ray polarimetry techniques have demonstrated a significant increase in sensitivity, enabling several new mission concepts, e.g., Polarimeters for Energetic Transients (POET), providing wide field of view and broadband polarimetry measurements. If launched, missions of this kind would finally provide definitive measurements of GRB polarizations. We perform Monte Carlo simulations to derive the distribution of GRB polarizations in three emission models; the synchrotron model with a globally ordered magnetic field (SO model), the synchrotron model with a small-scale random magnetic field (SR model), and the Compton drag model (CD model). The results show that POET, or other polarimeters with similar capabilities, can constrain the GRB emission models by using the statistical properties of GRB polarizations. In particular, the ratio of the number of GRBs for which the polarization degrees can be measured to the number of GRBs that are detected (N m /N d ) and the distributions of the polarization degrees (Π) can be used as the criteria. If N m /N d > 30% and Π is clustered between 0.2 and 0.7, the SO model will be favored. If, instead, N m /N d 0.8 are observed, then the CD model will be favored.

  11. Optimization of Monte Carlo algorithms and ray tracing on GPUs

    International Nuclear Information System (INIS)

    Bergmann, R.M.; Vujic, J.L.

    2013-01-01

    To take advantage of the computational power of GPUs (Graphical Processing Units), algorithms that work well on CPUs must be modified to conform to the GPU execution model. In this study, typical task-parallel Monte Carlo algorithms have been reformulated in a data-parallel way, and the benefits of doing so are examined. We were able to show that the data-parallel approach greatly improves thread coherency and keeps thread blocks busy, improving GPU utilization compared to the task-parallel approach. Data-parallel does not, however, outperform the task-parallel approach in regards to speedup over CPU. Regarding the ray-tracing acceleration, OptiX shows promise for providing enough ray tracing speed to be used in a full 3D Monte Carlo neutron transport code for reactor calculations. It is important to note that it is necessary to operate on large datasets of particle histories in order to have good performance in both OptiX and the data-parallel algorithm since this reduces the impact of latency. Our paper also shows the need to rewrite standard Monte Carlo algorithms in order to take full advantage of these new, powerful processor architectures

  12. High performance dosimetry calculations using adapted ray-tracing

    International Nuclear Information System (INIS)

    Perrotte, Lancelot; Saupin, Guillaume

    2010-01-01

    When preparing interventions on nuclear sites, it is interesting to study different scenarios, to identify the most appropriate one for the operator(s). Using virtual reality tools is a good way to simulate the potential scenarios. Thus, taking advantage of very efficient computation times can help the user studying different complex scenarios, by immediately evaluating the impact of any changes. In the field of radiation protection, people often use computation codes based on the straight line attenuation method with build-up factors. As for other approaches, geometrical computations (finding all the interactions between radiation rays and the scene objects) remain the bottleneck of the simulation. We present in this paper several optimizations used to speed up these geometrical computations, using innovative GPU ray-tracing algorithms. For instance, we manage to compute every intersection between 600 000 rays and a huge 3D industrial scene in a fraction of second. Moreover, our algorithm works the same way for both static and dynamic scenes, allowing easier study of complex intervention scenarios (where everything moves: the operator(s), the shielding objects, the radiation sources).

  13. POLAR - novel hard X-ray polarimeter for Gamma Ray Bursts

    Science.gov (United States)

    Hajdas, Wojtek

    Our present knowledge of the Gamma Ray Bursts GRBs - the most powerful explosions in the universe after the Big Bang - links them with a birth of the black holes and localize at cosmological distances. There is also a strong evidence relating some of them with Supernovae and thus with gravitational waves. Despite of such significant role of GRBs only little is known about their mechanisms and progenitors. Existing theories still have troubles describing bursts prompt emissions while predictions of the photon polarization show large divergences. On the observational side there are just few isolated measurements of the hard X-ray polarization affected by large experimental uncertainties. Nevertheless, it became clear that determining the GRB polarization could be an ultimate step for understanding their genuine nature. To participate in this task we propose POLAR - novel instrument for hard X-ray and low energy gamma ray polarimetry. The instrument goal is to perform highly precise polarization studies from a very large number of GRBs. Measurements of the linear polarization in the GRB prompt emission at photon energies from 5 keV to 500 keV will be carried out using continuous observations of the sky. Our calculations showed that for several bursts per year the experimental precision will reach a 1 sigma level of 3 per cent. For the strongest events it will be possible to study polarization as a function of energy achieving much more detailed view of the emitting system structure. POLAR uses a uniform array of 1600 weakly shielded plastic detectors coupled with the new multi-anode photo-multipliers. The polarization measurement is based on Compton scattering and relies on detection of fast coincidences between plastic scintillator bars. The total mass (28 kg) and power requirements (30 W) are very moderate. POLAR has relatively small dimensions and it was designed to be not only non-intrusive but also highly adaptable. The qualification model is currently under

  14. Development of a New X-Ray Polarization Detection Device

    Science.gov (United States)

    Thompson, Jahreem R.; Hill, Joanne E.; Jahoda, Keith; Black, Kevin; Querrard, Rodney

    2018-01-01

    The aim of this research is to confirm the functionality of a Gas Electron Multiplier made of stainless steel in a detection medium of carbon dioxide and nitromethane through a series of X-ray tests in a vacuum chamber. Utilizing the photoelectric effect with carbon dioxide and nitromethane, we can confirm polarization of X-rays emitted from the most extreme astronomical conditions. We chose to use CO2 because we can confirm that it works well with the stainless-steel detector based on previous tests and nitromethane because we suspect that the ionization electrons created by the photoelectron during the photoelectric effect will experience less diffusion if they are bonded to a large molecule such as nitromethane as they diffuse towards the drift plate. The development of these new X-ray polarimeters will help to further the study of gravitational fields near black holes, their effects on matter they encounter, and the magnetic fields of neutron stars.

  15. X-ray polarization capabilities of a small explorer mission

    Science.gov (United States)

    Jahoda, Keith M.; Black, J. Kevin; Hill, Joanne E.; Kallman, Timothy R.; Kaaret, Philip E.; Markwardt, Craig B.; Okajima, Takashi; Petre, Robert; Soong, Yang; Strohmayer, Tod E.; Tamagawa, Toru; Tawara, Yuzuru

    2014-07-01

    X-ray polarization measurements hold great promise for studying the geometry and emission mechanisms in the strong gravitational and magnetic fields that surround black holes and neutron stars. In spite of this, the observational situation remains very limited; the last instrument dedicated to X-ray polarimetry flew decades ago on OSO-8, and the few recent measurements have been made by instruments optimized for other purposes. However, the technical capabilities to greatly advance the observational situation are in hand. Recent developments in micro-pattern gas detectors allow use of the polarization sensitivity of the photo-electric effect, which is the dominant interaction in the band above 2 keV. We present the scientific and technical requirements for an X-ray polarization observatory consistent with the scope of a NASA Small Explorer (SMEX) mission, along with a representative catalog of what the observational capabilities and expected sensitivities for the first year of operation could be. The mission is based on the technically robust design of the Gravity and Extreme Magnetism SMEX (GEMS) which completed a Phase B study and Preliminary Design Review in 2012. The GEMS mission is enabled by time projection detectors sensitive to the photo-electric effect. Prototype detectors have been designed, and provide engineering and performance data which support the mission design. The detectors are further characterized by low background, modest spectral resolution, and sub-millisecond timing resolution. The mission also incorporates high efficiency grazing incidence X-ray mirrors, design features that reduce systematic errors (identical telescopes at different azimuthal angles with respect to the look axis, and mounted on a rotating spacecraft platform), and a moderate capability to perform Target of Opportunity observations. The mission operates autonomously in a low earth, low inclination orbit with one to ten downlinks per day and one or more uplinks per week

  16. Geometry-invariant gradient refractive index lens: analytical ray tracing.

    Science.gov (United States)

    Bahrami, Mehdi; Goncharov, Alexander V

    2012-05-01

    A new class of gradient refractive index (GRIN) lens is introduced and analyzed. The interior iso-indicial contours mimic the external shape of the lens, which leads to an invariant geometry of the GRIN structure. The lens model employs a conventional surface representation using a coincoid of revolution with a higher-order aspheric term. This model has a unique feature, namely, it allows analytical paraxial ray tracing. The height and the angle of an arbitrary incident ray can be found inside the lens in a closed-form expression, which is used to calculate the main optical characteristics of the lens, including the optical power and third-order monochromatic aberration coefficients. Moreover, due to strong coupling of the external surface shape to the GRIN structure, the proposed GRIN lens is well suited for studying accommodation mechanism in the eye. To show the power of the model, several examples are given emphasizing the usefulness of the analytical solution. The presented geometry-invariant GRIN lens can be used for modeling and reconstructing the crystalline lens of the human eye and other types of eyes featuring a GRIN lens.

  17. SYSTEMATIC STUDY OF GAMMA-RAY-BRIGHT BLAZARS WITH OPTICAL POLARIZATION AND GAMMA-RAY VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Ryosuke; Fukazawa, Yasushi; Kanda, Yuka; Shiki, Kensei; Kawabata, Miho; Nakaoka, Tatsuya; Takaki, Katsutoshi; Takata, Koji; Ui, Takahiro [Department of Physical Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Nalewajko, Krzysztof; Madejski, Greg M. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road M/S 29, Menlo Park, CA 94025 (United States); Uemura, Makoto; Tanaka, Yasuyuki T.; Kawabata, Koji S.; Akitaya, Hiroshi; Ohsugi, Takashi [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Schinzel, Frank K. [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States); Moritani, Yuki [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Sasada, Mahito [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Yamanaka, Masayuki, E-mail: itoh@hep01.hepl.hiroshima-u.ac.jp, E-mail: itoh@hp.phys.titech.ac.jp [Department of Physics, Faculty of Science and Engineering, Konan University, Okamoto, Kobe, Hyogo 658-8501 (Japan); and others

    2016-12-10

    Blazars are highly variable active galactic nuclei that emit radiation at all wavelengths from radio to gamma rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies, and it also varies dramatically. The polarization of blazars is of interest for understanding the origin, confinement, and propagation of jets. However, even though numerous measurements have been performed, the mechanisms behind jet creation, composition, and variability are still debated. We performed simultaneous gamma-ray and optical photopolarimetry observations of 45 blazars between 2008 July and 2014 December to investigate the mechanisms of variability and search for a basic relation between the several subclasses of blazars. We identify a correlation between the maximum degree of optical linear polarization and the gamma-ray luminosity or the ratio of gamma-ray to optical fluxes. Since the maximum polarization degree depends on the condition of the magnetic field (chaotic or ordered), this result implies a systematic difference in the intrinsic alignment of magnetic fields in parsec-scale relativistic jets between different types of blazars (flat-spectrum radio quasars vs. BL Lacs) and consequently between different types of radio galaxies (FR I versus FR II).

  18. MARXS: A Modular Software to Ray-trace X-Ray Instrumentation

    Science.gov (United States)

    Günther, Hans Moritz; Frost, Jason; Theriault-Shay, Adam

    2017-12-01

    To obtain the best possible scientific result, astronomers must understand the properties of the available instrumentation well. This is important both when designing new instruments and when using existing instruments close to the limits of their specified capabilities or beyond. Ray-tracing is a technique for numerical simulations where the path of many light rays is followed through the system to understand how individual system components influence the observed properties, such as the shape of the point-spread-function. In instrument design, such simulations can be used to optimize the performance. For observations with existing instruments, this helps to discern instrumental artefacts from a true signal. Here, we describe MARXS, a new python package designed to simulate X-ray instruments on satellites and sounding rockets. MARXS uses probability tracking of photons and has polarimetric capabilities.

  19. IonRayTrace: An HF Propagation Model for Communications and Radar Applications

    Science.gov (United States)

    2014-12-01

    unnecessary. 3 Note that some of these fixes (1 and 3), while necessary for correct estimation and reinsertion into the next AREPS distribution, are...TRANSITIONS Beyond reinsertion of the high-fidelity HF ray trace code into future AREPS distributions, there is considerable interest in adding IonRayTrace

  20. Computation and analysis of backward ray-tracing in aero-optics flow fields.

    Science.gov (United States)

    Xu, Liang; Xue, Deting; Lv, Xiaoyi

    2018-01-08

    A backward ray-tracing method is proposed for aero-optics simulation. Different from forward tracing, the backward tracing direction is from the internal sensor to the distant target. Along this direction, the tracing in turn goes through the internal gas region, the aero-optics flow field, and the freestream. The coordinate value, the density, and the refractive index are calculated at each tracing step. A stopping criterion is developed to ensure the tracing stops at the outer edge of the aero-optics flow field. As a demonstration, the analysis is carried out for a typical blunt nosed vehicle. The backward tracing method and stopping criterion greatly simplify the ray-tracing computations in the aero-optics flow field, and they can be extended to our active laser illumination aero-optics study because of the reciprocity principle.

  1. Advanced simulations of x-ray beam propagation through CRL transfocators using ray-tracing and wavefront propagation methods

    DEFF Research Database (Denmark)

    Baltser, Jana; Bergbäck Knudsen, Erik; Vickery, Anette

    2011-01-01

    of X-ray beamline designs for particular user experiments. In this work we used the newly developed McXtrace ray-tracing package and the SRW wave-optics code to simulate the beam propagation of X-ray undulator radiation through such a "transfocator" as implemented at ID- 11 at ESRF. By applying two...

  2. Magnetic imaging with polarized soft x-rays

    Science.gov (United States)

    Fischer, Peter

    2017-08-01

    Properties, behavior, and functionalities of magnetic materials are largely determined by microscopic spin textures, particularly their formation into domains, their coupling mechanisms and their dynamic behavior. Advanced characterization tools are prerequisite to fundamentally understand magnetic materials and control spins for novel magnetic applications. Magnetic microscopies allow us to image directly the static and dynamic features of the relevant microscopic magnetization structures in advanced magnetic materials and thus provide detailed and direct insight into underlying physical phenomena. A large variety of magnetic imaging techniques has become available with particular strengths but also certain limitations. Essential features of magnetic microscopies are a high spatial resolution down into the nanometer regime, as this is the fundamental length scale of magnetic exchange interaction and the ultimate length scale in advanced magnetic technologies; magnetic and elemental sensitivity with quantitative capabilities, as the properties of advanced magnetic materials can be tailored by combining various magnetic elements and their magnetic moments; high temporal resolution from the ns to the fs regime to understand the associated spin dynamic processes and the functionality in magnetic devices; tomographic capabilities with nm resolution as new directions in nanoscience and technologies are moving into 3 dim arrangements of spin structures; and interfacial sensitivity as novel ways to control spins harness either the coupling across interfaces in multilayered structures or utilize non-collinear spin arrangements, which often occur from symmetry breaking at surfaces and interfaces. The unique properties of polarized soft x-rays, their abundancy and specific interaction with magnetic materials in form of dichroism effects have triggered the development of various magnetic x-ray imaging techniques. This review will provide an overview of the current state

  3. X-ray polarization spectroscopy from ultra-intense interactions

    Science.gov (United States)

    Booth, N.; Clarke, R.; Gallegos, P.; Gizzi, L.; Gregori, G.; Koester, P.; Labate, L.; Levato, T.; Li, B.; Makita, M.; Pasley, J.; Rajeev, P. P.; Riley, D.; Wagenaars, E.; Waugh, J. N.; Woolsey, N. C.

    2010-08-01

    Detailed knowledge of fast electron energy transport following the interaction of ultrashort intense laser pulses is a key subject for fast ignition. This is a problem relevant to many areas of laser-plasma physics with particular importance to fast ignition and X-ray secondary source development, necessary for the development of large-scale facilities such as HiPER and ELI. Operating two orthogonal crystal spectrometers set at Bragg angles close to 45° determines the X-ray s- and p- polarization ratio. From this ratio, it is possible to infer the velocity distribution function of the fast electron beam within the dense plasma. We report on results of polarization measurements at high density for sulphur and nickel buried layer targets in the high intensity range of 1019 - 1021 Wcm-2. We observe at 45° the Ly-α doublet using two sets of orthogonal highly-orientated pyrolytic graphite (HOPG) crystals set in 1st order for sulphur and 3rd order for nickel.

  4. X-ray polarization spectroscopy from ultra-intense interactions

    Energy Technology Data Exchange (ETDEWEB)

    Booth, N; Pasley, J; Wagenaars, E; Waugh, J N; Woolsey, N C [Department of Physics, University of York, Heslington, York, YO10 5DD (United Kingdom); Clarke, R; Gallegos, P; Rajeev, P P [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QN (United Kingdom); Gizzi, L; Koester, P; Labate, L; Levato, T [ILIL-IPCF, Consiglio Nazionale delle Ricerche, and INFN, Pisa (Italy); Gregori, G; Li, B [Department of Physics, University of Oxford, OX4 1PJ (United Kingdom); Makita, M; Riley, D, E-mail: nb505@york.ac.u [Department of Physics and Mathematics, Queens University Belfast, Belfast, BT1 4NN (United Kingdom)

    2010-08-01

    Detailed knowledge of fast electron energy transport following the interaction of ultrashort intense laser pulses is a key subject for fast ignition. This is a problem relevant to many areas of laser-plasma physics with particular importance to fast ignition and X-ray secondary source development, necessary for the development of large-scale facilities such as HiPER and ELI. Operating two orthogonal crystal spectrometers set at Bragg angles close to 45{sup 0} determines the X-ray s- and p- polarization ratio. From this ratio, it is possible to infer the velocity distribution function of the fast electron beam within the dense plasma. We report on results of polarization measurements at high density for sulphur and nickel buried layer targets in the high intensity range of 10{sup 19} - 10{sup 21} Wcm{sup -2}. We observe at 45{sup 0} the Ly-{alpha} doublet using two sets of orthogonal highly-orientated pyrolytic graphite (HOPG) crystals set in 1st order for sulphur and 3rd order for nickel.

  5. Detecting polarized gamma-rays by pair production

    CERN Document Server

    De Paola, G O

    1998-01-01

    Recently, a GEANT Monte Carlo code was used to design an outline of the geometry and to simulate the performance of a high energy (10 MeV-10 GeV) gamma-ray detector (Monte Carlo simulation of the ARGO. Nuclear Instruments and Methods A 342, 302-307). It was shown that the incident direction and energy of the incoming photons can be determined from the tracks of the produced electrons-positron pairs. A natural follow-up problem is to study whether this system can be used to detect linearly polarized gamma-rays. In principle, this can be done by measuring the azimuthal distribution of the produced pairs since the cross-section has a dependence with the vector polarization direction. In this work we first determine the azimuthal angular distribution from the differential cross-section for pair production. We then show that the azimuthal distribution of the produced pairs has a very simple angular dependence and can be approximated very accurately by cross-section for coplanar events. Finally, we use the simplifi...

  6. ON THE STATISTICAL ANALYSIS OF X-RAY POLARIZATION MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Strohmayer, T. E.; Kallman, T. R. [X-ray Astrophysics Lab, Astrophysics Science Division, NASA' s Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-08-20

    In many polarimetry applications, including observations in the X-ray band, the measurement of a polarization signal can be reduced to the detection and quantification of a deviation from uniformity of a distribution of measured angles of the form A + Bcos {sup 2}({phi} - {phi}{sub 0}) (0 < {phi} < {pi}). We explore the statistics of such polarization measurements using Monte Carlo simulations and {chi}{sup 2} fitting methods. We compare our results to those derived using the traditional probability density used to characterize polarization measurements and quantify how they deviate as the intrinsic modulation amplitude grows. We derive relations for the number of counts required to reach a given detection level (parameterized by {beta} the ''number of {sigma}'s'' of the measurement) appropriate for measuring the modulation amplitude a by itself (single interesting parameter case) or jointly with the position angle {phi} (two interesting parameters case). We show that for the former case, when the intrinsic amplitude is equal to the well-known minimum detectable polarization, (MDP) it is, on average, detected at the 3{sigma} level. For the latter case, when one requires a joint measurement at the same confidence level, then more counts are needed than what was required to achieve the MDP level. This additional factor is amplitude-dependent, but is Almost-Equal-To 2.2 for intrinsic amplitudes less than about 20%. It decreases slowly with amplitude and is Almost-Equal-To 1.8 when the amplitude is 50%. We find that the position angle uncertainty at 1{sigma} confidence is well described by the relation {sigma}{sub {phi}} = 28. Degree-Sign 5/{beta}.

  7. use of x-ray fluorescence spectrometry to determine trace elements ...

    African Journals Online (AJOL)

    NIJOTECH

    here, an X-ray spectrometer was constructed and used to detect the presence of trace elements in graphite matrix by their K fluorescence X-ray lines. Equipment. The spectrometer consisted of an X-ray tube. (as primary source), a sample holder and a turn-table carrying the analyzer crystal and the detector, all mounted on ...

  8. Quantitative evaluation of ultrasonic sound fields in anisotropic austenitic welds using 2D ray tracing model

    Science.gov (United States)

    Kolkoori, S. R.; Rahaman, M.-U.; Chinta, P. K.; Kreutzbruck, M.; Prager, J.

    2012-05-01

    Ultrasonic investigation of inhomogeneous anisotropic materials such as austenitic welds is complicated because its columnar grain structure leads to curved energy paths, beam splitting and asymmetrical beam profiles. A ray tracing model has potential advantage in analyzing the ultrasonic sound field propagation and there with optimizing the inspection parameters. In this contribution we present a 2D ray tracing model to predict energy ray paths, ray amplitudes and travel times for the three wave modes quasi longitudinal, quasi shear vertical, and shear horizontal waves in austenitic weld materials. Inhomogenity in the austenitic weld material is represented by discretizing the inhomogeneous region into several homogeneous layers. At each interface between the layers the reflection and transmission problem is computed and yields energy direction, amplitude and energy coefficients. The ray amplitudes are computed accurately by taking into account directivity, divergence and density of rays, phase relations as well as transmission coefficients. Ultrasonic sound fields obtained from the ray tracing model are compared quantitatively with the 2D Elastodynamic Finite Integration Technique (EFIT). The excellent agreement between both models confirms the validity of the presented ray tracing results. Experiments are conducted on austenitic weld samples with longitudinal beam transducer as transmitting probe and amplitudes at the rear surface are scanned by means of electrodynamical probes. Finally, the ray tracing model results are also validated through the experiments.

  9. Method for analysis of polar volatile trace components in aqueous samples by gas chromatography.

    Science.gov (United States)

    Pettersson, Johan; Roeraade, Johan

    2005-05-15

    A new method has been developed for direct analysis of volatile polar trace compounds in aqueous samples by gas chromatography. Water samples are injected onto a short packed precolumn containing anhydrous lithium chloride. A capillary column is coupled in series with the prefractionation column for final separation of the analytes. The enrichment principle of the salt precolumn is reverse to the principles employed in conventional methods such as SPE or SPME in which a sorbent or adsorbent is utilized to trap or concentrate the analytes. Such methods are not efficient for highly polar compounds. In the LiCl precolumn concept, the water matrix is strongly retained on the hygroscopic salt, whereas polar as well as nonpolar volatile organic compounds show very low retention and are eluted ahead of the water. After transfer of the analytes to the capillary column, the retained bulk water is removed by backflushing the precolumn at elevated temperature. For direct injections of 120 microL of aqueous samples, the combined time for injection and preseparation is only 3.5 min. With this procedure, direct repetitive automated analyses of highly volatile polar compounds such as methanol or tetrahydrofuran can be performed, and a limit of quantification in the low parts-per-billion region utilizing a flame ionization detector is demonstrated.

  10. Fast voxel and polygon ray-tracing algorithms in intensity modulated radiation therapy treatment planning

    International Nuclear Information System (INIS)

    Fox, Christopher; Romeijn, H. Edwin; Dempsey, James F.

    2006-01-01

    We present work on combining three algorithms to improve ray-tracing efficiency in radiation therapy dose computation. The three algorithms include: An improved point-in-polygon algorithm, incremental voxel ray tracing algorithm, and stereographic projection of beamlets for voxel truncation. The point-in-polygon and incremental voxel ray-tracing algorithms have been used in computer graphics and nuclear medicine applications while the stereographic projection algorithm was developed by our group. These algorithms demonstrate significant improvements over the current standard algorithms in peer reviewed literature, i.e., the polygon and voxel ray-tracing algorithms of Siddon for voxel classification (point-in-polygon testing) and dose computation, respectively, and radius testing for voxel truncation. The presented polygon ray-tracing technique was tested on 10 intensity modulated radiation therapy (IMRT) treatment planning cases that required the classification of between 0.58 and 2.0 million voxels on a 2.5 mm isotropic dose grid into 1-4 targets and 5-14 structures represented as extruded polygons (a.k.a. Siddon prisms). Incremental voxel ray tracing and voxel truncation employing virtual stereographic projection was tested on the same IMRT treatment planning cases where voxel dose was required for 230-2400 beamlets using a finite-size pencil-beam algorithm. Between a 100 and 360 fold cpu time improvement over Siddon's method was observed for the polygon ray-tracing algorithm to perform classification of voxels for target and structure membership. Between a 2.6 and 3.1 fold reduction in cpu time over current algorithms was found for the implementation of incremental ray tracing. Additionally, voxel truncation via stereographic projection was observed to be 11-25 times faster than the radial-testing beamlet extent approach and was further improved 1.7-2.0 fold through point-classification using the method of translation over the cross product technique

  11. Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Jirong; Wang, Jiancheng, E-mail: jirongmao@mail.ynao.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, 650011 Kunming, Yunnan Province (China)

    2017-04-01

    Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radio bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.

  12. Analysis of the COS B data for evidence of linear polarization of Vela pulsar gamma rays

    Science.gov (United States)

    Mattox, John R.; Mayer-Hasselwander, Hans A.; Strong, Andy W.

    1990-01-01

    The COS B spark chamber telescope observations of the Vela pulsar were analyzed for gamma-ray polarization. No significant quadrupole moment is found in the azimuthal distribution of the electron-positron pair production planes. However, analysis of the sensitivity indicates that even 100-percent polarization would not be detected. Therefore, the null result does not constrain the polarization of the Vela pulsar gamma-ray emission. This result contradicts the report of Caraveo et al. (1988) of possible evidence for polarization of the Vela pulsar gamma rays.

  13. Refined ray tracing inside single- and double-curvatured concave surfaces

    CERN Document Server

    Choudhury, Balamati

    2016-01-01

    This book describes the ray tracing effects inside different quadric surfaces. Analytical surface modeling is a priori requirement for electromagnetic (EM) analysis over aerospace platforms. Although numerically-specified surfaces and even non-uniform rational basis spline (NURBS) can be used for modeling such surfaces, for most practical EM applications, it is sufficient to model them as quadric surface patches and the hybrids thereof. It is therefore apparent that a vast majority of aerospace bodies can be conveniently modeled as combinations of simpler quadric surfaces, i.e. hybrid of quadric cylinders and quadric surfaces of revolutions. Hence the analysis of geometric ray tracing inside is prerequisite to analyzing the RF build-up. This book, describes the ray tracing effects inside different quadric surfaces such as right circular cylinder, general paraboloid of revolution (GPOR), GPOR frustum of different shaping parameters and the corresponding visualization of the ray-path details. Finally ray tracin...

  14. Application of ray tracing towards a correction for refracting effects in computed tomography with diffracting sources

    International Nuclear Information System (INIS)

    Andersen, A.H.

    1983-01-01

    Ray tracing methods are investigated in forward and inverse processes and applied for image restoration and resolution enhancement in computed tomography with diffracting sources. Within the geometrical optics approximation for a given refractive field, a mathematical model for the forward propagation and inverse reconstruction process is presented. For a finite set of rays in a discrete image representation, an algebraic reconstruction technique is derived which is analogous to the inverse process for a continuum of rays. The geometrical theory of diffraction is invoked to describe ray patterns arising from the introduction of object discontinuity surfaces. We have compared the performance of existing recursive ray tracing techniques for the reconstruction of objects exhibiting discontinuity boundaries. A novel ray tracing and reconstruction technique is presented which enjoys significant computational savings over traditional implementations incorporating tedious ray linking procedures. Simulation studies illustrate the macro-structural distortion and loss of fine resolution when ray refraction is unaccounted for. Restoration and resolution enhancement is achieved with a recursive ray tracing approach. Successful experimental studies with tissue equivalent phantoms are presented. The comparison of simulation and experimental results demonstrated the reasonable assumption of the geometrical optics approximation. Simulation results for larger refractive deviations are encouraging

  15. In vivo x-ray fluorescence of lead and other toxic trace elements

    International Nuclear Information System (INIS)

    Chettle, D.R.

    1995-01-01

    The first in vivo x-ray fluorescence measurements of lead in bone used y-rays from a 57 Co source to excite Pb K x-rays. Later systems used γ-rays from 109 Cd to excite Pb K x-rays or polarized x-rays to excite Ph L x-rays. All three approaches involve an extremely low effective dose to the subject. Of the two K x-ray techniques, 109 Cd is more precise and more flexible in choice of measurement site. Pb L x-ray fluorescence (L-XRF) effectively samples lead at bone surfaces, whereas Ph K x-ray fluorescence (K-XRF) samples through the bulk of a bone. Both the polarized L-XRF and 109 Cd K-XRF achieve similar precision. Renal mercury has recently been determined using a polarized x-ray source, Both renal and hepatic cadmium can be measured using polarized x-rays in conjunction with a Si(Li) detector. Platinum and gold have been measured both by radioisotopic source excitation and by using polarized x-rays, but the latter is to be preferred. Applications of Pb K-XRF have shown that measured bone lead relates strongly to cumulative lead exposure. Secondly, biological half lives of lead in different bone types have been estimated from limited longitudinal data sets and from some cross sectional surveys. Thirdly, the effect of bone lead as an endogenous source of lead has been demonstrated and it has been shown that a majority of circulating blood lead can be mobilized from bone, rather than deriving from new exposure, in some retired lead workers. 35 refs., 5 tabs

  16. ABCD transfer matrices and paraxial ray tracing for elliptic and hyperbolic lenses and mirrors

    International Nuclear Information System (INIS)

    Bruce, I

    2006-01-01

    A method is introduced for evaluating the ABCD transfer matrices for paraxial rays refracted/reflected by lenses/mirrors with elliptic or hyperbolic surfaces, which relies on the use of certain cusp points of the evolutes of the curves. Paraxial ray tracing techniques are developed. Applications examined include early hypothetical refracting telescopes by Descartes and Gregory

  17. Ray tracing a three-dimensional scene using a hierarchical data structure

    Science.gov (United States)

    Wald, Ingo; Boulos, Solomon; Shirley, Peter

    2012-09-04

    Ray tracing a three-dimensional scene made up of geometric primitives that are spatially partitioned into a hierarchical data structure. One example embodiment is a method for ray tracing a three-dimensional scene made up of geometric primitives that are spatially partitioned into a hierarchical data structure. In this example embodiment, the hierarchical data structure includes at least a parent node and a corresponding plurality of child nodes. The method includes a first act of determining that a first active ray in the packet hits the parent node and a second act of descending to each of the plurality of child nodes.

  18. SU-F-T-555: Accurate Stereotactic Cone TMRs Converted from PDDs Scanned with Ray Trace

    International Nuclear Information System (INIS)

    Li, H; Zhong, H; Qin, Y; Snyder, K; Chetty, I; Wen, N

    2016-01-01

    Purpose: To investigate whether the accuracy of TMRs for stereotactic cones converted from PDDs scanned with Ray Trace can be improved, when compared against the TMRs converted from the traditional PDDs. Methods: Ray Trace measurement in Sun Nuclear 3D Scanner is for accurate scan of small field PDDs. The system detects the center of field at two depths, for example, at 3 and 20 cm in our study, and then performs scan along the line passing the two centers. With both Ray Trace and the traditional method, PDDs for conical cones of 4, 5, 7.5, 10, 12.5, 15, and 17.5 mm diameter (jaws set to 5×5 cm) were obtained for 6X FFF and 10X FFF energies on a Varian Edge linac, using Edge detectors. The formalism of converting PDD to TMR given in Khan’s book (4th Edition, p.161) was applied. Sp values at dmax were obtained by measuring cone Scp and Sc. Continuous direct measurement of TMR by filling/draining water to/from the tank and spot measurement by moving the tank and detector were also performed with the same equipment, using 100 cm SDD. Results: For 6XFFF energy and all the cones, TMRs converted from Ray Trace were very close to the continuous and spot measurement, while TMRs converted from traditional PDDs had larger deviation. Along the central axis beyond dmax, 1.7% of TMR data points calculated from Ray Trace had more 3% deviation from measurement, with maximal deviation of 5.2%. Whereas, 34% of TMR points calculated from traditional PDDs had more than 3% deviation, with maximum of 5.7%. In this initial study, Ray Trace scans for 10XFFF beam were noisy, further measurement is warranted. Conclusion: The Ray Trace could improve the accuracy of PDDs measurement and the calculated TMRs for stereotactic cones, which was within 3% of the measured TMRs.

  19. High-efficiency photorealistic computer-generated holograms based on the backward ray-tracing technique

    Science.gov (United States)

    Wang, Yuan; Chen, Zhidong; Sang, Xinzhu; Li, Hui; Zhao, Linmin

    2018-03-01

    Holographic displays can provide the complete optical wave field of a three-dimensional (3D) scene, including the depth perception. However, it often takes a long computation time to produce traditional computer-generated holograms (CGHs) without more complex and photorealistic rendering. The backward ray-tracing technique is able to render photorealistic high-quality images, which noticeably reduce the computation time achieved from the high-degree parallelism. Here, a high-efficiency photorealistic computer-generated hologram method is presented based on the ray-tracing technique. Rays are parallelly launched and traced under different illuminations and circumstances. Experimental results demonstrate the effectiveness of the proposed method. Compared with the traditional point cloud CGH, the computation time is decreased to 24 s to reconstruct a 3D object of 100 ×100 rays with continuous depth change.

  20. The optical polarization of X-ray binaries

    International Nuclear Information System (INIS)

    Dolan, J.F.

    1977-01-01

    Polarimetric observations of close binaries may reveal the presence of a black-hole secondary. The Einstein photometric effect will introduce a characteristic, time-varying signature upon the interstellar polarization. For several reasons, it is concluded that the short time-scale variability in the polarization in HDE 226868 is caused by Rayleigh scattering from gas streams known to exist in the system. X Persei may have a variable polarization consistent with the predicted effectics and (Auth)

  1. Total reflection X-ray spectrometry (TXRF) for trace elements assessment in edible clams.

    Science.gov (United States)

    Marguí, Eva; de Fátima Marques, Alexandra; de Lurdes Prisal, Maria; Hidalgo, Manuela; Queralt, Ignasi; Carvalho, Maria Luisa

    2014-01-01

    The present contribution presents a preliminary investigation of the chemical composition with respect to major, minor, trace, and ultratrace elements in several clam species that are frequently used for human consumption in Portuguese markets and worldwide. In order to use a simple and rapid analytical methodology for clam analysis, energy dispersive X-ray fluorescence (EDXRF) spectrometry and total reflection X-ray fluorescence (TXRF) spectrometry were selected as analytical techniques. The analytical capabilities of TXRF spectrometry were evaluated for the determination of minor and trace elements in commercial edible clams. We compared the direct analysis of powdered suspensions (using different sample amounts and dispersant agents) with the analysis of the digested samples for trace element determination. Inductively coupled plasma mass spectrometry analysis of clam digests was also performed to evaluate the analytical possibilities of TXRF spectrometry for trace and ultratrace analysis.

  2. SolTrace: A Ray-Tracing Code for Complex Solar Optical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wendelin, Tim [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dobos, Aron [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lewandowski, Allan [Allan Lewandowski Solar Consulting LLC, Evergreen, CO (United States)

    2013-10-01

    SolTrace is an optical simulation tool designed to model optical systems used in concentrating solar power (CSP) applications. The code was first written in early 2003, but has seen significant modifications and changes since its inception, including conversion from a Pascal-based software development platform to C++. SolTrace is unique in that it can model virtually any optical system utilizingthe sun as the source. It has been made available for free and as such is in use worldwide by industry, universities, and research laboratories. The fundamental design of the code is discussed, including enhancements and improvements over the earlier version. Comparisons are made with other optical modeling tools, both non-commercial and commercial in nature. Finally, modeled results are shownfor some typical CSP systems and, in one case, compared to measured optical data.

  3. Robust ray-tracing algorithms for interactive dose rate evaluation

    International Nuclear Information System (INIS)

    Perrotte, L.

    2011-01-01

    More than ever, it is essential today to develop simulation tools to rapidly evaluate the dose rate received by operators working on nuclear sites. In order to easily study numerous different scenarios of intervention, computation times of available softwares have to be all lowered. This mainly implies to accelerate the geometrical computations needed for the dose rate evaluation. These computations consist in finding and sorting the whole list of intersections between a big 3D scene and multiple groups of 'radiative' rays meeting at the point where the dose has to be measured. In order to perform all these computations in less than a second, we first propose a GPU algorithm that enables the efficient management of one big group of coherent rays. Then we present a modification of this algorithm that guarantees the robustness of the ray-triangle intersection tests through the elimination of the precision issues due to floating-point arithmetic. This modification does not require the definition of scene-dependent coefficients ('epsilon' style) and only implies a small loss of performance (less than 10%). Finally we propose an efficient strategy to handle multiple ray groups (corresponding to multiple radiative objects) which use the previous results.Thanks to these improvements, we are able to perform an interactive and robust dose rate evaluation on big 3D scenes: all of the intersections (more than 13 million) between 700 000 triangles and 12 groups of 100 000 rays each are found, sorted along each ray and transferred to the CPU in 470 milliseconds. (author) [fr

  4. Particle induced X-ray emission for quantitative trace-element analysis using the Eindhoven cyclotron

    International Nuclear Information System (INIS)

    Kivits, H.

    1980-01-01

    Development of a multi-elemental trace analysis technique using PIXE (Particle Induced X-ray Emission), was started almost five years ago at the Eindhoven University of Technology, in the Cyclotron Applications Group of the Physics Department. The aim of the work presented is to improve the quantitative aspects of trace-element analysis with PIXE, as well as versatility, speed and simplicity. (Auth.)

  5. X-ray fluorescent analysis of iodin traces in urine

    International Nuclear Information System (INIS)

    Mikhajlov, I.F.; Baturin, A.A.; Mikhajlov, A.I.; Borisova, S.S.; Reshetnyak, M.V.; Shlyakhova, N.V.; Budrejko, E.A.; Galata, D.I.

    2015-01-01

    Using XFA method, determination of iodine concentration in urine for 35 children of 10-15 with endocrine pathology (delay of sexual development, diffuse goiter, obesity) and 10 practically healthy children being observed under conditions of the consultative polyclinic and the department of endocrinology of SI ''ISHCJ NAMSU''. The proposed optimized XFA method allows by 1-2 orders increasing detection sensitivity for micro-elements measurements in biology objects and attaining the iodine trace contents in urine in the range from 50 to 200 gg/dm 3

  6. Optimizing detector geometry for trace element mapping by X-ray fluorescence.

    Science.gov (United States)

    Sun, Yue; Gleber, Sophie-Charlotte; Jacobsen, Chris; Kirz, Janos; Vogt, Stefan

    2015-05-01

    Trace metals play critical roles in a variety of systems, ranging from cells to photovoltaics. X-Ray Fluorescence (XRF) microscopy using X-ray excitation provides one of the highest sensitivities available for imaging the distribution of trace metals at sub-100 nm resolution. With the growing availability and increasing performance of synchrotron light source based instruments and X-ray nanofocusing optics, and with improvements in energy-dispersive XRF detectors, what are the factors that limit trace element detectability? To address this question, we describe an analytical model for the total signal incident on XRF detectors with various geometries, including the spectral response of energy dispersive detectors. This model agrees well with experimentally recorded X-ray fluorescence spectra, and involves much shorter calculation times than with Monte Carlo simulations. With such a model, one can estimate the signal when a trace element is illuminated with an X-ray beam, and when just the surrounding non-fluorescent material is illuminated. From this signal difference, a contrast parameter can be calculated and this can in turn be used to calculate the signal-to-noise ratio (S/N) for detecting a certain elemental concentration. We apply this model to the detection of trace amounts of zinc in biological materials, and to the detection of small quantities of arsenic in semiconductors. We conclude that increased detector collection solid angle is (nearly) always advantageous even when considering the scattered signal. However, given the choice between a smaller detector at 90° to the beam versus a larger detector at 180° (in a backscatter-like geometry), the 90° detector is better for trace element detection in thick samples, while the larger detector in 180° geometry is better suited to trace element detection in thin samples. Copyright © 2015. Published by Elsevier B.V.

  7. Simulations Of Neutron Beam Optic For Neutron Radiography Collimator Using Ray Tracing Methodology

    International Nuclear Information System (INIS)

    Norfarizan Mohd Said; Muhammad Rawi Mohamed Zin

    2014-01-01

    Ray- tracing is a technique for simulating the performance of neutron instruments. McStas, the open-source software package based on a meta-language, is a tool for carrying out ray-tracing simulations. The program has been successfully applied in investigating neutron guide design, flux optimization and other related areas with high complexity and precision. The aim of this paper is to discuss the implementation of ray-tracing technique with McStas for simulating the performance of neutron collimation system developed for imaging system of TRIGA RTP reactor. The code for the simulation was developed and the results are presented. The analysis of the performance is reported and discussed. (author)

  8. Three-dimensional ray-tracing model for the study of advanced refractive errors in keratoconus.

    Science.gov (United States)

    Schedin, Staffan; Hallberg, Per; Behndig, Anders

    2016-01-20

    We propose a numerical three-dimensional (3D) ray-tracing model for the analysis of advanced corneal refractive errors. The 3D modeling was based on measured corneal elevation data by means of Scheimpflug photography. A mathematical description of the measured corneal surfaces from a keratoconus (KC) patient was used for the 3D ray tracing, based on Snell's law of refraction. A model of a commercial intraocular lens (IOL) was included in the analysis. By modifying the posterior IOL surface, it was shown that the imaging quality could be significantly improved. The RMS values were reduced by approximately 50% close to the retina, both for on- and off-axis geometries. The 3D ray-tracing model can constitute a basis for simulation of customized IOLs that are able to correct the advanced, irregular refractive errors in KC.

  9. Probing the Accretion Geometry of Black Holes with X-Ray Polarization

    Science.gov (United States)

    Schnitman, Jeremy D.

    2011-01-01

    In the coming years, new space missions will be able to measure X-ray polarization at levels of 1% or better in the approx.1-10 keV energy band. In particular, X-ray polarization is an ideal tool for determining the nature of black hole (BH) accretion disks surrounded by hot coronae. Using a Monte Carlo radiation transport code in full general relativity, we calculate the spectra and polarization features of these BH systems. At low energies, the signal is dominated by the thermal flux coming directly from the optically thick disk. At higher energies, the thermal seed photons have been inverse-Compton scattered by the corona, often reflecting back off the disk before reaching the observer, giving a distinctive polarization signature. By measuring the degree and angle of this X-ray polarization, we can infer the BH inclination, the emission geometry of the accretion flow, and also determine the spin of the black hole.

  10. Accelerated ray tracing for radiotherapy dose calculations on a GPU

    NARCIS (Netherlands)

    de Greef, M.; Crezee, J.; van Eijk, J. C.; Pool, R.; Bel, A.

    2009-01-01

    PURPOSE: The graphical processing unit (GPU) on modern graphics cards offers the possibility of accelerating arithmetically intensive tasks. By splitting the work into a large number of independent jobs, order-of-magnitude speedups are reported. In this article, the possible speedup of PLATO's ray

  11. Environmental trace-element analysis using a benchtop total reflection X-ray fluorescence spectrometer.

    Science.gov (United States)

    Stosnach, Hagen

    2005-07-01

    Total reflection X-ray fluorescence (TXRF) analysis is an established technique for trace-element analysis in various types of samples. Though expensive large-scale systems restricted the applications in the past, in this study the capability of a benchtop system for trace elemental analysis is reported. The suitability of this system for the mobile on-site analysis of heavy metal contaminated soils and sediments is reported as well as the possibilities and restrictions of TXRF for additional applications, including trace-element analysis of water, glass and biological samples.

  12. Polarization of X rays of multiply charged ions in dense high-temperature plasma

    NARCIS (Netherlands)

    Baronova, EO; Dolgov, AN; Yakubovskii, LK

    2004-01-01

    The development of a method for studying the features of X-ray emission by multiply charged ions in a dense hot plasma is considered. These features are determined by the radiation polarization phenomenon.

  13. A Sub-band Divided Ray Tracing Algorithm Using the DPS Subspace in UWB Indoor Scenarios

    DEFF Research Database (Denmark)

    Gan, Mingming; Xu, Zhinan; Hofer, Markus

    2015-01-01

    Sub-band divided ray tracing (SDRT) is one technique that has been extensively used to obtain the channel characteristics for ultra-wideband (UWB) radio wave propagation in realistic indoor environments. However, the computational complexity of SDRT scales directly with the number of sub-bands. A......Sub-band divided ray tracing (SDRT) is one technique that has been extensively used to obtain the channel characteristics for ultra-wideband (UWB) radio wave propagation in realistic indoor environments. However, the computational complexity of SDRT scales directly with the number of sub...

  14. Trace element analysis in liquids by proton induced x-ray emission

    International Nuclear Information System (INIS)

    Deconninck, G.

    Proton induced x-ray emission (PIXE) from liquid has been developed for quantitative and simultaneous analysis of trace elements. Liquid drops and trickles are bombarded at atmospheric pressure, x-rays are detected in a non dispersive Si(Li) solid state detector. Absolute determinations are made by comparison with standard solutions. Detection limits in a 5 minutes run are in the ppm range for a single drop (0.05 ml). The application of this technique to the determination of trace elements in biological liquids is investigated (Cr, Mn, Fe, Co, Ni, Cu, Zn, in plant extracts, haemocyanine, albumins...). (author)

  15. Simulation of ultrasonic fields in anisotropic materials using 2D ray tracing method

    Science.gov (United States)

    Kolkoori, S. R.; Rahaman, M.-U.; Chinta, P. K.; Boehm, R.; Prager, J.

    2012-05-01

    Ultrasound propagation in inhomogeneous anisotropic materials is difficult to examine because of the directional dependency of elastic properties. Simulation tools play an important role in developing advanced reliable ultrasonic testing techniques for the inspection of anisotropic materials particularly austenitic cladded materials and dissimilar welds. A 2-D Ray tracing method is developed for evaluating ray path, amplitude and travel time for three wave modes namely quasi longitudinal wave (qP), quasi shear vertical wave (qSV) and shear horizontal waves (SH) in anisotropic materials such as austenitic cladded materials. The inhomogenity in the anisotropic material is represented by discretizing the anisotropic region into several homogeneous layers. The ray paths are traced during its propagation through the various interfaces between those layers. At each interface the problem of reflection and refraction is solved. The ray amplitudes are computed by taking into account the directivity and phase relations. Ray divergence variation and ray transmission coefficients at each refraction boundary are considered. The Ray tracing results for ultrasonic field profiles in austenitic cladded materials are validated quantitatively by 2-D Elastodynamic Finite Integration Technique (EFIT) results and by the experiments.

  16. Instrumentations in x-ray plasma polarization spectroscopy. Crystal spectrometer, polarimeter and detectors for astronomical observations

    Energy Technology Data Exchange (ETDEWEB)

    Baronova, Elena O.; Stepanenko, Mikhail M. [RRC Kurchatov Institute, Nuclear Fusion Institute, Moscow (Russian Federation); Jakubowski, Lech [Soltan Institute for Nuclear Studies, Swierk-Otwock (Poland); Tsunemi, Hiroshi [Osaka Univ., Graduate School of Science, Osaka (Japan)

    2002-08-01

    This report discusses the various problems which are encountered when a crystal spectrometer is used for the purpose of observing polarized x-ray lines. A polarimeter is proposed based on the novel idea of using two series of equivalent atomic planes in a single crystal. The present status of the astronomical x-ray detection techniques are described with emphasis on two dimensional detectors which are polarization sensitive. (author)

  17. X-ray polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR)

    DEFF Research Database (Denmark)

    Krawczynski, Henric S.; Stern, Daniel; Harrison, Fiona A.

    2016-01-01

    This paper describes the Polarization Spectroscopic Telescope Array (PolSTAR), a mission proposed to NASA's 2014 Small Explorer (SMEX) announcement of opportunity. PolSTAR measures the linear polarization of 3-50 keV (requirement; goal: 2.5-70 keV) X-rays probing the behavior of matter,radiation ...

  18. A boundary integral formalism for stochastic ray tracing in billiards

    International Nuclear Information System (INIS)

    Chappell, David J.; Tanner, Gregor

    2014-01-01

    Determining the flow of rays or non-interacting particles driven by a force or velocity field is fundamental to modelling many physical processes. These include particle flows arising in fluid mechanics and ray flows arising in the geometrical optics limit of linear wave equations. In many practical applications, the driving field is not known exactly and the dynamics are determined only up to a degree of uncertainty. This paper presents a boundary integral framework for propagating flows including uncertainties, which is shown to systematically interpolate between a deterministic and a completely random description of the trajectory propagation. A simple but efficient discretisation approach is applied to model uncertain billiard dynamics in an integrable rectangular domain

  19. Influence of carbon and lipid sources on variation of mercury and other trace elements in polar bears (Ursus maritimus).

    Science.gov (United States)

    Routti, Heli; Letcher, Robert J; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; McKinney, Melissa A; Peacock, Elizabeth; Sonne, Christian

    2012-12-01

    In the present study, the authors investigated the influence of carbon and lipid sources on regional differences in liver trace element (As, Cd, Cu, total Hg, Mn, Pb, Rb, Se, and Zn) concentrations measured in polar bears (Ursus maritimus) (n = 121) from 10 Alaskan, Canadian Arctic, and East Greenland subpopulations. Carbon and lipid sources were assessed using δ(13) C in muscle tissue and fatty acid (FA) profiles in subcutaneous adipose tissue as chemical tracers. A negative relationship between total Hg and δ(13) C suggested that polar bears feeding in areas with higher riverine inputs of terrestrial carbon accumulate more Hg than bears feeding in areas with lower freshwater input. Mercury concentrations were also positively related to the FA 20:1n-9, which is biosynthesized in large amounts in Calanus copepods. This result raises the hypothesis that Calanus glacialis are an important link in the uptake of Hg in the marine food web and ultimately in polar bears. Unadjusted total Hg, Se, and As concentrations showed greater geographical variation among polar bear subpopulations compared with concentrations adjusted for carbon and lipid sources. The Hg concentrations adjusted for carbon and lipid sources in Bering-Chukchi Sea polar bear liver tissue remained the lowest among subpopulations. Based on these findings, the authors suggest that carbon and lipid sources for polar bears should be taken into account when one is assessing spatial and temporal trends of long-range transported trace elements. Copyright © 2012 SETAC.

  20. Modeling ionospheric disturbance features in quasi-vertically incident ionograms using 3-D magnetoionic ray tracing and atmospheric gravity waves

    Science.gov (United States)

    Cervera, M. A.; Harris, T. J.

    2014-01-01

    The Defence Science and Technology Organisation (DSTO) has initiated an experimental program, Spatial Ionospheric Correlation Experiment, utilizing state-of-the-art DSTO-designed high frequency digital receivers. This program seeks to understand ionospheric disturbances at scales < 150 km and temporal resolutions under 1 min through the simultaneous observation and recording of multiple quasi-vertical ionograms (QVI) with closely spaced ionospheric control points. A detailed description of and results from the first campaign conducted in February 2008 were presented by Harris et al. (2012). In this paper we employ a 3-D magnetoionic Hamiltonian ray tracing engine, developed by DSTO, to (1) model the various disturbance features observed on both the O and X polarization modes in our QVI data and (2) understand how they are produced. The ionospheric disturbances which produce the observed features were modeled by perturbing the ionosphere with atmospheric gravity waves.

  1. A comparison of three different ray trace programs for x-ray and infrared synchrotron beamline designs

    International Nuclear Information System (INIS)

    Irick, S.C.; Jung, C.R.

    1997-07-01

    There are a number of ray trace programs currently used for the design of synchrotron beamlines. While several of these programs have been written and used mostly within the programmer''s institution, many have also been available to the general public. This paper discusses three such programs. One is a commercial product oriented for the general optical designer (not specifically for synchrotron beamlines). One is designed for synchrotron beamlines and is free with restricted availability. Finally, one is designed for synchrotron beamlines and is used primarily in one institution. The wealth of information from general optical materials and components catalogs is readily available in the commercial program for general optical designs. This makes the design of an infrared beamline easier from the standpoint of component selection. However, this program is not easily configured for synchrotron beamline designs, particularly for a bending magnet source. The synchrotron ray trace programs offer a variety of sources, but generally are not as easy to use from the standpoint of the user interface. This paper shows ray traces of the same beamline Optikwerks, SHADOW, and RAY, and compares the results

  2. A Ray-tracing Method to Analyzing Modulated Planar Fabry-Perot Antennas

    DEFF Research Database (Denmark)

    Hougs, Mikkel Dahl; Kim, Oleksiy S.; Breinbjerg, Olav

    2015-01-01

    A new approach for fast modelling of Fabry-Perot antennas with modulated partially reflective surfaces (PRS) using ray-tracing is proposed. For validation of the method, a configuration is introduced which consists of a cavity with a modulated PRS, fed internally by a magnetic dipole. The PRS...

  3. The transport of trace elements during hemodialysis measured with proton induced X-ray emission

    International Nuclear Information System (INIS)

    Vis, R.D.; Bos, A.J.J.; Verheul, H.

    1979-01-01

    Particle induced X-ray emission (PIXE) is used to follow the behaviour of some trace elements in blood during the treatment of uremic patients with artificial kidney. Of course, this behaviour is dependent on the concentrations of these elements in the water used for the treatment. (author)

  4. Proton induced X-ray emission analysis of trace elements in human blood serum

    International Nuclear Information System (INIS)

    Cheek, D.B.; Hay, H.J.; Newton, C.S.

    1979-01-01

    Proton induced x-ray emission has been used for quantitative analyses of trace elements in blood serum samples. This work is part of a survey concerned with Zn, Cu, Fe, Cr, Mn and Se in Australian Aboriginal people not receiving optimal diet. Special attention is being directed to Cr because of the high incidence of diabetes mellitus in these people

  5. Emulating Ray-Tracing Channels in Multi-probe Anechoic Chamber Setups for Virtual Drive Testing

    DEFF Research Database (Denmark)

    Fan, Wei; Llorente, Ines Carton; Kyösti, Pekka

    2016-01-01

    This paper discusses virtual drive testing (VDT) for multiple-input multiple-output (MIMO) capable terminals in multi-probe anechoic chamber (MPAC) setups. We propose to perform VDT, via reproducing ray tracing (RT) simulated channels with the field synthesis technique. Simulation results demonst...

  6. Robust Image Denoising using a Virtual Flash Image for Monte Carlo Ray Tracing

    DEFF Research Database (Denmark)

    Moon, Bochang; Jun, Jong Yun; Lee, JongHyeob

    2013-01-01

    We propose an efficient and robust image-space denoising method for noisy images generated by Monte Carlo ray tracing methods. Our method is based on two new concepts: virtual flash images and homogeneous pixels. Inspired by recent developments in flash photography, virtual flash images emulate...

  7. An Energy Conservative Ray-Tracing Method With a Time Interpolation of the Force Field

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-02-10

    A new algorithm that constructs a continuous force field interpolated in time is proposed for resolving existing difficulties in numerical methods for ray-tracing. This new method has improved accuracy, but with the same degree of algebraic complexity compared to Kaisers method.

  8. Polarized Gamma-Ray Emission from the Galactic Black Hole Cygnus X-1

    Science.gov (United States)

    Laurent, P.; Rodriquez, J.; Wilms, J.; Bel, M. Cadolle; Pottschmidt, K.; Grinberg, V.

    2011-01-01

    Because of their inherently high flux allowing the detection of clear signals, black hole X-ray binaries are interesting candidates for polarization studies, even if no polarization signals have been observed from them before. Such measurements would provide further detailed insight into these sources' emission mechanisms. We measured the polarization of the gamma-ray emission from the black hole binary system Cygnus X-I with the INTEGRAL/IBIS telescope. Spectral modeling ofthe data reveals two emission mechanisms: The 250-400 keY data are consistent with emission dominated by Compton scattering on thermal electrons and are weakly polarized. The second spectral component seen in the 400keV-2MeV band is by contrast strongly polarized, revealing that the MeV emission is probably related to the jet first detected in the radio band.

  9. On the Polarization of Gamma Ray Bursts and their Optical Afterglows

    CERN Document Server

    Dado, S; De Rújula, Alvaro; Dado, Shlomo; Dar, Arnon

    2004-01-01

    The polarization of the optical afterglow (AG) of Gamma-Ray Bursts (GRBs) has only been measured in a few instances at various times after the GRB. In all cases except the best measured one (GRB 030329) the observed polarization and its evolution are simple and easy to explain in the most naive version of the "Cannonball'' model of GRBs: the "intrinsic" AG polarization is small and the observations reflect the "foreground" effects of the host galaxy and ours. The polarization observed in GRB 030329 behaves chaotically, its understanding requires reasonable but ad-hoc ingredients. The polarization of the gamma rays of a GRB has only been measured in the case of GRB 021206. The result is debated, but similar measurements would be crucial to the determination of the GRB-generating mechanism.

  10. Total-reflection X-ray fluorescence studies of trace elements in biomedical samples

    Energy Technology Data Exchange (ETDEWEB)

    Kubala-Kukus, A. [Institute of Physics, Swietokrzyska Academy, Swietokrzyska 15, 25-406 Kielce (Poland)]. E-mail: Aldona.Kubala-Kukus@pu.kielce.pl; Braziewicz, J. [Institute of Physics, Swietokrzyska Academy, Swietokrzyska 15, 25-406 Kielce (Poland); Pajek, M. [Institute of Physics, Swietokrzyska Academy, Swietokrzyska 15, 25-406 Kielce (Poland)

    2004-08-31

    Application of the total-reflection X-ray fluorescence (TXRF) analysis in the studies of trace element contents in biomedical samples is discussed in the following aspects: (i) a nature of trace element concentration distributions, (ii) censoring approach to the detection limits, and (iii) a comparison of two sets of censored data. The paper summarizes the recent results achieved in this topics, in particular, the lognormal, or more general logstable, nature of concentration distribution of trace elements, the random left-censoring and the Kaplan-Meier approach accounting for detection limits and, finally, the application of the logrank test to compare the censored concentrations measured for two groups. These new aspects, which are of importance for applications of the TXRF in different fields, are discussed here in the context of TXRF studies of trace element in various samples of medical interest.

  11. Pixels grouping and shadow cache for faster integral 3D ray tracing

    Science.gov (United States)

    Youssef, Osama; Aggoun, Amar; Wolf, Wayne H.; McCormick, Malcolm

    2002-05-01

    This paper presents for the first time, a theory for obtaining the optimum pixel grouping for improving the coherence and the shadow cache in integral 3D ray-tracing in order to reduce execution time. A theoretical study of the number of shadow cache hits with respect to the properties of the lenses and the shadow size and its location is discussed with analysis for three different styles of pixel grouping in order to obtain the optimum grouping. The first style traces rows of pixels in the horizontal direction, the second traces similar pixels in adjacent lenses in the horizontal direction, and the third traces columns of pixels in the vertical direction. The optimum grouping is a combination of all three dependant up on the number of cache hits in each. Experimental results show validation of the theory and tests on benchmark scenes show that up to a 37% improvement in execution time can be achieved by proper pixel grouping.

  12. Evaluation of Empirical Ray-Tracing Model for an Urban Outdoor Scenario at 73 GHz E-Band

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; R. MacCartney Jr., George; Thomas, Timothy

    2014-01-01

    the measurements for immediate model development and eventual site planning, this paper presents an empirical ray-tracing model, with the goal of finding a suitable approach that ray-tracing (RT) can fill in the gaps of the measurements. Here, we use the measured data to investigate the prediction capability...

  13. Optical ray tracing-guided myopic laser in situ keratomileusis: 1-year clinical outcomes.

    Science.gov (United States)

    Cummings, Arthur B; Kelly, Gabrielle E

    2013-01-01

    To compare the safety, efficacy, and predictability of laser in situ keratomileusis treatments at 1 year postprocedure using a novel geometric ray tracing algorithm with outcomes of treatments using wavefront-optimized, wavefront-guided, and topography-guided ablation profiles of an excimer laser (WaveLight GmbH, Erlangen, Germany; Alcon Laboratories, Fort Worth, TX, USA). Wellington Eye Clinic, Dublin, Ireland. Retrospective comparative case series. Eyes having a preoperative myopic spherical equivalent refractive error >4.00 D and/or astigmatism between 2.00-6.00 D resulting in a spherical equivalent power greater than -4.00 D received laser in situ keratomileusis treatments using a ray tracing algorithm. Refractive outcomes were analyzed postoperatively at 6 and 12 months and were compared to outcomes of wavefront-optimized, wavefront-guided, and topography-guided treatments in eyes with the same pretreatment refractive range. Forty-seven eyes of 26 patients were treated using the ray tracing algorithm. At 12 months postprocedure, uncorrected visual acuity was better than the preoperative best-corrected visual acuity in this group. The percentage of eyes achieving an uncorrected visual acuity or best-corrected visual acuity ≥20/20 significantly exceeded the rates achieved in the wavefront-optimized and topography-guided groups. A greater percentage of eyes achieved an uncorrected visual acuity ≥20/20 and ≥20/16 in the wavefront-guided group, but no eyes in the wavefront-guided group had an uncorrected visual acuity ≥20/12.5 in comparison to 9.5% of eyes in the ray tracing group. This study provides further evidence of the safety, efficacy, and predictability of laser in situ keratomileusis outcomes using an optical ray tracing algorithm to treat moderate to high myopic astigmatism and shows that good results are sustained through 1 year.

  14. Invisibility cloaking via non-smooth transformation optics and ray tracing

    International Nuclear Information System (INIS)

    Crosskey, Miles M.; Nixon, Andrew T.; Schick, Leland M.; Kovacic, Gregor

    2011-01-01

    We present examples of theoretically-predicted invisibility cloaks with shapes other than spheres and cylinders, including cones and ellipsoids, as well as shapes spliced from parts of these simpler shapes. In addition, we present an example explicitly displaying the non-uniqueness of invisibility cloaks of the same shape. We depict rays propagating through these example cloaks using ray tracing for geometric optics. - Highlights: → Theoretically-predicted conical and ellipsoidal invisibility cloaks. → Non-smooth cloaks spliced from parts of simpler shapes. → Example displaying non-uniqueness of invisibility cloaks of the same shape. → Rays propagating through example cloaks depicted using geometric optics.

  15. Simplifying numerical ray tracing for two-dimensional non circularly symmetric models of the human eye.

    Science.gov (United States)

    Jesus, Danilo A; Iskander, D Robert

    2015-12-01

    Ray tracing is a powerful technique to understand the light behavior through an intricate optical system such as that of a human eye. The prediction of visual acuity can be achieved through characteristics of an optical system such as the geometrical point spread function. In general, its precision depends on the number of discrete rays and the accurate surface representation of each eye's components. Recently, a method that simplifies calculation of the geometrical point spread function has been proposed for circularly symmetric systems [Appl. Opt.53, 4784 (2014)]. An extension of this method to 2D noncircularly symmetric systems is proposed. In this method, a two-dimensional ray tracing procedure for an arbitrary number of surfaces and arbitrary surface shapes has been developed where surfaces, rays, and refractive indices are all represented in functional forms being approximated by Chebyshev polynomials. The Liou and Brennan anatomically accurate eye model has been adapted and used for evaluating the method. Further, real measurements of the anterior corneal surface of normal, astigmatic, and keratoconic eyes were substituted for the first surface in the model. The results have shown that performing ray tracing, utilizing the two-dimensional Chebyshev function approximation, is possible for noncircularly symmetric models, and that such calculation can be performed with a newly created Chebfun toolbox.

  16. Rapid simulation of X-ray transmission imaging for baggage inspection via GPU-based ray-tracing

    Science.gov (United States)

    Gong, Qian; Stoian, Razvan-Ionut; Coccarelli, David S.; Greenberg, Joel A.; Vera, Esteban; Gehm, Michael E.

    2018-01-01

    We present a pipeline that rapidly simulates X-ray transmission imaging for arbitrary system architectures using GPU-based ray-tracing techniques. The purpose of the pipeline is to enable statistical analysis of threat detection in the context of airline baggage inspection. As a faster alternative to Monte Carlo methods, we adopt a deterministic approach for simulating photoelectric absorption-based imaging. The highly-optimized NVIDIA OptiX API is used to implement ray-tracing, greatly speeding code execution. In addition, we implement the first hierarchical representation structure to determine the interaction path length of rays traversing heterogeneous media described by layered polygons. The accuracy of the pipeline has been validated by comparing simulated data with experimental data collected using a heterogenous phantom and a laboratory X-ray imaging system. On a single computer, our approach allows us to generate over 400 2D transmission projections (125 × 125 pixels per frame) per hour for a bag packed with hundreds of everyday objects. By implementing our approach on cloud-based GPU computing platforms, we find that the same 2D projections of approximately 3.9 million bags can be obtained in a single day using 400 GPU instances, at a cost of only 0.001 per bag.

  17. Solar Proton Transport Within an ICRU Sphere Surrounded by a Complex Shield: Ray-trace Geometry

    Science.gov (United States)

    Slaba, Tony C.; Wilson, John W.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

    2015-01-01

    A computationally efficient 3DHZETRN code with enhanced neutron and light ion (Z is less than or equal to 2) propagation was recently developed for complex, inhomogeneous shield geometry described by combinatorial objects. Comparisons were made between 3DHZETRN results and Monte Carlo (MC) simulations at locations within the combinatorial geometry, and it was shown that 3DHZETRN agrees with the MC codes to the extent they agree with each other. In the present report, the 3DHZETRN code is extended to enable analysis in ray-trace geometry. This latest extension enables the code to be used within current engineering design practices utilizing fully detailed vehicle and habitat geometries. Through convergence testing, it is shown that fidelity in an actual shield geometry can be maintained in the discrete ray-trace description by systematically increasing the number of discrete rays used. It is also shown that this fidelity is carried into transport procedures and resulting exposure quantities without sacrificing computational efficiency.

  18. X-ray polarization measurements at relativistic laser intensities

    International Nuclear Information System (INIS)

    Beiersdorfer, P.; Shepherd, R.; Mancini, R.C.

    2004-01-01

    An effort has been started to measure the short pulse laser absorption and energy partition at relativistic laser intensities up to 10 21 W/cm 2 . Plasma polarization spectroscopy is expected to play an important role in determining fast electron generation and measuring the electron distribution function. (author)

  19. ACCELERATION RENDERING METHOD ON RAY TRACING WITH ANGLE COMPARISON AND DISTANCE COMPARISON

    Directory of Open Access Journals (Sweden)

    Liliana liliana

    2007-01-01

    Full Text Available In computer graphics applications, to produce realistic images, a method that is often used is ray tracing. Ray tracing does not only model local illumination but also global illumination. Local illumination count ambient, diffuse and specular effects only, but global illumination also count mirroring and transparency. Local illumination count effects from the lamp(s but global illumination count effects from other object(s too. Objects that are usually modeled are primitive objects and mesh objects. The advantage of mesh modeling is various, interesting and real-like shape. Mesh contains many primitive objects like triangle or square (rare. A problem in mesh object modeling is long rendering time. It is because every ray must be checked with a lot of triangle of the mesh. Added by ray from other objects checking, the number of ray that traced will increase. It causes the increasing of rendering time. To solve this problem, in this research, new methods are developed to make the rendering process of mesh object faster. The new methods are angle comparison and distance comparison. These methods are used to reduce the number of ray checking. The rays predicted will not intersect with the mesh, are not checked weather the ray intersects the mesh. With angle comparison, if using small angle to compare, the rendering process will be fast. This method has disadvantage, if the shape of each triangle is big, some triangles will be corrupted. If the angle to compare is bigger, mesh corruption can be avoided but the rendering time will be longer than without comparison. With distance comparison, the rendering time is less than without comparison, and no triangle will be corrupted.

  20. Trace metal content in aspirin and women's cosmetics via proton induced x-ray emission (PIXE)

    International Nuclear Information System (INIS)

    Hichwa, B.P.; Pun, D.D.; Wang, D.

    1981-01-01

    A multielemental analysis to determine the trace metal content of generic and name-brand aspirins and name-brand lipsticks was done via proton induced x-ray (PIXE) measurements. The Hope College PIXE system is described as well as the target preparation methods. The trace metal content of twelve brands of aspirin and aspirin substitutes and fourteen brands of lipstick are reported. Detection limits for most elements are in the range of 100 parts per billion (ppb) to 10 parts per million

  1. TIM, a ray-tracing program for METATOY research and its dissemination

    Science.gov (United States)

    Lambert, Dean; Hamilton, Alasdair C.; Constable, George; Snehanshu, Harsh; Talati, Sharvil; Courtial, Johannes

    2012-03-01

    TIM (The Interactive METATOY) is a ray-tracing program specifically tailored towards our research in METATOYs, which are optical components that appear to be able to create wave-optically forbidden light-ray fields. For this reason, TIM possesses features not found in other ray-tracing programs. TIM can either be used interactively or by modifying the openly available source code; in both cases, it can easily be run as an applet embedded in a web page. Here we describe the basic structure of TIM's source code and how to extend it, and we give examples of how we have used TIM in our own research. Program summaryProgram title: TIM Catalogue identifier: AEKY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License No. of lines in distributed program, including test data, etc.: 124 478 No. of bytes in distributed program, including test data, etc.: 4 120 052 Distribution format: tar.gz Programming language: Java Computer: Any computer capable of running the Java Virtual Machine (JVM) 1.6 Operating system: Any; developed under Mac OS X Version 10.6 RAM: Typically 145 MB (interactive version running under Mac OS X Version 10.6) Classification: 14, 18 External routines: JAMA [1] (source code included) Nature of problem: Visualisation of scenes that include scene objects that create wave-optically forbidden light-ray fields. Solution method: Ray tracing. Unusual features: Specifically designed to visualise wave-optically forbidden light-ray fields; can visualise ray trajectories; can visualise geometric optic transformations; can create anaglyphs (for viewing with coloured "3D glasses") and random-dot autostereograms of the scene; integrable into web pages. Running time: Problem-dependent; typically seconds for a simple scene.

  2. PEMBUATAN PERANGKAT LUNAK UNTUK MEMVISUALISASIKAN BENDA TEMBUS PANDANG DENGAN METODE RAY TRACING

    Directory of Open Access Journals (Sweden)

    Liliana Liliana

    2004-01-01

    Full Text Available Today computer graphics is used in many aspects, especially to make animation, advertisement and game. We hope this technology can produce realistic pictures which same quality with photo. Metode to get the realistic 3D image is ray tracing. In this journal, make a software which can produce realistic 3D image, especially for reflective and transparent object. Reflective object will modeled can reflect another object surrounding it. And transparent object will modeled can produce caustic effect, that's rays which refract in one area. So that area will appear brighter than area surround it. Abstract in Bahasa Indonesia : Dewasa ini grafika komputer semakin banyak digunakan di berbagai bidang terutama untuk pembuatan film animasi, iklan dan pembuatan game. Diharapkan teknologi grafika komputer mampu menghasilkan gambar-gambar realistik yang kualitasnya sama dengan kualitas foto. Salah satu metode yang digunakan untuk menghasilkan gambar 3D yang realistik tersebut adalah metode ray tracing. Dalam penelitian ini dibuat perangkat lunak yang mampu menghasilkan gambar-gambar 3D yang realistik terutama untuk benda-benda yang mengkilap dan benda-benda transparan. Benda mengkilap yang dimodelkan bisa memantulkan bayangan benda lain yang berada di sekitarnya. Benda transparan yang dimodelkan adalah benda transparan yang menghasilkan efek kaustik, yaitu pembiasan sinar dari sumber cahaya yang mengumpul di suatu daerah sehingga pada daerah tersebut akan tampak lebih terang daripada daerah sekitarnya. Kata kunci: efek kaustik, ray tracing.

  3. Polar gamma ray mode for testing weld quality natural gas pipeline

    International Nuclear Information System (INIS)

    Shahout, A. M.; Mahmood, A.Sh.

    2005-01-01

    The polar gamma-ray radiography method was studied extensively, gamma ray from Ir 192 source was used to detect weld defects in the main gas pipeline extending from Kh oms to Tripoli, gamma ray radiographic inspections were carried out according to the Astm(1) standards, and the radiographs were analyzed according to quality specifications API(2) standard-1104. The polar gamma ray mode has been applied to specimens of weld joints of pipes used in this pipeline in the reg [the kilometer 118(3)] and [the kilometer 123], and weld joints in the SLR 7 stz in the region [the kilometer 125]. The results obtained from gamma-rays have discussed and analyzed

  4. Optical ray tracing-guided myopic laser in situ keratomileusis: 1-year clinical outcomes

    Directory of Open Access Journals (Sweden)

    Cummings AB

    2013-06-01

    Full Text Available Arthur B Cummings,1 Gabrielle E Kelly21Wellington Eye Clinic, Dublin, Ireland; 2School of Mathematical Sciences, University College Dublin, Dublin, IrelandPurpose: To compare the safety, efficacy, and predictability of laser in situ keratomileusis treatments at 1 year postprocedure using a novel geometric ray tracing algorithm with outcomes of treatments using wavefront-optimized, wavefront-guided, and topography-guided ablation profiles of an excimer laser (WaveLight GmbH, Erlangen, Germany; Alcon Laboratories, Fort Worth, TX, USA.Setting: Wellington Eye Clinic, Dublin, Ireland.Design: Retrospective comparative case series.Methods: Eyes having a preoperative myopic spherical equivalent refractive error >4.00 D and/or astigmatism between 2.00–6.00 D resulting in a spherical equivalent power greater than −4.00 D received laser in situ keratomileusis treatments using a ray tracing algorithm. Refractive outcomes were analyzed postoperatively at 6 and 12 months and were compared to outcomes of wavefront-optimized, wavefront-guided, and topography-guided treatments in eyes with the same pretreatment refractive range.Results: Forty-seven eyes of 26 patients were treated using the ray tracing algorithm. At 12 months postprocedure, uncorrected visual acuity was better than the preoperative best-corrected visual acuity in this group. The percentage of eyes achieving an uncorrected visual acuity or best-corrected visual acuity ≥20/20 significantly exceeded the rates achieved in the wavefront-optimized and topography-guided groups. A greater percentage of eyes achieved an uncorrected visual acuity ≥20/20 and ≥20/16 in the wavefront-guided group, but no eyes in the wavefront-guided group had an uncorrected visual acuity ≥20/12.5 in comparison to 9.5% of eyes in the ray tracing group.Conclusion: This study provides further evidence of the safety, efficacy, and predictability of laser in situ keratomileusis outcomes using an optical ray tracing

  5. Adsorptive micro-extraction techniques--novel analytical tools for trace levels of polar solutes in aqueous media.

    Science.gov (United States)

    Neng, N R; Silva, A R M; Nogueira, J M F

    2010-11-19

    A novel enrichment technique, adsorptive μ-extraction (AμE), is proposed for trace analysis of polar solutes in aqueous media. The preparation, stability tests and development of the analytical devices using two geometrical configurations, i.e. bar adsorptive μ-extraction (BAμE) and multi-spheres adsorptive μ-extraction (MSAμE) is fully discussed. From the several sorbent materials tested, activated carbons and polystyrene divinylbenzene phases demonstrated the best stability, robustness and to be the most suitable for analytical purposes. The application of both BAμE and MSAμE devices proved remarkable performance for the determination of trace levels of polar solutes and metabolites (e.g. pesticides, disinfection by-products, drugs of abuse and pharmaceuticals) in water matrices and biological fluids. By comparing AμE techniques with stir bar sorptive extraction based on polydimethylsiloxane phase, great effectiveness is attained overcoming the limitations of the latter enrichment approach regarding the more polar solutes. Furthermore, convenient sensitivity and selectivity is reached through AμE techniques, since the great advantage of this new analytical technology is the possibility to choose the most suitable sorbent to each particular type of application. The enrichment techniques proposed are cost-effective, easy to prepare and work-up, demonstrating robustness and to be a remarkable analytical tool for trace analysis of priority solutes in areas of recognized importance such as environment, forensic and other related life sciences. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Strict limit on CPT violation from polarization of γ-ray bursts.

    Science.gov (United States)

    Toma, Kenji; Mukohyama, Shinji; Yonetoku, Daisuke; Murakami, Toshio; Gunji, Shuichi; Mihara, Tatehiro; Morihara, Yoshiyuki; Sakashita, Tomonori; Takahashi, Takuya; Wakashima, Yudai; Yonemochi, Hajime; Toukairin, Noriyuki

    2012-12-14

    We report the strictest observational verification of CPT invariance in the photon sector, as a result of γ-ray polarization measurement of distant gamma-ray bursts (GRBs), which are the brightest stellar-sized explosions in the Universe. We detected γ-ray polarization of three GRBs with high significance levels, and the source distances may be constrained by a well-known luminosity indicator for GRBs. For the Lorentz- and CPT-violating dispersion relation E(±)(2) = p(2) ± 2ξp(3)/M(Pl), where ± denotes different circular polarization states of the photon, the parameter ξ is constrained as |ξ|

  7. Polarization-selectable cavity locking method for generation of laser Compton scattered γ-rays.

    Science.gov (United States)

    Kosuge, Atsushi; Mori, Michiaki; Okada, Hajime; Hajima, Ryoichi; Nagashima, Keisuke

    2014-03-24

    Nowadays, generation of energy-tunable, monochromatic γ-rays is needed to establish a nondestructive assay method of nuclear fuel materials. The γ-rays are generated by collision of laser photons stored in a cavity and relativistic electrons. We propose a configuration of an enhancement cavity capable of performing polarization control fabricated by a combination of a four-mirror ring cavity with a small spot inside a cavity and a three-mirror of reflective optics as an image inverter for polarization-selectable γ-rays. The image inverter introduces a phase shift of specific polarization which can be used to generate an error signal to lock an optical cavity at a resonance condition.

  8. Polarized NIR and X-ray flares from Sagittarius A*

    NARCIS (Netherlands)

    Eckart, A.; Baganoff, F.K.; Zamaninasab, M.; Morris, M.R.; Schödel, R.; Meyer, L.; Muzic, K.; Bautz, M.W.; Brandt, W.N.; Garmire, G.P.; Ricker, G.R.; Kunneriath, D.; Straubmeier, C.; Duschl, W.; Dovciak, M.; Karas, V.; Markoff, S.; Najarro, F.; Mauerhan, J.; Moultaka, J.; Zensus, A.

    2008-01-01

    Context. Stellar dynamics indicate the presence of a supermassive 3 - 4 x 10(6) M-circle dot black hole at the Galactic Center. It is associated with the variable radio, near-infrared, and X-ray source Sagittarius A*(SgrA*). Aims. The goal is the investigation and understanding of the physical

  9. Polarized x-ray absorption spectroscopy for the study of superconductors and magnetic materials

    Science.gov (United States)

    Ramanathan, Mohan; Alp, Esen E.; Mini, Susan M.; Salem-Sugui, S.; Bommannavar, A.

    1991-11-01

    Synchrotron radiation is a good source of polarized radiation in the x-ray regime. The radiation obtained from a bending magnet source is linearly polarized in the bending plane and has a varying degree of circular polarization away from the bending plane. This feature of synchrotron radiation can be taken advantage of with proper optics to selectively use the type of polarized radiation required for the experiment in question. Linear polarized radiation is used to study the anisotropic nature of electronic and atomic structure by x-ray absorption techniques from single crystal and oriented powder samples. We will give a specific example of the use of linearly polarized x-ray absorption spectroscopy measurements for the study of the magnetically oriented layered copper oxide superconductors. While such linear dichroism measurements help identify the symmetry of the empty electronic states, circular dichroism measurements in magnetic systems help in determining the spin contribution to the absorption process. We will discuss magnetic circular dichroism measurements of the ordered-disordered invar alloy Fe(subscript 3)Pt.

  10. Random ray-tracing and graphic analysing of charged particle trajectories

    International Nuclear Information System (INIS)

    Lin Xiaomei; Mao Naifeng; Chen Jingxian

    1990-01-01

    In order to describe the optical properties of a charged particle beam realistically, the random sampling of initial conditions of particles in ray-tracing is discussed. The emission surface of particles may be a plane, a cylindrical surface or a spherical surface. The distribution functions may be expressed analytically or numerically. In order to analyse the properties of the charged particle beam systematically by use of the results from ray-tracing efficiently, the graphic processing and analysing of particle trajectories are also discussed, including the spline function fitting of trajectories, the graphic drafting of trajectories and beam envelopes, the determining of image dimensions and the correspinding positions, and also the graphic drafting of particle distributions on arbitrary cross sections

  11. Analysis of KVN 21m Radio Antenna Optics using Ray-Tracing Method

    Directory of Open Access Journals (Sweden)

    Jae-Han Bae

    2009-06-01

    Full Text Available In this work, we calculate drop in antenna gain, aperture phase distribution, and antenna pointing shift of KVN(Korean VLBI Network 21m shaped Cassegrain antenna due to misalignments of antenna optics using ray-tracing method. The misalignments we considered are axial displacement of feed, axial displacement of sub-reflector, lateral displacement of feed, lateral displacement of sub-reflector, and sub-reflector tilt. Calculations are performed not only when these misalignments exist separately, but also when they exist at the same time. Although ray-tracing method is based on geometric optics which does not consider electromagnetic effects, we expect that this work enables us to align antenna optics which give the maximum gain.

  12. [Particle Induced X-ray Emission (PIXE) for analysis of trace elements in biological materials].

    Science.gov (United States)

    Iwata, Y

    1996-01-01

    Outline of Particle Induced X-ray Emission (PIXE) and its application to biomedical samples are described. Charged particles from cyclotron or van de Graaff generator bombards analytical samples and semiconductor detector measures energy and intensity of induced characteristic x-ray. Simultaneous determination for 22Na to 92U is possible by PIXE. 100 nA of 3 MeV protons bombards biomedical samples and detection limits for almost all trace essential elements are sub microgram/g. Only 1 mg of biomedical sample is necessary for determination of trace elements and no chemical procedure is necessary for preparation of analytical sample. PIXE is powerful tool for determination of essential elements and applied for diagnosis for several diseases.

  13. Accelerated algorithm for three-dimensional computer generated hologram based on the ray-tracing method

    Science.gov (United States)

    Xie, Z. W.; Zang, J. L.; Zhang, Y.

    2013-06-01

    An accelerated algorithm for three-dimensional computer generated holograms (CGHs) based on the ray-tracing method is proposed. The complex amplitude distribution from the center point of an object is calculated in advance and the field distributions of rest points on the hologram plane can be given by doing a small translation and an aberration to the pre-calculated field. A static two-dimensional car, a three-dimensional teapot, and a dynamic three-dimensional rotating teapot are reconstructed from CGHs calculated with the accelerated algorithm to prove its validity. The simulation results demonstrate that the accelerated algorithm is eight times faster than the conventional ray-tracing algorithm.

  14. An efficient ray tracing method for propagation prediction along a mobile route in urban environments

    Science.gov (United States)

    Hussain, S.; Brennan, C.

    2017-07-01

    This paper presents an efficient ray tracing algorithm for propagation prediction in urban environments. The work presented in this paper builds upon previous work in which the maximum coverage area where rays can propagate after interaction with a wall or vertical edge is described by a lit polygon. The shadow regions formed by buildings within the lit polygon are described by shadow polygons. In this paper, the lit polygons of images are mapped to a coarse grid superimposed over the coverage area. This mapping reduces the active image tree significantly for a given receiver point to accelerate the ray finding process. The algorithm also presents an efficient method of quickly determining the valid ray segments for a mobile receiver moving along a linear trajectory. The validation results show considerable computation time reduction with good agreement between the simulated and measured data for propagation prediction in large urban environments.

  15. Impact of a Vertically Polarized Undulator on LCLS Hard X-ray Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2014-11-14

    The LCLS-II project will install two variable gap, horizontally polarized undulators into the LCLS undulator hall. One undulator is designed to produce soft x-rays spanning an energy range of 200-1250 eV (SXU) while the other is designed for the hard spectral range of 1-25 keV (HXU). The hard x-ray LCLS instruments (X-ray Pump- Probe [XPP], X-ray correlation Spectroscopy [XCS], Coherent X-ray Imaging [CXI], Matter in Extreme Conditions [MEC]) will be repurposed to operate on the HXU line while two new soft x-ray beamlines will be created for the SXU line. An alternate HXU undulator design is being considered that could provide advantages over the present design choice. In particular, the project team is collaborating with Argonne National Laboratory to develop a vertically polarized undulator (VPU). A 1-m prototype VPU device was successfully constructed this year and a full size prototype is in process. A decision to alter the project baseline, which is the construction of a horizontally polarized device, must be made in the coming weeks to not impact the present project schedule. Please note that a change to the soft x-ray undulator is not under discussion at the moment.

  16. Combining ray tracing and CFD in the thermal analysis of a parabolic dish tubular cavity receiver

    Science.gov (United States)

    Craig, Ken J.; Marsberg, Justin; Meyer, Josua P.

    2016-05-01

    This paper describes the numerical evaluation of a tubular receiver used in a dish Brayton cycle. In previous work considering the use of Computational Fluid Dynamics (CFD) to perform the calculation of the absorbed radiation from the parabolic dish into the cavity as well as the resulting conjugate heat transfer, it was shown that an axi-symmetric model of the dish and receiver absorbing surfaces was useful in reducing the computational cost required for a full 3-D discrete ordinates solution, but concerns remained about its accuracy. To increase the accuracy, the Monte Carlo ray tracer SolTrace is used to perform the calculation of the absorbed radiation profile to be used in the conjugate heat transfer CFD simulation. The paper describes an approach for incorporating a complex geometry like a tubular receiver generated using CFD software into SolTrace. The results illustrate the variation of CFD mesh density that translates into the number of elements in SolTrace as well as the number of rays used in the Monte Carlo approach and their effect on obtaining a resolution-independent solution. The conjugate heat transfer CFD simulation illustrates the effect of applying the SolTrace surface heat flux profile solution as a volumetric heat source to heat up the air inside the tube. Heat losses due to convection and thermal re-radiation are also determined as a function of different tube absorptivities.

  17. Proton induced X-Ray fluorescence study as a tool trace element analysis

    International Nuclear Information System (INIS)

    El-Kady, Ahmed A.

    1978-01-01

    Usefulness and limitations of trace elemental analysis by high energy charged particles and photon induced X-ray have been discussed. Comparison with the well established neutron activation analysis technique is also given. Back-ground radiation due to bremsstrahlung from secondary electrons and due to charged particle bremsstrahlung have been reviewed for different projectiles. The sensitivity of elemental analysis by proton induced X-ray fluorescence have been examined by measuring the characteristic X-ray emission cross section for K and L transitions of many elements and for different proton energies and compared with theroretical values. The discussion given in this report show that with suitable proton generator and a high resolution X-ray detector, proton X-ray fluorescence technique is capable of analyzing many elements simultaneously at the part per million level and offers a rapid and reliable method for trace element analysis. Data on water, blood and tissue samples given in this report are few examples of many possible applications

  18. X-ray fluorescence analysis for trace element determination in foodstuff chemistry

    International Nuclear Information System (INIS)

    Wildanger, W.

    The physical fundamentals of X-ray fluorescence analysis are given and the routine spectrometers described. The basic principles are given of analytical methods used in qualitative and quantitative fluorescence analyses. Examples are given of the use of the method in a number of fields and the possibility and usefulness is discussed for the determination of trace elements in foodstuffs. The preparation of samples, preliminary concentration of components and calibration methods are discussed. (M.K.)

  19. Ultrasonic field profile evaluation in acoustically inhomogeneous anisotropic materials using 2D ray tracing model: Numerical and experimental comparison.

    Science.gov (United States)

    Kolkoori, S R; Rahman, M-U; Chinta, P K; Ktreutzbruck, M; Rethmeier, M; Prager, J

    2013-02-01

    Ultrasound propagation in inhomogeneous anisotropic materials is difficult to examine because of the directional dependency of elastic properties. Simulation tools play an important role in developing advanced reliable ultrasonic non destructive testing techniques for the inspection of anisotropic materials particularly austenitic cladded materials, austenitic welds and dissimilar welds. In this contribution we present an adapted 2D ray tracing model for evaluating ultrasonic wave fields quantitatively in inhomogeneous anisotropic materials. Inhomogeneity in the anisotropic material is represented by discretizing into several homogeneous layers. According to ray tracing model, ultrasonic ray paths are traced during its energy propagation through various discretized layers of the material and at each interface the problem of reflection and transmission is solved. The presented algorithm evaluates the transducer excited ultrasonic fields accurately by taking into account the directivity of the transducer, divergence of the ray bundle, density of rays and phase relations as well as transmission coefficients. The ray tracing model is able to calculate the ultrasonic wave fields generated by a point source as well as a finite dimension transducer. The ray tracing model results are validated quantitatively with the results obtained from 2D Elastodynamic Finite Integration Technique (EFIT) on several configurations generally occurring in the ultrasonic non destructive testing of anisotropic materials. Finally, the quantitative comparison of ray tracing model results with experiments on 32mm thick austenitic weld material and 62mm thick austenitic cladded material is discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Vacuum birefringence and the x-ray polarization from black-hole accretion disks

    Science.gov (United States)

    Caiazzo, Ilaria; Heyl, Jeremy

    2018-04-01

    In the next decade, x-ray polarimetry will open a new window on the high-energy Universe, as several missions that include an x-ray polarimeter are currently under development. Observations of the polarization of x rays coming from the accretion disks of stellar-mass and supermassive black holes are among the new polarimeters' major objectives. In this paper, we show that these observations can be affected by the quantum electrodynamic (QED) effect of vacuum birefringence: after an x-ray photon is emitted from the accretion disk, its polarization changes as the photon travels through the accretion disk's magnetosphere, as a result of the vacuum becoming birefringent in the presence of a magnetic field. We show that this effect can be important for black holes in the energy band of the upcoming polarimeters and has to be taken into account in a complete model of the x-ray polarization that we expect to detect from black-hole accretion disks, both for stellar mass and for supermassive black holes. We find that, for a chaotic magnetic field in the disk, QED can significantly decrease the linear polarization fraction of edge-on photons, depending on the spin of the hole and on the strength of the magnetic field. This effect can provide, for the first time, a direct way to probe the magnetic field strength close to the innermost stable orbit of black-hole accretion disks and to study the role of magnetic fields in astrophysical accretion in general.

  1. Integrated Ray Tracing Model for End-to-end Performance Verification of Amon-Ra Instrument

    Science.gov (United States)

    Lee, Jae-Min; Park, Won Hyun; Ham, Sun-Jeong, Yi, Hyun-Su; Yoon, Jee Yeon; Kim, Sug-Whan; Choi, Ki-Hyuk; Kim, Zeen Chul; Lockwood, Mike

    2007-03-01

    The international EARTHSHINE mission is to measure 1% anomaly of the Earth global albedo and total solar irradiance using Amon-Ra instrument around Lagrange point 1. We developed a new ray tracing based integrated end-to-end simulation tool that overcomes the shortcomings of the existing end-to-end performance simulation techniques. We then studied the in-orbit radiometric performance of the breadboard Amon-Ra visible channel optical system. The TSI variation and the Earth albedo anomaly, reported elsewhere, were used as the key input variables in the simulation. The output flux at the instrument focal plane confirms that the integrated ray tracing based end-to-end science simulation delivers the correct level of incident power to the Amon-Ra instrument well within the required measurement error budget of better than ±0.28%. Using the global angular distribution model (ADM), the incident flux is then used to estimate the Earth global albedo and the TSI variation, confirming the validity of the primary science cases at the L1 halo orbit. These results imply that the integrated end-to-end ray tracing technique, reported here, can serve as an effective and powerful building block of the on-line science analysis tool in support of the international EARTHSHINE mission currently being developed.

  2. Resonant magnetic scattering of polarized soft x rays

    Energy Technology Data Exchange (ETDEWEB)

    Sacchi, M. [Centre Universitaire Paris-Sud, Orsay (France); Hague, C.F. [Universite Pierre et Marie Curie, Paris (France); Gullikson, E.M.; Underwood, J. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Magnetic effects on X-ray scattering (Bragg diffraction, specular reflectivity or diffuse scattering) are a well known phenomenon, and they also represent a powerful tool for investigating magnetic materials since it was shown that they are strongly enhanced when the photon energy is tuned across an absorption edge (resonant process). The resonant enhancement of the magnetic scattering has mainly been investigated at high photon energies, in order to match the Bragg law for the typical lattice spacings of crystals. In the soft X-ray range, even larger effects are expected, working for instance at the 2p edges of transition metals of the first row or at the 3d edges of rare earths (300-1500 eV), but the corresponding long wavelengths prevent the use of single crystals. Two approaches have been recently adopted in this energy range: (i) the study of the Bragg diffraction from artificial structures of appropriate 2d spacing; (ii) the analysis of the specular reflectivity, which contains analogous information but has no constraints related to the lattice spacing. Both approaches have their own specific advantages: for instance, working under Bragg conditions provides information about the (magnetic) periodicity in ordered structures, while resonant reflectivity can easily be related to electronic properties and absorption spectra. An important aspect common to all the resonant X-ray scattering techniques is the element selectivity inherent to the fact of working at a specific absorption edge: under these conditions, X-ray scattering becomes in fact a spectroscopy. Results are presented for films of iron and cobalt.

  3. Large-Area Balloon-Borne Polarized Gamma Ray Observer (PoGO)

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, V.; Chen, P.; Kamae, T.; Madejski, G.; Mizuno, T.; Ng, J.; Tajima, H.; Thurston, T.; /SLAC; Bogaert, G.; /Ecole Polytechnique; Fukazawa, Y.; /Hiroshima U.; Saito,; Takahashi, T.; /Sagamihara, Inst. Space Astron. Sci.; Barbier, L.; Bloser, P.; Harding, A.; Hunter, S.; Krizmanic, J.; Mitchell, J.; Streitmatter, R.; Fernholz, R.; Groth, E.; /NASA, Goddard /Princeton U. /Royal Inst. Tech., Kista /Stockholm U. /Tokyo Inst. Tech. /Yamagata U.

    2005-06-30

    We are developing a new balloon-borne instrument (PoGO), to measure polarization of soft gamma rays (30-200 keV) using asymmetry in azimuth angle distribution of Compton scattering. PoGO is designed to detect 10% polarization in 100mCrab sources in a 6-8 hour observation and bring a new dimension to studies on gamma ray emission/transportation mechanism in pulsars, AGNs, black hole binaries, and neutron star surface. The concept is an adaptation to polarization measurements of well-type phoswich counter consisting of a fast plastic scintillator (the detection part), a slow plastic scintillator (the active collimator) and a BGO scintillator (the bottom anti-counter). PoGO consists of close-packed array of 217 hexagonal well-type phoswich counters and has a narrow field-of-view ({approx} 5 deg{sup 2}) to reduce possible source confusion. A prototype instrument has been tested in the polarized soft gamma-ray beams at Advanced Photon Source (ANL) and at Photon Factory (KEK). On the results, the polarization dependence of EGS4 has been validated and that of Geant4 has been corrected.

  4. Assessment of diffusive isotopic fractionation in polar firn, and application to ice core trace gas records

    DEFF Research Database (Denmark)

    Buizert, C.; Sowers, T.; Blunier, T.

    2013-01-01

    During rapid variations of the atmospheric mixing ratio of a trace gas, diffusive transport in the porous firn layer atop ice sheets and glaciers alters the isotopic composition of that gas relative to the overlying atmosphere. Records of past atmospheric trace gas isotopic composition from ice...

  5. Soft matter interfaces beamline at NSLS-II: geometrical ray-tracing vs. wavefront propagation simulations

    Science.gov (United States)

    Zhernenkov, Mikhail; Canestrari, Niccolo; Chubar, Oleg; DiMasi, Elaine

    2014-09-01

    We report on the implications of the design of a Soft Matter Interfaces beamline, a long energy range canted in-vacuum undulator (IVU) beamline at National Synchrotron Light Source II, based on comparison of geometrical ray-tracing and partially coherent x-ray wavefront propagation simulation software packages, namely, SHADOW and Synchrotron Radiation Workshop (SRW). For SHADOW, we employed an SRW-generated source file which simulated spectralangular distribution and apparent source characteristics of radiation produced by a 2.8 m long IVU with a 23 mm period and allowed us to realistically estimate the beam intensity at the sample positions. We highlight the necessity to use realistic mirror surface profiles with expected slope errors as opposed to "standard" built-in SHADOW surface error options. The beamline performances at three different x-ray photon energies: 20358 eV, 10778 eV, and 2101 eV, under different focusing conditions, have been studied. We compare beamline simulations performed with both software packages. In particular, we stress that the neglect of wavefront diffraction effects in geometrical ray-tracing approach results in significant discrepancies in beam spot size and beam shape, the correct assessments of which are crucial in determining the future performance of an instrument.

  6. Konstruksi Bounding Volume Hierarchy dengan Metode Agglomerative Clustering untuk Meningkatkan Performa Ray Tracing

    Directory of Open Access Journals (Sweden)

    Arif Fathur Mahmuda

    2017-03-01

    Full Text Available Ray Tracing sebagai algoritma rendering yang menghasilkan citra realistis memiliki beberapa kekurangan. Salah satu di antaranya adalah perhitungan persilangan ray-object pada tiap pixel yang memakan 75% waktu dari keseluruhan proses rendering. Penelitian ini menerapkan metode yang diharapkan dapat mempersingkat proses perhitungan persilangan ray-object dengan membangun struktur data berupa binary tree. Tree yang dibangun sering juga disebut sebagai Bounding Volume Hierarchy (BVH di mana masing-masing node-nya adalah sebuah container. Struktur data tersebut akan dibangun dengan metode Approximate Agglomerative Clustering (AAC yang merupakan metode bottom-up clustering dengan top-down preprocessing. Metode AAC dengan parameter yang baik dapat meningkatkan performa Ray Tracing. Metode-metode yang diterapkan sangat mudah diparalelkan sehingga performa algoritma meningkat jika dijalankan pada lingkungan paralel. Hasil uji coba menunjukkan peningkatan kecepatan hingga 3 kali lipat dibandingkan tanpa menerapkan paralelisme. Pada hasil uji coba,  juga didapatkan dua jenis parameter yang masing-masing memiliki karakteristik tersendiri (6= cepat, 12= kualitas baik.

  7. R-LODs: fast LOD-based ray tracing of massive models

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sung-Eui; Lauterbach, Christian; Manocha, Dinesh

    2006-08-25

    We present a novel LOD (level-of-detail) algorithm to accelerate ray tracing of massive models. Our approach computes drastic simplifications of the model and the LODs are well integrated with the kd-tree data structure. We introduce a simple and efficient LOD metric to bound the error for primary and secondary rays. The LOD representation has small runtime overhead and our algorithm can be combined with ray coherence techniques and cache-coherent layouts to improve the performance. In practice, the use of LODs can alleviate aliasing artifacts and improve memory coherence. We implement our algorithm on both 32bit and 64bit machines and able to achieve up to 2.20 times improvement in frame rate of rendering models consisting of tens or hundreds of millions of triangles with little loss in image quality.

  8. The flux distribution from a 1.25m2 target aligned heliostat: comparison of ray tracing and experimental results

    CSIR Research Space (South Africa)

    Maliage, M

    2012-05-01

    Full Text Available The purpose of this paper is to validate SolTrace for concentrating solar investigations at CSIR by means of a test case: the comparison of the flux distribution in the focal spot of a 1.25 m2 target aligned heliostat predicted by the ray tracing...

  9. X-RAY VARIABILITY STUDY OF POLAR SCATTERED SEYFERT1 GALAXIES

    Directory of Open Access Journals (Sweden)

    Tobias Beuchert

    2014-08-01

    Full Text Available We study 12 Seyfert 1 galaxies with a high level of optical polarization. Optical light emerging from the innermost regions is predominantly scattered in a polar region above the central engine directly in our line of sight. These sources show characteristics of Seyfert 2 galaxies, e.g. polarized broad lines. The polarization signatures suggest a viewing angle of 45°, classifying them as intermediate Seyfert 1/2 types. The unified model predicts this line of sight to pass through the outer layer of the torus resulting in significant soft X-ray variability due to a strongly varying column density. The aim is to find evidence for this geometrical assumption in the spectral variability of all available historical observations of these sources by XMM-Newton and Swift.

  10. Polarization and dipole effects in hard X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Novak, M. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium); Pauly, N., E-mail: nipauly@ulb.ac.be [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium); Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer X-rays are unpolarized or linearly polarized. Black-Right-Pointing-Pointer A difference of polarization implies a variation in path travelled by the photoelectrons. Black-Right-Pointing-Pointer We show the influence of the polarization on the partial intensity distributions. Black-Right-Pointing-Pointer We also point out the influence of the dipole approximation. Black-Right-Pointing-Pointer We use Monte Carlo simulations. - Abstract: Hard X-ray photoelectron spectroscopy (HXPS) using X-rays in the 1.5-15 keV energy range generated by synchrotron sources becomes an increasingly important analysis technique due to its potential for bulk sensitive measurements. However, besides their high energy, another characteristic of photons generated by synchrotron sources is their linear polarization while X-rays from Al K{alpha} or Mg K{alpha} for instance are unpolarized. This difference implies a possible variation in total path travelled by the photoelectrons generated by the X-rays inside the medium and consequently a modification of the resulting spectrum shape. We show the influence of the polarization on the partial intensity distributions, namely the number of electrons escaping after n inelastic scattering events, for photoelectron with energies of 0.5, 1, 2, 3, 4 and 5 keV and originating from Si 1s{sub 1/2}, Cu 1s{sub 1/2}, Cu 2p{sub 3/2}, Au 4d{sub 3/2} and Au 4f{sub 7/2} subshells. Moreover, we point out the influence of the dipole approximation leading to an underestimation of the partial intensity distributions due to the neglect of the forward-backward asymmetry of the angular photoelectron distribution.

  11. Ray-tracing 3D dust radiative transfer with DART-Ray: code upgrade and public release

    Science.gov (United States)

    Natale, Giovanni; Popescu, Cristina C.; Tuffs, Richard J.; Clarke, Adam J.; Debattista, Victor P.; Fischera, Jörg; Pasetto, Stefano; Rushton, Mark; Thirlwall, Jordan J.

    2017-11-01

    We present an extensively updated version of the purely ray-tracing 3D dust radiation transfer code DART-Ray. The new version includes five major upgrades: 1) a series of optimizations for the ray-angular density and the scattered radiation source function; 2) the implementation of several data and task parallelizations using hybrid MPI+OpenMP schemes; 3) the inclusion of dust self-heating; 4) the ability to produce surface brightness maps for observers within the models in HEALPix format; 5) the possibility to set the expected numerical accuracy already at the start of the calculation. We tested the updated code with benchmark models where the dust self-heating is not negligible. Furthermore, we performed a study of the extent of the source influence volumes, using galaxy models, which are critical in determining the efficiency of the DART-Ray algorithm. The new code is publicly available, documented for both users and developers, and accompanied by several programmes to create input grids for different model geometries and to import the results of N-body and SPH simulations. These programmes can be easily adapted to different input geometries, and for different dust models or stellar emission libraries.

  12. Intense γ-ray generation for a polarized positron beam in a linear collider

    Directory of Open Access Journals (Sweden)

    Y. Miyahara

    2001-12-01

    Full Text Available γ-ray generation by Compton backscattering in an optical lens series with periodic focal points is considered to produce a polarized positron beam for a linear collider. The lens series is composed of 20 unit cells with a length of 210 mm. Each lens has a hole to pass an electron beam with an energy of 5.8 GeV and the generated γ rays. It is shown by diffraction analysis that laser beam loss in the series is very small, and the beam size is periodically reduced to 26 μm. Electron beam size is reduced to 34 μm in a superconducting solenoid with a field of 15 T. To get a required γ-ray yield of 7×10^{15} γ/s, only one circularly polarized CO_{2} laser source with a power of 24 kW is needed.

  13. Probing the Accretion Processes in Soft X-Ray Selected Polars

    Directory of Open Access Journals (Sweden)

    I. Traulsen

    2015-02-01

    Full Text Available High-energy data of accreting white dwarfs give access to the regime of the primary accretion-induced energy release and the different proposed accretion scenarios. We perform XMM-Newton observations of polars selected due to their ROSAT hardness ratios close to -1.0 and model the emission processes in accretion column and accretion region. Our models consider the multi-temperature structure of the emission regions and are mainly determined by mass-flow density, magnetic field strength, and white-dwarf mass. To describe the full spectral energy distribution from infrared to X-rays in a physically consistent way, we include the stellar contributions and establish composite models, which will also be of relevance for future X-ray missions. We confirm the X-ray soft nature of three polars.

  14. Imaging nanoscale magnetic structures with polarized soft x-ray photons

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, P.; Im, M.-Y.

    2010-01-18

    Imaging nanoscale magnetic structures and their fast dynamics is scientifically interesting and technologically of highest relevance. The combination of circularly polarized soft X-ray photons which provide a strong X-ray magnetic circular dichroism effect at characteristic X-ray absorption edges, with a high resolution soft X-ray microscope utilizing Fresnel zone plate optics allows to study in a unique way the stochastical behavior in the magnetization reversal process of thin films and the ultrafast dynamics of magnetic vortices and domain walls in confined ferromagnetic structures. Future sources of fsec short and high intense soft X-ray photon pulses hold the promise of magnetic imaging down to fundamental magnetic length and time scales.

  15. Trace element determination in tomato puree using particle induced X-ray emission and Rutherford backscattering

    International Nuclear Information System (INIS)

    Romero-Davila, E.; Miranda, J.

    2004-01-01

    Particle induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) were used to determine the concentrations of trace elements in samples of 12 tomato puree brands sold in the Mexican market. While RBS offered information about the main elements present in the matrix, PIXE gave results on trace elements. As a whole, data for 17 elements (C, N, O, Na, Mg, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn) were obtained. To evaluate the results, a comparison with brands from USA, Japan, Colombia, and Chile was carried out, using tomato purees produced following the domestic technology recipe. Additionally, the results were considered in the light of the Codex Alimentarius and the Mexican standard. It was found that all of the brands fall within the limits established by these standards, being of the same order of magnitude as the foreign brands. (author)

  16. [Progress in sample preparation and analytical methods for trace polar small molecules in complex samples].

    Science.gov (United States)

    Zhang, Qianchun; Luo, Xialin; Li, Gongke; Xiao, Xiaohua

    2015-09-01

    Small polar molecules such as nucleosides, amines, amino acids are important analytes in biological, food, environmental, and other fields. It is necessary to develop efficient sample preparation and sensitive analytical methods for rapid analysis of these polar small molecules in complex matrices. Some typical materials in sample preparation, including silica, polymer, carbon, boric acid and so on, are introduced in this paper. Meanwhile, the applications and developments of analytical methods of polar small molecules, such as reversed-phase liquid chromatography, hydrophilic interaction chromatography, etc., are also reviewed.

  17. Development of Ray Tracing Algorithms for Scanning Plane and Transverse Plane Analysis for Satellite Multibeam Application

    Directory of Open Access Journals (Sweden)

    N. H. Abd Rahman

    2014-01-01

    Full Text Available Reflector antennas have been widely used in many areas. In the implementation of parabolic reflector antenna for broadcasting satellite applications, it is essential for the spacecraft antenna to provide precise contoured beam to effectively serve the required region. For this purpose, combinations of more than one beam are required. Therefore, a tool utilizing ray tracing method is developed to calculate precise off-axis beams for multibeam antenna system. In the multibeam system, each beam will be fed from different feed positions to allow the main beam to be radiated at the exact direction on the coverage area. Thus, detailed study on caustics of a parabolic reflector antenna is performed and presented in this paper, which is to investigate the behaviour of the rays and its relation to various antenna parameters. In order to produce accurate data for the analysis, the caustic behaviours are investigated in two distinctive modes: scanning plane and transverse plane. This paper presents the detailed discussions on the derivation of the ray tracing algorithms, the establishment of the equations of caustic loci, and the verification of the method through calculation of radiation pattern.

  18. A comprehensive ray tracing study on the impact of solar reflections from glass curtain walls.

    Science.gov (United States)

    Wong, Justin S J

    2016-01-01

    To facilitate the investigation of the impact of solar reflection from the façades of skyscrapers to surrounding environment, a comprehensive ray tracing model has been developed using the International Commerce Centre (ICC) in Hong Kong as an example. Taking into account the actual physical dimensions of buildings and meteorological data, the model simulates and traces the paths of solar reflections from ICC to the surrounding buildings, assessing the impact in terms of hit locations, light intensity and the hit time on each day throughout the year. Our analyses show that various design and architectural features of ICC have amplified the intensity of reflected solar rays and increased the hit rates of surrounding buildings. These factors include the high reflectivity of glass panels, their upward tilting angles, the concave profile of the 'Dragon Tail' (glass panels near the base), the particular location and orientation of ICC, as well as the immense height of ICC with its large reflective surfaces. The simulation results allow us to accurately map the date and time when the ray projections occur on each of the target buildings, rendering important information such as the number of converging (overlapping) projections, and the actual light intensity hitting each of the buildings at any given time. Comparisons with other skyscrapers such as Taipei 101 in Taiwan and 2-IFC (International Finance Centre) Hong Kong are made. Remedial actions for ICC and preventive measures are also discussed.

  19. Spin tracking simulations in AGS based on ray-tracing methods - bare lattice, no snakes -

    Energy Technology Data Exchange (ETDEWEB)

    Meot, F.; Ahrens, L.; Gleen, J.; Huang, H.; Luccio, A.; MacKay, W. W.; Roser, T.; Tsoupas, N.

    2009-09-01

    This Note reports on the first simulations of and spin dynamics in the AGS using the ray-tracing code Zgoubi. It includes lattice analysis, comparisons with MAD, DA tracking, numerical calculation of depolarizing resonance strengths and comparisons with analytical models, etc. It also includes details on the setting-up of Zgoubi input data files and on the various numerical methods of concern in and available from Zgoubi. Simulations of crossing and neighboring of spin resonances in AGS ring, bare lattice, without snake, have been performed, in order to assess the capabilities of Zgoubi in that matter, and are reported here. This yields a rather long document. The two main reasons for that are, on the one hand the desire of an extended investigation of the energy span, and on the other hand a thorough comparison of Zgoubi results with analytical models as the 'thin lens' approximation, the weak resonance approximation, and the static case. Section 2 details the working hypothesis : AGS lattice data, formulae used for deriving various resonance related quantities from the ray-tracing based 'numerical experiments', etc. Section 3 gives inventories of the intrinsic and imperfection resonances together with, in a number of cases, the strengths derived from the ray-tracing. Section 4 gives the details of the numerical simulations of resonance crossing, including behavior of various quantities (closed orbit, synchrotron motion, etc.) aimed at controlling that the conditions of particle and spin motions are correct. In a similar manner Section 5 gives the details of the numerical simulations of spin motion in the static case: fixed energy in the neighboring of the resonance. In Section 6, weak resonances are explored, Zgoubi results are compared with the Fresnel integrals model. Section 7 shows the computation of the {rvec n} vector in the AGS lattice and tuning considered. Many details on the numerical conditions as data files etc. are given in the

  20. Polarization periodicity in the B1 columnar phase determined by resonant x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Folcia, C.L.; Pindak, R.; Ortega, J.; Etxebarria, J.; Pan, L.; Wang, S.; Huang, C.C.; Ponsinet, V.; Barois, P. and Gimeno, N.

    2011-07-14

    We report structural results that evidence the polarization distribution of the blocks in the columnar phase of an achiral bent-core liquid crystal. The study was performed using resonant x-ray diffraction at the sulfur K edge on oriented samples aligned on substrates. The extra periodicity is revealed through the violation of the systematic extinction rule of the structural symmetry group along the experimentally accessible diffraction direction. Further data obtained from the polarization analysis of a resonant reflection give information concerning the transition mechanism between B{sub 1} and B{sub 2} phases.

  1. Polarization Periodicity in the B(1) Columnar Phase Determined by Resonant X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    C Folcia; J Ortega; J Etxebarria; L Pan; S Wang; C Huang; V Ponsinet; P Barois; R Pindak; N Gimeno

    2011-12-31

    We report structural results that evidence the polarization distribution of the blocks in the columnar phase of an achiral bent-core liquid crystal. The study was performed using resonant x-ray diffraction at the sulfur K edge on oriented samples aligned on substrates. The extra periodicity is revealed through the violation of the systematic extinction rule of the structural symmetry group along the experimentally accessible diffraction direction. Further data obtained from the polarization analysis of a resonant reflection give information concerning the transition mechanism between B{sub 1} and B{sub 2} phases.

  2. Fast helicity switching of x-ray circular polarization at beamline P09 at PETRA III

    International Nuclear Information System (INIS)

    Strempfer, J.; Mardegan, J. R. L.; Francoual, S.; Veiga, L. S. I.; Spitzbart, T.; Zink, H.; Bouchenoire, L.

    2016-01-01

    At the resonant scattering and diffraction beamline P09 at PETRA III/DESY, polarization manipulation in the X-ray energy range 3-13 keV is possible using wave-plates. Recently, fast flipping of circular polarization helicity using the Raspberry Pi controlled FPGA (PiLC) device developed at DESY and dedicated piezo-electric flippers has been commissioned. Functionality of the PiLC for XMCD and first XMCD measurements at the Fe K-and Dy-L 3 absorption edges are presented.

  3. Fast helicity switching of x-ray circular polarization at beamline P09 at PETRA III

    Energy Technology Data Exchange (ETDEWEB)

    Strempfer, J., E-mail: Joerg.Strempfer@desy.de; Mardegan, J. R. L.; Francoual, S.; Veiga, L. S. I.; Spitzbart, T.; Zink, H. [Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, 22603 Hamburg (Germany); Bouchenoire, L. [XMaS, ESRF, 6 rue Jules Horowitz, BP220, Grenoble 38043 (France); Department of Physics, University of Liverpool, Liverpool, L69 7ZE (United Kingdom)

    2016-07-27

    At the resonant scattering and diffraction beamline P09 at PETRA III/DESY, polarization manipulation in the X-ray energy range 3-13 keV is possible using wave-plates. Recently, fast flipping of circular polarization helicity using the Raspberry Pi controlled FPGA (PiLC) device developed at DESY and dedicated piezo-electric flippers has been commissioned. Functionality of the PiLC for XMCD and first XMCD measurements at the Fe K-and Dy-L{sub 3} absorption edges are presented.

  4. Trace elements in tobacco and tobacco smoke by x-ray fluorescence technique

    International Nuclear Information System (INIS)

    Mishra, U.C.; Shaikh, G.N.; Sadasivan, S.

    1986-01-01

    Trace elements in tobacco and tobacco smoke of a large number of commonly available brands of cigarettes were analyzed by energy dispersive x-ray fluorescence. This work supplements the data on the same samples gathered by INAA and reported earlier. Data on some toxic elements like Pb, Cu and Ni that could not be measured by INAA are presented. A number of chewing and snuff tobacco samples were also analyzed. The concentrations of Ca, K, Cl, Br, Cu, Fe, Ni, Pb, Rb, Sr, Ti and Zn in all these samples are presented and their relative hazards are discussed. (author)

  5. Infrasonic ray tracing applied to mesoscale atmospheric structures: refraction by hurricanes.

    Science.gov (United States)

    Bedard, Alfred J; Jones, R Michael

    2013-11-01

    A ray-tracing program is used to estimate the refraction of infrasound by the temperature structure of the atmosphere and by hurricanes represented by a Rankine-combined vortex wind plus a temperature perturbation. Refraction by the hurricane winds is significant, giving rise to regions of focusing, defocusing, and virtual sources. The refraction of infrasound by the temperature anomaly associated with a hurricane is small, probably no larger than that from uncertainties in the wind field. The results are pertinent to interpreting ocean wave generated infrasound in the vicinities of tropical cyclones.

  6. n-Hindle-sphere arrangement with an exact ray trace for testing hyperboloid convex mirrors.

    Science.gov (United States)

    Percino-Zacarias, M E; Cordero-Dávila, A

    1999-10-01

    We present calculations with an exact ray trace to determine the dimensions that define one or two Hindle spheres, since the paraxial theory is incongruent for convex hyperboloid mirrors with small f numbers. The equations are generalized to calculate the dimensions of n Hindle spheres, since in this way it is possible to reduce the dimensions of the spheres more. Actual calculations are done for the secondary mirrors of the Benemerita Universidad Autonoma de Puebla and Large Milimetric Telescopes; experimental results are shown for the latter.

  7. Circular polarization control for the European XFEL in the soft X-ray regime

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-06-01

    The possibility of producing X-ray radiation with high degree of circular polarization is an important asset at XFEL facilities. Polarization control is most important in the soft X-ray region.However, the baseline of the European XFEL, including the soft X-ray SASE3 line, foresees planar undulators only, yielding linearly-polarized radiation. It is clear that the lowest-risk strategy for implementing polarization control at SASE3 involves adding an APPLE II-type undulator at the end of the planar undulator, in order to exploit the micro bunching from the baseline FEL. Detailed experience is available in synchrotron radiation laboratories concerning the manufacturing of 5 m-long APPLE II undulators. However, the choice of a short helical radiator leads to the problem of background suppression. The driving idea of our proposal is that the background radiation can be suppressed by spatial filtering. This operation can be performed by inserting slits behind the APPLE II radiator, where the linearly-polarized radiation spot size is about 30 times larger than the radiation spot size from the helical radiator. The last 7 cells of the SASE3 undulator are left with an open gap in order to provide a total 42 m drift section for electron beam and radiation. Due to the presence of the drift the linearly-polarized radiation spot size increases, and the linearly polarized background radiation can be suppressed by the slits. At the same time, the microbunch structure is easily preserved, so that intense (100 GW) coherent radiation is emitted in the helical radiator. We propose a filtering setup consisting of a pair of water cooled slits for X-ray beam filtering and of a 5 m-long magnetic chicane, which creates an offset for slit installation immediately behind the helical radiator. Electrons and X-rays are separated before the slits by the magnetic chicane, so that the electron beam can pass by the filtering setup without perturbations. Based on start-to-end simulations we

  8. Calibration of the Gamma-RAy Polarimeter Experiment (GRAPE) at a polarized hard X-ray beam

    International Nuclear Information System (INIS)

    Bloser, P.F.; Legere, J.S.; McConnell, M.L.; Macri, J.R.; Bancroft, C.M.; Connor, T.P.; Ryan, J.M.

    2009-01-01

    The Gamma-RAy Polarimeter Experiment (GRAPE) is a concept for an astronomical hard X-ray Compton polarimeter operating in the 50-500 keV energy band. The instrument has been optimized for wide-field polarization measurements of transient outbursts from energetic astrophysical objects such as gamma-ray bursts and solar flares. The GRAPE instrument is composed of identical modules, each of which consists of an array of scintillator elements read out by a multi-anode photomultiplier tube (MAPMT). Incident photons Compton scatter in plastic scintillator elements and are subsequently absorbed in inorganic scintillator elements; a net polarization signal is revealed by a characteristic asymmetry in the azimuthal scattering angles. We have constructed a prototype GRAPE module containing a single CsI(Na) calorimeter element, at the center of the MAPMT, surrounded by 60 plastic elements. The prototype has been combined with custom readout electronics and software to create a complete 'engineering model' of the GRAPE instrument. This engineering model has been calibrated using a nearly 100% polarized hard X-ray beam at the Advanced Photon Source at Argonne National Laboratory. We find modulation factors of 0.46±0.06 and 0.48±0.03 at 69.5 and 129.5 keV, respectively, in good agreement with Monte Carlo simulations. In this paper we present details of the beam test, data analysis, and simulations, and discuss the implications of our results for the further development of the GRAPE concept.

  9. Variations in Solar Parameters and Cosmic Rays with Solar Magnetic Polarity

    Energy Technology Data Exchange (ETDEWEB)

    Oh, S. [Department of Earth Science Education, Chonnam National University, Gwangju, 61186 (Korea, Republic of); Yi, Y., E-mail: suyeonoh@jnu.ac.kr [Department of Astronomy, Space Science and Geology, Chungnam National University, Daejeon, 34134 (Korea, Republic of)

    2017-05-01

    The sunspot number varies with the 11-year Schwabe cycle, and the solar magnetic polarity reverses every 11 years approximately at the solar maximum. Because of polarity reversal, the difference between odd and even solar cycles is seen in solar activity. In this study, we create the mean solar cycle expressed by phase using the monthly sunspot number for all solar cycles 1–23. We also generate the mean solar cycle for sunspot area, solar radio flux, and cosmic ray flux within the allowance of observational range. The mean solar cycle has one large peak at solar maximum for odd solar cycles and two small peaks for most even solar cycles. The odd and even solar cycles have the statistical difference in value and shape at a confidence level of at least 98%. For solar cycles 19–23, the second peak in the even solar cycle is larger than the first peak. This result is consistent with the frequent solar events during the declining phase after the solar maximum. The difference between odd and even solar cycles can be explained by a combined model of polarity reversal and solar rotation. In the positive/negative polarity, the polar magnetic field introduces angular momentum in the same/opposite direction as/to the solar rotation. Thus the addition/subtraction of angular momentum can increase/decrease the motion of plasma to support the formation of sunspots. Since the polarity reverses at the solar maximum, the opposite phenomenon occurs in the declining phase.

  10. Effects of Ice-Crystal Structure on Halo Formation: Cirrus Cloud Experimental and Ray-Tracing Modeling Studies

    Science.gov (United States)

    Sassen, Kenneth; Knight, Nancy C.; Takano, Yoshihide; Heymsfield, Andrew J.

    1994-01-01

    During the 1986 Project FIRE (First International Satellite Cloud Climatology Project Regional Experiment) field campaign, four 22 deg halo-producing cirrus clouds were studied jointly from a ground-based polarization lidar and an instrumented aircraft. The lidar data show the vertical cloud structure and the relative position of the aircraft, which collected a total of 84 slides by impaction, preserving the ice crystals for later microscopic examination. Although many particles were too fragile to survive impaction intact, a large fraction of the identifiable crystals were columns and radial bullet rosettes, with both displaying internal cavitations and radial plate-column combinations. Particles that were solid or displayed only a slight amount of internal structure were relatively rare, which shows that the usual model postulated by halo theorists, i.e., the randomly oriented, solid hexagonal crystal, is inappropriate for typical cirrus clouds. With the aid of new ray-tracing simulations for hexagonal hollow-ended column and bullet-rosette models, we evaluate the effects of more realistic ice-crystal structures on halo formation and lidar depolarization and consider why the common halo is not more common in cirrus clouds.

  11. Application of energy dispersive X-ray fluorescence technique for investigations of trace element composition in medicinal plants from Manipur

    International Nuclear Information System (INIS)

    Joseph, Daisy; Singh, Toudam Sony; Singh, Rajmohan

    2009-01-01

    Seven medicinal plants from remote areas of Manipur were analyzed for their trace elemental composition using an X-ray spectrometer consisting of a radioisotope source of 109 Cd and Si (Li) X-ray detector of resolution 170 eV at 5.9 keV Mn K-X-ray and its associated electronics. In most samples Ca, Mn, Fe and Sr were predominantly seen and Cu, Zn and Pb were detected at trace levels. The presence and significance of the elements in these medicinal plants will be presented and discussed in the following sections of the paper. (author)

  12. Accurate Ray-tracing of Realistic Neutron Star Atmospheres for Constraining Their Parameters

    Science.gov (United States)

    Vincent, Frederic H.; Bejger, Michał; Różańska, Agata; Straub, Odele; Paumard, Thibaut; Fortin, Morgane; Madej, Jerzy; Majczyna, Agnieszka; Gourgoulhon, Eric; Haensel, Paweł; Zdunik, Leszek; Beldycki, Bartosz

    2018-03-01

    Thermal-dominated X-ray spectra of neutron stars in quiescent, transient X-ray binaries and neutron stars that undergo thermonuclear bursts are sensitive to mass and radius. The mass–radius relation of neutron stars depends on the equation of state (EoS) that governs their interior. Constraining this relation accurately is therefore of fundamental importance to understand the nature of dense matter. In this context, we introduce a pipeline to calculate realistic model spectra of rotating neutron stars with hydrogen and helium atmospheres. An arbitrarily fast-rotating neutron star with a given EoS generates the spacetime in which the atmosphere emits radiation. We use the LORENE/NROTSTAR code to compute the spacetime numerically and the ATM24 code to solve the radiative transfer equations self-consistently. Emerging specific intensity spectra are then ray-traced through the neutron star’s spacetime from the atmosphere to a distant observer with the GYOTO code. Here, we present and test our fully relativistic numerical pipeline. To discuss and illustrate the importance of realistic atmosphere models, we compare our model spectra to simpler models like the commonly used isotropic color-corrected blackbody emission. We highlight the importance of considering realistic model-atmosphere spectra together with relativistic ray-tracing to obtain accurate predictions. We also insist upon the crucial impact of the star’s rotation on the observables. Finally, we close a controversy that has been ongoing in the literature in the recent years, regarding the validity of the ATM24 code.

  13. Accounting for partiality in serial crystallography using ray-tracing principles

    International Nuclear Information System (INIS)

    Kroon-Batenburg, Loes M. J.; Schreurs, Antoine M. M.; Ravelli, Raimond B. G.; Gros, Piet

    2015-01-01

    Serial crystallography generates partial reflections from still diffraction images. Partialities are estimated with EVAL ray-tracing simulations, thereby improving merged reflection data to a similar quality as conventional rotation data. Serial crystallography generates ‘still’ diffraction data sets that are composed of single diffraction images obtained from a large number of crystals arbitrarily oriented in the X-ray beam. Estimation of the reflection partialities, which accounts for the expected observed fractions of diffraction intensities, has so far been problematic. In this paper, a method is derived for modelling the partialities by making use of the ray-tracing diffraction-integration method EVAL. The method estimates partialities based on crystal mosaicity, beam divergence, wavelength dispersion, crystal size and the interference function, accounting for crystallite size. It is shown that modelling of each reflection by a distribution of interference-function weighted rays yields a ‘still’ Lorentz factor. Still data are compared with a conventional rotation data set collected from a single lysozyme crystal. Overall, the presented still integration method improves the data quality markedly. The R factor of the still data compared with the rotation data decreases from 26% using a Monte Carlo approach to 12% after applying the Lorentz correction, to 5.3% when estimating partialities by EVAL and finally to 4.7% after post-refinement. The merging R int factor of the still data improves from 105 to 56% but remains high. This suggests that the accuracy of the model parameters could be further improved. However, with a multiplicity of around 40 and an R int of ∼50% the merged still data approximate the quality of the rotation data. The presented integration method suitably accounts for the partiality of the observed intensities in still diffraction data, which is a critical step to improve data quality in serial crystallography

  14. Assessing the ability to derive rates of polar middle-atmospheric descent using trace gas measurements from remote sensors

    Science.gov (United States)

    Ryan, Niall J.; Kinnison, Douglas E.; Garcia, Rolando R.; Hoffmann, Christoph G.; Palm, Mathias; Raffalski, Uwe; Notholt, Justus

    2018-02-01

    We investigate the reliability of using trace gas measurements from remote sensing instruments to infer polar atmospheric descent rates during winter within 46-86 km altitude. Using output from the Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM) between 2008 and 2014, tendencies of carbon monoxide (CO) volume mixing ratios (VMRs) are used to assess a common assumption of dominant vertical advection of tracers during polar winter. The results show that dynamical processes other than vertical advection are not negligible, meaning that the transport rates derived from trace gas measurements do not represent the mean descent of the atmosphere. The relative importance of vertical advection is lessened, and exceeded by other processes, during periods directly before and after a sudden stratospheric warming, mainly due to an increase in eddy transport. It was also found that CO chemistry cannot be ignored in the mesosphere due to the night-time layer of OH at approximately 80 km altitude. CO VMR profiles from the Kiruna Microwave Radiometer and the Microwave Limb Sounder were compared to SD-WACCM output, and show good agreement on daily and seasonal timescales. SD-WACCM CO profiles are combined with the CO tendencies to estimate errors involved in calculating the mean descent of the atmosphere from remote sensing measurements. The results indicate errors on the same scale as the calculated descent rates, and that the method is prone to a misinterpretation of the direction of air motion. The true rate of atmospheric descent is seen to be masked by processes, other than vertical advection, that affect CO. We suggest an alternative definition of the rate calculated using remote sensing measurements: not as the mean descent of the atmosphere, but as an effective rate of vertical transport for the trace gas under observation.

  15. Circularly Polarized X Rays: Another Probe of Ultrafast Molecular Decay Dynamics

    International Nuclear Information System (INIS)

    Travnikova, Oksana; Lindblad, Andreas; Nicolas, Christophe; Soederstroem, Johan; Kimberg, Victor; Miron, Catalin; Liu Jicai; Gel'mukhanov, Faris

    2010-01-01

    Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s→a 1g * inner-shell excitation by circularly polarized x rays in SF 6 . In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.

  16. Field modeling and ray-tracing of a miniature scanning electron microscope beam column.

    Science.gov (United States)

    Loyd, Jody S; Gregory, Don A; Gaskin, Jessica A

    2017-08-01

    A miniature scanning electron microscope (SEM) focusing column design is introduced and its potential performance assessed through an estimation of parameters that affect the probe radius, to include source size, spherical and chromatic aberration, diffraction and space charge broadening. The focusing column, a critical component of any SEM capable of operating on the lunar surface, was developed by the NASA Marshall Space Flight Center and Advanced Research Systems. The ray-trace analysis presented uses a model of the electrostatic field (within the focusing column) that is first calculated using the boundary element method (BEM). This method provides flexibility in modeling the complex electrode shapes of practical electron lens systems. A Fourier series solution of the lens field is then derived within a cylindrical domain whose boundary potential is provided by the BEM. Used in this way, the Fourier series solution is an accuracy enhancement to the BEM solution, allowing sufficient precision to assess geometric aberrations through direct ray-tracing. Two modes of operation with distinct lens field solutions are described. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. MCViNE - An object oriented Monte Carlo neutron ray tracing simulation package

    Science.gov (United States)

    Lin, Jiao Y. Y.; Smith, Hillary L.; Granroth, Garrett E.; Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry; Aczel, Adam A.; Aivazis, Michael; Fultz, Brent

    2016-02-01

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is an open-source Monte Carlo (MC) neutron ray-tracing software for performing computer modeling and simulations that mirror real neutron scattering experiments. We exploited the close similarity between how instrument components are designed and operated and how such components can be modeled in software. For example we used object oriented programming concepts for representing neutron scatterers and detector systems, and recursive algorithms for implementing multiple scattering. Combining these features together in MCViNE allows one to handle sophisticated neutron scattering problems in modern instruments, including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can use simulation components from linear-chain-based MC ray tracing packages which facilitates porting instrument models from those codes. Furthermore it allows for components written solely in Python, which expedites prototyping of new components. These developments have enabled detailed simulations of neutron scattering experiments, with non-trivial samples, for time-of-flight inelastic instruments at the Spallation Neutron Source. Examples of such simulations for powder and single-crystal samples with various scattering kernels, including kernels for phonon and magnon scattering, are presented. With simulations that closely reproduce experimental results, scattering mechanisms can be turned on and off to determine how they contribute to the measured scattering intensities, improving our understanding of the underlying physics.

  18. Fast ray-tracing of human eye optics on Graphics Processing Units.

    Science.gov (United States)

    Wei, Qi; Patkar, Saket; Pai, Dinesh K

    2014-05-01

    We present a new technique for simulating retinal image formation by tracing a large number of rays from objects in three dimensions as they pass through the optic apparatus of the eye to objects. Simulating human optics is useful for understanding basic questions of vision science and for studying vision defects and their corrections. Because of the complexity of computing such simulations accurately, most previous efforts used simplified analytical models of the normal eye. This makes them less effective in modeling vision disorders associated with abnormal shapes of the ocular structures which are hard to be precisely represented by analytical surfaces. We have developed a computer simulator that can simulate ocular structures of arbitrary shapes, for instance represented by polygon meshes. Topographic and geometric measurements of the cornea, lens, and retina from keratometer or medical imaging data can be integrated for individualized examination. We utilize parallel processing using modern Graphics Processing Units (GPUs) to efficiently compute retinal images by tracing millions of rays. A stable retinal image can be generated within minutes. We simulated depth-of-field, accommodation, chromatic aberrations, as well as astigmatism and correction. We also show application of the technique in patient specific vision correction by incorporating geometric models of the orbit reconstructed from clinical medical images. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  19. Reviewed approach to defining the Active Interlock Envelope for Front End ray tracing

    Energy Technology Data Exchange (ETDEWEB)

    Seletskiy, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Shaftan, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-24

    To protect the NSLS-II Storage Ring (SR) components from damage from synchrotron radiation produced by insertion devices (IDs) the Active Interlock (AI) keeps electron beam within some safe envelope (a.k.a Active Interlock Envelope or AIE) in the transverse phase space. The beamline Front Ends (FEs) are designed under assumption that above certain beam current (typically 2 mA) the ID synchrotron radiation (IDSR) fan is produced by the interlocked e-beam. These assumptions also define how the ray tracing for FE is done. To simplify the FE ray tracing for typical uncanted ID it was decided to provide the Mechanical Engineering group with a single set of numbers (x,x’,y,y’) for the AIE at the center of the long (or short) ID straight section. Such unified approach to the design of the beamline Front Ends will accelerate the design process and save valuable human resources. In this paper we describe our new approach to defining the AI envelope and provide the resulting numbers required for design of the typical Front End.

  20. Investigation of temporal and lateral variations of seismic velocities in south Iceland using ray tracing.

    Science.gov (United States)

    Kjartansson, Einar; Bjarnason, Ingi Th.

    2017-04-01

    Tools for ray-tracing through one dimensional earth models consisting of layers of constant velocity gradients, and continuous values across layers, have been developed. They are used to investigate stability and robustness of earthquake locations and velocity determinations in the South Iceland Lowlands (SIL) a transform seismic zone. These tools will also be used to invert for velocity functions for different regions and time periods, by inverting simultaneously for micro-earthquake source parameters and P and S velocities. Increase of velocity gradient with depth will cause rays with different take-off angles to cross, which can result in focusing and triplication when velocity is plotted versus time. It is therefore important to constrain the velocity solutions to avoid this. Large changes in gradient between adjacent layers causes variability of ray density and geometrical spreading, particularly for rays that turn just below the boundaries. This may create artificial clustering in the depth distribution of micro-earthquake source solutions. Resampling of the velocity functions using cubic spline interpolation can be used to reduce these effects. The software is open source and can be accessed at https://github.com/4dseismic

  1. X-ray polarization fluctuations induced by cloud eclipses in active galactic nuclei

    Czech Academy of Sciences Publication Activity Database

    Marin, Frederic; Dovčiak, Michal

    2015-01-01

    Roč. 573, January (2015), A60/1-A60/8 ISSN 0004-6361 R&D Projects: GA MŠk LD12010 Grant - others:EU(XE) COST action MP1104 Institutional support: RVO:67985815 Keywords : galaxies: Seyfert * polarization * radiative transfer * relativistic processes * scattering * X-rays: general Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

  2. GaN quantum dot polarity determination by X-ray photoelectron diffraction

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Olexandr; Bartoš, Igor; Brault, J.; De Mierry, P.; Paskova, T.; Jiříček, Petr

    2016-01-01

    Roč. 389, Dec (2016), s. 1156-1160 ISSN 0169-4332 R&D Projects: GA ČR GA15-01687S; GA MŠk LM2015088 Institutional support: RVO:68378271 Keywords : GaN * semipolar GaN * quantum dots * X-ray photoelectron diffraction * surface polarity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.387, year: 2016

  3. Large-Area Balloon-Borne Polarized Gamma Ray Observer (PoGO)

    Energy Technology Data Exchange (ETDEWEB)

    Blanford, R.

    2005-04-06

    We are developing a new balloon-borne instrument (PoGO), to measure polarization of soft gamma rays (25-200 keV) using asymmetry in azimuth angle distribution of Compton scattering. PoGO will detect 10% polarization in 100mCrab sources in a 6-8 hour observation and bring a new dimension to studies on gamma ray emission/transportation mechanism in pulsars, AGNs, black hole binaries, and neutron star surface. The concept is an adaptation to polarization measurements of well-type phoswich counter technology used in balloon-borne experiments (Welcome-1) and AstroE2 Hard X-ray Detector. PoGO consists of close-packed array of 397 hexagonal well-type phoswich counters. Each unit is composed of a long thin tube (well) of slow plastic scintillator, a solid rod of fast plastic scintillator, and a short BGO at the base. A photomultiplier coupled to the end of the BGO detects light from all 3 scintillators. The rods with decay times < 10 ns, are used as the active elements; while the wells and BGOs, with decay times {approx}250 ns are used as active anti-coincidence. The fast and slow signals are separated out electronically. When gamma rays entering the field-of-view (fwhm {approx} 3deg{sup 2}) strike a fast scintillator, some are Compton scattered. A fraction of the scattered photons are absorbed in another rod (or undergo a second scatter). A valid event requires one clean fast signal of pulse-height compatible with photo-absorption (> 20keV) and one or more compatible with Compton scattering (< 10keV). Studies based on EGS4 (with polarization features) and Geant4 predict excellent background rejection and high sensitivity.

  4. Thermal disc emission from a rotating black hole: X-ray polarization signatures

    Czech Academy of Sciences Publication Activity Database

    Dovčiak, Michal; Muleri, F.; Goosmann, René; Karas, Vladimír; Matt, G.

    2008-01-01

    Roč. 391, č. 1 (2008), s. 32-38 ISSN 0035-8711 R&D Projects: GA ČR GA205/07/0052; GA MŠk(CZ) LC06014 Grant - others:ESA(XE) ESA-PECS project No. 98040 Institutional research plan: CEZ:AV0Z10030501 Keywords : polarization * relativity * instrumentation: polarimeters * X-rays: binaries Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.185, year: 2008

  5. Gamma-Ray Pulsar Light Curves in Offset Polar Cap Geometry

    Science.gov (United States)

    Harding, Alice K.; DeCesar, Megan; Miller, M. Coleman

    2011-01-01

    Recent studies have shown that gamma-ray pulsar light curves are very sensitive to the geometry of the pulsar magnetic field. Pulsar magnetic field geometries, such as the retarded vacuum dipole and force-free magnetospheres, used to model high-energy light curves have distorted polar caps that are offset from the magnetic axis in the direction opposite to rotation. Since this effect is due to the sweepback of field lines near the light cylinder, offset polar caps are a generic property of pulsar magnetospheres and their effects should be included in gamma-ray pulsar light curve modeling. In slot gap models (having two-pole caustic geometry), the offset polar caps cause a strong azimuthal asymmetry of the particle acceleration around the magnetic axis. We have studied the effect of the offset polar caps in both retarded vacuum dipole and force-free geometry on the model high-energy pulse profile. We find that. corn pared to the profile:-; derived from :-;ymmetric caps, the flux in the pulse peaks, which are caustics formed along the trailing magnetic field lines. increases significantly relative to the off-peak emission. formed along leading field lines. The enhanced contrast produces greatly improved slot gap model fits to Fermi pulsar light curves like Vela, which show very little off-peak emIssIon.

  6. [Rapid determination of major and trace elements in the salt lake clay minerals by X-ray fluorescence spectrometry].

    Science.gov (United States)

    Wang, Xiao-Huan; Meng, Qing-Fen; Dong, Ya-Ping; Chen, Mei-Da; Li, Wu

    2010-03-01

    A rapid multi-element analysis method for clay mineral samples was described. This method utilized a polarized wave-length dispersive X-ray fluorescence spectrometer--Axios PW4400, which had a maximum tube power of 4 000 watts. The method was developed for the determination of As, Mn, Co, Cu, Cr, Dy, Ga, Mo, P, Pb, Rb, S, Sr, Ni, ,Cs, Ta, Th, Ti, U, V, Y, Zn, Zr, MgO, K2O, Na2O, CaO, Fe2O3, Al2O3, SiO2 and so on. Thirty elements in clay mineral species were measured by X-ray fluorescence spectrometry with pressed powder pellets. Spectral interferences, in particular the indirect interferences of each element, were studied. A method to distinguish the interference between each other periodic elements in element periodic table was put forward. The measuring conditions and existence were mainly investigated, and the selected background position as well as corrected spectral overlap for the trace elements were also discussed. It was found that the indirect spectral overlap line was the same important as direct spectral overlap line. Due to inducing the effect of indirect spectral overlap, some elements jlike Bi, Sn, W which do not need analysis were also added to the elements channel. The relative standard deviation (RSD) was in the range of 0.01% to 5.45% except three elements Mo, Cs and Ta. The detection limits, precisions and accuracies for most elements using this method can meet the requirements of sample analysis in clay mineral species.

  7. Polarization of TGFs and X-rays from natural and rocket-triggered lightning and its association with source geometry

    Science.gov (United States)

    Bagheri, M.; Dwyer, J. R.

    2017-12-01

    Terrestrial gamma-ray flashes (TGFs) are bright bursts of gamma rays produced by thunderstorms, most often observed by spacecraft in the low-Earth orbit. Two important properties of TGFs are their source altitudes and the width and direction of the gamma-ray beam. Unfortunately, it has been difficult to disentangle these properties using single point spacecraft measurements, which has hampered attempts to constrain TGF models. X-ray and gamma-ray polarization measurements of astrophysical sources has been of interest for many decades, and new space missions are being proposed to make such measurements. This raises the question, do TGFs and the related X-ray emissions from lightning have observable gamma-ray or X-ray polarization, and, if so, what would this polarization tell us about their source? In this work, the REAM Monte Carlo code, which has been used to model TGFs for many years, has been modified to record the linear polarization of X-rays and gamma rays. The predicted polarization and fluence of TGFs and X-rays from lightning are presented as a function of source altitude and beam geometry. It is found that mid-altitude TGFs, near of just above the tops of thunderclouds, could have polarizations as high as 10%, but because only a few tens of counts are typically detected by spacecraft in low-Earth orbit from TGFs, detecting this polarization level is unlikely. It is also found that low-altitude TGFs ( 3.5 km) could produce gamma ray polarizations up to about 5% on the ground, which may be detectable since the number of counts detected during ground-level TGFs can be large. For both TGFs seen from space and ground-level TGFs, the dominant process for producing the polarization is found to be Compton scattering. On the other hand, avalanches of X-rays produced from rocket-triggered lightning measured on the ground showed a maximum polarization of 13% which is also due to Compton scattering. This level of polarization seems detectable by polarimeters on the

  8. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Pal Arindam

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  9. Evaluation of Diversity Antenna Designs Using Ray Tracing, Measured Radiation Patterns, and MIMO Channel Measurements

    Directory of Open Access Journals (Sweden)

    Arindam Pal

    2007-01-01

    Full Text Available This paper presents an evaluation of the MIMO performance of three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside channel simulations. A channel model which employs the plane-wave approximation was used to combine the embedded antenna radiation patterns of the candidate devices obtained from far-field pattern measurements and multipath component parameters from an indoor ray-tracer. The 4-element candidate arrays were each constructed using a different type of antenna element, and despite the diverse element directivities, pattern characteristics, and polarization purities, all three devices were constructed to fully exploit diversity in polarization, space, and angle. Thus, low correlation and high information theoretic capacity was observed in each case. A good match between the model and the measurements is also demonstrated, especially for 2×2 MIMO subsets of identically or orthogonally polarized linear slot antennas. The interdependencies between the channel XPD, directional spread and pathloss, and the respective impact on channel capacity are also discussed in this paper.

  10. THE EFFECT OF GRAVITATION ON THE POLARIZATION STATE OF A LIGHT RAY

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Tanay; Sen, A. K. [Department of Physics Assam University, Silchar-788011, Assam (India)

    2016-12-10

    In the present work, detailed calculations have been carried out on the rotation of the polarization vector of an electromagnetic wave due to the presence of a gravitational field of a rotating body. This has been done using the general expression of Maxwell’s equation in curved spacetime. Considering the far-field approximation (i.e., the impact parameter is greater than the Schwarzschild radius and rotation parameter), the amount of rotation of the polarization vector as a function of impact parameter has been obtained for a rotating body (considering Kerr geometry). The present work shows that the rotation of the polarization vector cannot be observed in the case of Schwarzschild geometry. This work also calculates the rotational effect when considering prograde and retrograde orbits for the light ray. Although the present work demonstrates the effect of rotation of the polarization vector, it confirms that there would be no net polarization of an electromagnetic wave due to the curved spacetime geometry in a Kerr field.

  11. A Fluorescence Polarization Assay To Detect Steroid Hormone Traces in Milk.

    Science.gov (United States)

    Varriale, Antonio; Pennacchio, Anna; Pinto, Gabriella; Oliviero, Giorgia; D'Errico, Stefano; Majoli, Adelia; Scala, Andrea; Capo, Alessandro; Pennacchio, Angela; Di Giovanni, Stefano; Staiano, Maria; D'Auria, Sabato

    2015-10-21

    Steroids are a class of hormones improperly used in livestock as growth-promoting agents. Due to their high risk for human health, the European Union (EU) has strictly forbidden the administration of all natural and synthetic steroid hormones to food-producing animals, and the development of new rapid detection methods are greatly encouraged. This work reports a novel fluorescence polarization assay, ready to use, capable of detecting 17β-estradiol directly in milk samples with a low limit of detection of <10 pmol. It is based on the coupling of monospecific antibodies against 17β-estradiol and fluorophores, capable of modulating the fluorescence polarization emission on the basis of the specific binding of antibodies to fluorescence-labeled 17β-estradiol derivative. The successful detection of 17β-estradiol has disclosed the development of an efficient method, easily extensible to any food matrix and having the potential to become a milestone in food quality and safety.

  12. Onset of the Magnetic Explosion in Solar Polar Coronal X-Ray Jets

    Science.gov (United States)

    Moore, Ronald L.; Sterling, Alphonse C.; Panesar, Navdeep

    2017-08-01

    We examine the onset of the driving magnetic explosion in 15 random polar coronal X-ray jets. Each eruption is observed in a coronal X-ray movie from Hinode and in a coronal EUV movie from Solar Dynamics Observatory. Contrary to the Sterling et al (2015, Nature, 523, 437) scenario for minifilament eruptions that drive polar coronal jets, these observations indicate: (1) in most polar coronal jets (a) the runaway internal tether-cutting reconnection under the erupting minifilament flux rope starts after the spire-producing breakout reconnection starts, not before it, and (b) aleady at eruption onset, there is a current sheet between the explosive closed magnetic field and ambient open field; and (2) the minifilament-eruption magnetic explosion often starts with the breakout reconnection of the outside of the magnetic arcade that carries the minifilament in its core. On the other hand, the diversity of the observed sequences of occurrence of events in the jet eruptions gives further credence to the Sterlling et al (2015, Nature, 523, 437) idea that the magnetic explosions that make a polar X-ray jet work the same way as the much larger magnetic explosions that make and flare and CME. We point out that this idea, and recent observations indicating that magnetic flux cancelation is the fundamental process that builds the field in and around pre-jet minifilaments and triggers the jet-driving magnetic explosion, together imply that usually flux cancelation inside the arcade that explodes in a flare/CME eruption is the fundamental process that builds the explosive field and triggers the explosion.This work was funded by the Heliophysics Division of NASA's Science Mission Directorate through its Living With a Star Targeted Research and Technology Program, its Heliophsyics Guest Investigators Program, and the Hinode Project.

  13. Determination of minor and trace elements in kidney stones by x-ray fluorescence analysis

    Science.gov (United States)

    Srivastava, Anjali; Heisinger, Brianne J.; Sinha, Vaibhav; Lee, Hyong-Koo; Liu, Xin; Qu, Mingliang; Duan, Xinhui; Leng, Shuai; McCollough, Cynthia H.

    2014-03-01

    The determination of accurate material composition of a kidney stone is crucial for understanding the formation of the kidney stone as well as for preventive therapeutic strategies. Radiations probing instrumental activation analysis techniques are excellent tools for identification of involved materials present in the kidney stone. In particular, x-ray fluorescence (XRF) can be very useful for the determination of minor and trace materials in the kidney stone. The X-ray fluorescence measurements were performed at the Radiation Measurements and Spectroscopy Laboratory (RMSL) of department of nuclear engineering of Missouri University of Science and Technology and different kidney stones were acquired from the Mayo Clinic, Rochester, Minnesota. Presently, experimental studies in conjunction with analytical techniques were used to determine the exact composition of the kidney stone. A new type of experimental set-up was developed and utilized for XRF analysis of the kidney stone. The correlation of applied radiation source intensity, emission of X-ray spectrum from involving elements and absorption coefficient characteristics were analyzed. To verify the experimental results with analytical calculation, several sets of kidney stones were analyzed using XRF technique. The elements which were identified from this techniques are Silver (Ag), Arsenic (As), Bromine (Br), Chromium (Cr), Copper (Cu), Gallium (Ga), Germanium (Ge), Molybdenum (Mo), Niobium (Nb), Rubidium (Rb), Selenium (Se), Strontium (Sr), Yttrium (Y), Zirconium (Zr). This paper presents a new approach for exact detection of accurate material composition of kidney stone materials using XRF instrumental activation analysis technique.

  14. Development of a compact grazing exit X-ray fluorescence spectrometer for fast trace elemental analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ashida, Takafumi, E-mail: ashidatakafumi@gmail.com; Tsuji, Kouichi

    2014-11-01

    A compact grazing exit X-ray fluorescence (GE-XRF) spectrometer was developed in the laboratory. An Al cylindrical collimator for the primary X-rays was placed just above the sample stage. This collimator also played the role of an exit slit to detect fluorescent X-rays at small grazing exit angles. Therefore, no additional exit slit was used in this setup, leading to a compact design. The entire size of the analysis equipment was 80 mm × 200 mm × 170 mm (horizontal × vertical × height). The maximum exit angle was adjusted to the height of the sample stage. The background was drastically reduced at grazing exit angles, enabling trace elemental analysis. A calibration curve was obtained using 10 μL Ga solutions. Accordingly, the detection limit for Ga was evaluated to be 20 ppb. - Highlights: • We developed a compact GE-XRF spectrometer. • The dimension of GE-XRF spectrometer was 80 mm × 200 mm × 170 mm. • A detection limit of 20 ppb for Ga was obtained. • Analytical performance was comparable with that of a table-top TXRF spectrometer.

  15. Seasonal variation of secondary cosmic rays in the low polar atmosphere

    Science.gov (United States)

    Germanenko, Alexey; Balabin, Yury

    Monitoring of different kind of secondary cosmic rays in the low atmosphere is carried out for some years in the Polar Geophysical Institute. At the present moment two monitoring stations (Apatity, Murmansk region and Barentsburg, Spitzbergen) are in operation. Additionally to conventional 18-NM-64 neutron monitor (NM) there are leadless 4-NM-64 section (LLNM), thermal neutron detector (TND) and scintillation detector of gamma-ray (SDG) of 20-400 keV energy range. SDG has 5 cm lead shield at bottom and sides, accepts radiation only from the atmosphere. In a row of neutron detectors from NM to TND seasonal variation grows up from 0 to ˜ 10 %. The distinct and big seasonal variation (˜ 30 %) is on SDG detector. Low energy gamma-rays are caused of pion and muon decay, first of all low energy muons. It was suggested muon seasonal variation, depending on atmosphere temperature and seasonal condition, determines the SDG-variation.

  16. Development of manufacture of mirror glass substrate for x-ray timing and polarization observatory

    Science.gov (United States)

    Wei, Zhenbo; Ge, Bing; Jin, Xin; Liu, Na; Liao, Yingyu; Ma, Bin; Bai, Yuhong; Wang, Zhanshan

    2016-07-01

    In China, X-ray timing and polarization (XTP) observatory will have a collection area of 9,000 cm2 at 2 6 keV. The observatory consists of five identical hard X-ray telescopes and ten identical soft X-ray telescopes. The angular resolution is about 1 arcminute of HPD (half-power diameter). Each telescope consists of a large number of mirror segments precisely assembled together. Our development of the mirror glass substrate is presented in this manuscript. These substrates are produced by slumping commercially available thin glass sheets. Here, we report on our work of manufacturing these substrates. The optimization of the slumping procedure is described and optimal procedure parameters are reported. The figure error of slumped glass substrates was measured by a laser scanner and an interferometer with CGH. The measurement demonstrated that the figure error is lower enough for the construction of XTP telescopes.

  17. On self-consistent ray-tracing and Fokker-Planck modeling of the hard X-ray emission during lower-hybrid current driven in Tokamaks

    International Nuclear Information System (INIS)

    Bizarro, J.P.; Peysson, Y.; Bonoli, P.T.; Carrasco, J.; Dudok de Wit, T.; Fuchs, V.; Hoang, G.T.; Litaudon, X.; Moreau, D.; Pocheau, C.; Shkarofsky, I.P.

    1993-04-01

    A detailed investigation is presented on the ability of combined ray-tracing and Fokker-Planck calculations to predict the hard x-ray (HXR) emission during lower-hybrid (LH) current drive in tokamaks when toroidally induced-ray-stochasticity is important. A large number of rays is used and the electron distribution function is obtained by self-consistently iterating the appropriate LH power deposition and Fokker-Planck calculations. Most of the experimentally observed features of the HXR emission are correctly predicted. It is found that corrections due to radial diffusion of suprathermal electrons and to radiation scattering by the inner wall can be significant

  18. Influence of Polarization of the Incident Beam on Integrated Intensities in X-Ray Energy-Dispersive Diffractometry

    DEFF Research Database (Denmark)

    Olsen, J. Staun; Buras, B.; Jensen, T.

    1978-01-01

    Polarization measurements of the primary X-ray beam produced by thick copper and tungsten anodes are reported and formulas derived for integrated intensities of Bragg reflections in energy-dispersive diffractometry with the polarization of the primary beam taken into account. It was found...

  19. Ray tracing analysis of stray light for charge exchange recombination spectroscopy on ITER

    International Nuclear Information System (INIS)

    Kajita, Shin; De Bock, Maarten; Von Hellermann, Manfred; Kukushkin, Andrei; Barnsley, Robin

    2015-01-01

    Charge exchange recombination spectroscopy (CXRS) provides basic measurements in ITER such as the ion temperature, plasma rotation, and the impurity and helium content. One of the issues concerning all spectroscopic measurements in ITER is the influence of the reflection of light in a vacuum vessel, since ITER will have a full metallic wall, which has higher optical reflectance than a carbon wall. The noise level can be enhanced and the signal can be disturbed by the reflection. In this study, the influences of the light reflection on the CXRS measurement have been investigated using a ray tracing simulation. Influences of the reflection of the active CXRS signal, the light emission from the divertor and scrape off layer, and bremsstrahlung are quantitatively shown in typical discharge scenario cases. (paper)

  20. Simulation of radiation damping in rings, using stepwise ray-tracing methods

    Science.gov (United States)

    Méot, F.

    2015-06-01

    The ray-tracing code Zgoubi computes particle trajectories in arbitrary magnetic and/or electric field maps or analytical field models. It includes a built-in fitting procedure, spin tracking, many Monte Carlo processes. The accuracy of the integration method makes it an efficient tool for multi-turn tracking in periodic machines. Energy loss by synchrotron radiation, based on Monte Carlo techniques, had been introduced in Zgoubi in the early 2000s for studies regarding the linear collider beam delivery system. However, only recently has this Monte Carlo tool been used for systematic beam dynamics and spin diffusion studies in rings, including the eRHIC electron-ion collider project at the Brookhaven National Laboratory. Some beam dynamics aspects of this recent use of Zgoubi capabilities, including considerations of accuracy as well as further benchmarking in the presence of synchrotron radiation in rings, are reported here.

  1. The determination of trace elements in uranium ores by x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    De Villiers, W. van Z.

    1983-11-01

    The determination of 17 trace elements (As, Ba, Co, Cr, Cu, Mo, Nb, Ni, Pb, Rb, Sr, Th, U, V, Y, Zn and Zr) in uranium ores by x-ray fluorescence spectrometry was investigated in this study. The determination of major elements was also necessary for the calculation of mass absorption coefficients. Initially a method was developed for the determination of the elements of interest in unmineralised silicates. Correction for absorption of radiation by the sample were made by means of mass absorption coefficients which were obtained from the relation between the inverse of the mass absorption coefficient and the intensity of the Compton scattering peak. The Feather and Willis method was used for determining the background intensity at the peak positions as well as for mass absorption coefficients. It was observed that the background intensity in the region of the uranium lines increases with increasing uranium content of the sample

  2. Sample preparation techniques in trace element analysis by X-ray emission spectroscopy

    International Nuclear Information System (INIS)

    Valkovic, V.

    1983-11-01

    The report, written under a research contract with the IAEA, contains a detailed presentation of the most difficult problem encountered in the trace element analysis by methods of the X-ray emission spectroscopy, namely the sample preparation techniques. The following items are covered. Sampling - with specific consideration of aerosols, water, soil, biological materials, petroleum and its products, storage of samples and their handling. Pretreatment of samples - preconcentration, ashing, solvent extraction, ion exchange and electrodeposition. Sample preparations for PIXE - analysis - backings, target uniformity and homogeneity, effects of irradiation, internal standards and specific examples of preparation (aqueous, biological, blood serum and solid samples). Sample preparations for radioactive sources or tube excitation - with specific examples (water, liquid and solid samples, soil, geological, plants and tissue samples). Finally, the problem of standards and reference materials, as well as that of interlaboratory comparisons, is discussed

  3. Tracing the accretion history of supermassive Black Holes through X-ray variability

    Science.gov (United States)

    Paolillo, M.; Papadakis, I.

    2017-10-01

    Using the 7Ms observations of the Chandra Deep Field South spanning more than 15 years, we study the variability properties of high-redshift AGNs. We show that distant supermassive Black Holes behave similarly to nearby sources, possessing a red noise PDS with a possible break at high frequencies. We test different models to describe the X-ray variability showing that the observations favour a dependence of the variability on both BH mass and accretion rate. Using this result we trace for the AGN accretion history up to z˜ 3 finding that it is consistent with values obtained by different tracers, suggesting an almost constant Eddington rate with a tentative slight increase at 2

  4. Ray tracing method for simulation of laser beam interaction with random packings of powders

    Science.gov (United States)

    Kovalev, O. B.; Kovaleva, I. O.; Belyaev, V. V.

    2018-03-01

    Selective laser sintering is a technology of rapid manufacturing of a free form that is created as a solid object by selectively fusing successive layers of powder using a laser. The motivation of this study is due to the currently insufficient understanding of the processes and phenomena of selective laser melting of powders whose time scales differ by orders of magnitude. To construct random packings from mono- and polydispersed solid spheres, the algorithm of their generation based on the discrete element method is used. A numerical method of ray tracing is proposed that is used to simulate the interaction of laser radiation with a random bulk packing of spherical particles and to predict the optical properties of the granular layer, the extinction and absorption coefficients, depending on the optical properties of a powder material.

  5. Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico

    Science.gov (United States)

    Martinez, T.; Lartigue, J.; Zarazua, G.; Avila-Perez, P.; Navarrete, M.; Tejeda, S.

    2010-06-01

    Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO 3 and H 2O 2 (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different ( α = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 μg g - 1 . A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of "Citrus Leaves" and a blank were treated in the same way.

  6. Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico

    International Nuclear Information System (INIS)

    Martinez, T.; Lartigue, J.; Zarazua, G.; Avila-Perez, P.; Navarrete, M.; Tejeda, S.

    2010-01-01

    Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO 3 and H 2 O 2 (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different (α = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 μg g -1 . A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of 'Citrus Leaves' and a blank were treated in the same way.

  7. Incorporating geometric ray tracing to generate initial conditions for intensity modulated arc therapy optimization.

    Science.gov (United States)

    Oliver, Mike; Gladwish, Adam; Craig, Jeff; Chen, Jeff; Wong, Eugene

    2008-07-01

    Intensity modulated arc therapy (IMAT) is a rotational variant of Intensity modulated radiation therapy (IMRT) that is achieved by allowing the multileaf collimator (MLC) positions to vary as the gantry rotates around the patient. This work describes a method to generate an IMAT plan through the use of a fast ray tracing technique based on dosimetric and geometric information for setting initial MLC leaf positions prior to final IMAT optimization. Three steps were used to generate an IMAT plan. The first step was to generate arcs based on anatomical contours. The second step was to generate ray importance factor (RIF) maps by ray tracing the dose distribution inside the planning target volume (PTV) to modify the MLC leaf positions of the anatomical arcs to reduce the maximum dose inside the PTV. The RIF maps were also segmented to create a new set of arcs to improve the dose to low dose voxels within the PTV. In the third step, the MLC leaf positions from all arcs were put through a leaf position optimization (LPO) algorithm and brought into a fast Monte Carlo dose calculation engine for a final dose calculation. The method was applied to two phantom cases, a clinical prostate case and the Radiological Physics Center (RPC)'s head and neck phantom. The authors assessed the plan improvements achieved by each step and compared plans with and without using RIF. They also compared the IMAT plan with an IMRT plan for the RPC phantom. All plans that incorporated RIF and LPO had lower objective function values than those that incorporated LPO only. The objective function value was reduced by about 15% after the generation of RIF arcs and 52% after generation of RIF arcs and leaf position optimization. The IMAT plan for the RPC phantom had similar dose coverage for PTV1 and PTV2 (the same dose volume histogram curves), however, slightly lower dose to the normal tissues compared to a six-field IMRT plan. The use of a ray importance factor can generate initial IMAT arcs

  8. POLARIZATION EVOLUTION OF EARLY OPTICAL AFTERGLOWS OF GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Mi-Xiang; Dai, Zi-Gao [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, Xue-Feng, E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-01-10

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on the polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock requires that the magnetization degree of the jet should not be high (σ ≤ 1), so that the jet is mainly composed of baryons and leptons. We then calculate the light curves and polarization evolution of early optical afterglows and find that when the polarization position angle changes by 90° during the early afterglow, the polarization degree is zero for a toroidal magnetic field but is very likely to be nonzero for an aligned magnetic field. This result would be expected to provide a probe for the central engine of GRBs because an aligned field configuration could originate from a magnetar central engine and a toroidal field configuration could be produced from a black hole via the Blandford–Znajek mechanism. Finally, for such two kinds of magnetic field configurations, we fit the observed data of the early optical afterglow of GRB 120308A equally well.

  9. Short bent-core molecules: X-ray, polarization, dielectricity, texture and electro-optics investigations.

    Science.gov (United States)

    Torgova, S; Sreenilayam, S P; Panarin, Yu P; Francescangeli, O; Vita, F; Vij, J K; Pozhidaev, E; Minchenko, M; Ferrero, C; Strigazzi, A

    2017-08-30

    Bent-core liquid crystals based on 1,2,4-oxadiazole as a central unit have been the first mesogens to exhibit a ferroelectric response in the nematic phase. This behavior has been widely recognized as due to the presence of smectic-like polar cybotactic clusters permeating the nematic phase. Unfortunately, these compounds exhibited rather high melting points, about 120 °C, due to the presence of four benzene rings in the molecules. Here we describe the synthesis and physical characterization of a new series of BC mesogens, featuring the same bent core as the previous compounds but shorter outer substituents. By keeping only two benzene rings, we were able to lower the melting points to about 70 °C. However, while X-ray diffraction and dielectric spectroscopy measurements confirm the cybotactic nature of the nematic phase of these compounds, polarization and electro-optical measurements ascribe their polar response to flexoelectricity rather than to spontaneous polarization. Finally, texture investigation suggests the biaxiality of the nematic phase, which is indicated also by conoscopic measurements. These results are important for recognizing size and rigidity limitations in designing bent-core liquid crystal molecules suitable for applications.

  10. Determination of trace elements in coffee beans by XRF spectrometer equipped with polarization optics and its application to identification of their production area

    International Nuclear Information System (INIS)

    Akamine, Takao; Otaka, Akiko; Nakai, Izumi; Hokura, Akiko; Ito, Yuji

    2010-01-01

    The production area of coffee beans becomes a brand name, which gives reputations for the products, which is related to the price. This leads to room for mislabeling the products by unscrupulous market dealers. A rapid and easy method for the analysis of trace-element composition of coffee beans, which could be a good indicator of their production area, was studied in the present work. Coffee beans of 6 different regions (Brazil, Colombia, Vietnam, Indonesia, Tanzania, Guatemala) were analyzed by using a highly sensitive X-ray fluorescence spectrometer with three dimensional polarization optics. The experimental conditions were optimized so as to analyze 6 elements (Mn, Fe, Ni, Rb, Sr, Ba) in coffee beans, and linear calibration curves were obtained for the quantitative analysis of those elements. The analytical results were used in principal-component analysis to classify the coffee beans according to the geographical origin, which results in a successful characterization of the 6 production areas. It is found that roasted beans can be used with the same criterion as their green beans. Consequently, a rapid and easy way for the characterization of the geographic origin of coffee beans has been established in this study. (author)

  11. Polarization-dependent X-ray absorption spectroscopy of MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, Nils; Hu, Zhiwei; Tjeng, Liu Hao [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Bohaty, Ladislav; Becker-Bohaty, Petra [Kristallographisches Institut, Universitaet zu Koeln (Germany); Tanaka, Arata [Department of Quantum Matter, Hiroshima University (Japan)

    2008-07-01

    Multiferroic materials which combine magnetism and ferroelectricity currently attract considerable attention. One of the recently discovered multiferroic materials is MnWO{sub 4} (Huebnerite). It belongs to the group of multiferroics where a spontaneous electric polarization is caused by a spiral magnetic structure with a spin rotation axis not coinciding with the propagation vector. To investigate the details of this astonishing combination of electronic and magnetic properties, we look at the electronic structure with the use of polarization-dependent X-ray absorption spectroscopy on single crystals of MnWO{sub 4}. The analysis of the experimental data on the L-edge of Mn is done by a configuration interaction calculation and is discussed.

  12. Full Polarization Analysis of Resonant Superlattice and Forbidden x-ray Reflections in Magnetite

    International Nuclear Information System (INIS)

    Wilkins, S.B.; Bland, S.R.; Detlefs, B.; Beale, T.A.W.; Mazzoli, C.; Joly, Y.; Hatton, P.D.; Lorenzo, J.E.; Brabers, V.A.M.

    2009-01-01

    Despite being one of the oldest known magnetic materials, and the classic mixed valence compound, thought to be charge ordered, the structure of magnetite below the Verwey transition is complex and the presence and role of charge order is still being debated. Here, we present resonant x-ray diffraction data at the iron K-edge on forbidden (0, 0, 2n+1) C and superlattice (0, 0, 2n+1/2)C reflections. Full linear polarization analysis of the incident and scattered light was conducted in order to explore the origins of the reflections. Through simulation of the resonant spectra we have confirmed that a degree of charge ordering takes place, while the anisotropic tensor of susceptibility scattering is responsible for the superlattice reflections below the Verwey transition. We also report the surprising result of the conversion of a significant proportion of the scattered light from linear to nonlinear polarization.

  13. Radiation parameters of the X-ray binary A 0535+26=HDE 245770 from the polarization and photometric data

    International Nuclear Information System (INIS)

    Larionov, V.M.

    1987-01-01

    An analysis of Shakhovskay et al's observations of the X-ray binary A 0535+26=HDE 245770 made it possible to distinguish in its radiation the two components connected with the visible star (O9 III) and the accretion disc around the neutron star. The interstellar polarization parameters are in accordance with Serkowski's formula and the observations of the field stars. The IR and optical variability can be explained in terms of variable accretion disc radiation. The intrinsic polarization parameters obtained can be used to predict, in the model proposed, the directions of the polarization vectors in the IR and X-ray bands

  14. Determination of trace elements in tea by wavelength dispersive X-ray fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Gong Chunhui; Zeng Guoqiang; Ge Liangquan; Li Jun; Wen Ziqiang

    2013-01-01

    Background: Measuring trace elements in tea can determine its nutritional value, verify the authenticity and place of origin, and detect the poisonous and harmful elements remaining in tea due to the application of chemical fertilizers and pesticides. Purpose: In order to reduce the time for sample preparation and the costs of equipment maintenance, wavelength dispersive X-ray fluorescence (WDXRF) spectroscopy was used to determine the trace elements in tea which is rapid, non-destructive and accurate. The contents of more than 20 elements can be measured simultaneously. Methods: Sample pieces were made by the sample preparation method of boric acid rebasing. To avoid the exogenous environmental pollution subjected in the growth of tea, we removed the residual dust of the tea by cleaning it. According to the principle that the standard samples should be similar types with the samples to be analyzed to select standard samples. The curves were built by SuperQ, which contained compiling the measurement conditions, establishing the measurement conditions, checking the angles, determining the measurement times, checking PHD and adding the contents and the names of sample pieces. The accuracy of the method can be obtained by comparing the measured values with the trace element contents of standard samples. The contents of trace elements in tea determined by WDXRF can be used to classify the tea attribution and the tea species through cluster analysis of SPSS software. Results: (1) The results show that the biggest relative standard deviation is 0.43% of Pb, and the precision is very good. (2) Five kinds of tea are taken separately in Fujian and Yunnan, measured three times with the established working curves. And tree diagram of cluster analysis can be obtained with SPSS software to analyze the measured average values with cluster analysis, coupling method between groups and Minkowski distance measurement techniques. It can be seen that in the tree diagram, when the

  15. Carbon nanotube enhanced membrane distillation for online preconcentration of trace pharmaceuticals in polar solvents.

    Science.gov (United States)

    Gethard, Ken; Mitra, Somenath

    2011-06-21

    Carbon nanotube enhanced membrane distillation (MD) is presented as a novel, online analytical preconcentration method for removing polar solvents thereby concentrating the analytes, making this technique an alternate to conventional thermal evaporation. In a carbon nanotube immobilized membrane (CNIM), the CNTs serve as sorbent sites and provide additional pathways for enhanced solvent vapor transport, thus enhancing preconcentration. Enrichment using CNIM doubled compared to membranes without CNTs, while the methanol flux and mass transfer coefficients increased by 61% and 519% respectively. The carbon nanotube enhanced MD process showed excellent precision (RSD of 3-5%), linearity, and the detection limits were in the range of 0.001 to 0.009 mg L(-1) by HPLC analysis.

  16. The hard X-ray emission spectra from accretion columns in intermediate polars

    Science.gov (United States)

    Yi, Insu; Vishniac, Ethan T.

    1994-01-01

    We consider the hard (greater than 2 keV) X-ray emission from accretion columns in an intermediate polar system, GK Per, using a simple settling solution. The rate of photon emission per logarithmic energy interval can be fitted with a power law, E(exp -gamma), with gamma approximately 2.0, in agreement with observations. This index is only weakly dependent on the mass accretion rate, dot-M, for dot-M in the range of a few times 10(exp 16-18) g/s. The peak energy of the photon spectra (after photoelectric absorption) is expected to be E(sub p) approximately (5 keV) gamma(exp -1/3) (N(sub H)/10(exp 23)/sq cm)(exp 1/3) where N(sub H) is the hydrogen column density along the line of sight. The observed spectra of GK Per and possibly of V1223 Sgr suggest N(sub H) approximately 10(exp 23)/sq cm. This large N(sub H) may be due to partially ionized preshock column material. Alternatively, we also consider absorption by the cool outer parts of an accretion disk. In this case the photoelectric absorption depth in the disk is a sensitive function of inclination. For GK Per the required inclination is approximately 83 deg. For mass accretion rates larger than a critical rate of approximately 10(exp 18) g/s, X-ray emission from the column accretion is significantly affected by radiation drag. Although the mass accretion rate increases dramatically during outbursts, the observed hard (greater than 2 keV) X-ray luminosity will not rise proportionately. The slope and peak energy of the outburst spectra are only weakly affected. We conclude that the observed X-ray spectra can be explained by this simple analytic solution and that the production of hard X-rays from the accretion shock at the magnetic poles in the intermediate polars is in general agreement with the observations. However, since the X-ray emission and absorption depend on the mass accretion rate in a complicated manner, observed hard X-ray luminosities (greater than 2 keV) are not a good indicator of the mass

  17. Three-dimensional ray tracing for refractive correction of human eye ametropies

    Science.gov (United States)

    Jimenez-Hernandez, J. A.; Diaz-Gonzalez, G.; Trujillo-Romero, F.; Iturbe-Castillo, M. D.; Juarez-Salazar, R.; Santiago-Alvarado, A.

    2016-09-01

    Ametropies of the human eye, are refractive defects hampering the correct imaging on the retina. The most common ways to correct them is by means of spectacles, contact lenses, and modern methods as laser surgery. However, in any case it is very important to identify the ametropia grade for designing the optimum correction action. In the case of laser surgery, it is necessary to define a new shape of the cornea in order to obtain the wanted refractive correction. Therefore, a computational tool to calculate the focal length of the optical system of the eye versus variations on its geometrical parameters is required. Additionally, a clear and understandable visualization of the evaluation process is desirable. In this work, a model of the human eye based on geometrical optics principles is presented. Simulations of light rays coming from a punctual source at six meter from the cornea are shown. We perform a ray-tracing in three dimensions in order to visualize the focusing regions and estimate the power of the optical system. The common parameters of ametropies can be easily modified and analyzed in the simulation by an intuitive graphic user interface.

  18. Quantification and localization of trace metals in natural plancton using a synchrotron x-ray fluorescence microprobe.

    Energy Technology Data Exchange (ETDEWEB)

    Twining, B. S.; Baines, S. B.; Fisher, N. S.; Jacobsen, C.; Maser, J.; State Univ. of New York at Stony Brook

    2003-03-01

    The accumulation of trace metals by planktonic protists influences the growth of primary producers, metal biogeochemical cycling, and metal bioaccumulation in aquatic food chains. Despite their importance, unequivocal measurements of trace element concentrations in individual plankton cells have not been possible to date. We have used the 2-ID-E side-branch hard x-ray microprobe at the Advanced Photon Source to measure trace elements in individual marine plankton cells. This microprobe employs zoneplate optics to produce the sub-micron spatial resolution and low background fluorescence required to produce trace element maps of planktonic protist cells ranging in size from 3 to >50 {micro}m. We have developed preservation, rinsing, and mounting protocols that remove most of the salt from our marine samples, thus simplifying the identification of unknown cells and reducing high Cl-related background fluorescence. We have also developed spectral modeling techniques that account for the frequent overlap of adjacent fluorescence peaks and non-uniform detector response. Finally, we have used parallel soft x-ray transmission and epifluorescence microscopy images to estimate C normalized trace element concentrations, identify functional cell types (e.g., photosynthetic vs. non-photosynthetic), and correlate cell structures with spatial patterns in trace element fluorescence.

  19. The Use of Pro/Engineer CAD Software and Fishbowl Tool Kit in Ray-tracing Analysis

    Science.gov (United States)

    Nounu, Hatem N.; Kim, Myung-Hee Y.; Ponomarev, Artem L.; Cucinotta, Francis A.

    2009-01-01

    This document is designed as a manual for a user who wants to operate the Pro/ENGINEER (ProE) Wildfire 3.0 with the NASA Space Radiation Program's (SRP) custom-designed Toolkit, called 'Fishbowl', for the ray tracing of complex spacecraft geometries given by a ProE CAD model. The analysis of spacecraft geometry through ray tracing is a vital part in the calculation of health risks from space radiation. Space radiation poses severe risks of cancer, degenerative diseases and acute radiation sickness during long-term exploration missions, and shielding optimization is an important component in the application of radiation risk models. Ray tracing is a technique in which 3-dimensional (3D) vehicle geometry can be represented as the input for the space radiation transport code and subsequent risk calculations. In ray tracing a certain number of rays (on the order of 1000) are used to calculate the equivalent thickness, say of aluminum, of the spacecraft geometry seen at a point of interest called the dose point. The rays originate at the dose point and terminate at a homogenously distributed set of points lying on a sphere that circumscribes the spacecraft and that has its center at the dose point. The distance a ray traverses in each material is converted to aluminum or other user-selected equivalent thickness. Then all equivalent thicknesses are summed up for each ray. Since each ray points to a direction, the aluminum equivalent of each ray represents the shielding that the geometry provides to the dose point from that particular direction. This manual will first list for the user the contact information for help in installing ProE and Fishbowl in addition to notes on the platform support and system requirements information. Second, the document will show the user how to use the software to ray trace a Pro/E-designed 3-D assembly and will serve later as a reference for troubleshooting. The user is assumed to have previous knowledge of ProE and CAD modeling.

  20. Accounting for partiality in serial crystallography using ray-tracing principles.

    Science.gov (United States)

    Kroon-Batenburg, Loes M J; Schreurs, Antoine M M; Ravelli, Raimond B G; Gros, Piet

    2015-09-01

    Serial crystallography generates `still' diffraction data sets that are composed of single diffraction images obtained from a large number of crystals arbitrarily oriented in the X-ray beam. Estimation of the reflection partialities, which accounts for the expected observed fractions of diffraction intensities, has so far been problematic. In this paper, a method is derived for modelling the partialities by making use of the ray-tracing diffraction-integration method EVAL. The method estimates partialities based on crystal mosaicity, beam divergence, wavelength dispersion, crystal size and the interference function, accounting for crystallite size. It is shown that modelling of each reflection by a distribution of interference-function weighted rays yields a `still' Lorentz factor. Still data are compared with a conventional rotation data set collected from a single lysozyme crystal. Overall, the presented still integration method improves the data quality markedly. The R factor of the still data compared with the rotation data decreases from 26% using a Monte Carlo approach to 12% after applying the Lorentz correction, to 5.3% when estimating partialities by EVAL and finally to 4.7% after post-refinement. The merging R(int) factor of the still data improves from 105 to 56% but remains high. This suggests that the accuracy of the model parameters could be further improved. However, with a multiplicity of around 40 and an R(int) of ∼50% the merged still data approximate the quality of the rotation data. The presented integration method suitably accounts for the partiality of the observed intensities in still diffraction data, which is a critical step to improve data quality in serial crystallography.

  1. Low-angle polarized neutron and X-ray scattering from magnetic nanolayers and nanostructures

    CERN Document Server

    Paul, Amitesh

    2017-01-01

    This research monograph presents the latest results related to the characterization of low dimensional systems. Low-angle polarized neutron scattering and X-ray scattering at grazing incidence are used as the two main techniques to explore various physical phenomena of these systems. Special focus is put on systems like thin film transition metal and rare-earth layers, oxide heterostructures, hybrid systems, self-assembled nanostructures and self-diffusion.  Readers will gain in-depth knowledge about the usage of specular scattering and off-specular scattering techniques. Investigation of in-plane and out-of-plane structures and magnetism with vector magnetometric information is illustrated comprehensively. The book caters to a wide audience working in the field of nano-dimensional magnetic systems and the neutron and X-ray reflectometry community in particular.

  2. Isolated elliptically polarized attosecond soft X-ray with high-brilliance using polarization gating of harmonics from relativistic plasmas at oblique incidence.

    Science.gov (United States)

    Chen, Zi-Yu; Li, Xiao-Ya; Li, Bo-Yuan; Chen, Min; Liu, Feng

    2018-02-19

    The production of intense isolated attosecond pulse is a major goal in ultrafast research. Recent advances in high harmonic generation from relativistic plasma mirrors under oblique incidence interactions gave rise to photon-rich attosecond pulses with circular or elliptical polarization. However, to achieve an isolated elliptical attosecond pulse via polarization gating using currently available long driving pulses remains a challenge, because polarization gating of high harmonics from relativistic plasmas is assumed only possible at normal or near-normal incidence. Here we numerically demonstrate a scheme around this problem. We show that via control of plasma dynamics by managing laser polarization, it is possible to gate an intense single attosecond pulse with high ellipticity extending to the soft X-ray regime at oblique incidence. This approach thus paves the way towards a powerful tool enabling high-time-resolution probe of dynamics of chiral systems and magnetic materials with current laser technology.

  3. A new hybrid algorithm using thermodynamic and backward ray-tracing approaches for modeling luminescent solar concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Ch. K.; Lim, Y. S.; Tan, S. G.; Rahman, F. A. [Faculty of Engineering and Science, University Tunku Abdul Rahman, Jalan Genting Klang, 53300, Kuala Lumpur (Malaysia)

    2010-12-15

    A Luminescent Solar Concentrator (LSC) is a transparent plate containing luminescent material with photovoltaic (PV) cells attached to its edges. Sunlight entering the plate is absorbed by the luminescent material, which in turn emits light. The emitted light propagates through the plate and arrives at the PV cells through total internal reflection. The ratio of the area of the relatively cheap polymer plate to that of the expensive PV cells is increased, and the cost per unit of solar electricity can be reduced by 75%. To improve the emission performance of LSCs, simulation modeling of LSCs becomes essential. Ray-tracing modeling is a popular approach for simulating LSCs due to its great ability of modeling various LSC structures under direct and diffuse sunlight. However, this approach requires substantial amount of measurement input data. Also, the simulation time is enormous because it is a forward-ray tracing method that traces all the rays propagating from the light source to the concentrator. On the other hand, the thermodynamic approach requires substantially less input parameters and simulation time, but it can only be used to model simple LSC designs with direct sunlight. Therefore, a new hybrid model was developed to perform various simulation studies effectively without facing the issues arisen from the existing ray-tracing and thermodynamic models. The simulation results show that at least 60% of the total output irradiance of a LSC is contributed by the light trapped and channeled by the LSC. The novelty of this hybrid model is the concept of integrating the thermodynamic model with a well-developed Radiance ray-tracing model, hence making this model as a fast, powerful and cost-effective tool for the design of LSCs. (authors)

  4. A New Hybrid Algorithm Using Thermodynamic and Backward Ray-Tracing Approaches for Modeling Luminescent Solar Concentrators

    Directory of Open Access Journals (Sweden)

    Chin Kim Lo

    2010-11-01

    Full Text Available A Luminescent Solar Concentrator (LSC is a transparent plate containing luminescent material with photovoltaic (PV cells attached to its edges. Sunlight entering the plate is absorbed by the luminescent material, which in turn emits light. The emitted light propagates through the plate and arrives at the PV cells through total internal reflection. The ratio of the area of the relatively cheap polymer plate to that of the expensive PV cells is increased, and the cost per unit of solar electricity can be reduced by 75%. To improve the emission performance of LSCs, simulation modeling of LSCs becomes essential. Ray-tracing modeling is a popular approach for simulating LSCs due to its great ability of modeling various LSC structures under direct and diffuse sunlight. However, this approach requires substantial amount of measurement input data. Also, the simulation time is enormous because it is a forward-ray tracing method that traces all the rays propagating from the light source to the concentrator. On the other hand, the thermodynamic approach requires substantially less input parameters and simulation time, but it can only be used to model simple LSC designs with direct sunlight. Therefore, a new hybrid model was developed to perform various simulation studies effectively without facing the issues arisen from the existing ray-tracing and thermodynamic models. The simulation results show that at least 60% of the total output irradiance of a LSC is contributed by the light trapped and channeled by the LSC. The novelty of this hybrid model is the concept of integrating the thermodynamic model with a well-developed Radiance ray-tracing model, hence making this model as a fast, powerful and cost-effective tool for the design of LSCs.

  5. Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, T., E-mail: tmc@servidor.unam.m [Facultad de Quimica, Departamento de Quimica Inorganica y Nuclear. Universidad Nacional Autonoma de Mexico, Mexico D.F. 04510 (Mexico); Lartigue, J. [Facultad de Quimica, Departamento de Quimica Inorganica y Nuclear. Universidad Nacional Autonoma de Mexico, Mexico, D.F. 04510 (Mexico); Zarazua, G.; Avila-Perez, P. [National Institute of Nuclear Research. Ocoyoacac, Edo. de Mexico, 05045 (Mexico); Navarrete, M. [Facultad de Quimica, Departamento de Quimica Inorganica y Nuclear. Universidad Nacional Autonoma de Mexico, Mexico, D.F. 04510 (Mexico); Tejeda, S. [National Institute of Nuclear Research. Ocoyoacac, Edo. de Mexico, 05045 (Mexico)

    2010-06-15

    Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO{sub 3} and H{sub 2}O{sub 2} (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different ({alpha} = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 {mu}g g{sup -1}. A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of 'Citrus Leaves' and a blank were treated in the same way.

  6. Accretion dynamics and polarized x-ray emission of magnetized neutron stars

    International Nuclear Information System (INIS)

    Arons, J.

    1991-01-01

    The basic ideas of accretion onto magnetized neutron stars are outlined. These are applied to a simple model of the structure of the plasma mound sitting at the magnetic poles of such as star, in which upward diffusion of photons is balanced by their downward advection. This steady flow model of the plasma's dynamical state is used to compute the emission of polarized X-rays from the optically thick, birefringent medium. The linear polarization of the continuum radiation emerging from the quasi-static mound is found to be as much as 40% at some rotation phases, but is insensitive to the geometry of the accretion flow. The role of the accretion shock, whose detailed polarimetric and spectral characteristics have yet to be calculated, is emphasized as the final determinant of the properties of the emerging X-rays. Some results describing the fully time dependent dynamics of the flow are also presented. In particular, steady flow onto a neutron star is shown to exhibit formation of ''photon bubbles,'' regions of greatly reduced plasma density filled with radiation which form and rise on millisecond time scales. The possible role of these complex structures in the flow for the formation of the emergent spectrum is briefly outlined

  7. Magnetospherically reflected chorus waves revealed by ray tracing with CLUSTER data

    Directory of Open Access Journals (Sweden)

    M. Parrot

    Full Text Available This paper is related to the propagation characteristics of a chorus emission recorded simultaneously by the 4 satellites of the CLUSTER mission on 29 October 2001 between 01:00 and 05:00 UT. During this day, the spacecraft (SC 1, 2, and 4 are relatively close to each other but SC3 has been delayed by half an hour. We use the data recorded aboard CLUSTER by the STAFF spectrum analyser. This instrument provides the cross spectral matrix of three magnetic and two electric field components. Dedicated software processes this spectral matrix in order to determine the wave normal directions relative to the Earth’s magnetic field. This calculation is done for the 4 satellites at different times and different frequencies and allows us to check the directions of these waves. Measurements around the magnetic equator show that the parallel component of the Poynting vector changes its sign when the satellites cross the equator region. It indicates that the chorus waves propagate away from this region which is considered as the source area of these emissions. This is valid for the most intense waves observed on the magnetic and electric power spectrograms. But it is also observed on SC1, SC2, and SC4 that lower intensity waves propagate toward the equator simultaneously with the SC3 intense chorus waves propagating away from the equator. Both waves are at the same frequency. Using the wave normal directions of these waves, a ray tracing study shows that the waves observed by SC1, SC2, and SC4 cross the equatorial plane at the same location as the waves observed by SC3. SC3 which is 30 minutes late observes the waves that originate first from the equator; meanwhile, SC1, SC2, and SC4 observe the same waves that have suffered a Lower Hybrid Resonance (LHR reflection at low altitudes (based on the ray tracing analysis and now return to the equator at a different location with a lower intensity. Similar phenomenon is observed when all SC are on the other side

  8. Magnetospherically reflected chorus waves revealed by ray tracing with CLUSTER data

    Directory of Open Access Journals (Sweden)

    M. Parrot

    2003-05-01

    Full Text Available This paper is related to the propagation characteristics of a chorus emission recorded simultaneously by the 4 satellites of the CLUSTER mission on 29 October 2001 between 01:00 and 05:00 UT. During this day, the spacecraft (SC 1, 2, and 4 are relatively close to each other but SC3 has been delayed by half an hour. We use the data recorded aboard CLUSTER by the STAFF spectrum analyser. This instrument provides the cross spectral matrix of three magnetic and two electric field components. Dedicated software processes this spectral matrix in order to determine the wave normal directions relative to the Earth’s magnetic field. This calculation is done for the 4 satellites at different times and different frequencies and allows us to check the directions of these waves. Measurements around the magnetic equator show that the parallel component of the Poynting vector changes its sign when the satellites cross the equator region. It indicates that the chorus waves propagate away from this region which is considered as the source area of these emissions. This is valid for the most intense waves observed on the magnetic and electric power spectrograms. But it is also observed on SC1, SC2, and SC4 that lower intensity waves propagate toward the equator simultaneously with the SC3 intense chorus waves propagating away from the equator. Both waves are at the same frequency. Using the wave normal directions of these waves, a ray tracing study shows that the waves observed by SC1, SC2, and SC4 cross the equatorial plane at the same location as the waves observed by SC3. SC3 which is 30 minutes late observes the waves that originate first from the equator; meanwhile, SC1, SC2, and SC4 observe the same waves that have suffered a Lower Hybrid Resonance (LHR reflection at low altitudes (based on the ray tracing analysis and now return to the equator at a different location with a lower intensity. Similar phenomenon is observed when all SC are on the other side

  9. Spatial and temporal trends of selected trace elements in liver tissue from polar bears (Ursus maritimus) from Alaska, Canada and Greenland.

    Science.gov (United States)

    Routti, Heli; Letcher, Robert J; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; Fisk, Aaron T; Peacock, Elizabeth; Sonne, Christian

    2011-08-01

    Spatial trends and comparative changes in time of selected trace elements were studied in liver tissue from polar bears from ten different subpopulation locations in Alaska, Canadian Arctic and East Greenland. For nine of the trace elements (As, Cd, Cu, Hg, Mn, Pb, Rb, Se and Zn) spatial trends were investigated in 136 specimens sampled during 2005-2008 from bears from these ten subpopulations. Concentrations of Hg, Se and As were highest in the (northern and southern) Beaufort Sea area and lowest in (western and southern) Hudson Bay area and Chukchi/Bering Sea. In contrast, concentrations of Cd showed an increasing trend from east to west. Minor or no spatial trends were observed for Cu, Mn, Rb and Zn. Spatial trends were in agreement with previous studies, possibly explained by natural phenomena. To assess temporal changes of Cd, Hg, Se and Zn concentrations during the last decades, we compared our results to previously published data. These time comparisons suggested recent Hg increase in East Greenland polar bears. This may be related to Hg emissions and/or climate-induced changes in Hg cycles or changes in the polar bear food web related to global warming. Also, Hg:Se molar ratio has increased in East Greenland polar bears, which suggests there may be an increased risk for Hg(2+)-mediated toxicity. Since the underlying reasons for spatial trends or changes in time of trace elements in the Arctic are still largely unknown, future studies should focus on the role of changing climate and trace metal emissions on geographical and temporal trends of trace elements.

  10. Mesospheric gravity waves observed near equatorial and low-middle latitude stations: wave characteristics and reverse ray tracing results

    Energy Technology Data Exchange (ETDEWEB)

    Wrasse, C.M.; Takahashi, H.; Gobbi, D.; Denardini, C.M.; Fechine, J. [Inst. Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos (Brazil); Nakamura, T. [Inst. for Sustainable Humanosphere (RISH), Kyoto Univ., Uji (Japan); Medeiros, A.F.; Buriti, R.A. [Univ. Federal de Campina Grande (UFCG), Campina Grande (Brazil); Taylor, M.J. [Space Dynamics Lab. and Physics Dept., Logan, UT (United States); Salatun, A.; Suratno; Achmad, E.; Admiranto, A.G. [Space Science Center, National Inst. of Aeronautics and Space, Jakarta (Indonesia)

    2006-07-01

    Gravity wave signatures were extracted from OH airglow observations using all-sky CCD imagers at four different stations: Cachoeira Paulista (CP) (22.7 S, 45 W) and Sao Joao do Cariri (7.4 S, 36.5 W), Brazil; Tanjungsari (TJS) (6.9 S, 107.9 E), Indonesia and Shigaraki (34.9 N, 136 E), Japan. The gravity wave parameters are used as an input in a reverse ray tracing model to study the gravity wave vertical propagation trajectory and to estimate the wave source region. Gravity waves observed near the equator showed a shorter period and a larger phase velocity than those waves observed at low-middle latitudes. The waves ray traced down into the troposphere showed the largest horizontal wavelength and phase speed. The ray tracing results also showed that at CP, Cariri and Shigaraki the majority of the ray paths slopped in the mesosphere due to the condition of m{sup 2} <0, while at TJS most of the waves are traced back into the troposphere. In summer time, most of the back traced waves have their final position stopped in the mesosphere due to m{sup 2}<0 or critical level interactions (vertical stroke m vertical stroke {yields}{infinity}), which suggests the presence of ducting waves and/or waves generated in-situ. In the troposphere, the possible gravity wave sources are related to meteorological front activities and cloud convections at CP, while at Cariri and TJS tropical cloud convections near the equator are the most probable gravity wave sources. The tropospheric jet stream and the orography are thought to be the major responsible sources for the waves observed at Shigaraki. (orig.)

  11. Resonant Compton Upscattering Models of Magnetar Hard X-ray Emission and Polarization

    Science.gov (United States)

    Baring, Matthew G.; Wadiasingh, Zorawar; Gonthier, Peter L.; Kust Harding, Alice

    2017-08-01

    Non-thermal quiescent X-ray emission extending between 10 keV and around 150 keV has been seen in about 10 magnetars by RXTE, INTEGRAL, Suzaku and Fermi-GBM. For inner magnetospheric models of such hard X-ray signals, resonant Compton upscattering is anticipated to be the most efficient process for generating the continuum radiation. This is because the scattering becomes resonant at the cyclotron frequency, and the effective cross section exceeds the classical Thomson value by over two orders of magnitude. We present angle-dependent hard X-ray upscattering model spectra for uncooled monoenergetic relativistic electrons injected in inner regions of pulsar magnetospheres. These spectra are integrated over closed field lines and obtained for different observing perspectives. The spectral cut-off energies are critically dependent on the observer viewing angles and electron Lorentz factor. We find that electrons with energies less than around 15 MeV will emit most of their radiation below 250 keV, consistent with the observed turnovers in magnetar hard X-ray tails. Moreover, electrons of higher energy still emit most of the radiation below around 1 MeV, except for quasi-equatorial emission locales for select pulses phases. In such cases, attenuation mechanisms such as pair creation will be prolific, thereby making it difficult to observe signals extending into the Fermi-LAT band. Our spectral computations use new state-of-the-art, spin-dependent formalism for the QED Compton scattering cross section in strong magnetic fields. The emission exhibits strong polarization above around 30 keV that is anticipated to be dependent on pulse phase, thereby defining science agendas for future hard X-ray polarimeters.

  12. Ray-tracing analysis of the Wien velocity filter for protons

    Science.gov (United States)

    Kim, Jae Hong; Kim, Yu-Soek

    2015-02-01

    A Wien velocity filter employs a combination of crossed magnetic and electrostatic fields in order to select the desired velocity of ions. Several microscopes and spectrometers are used as filters to ensure the introduction of a pure ion fraction into the lens, deflecting unnecessary particles which have slightly different energies. The Wien filter is also considered to be a useful device to transport mono-energy protons from a source to an injection system. In its simplest form, the Wien filter has two flat parallel electrodes that are arranged between two flat magnet poles, creating homogeneous electric and magnetic fields which cross each other. However, this type of filter has no focusing effect in the direction of the magnetic field and has an unmatched field distribution, which causes deflections of protons at the entrance and the exit of the filter. At higher magnetic field strengs, for fast protons, the deflection of the trajectories becomes larger; thus, the transport efficiency is reduced. A low-aberration velocity filter is needed for high transport efficiency. Recently, a stigmatic focusing of the filter by using hyperbolic cylindrical magnet pole pieces, which produce an inhomogeneous magnetic field inside the ExB filter, has been suggested. In this research, three types of Wien filters were designed in order to investigate the geometry of the electrodes and the magnet poles, thus minimizing aberrations. Ray-tracing analyses were carried out to estimate the performance of the proposed Wien filters within a useful velocity selector.

  13. Determination of trace elements and heavy metals in sediment using x-ray fluorescence

    International Nuclear Information System (INIS)

    Sidahmed, Muataz Ahmed Ibrahem

    2014-01-01

    In this study, 30 sediment samples were taken randomly from the area of Suba south of Khartoum state. Trace elements and heavy metal were determined in sediments samples using x-ray fluoresce spectroscopy (X RF). K, Ca, Ti, Mn, Fe, Cu, Zn, Pb, Rb, Sr, and Zr were determined by X RF. Standard Reference Material (SRM) from international Atomic Energy Agency (IAEA-Soil-7) has been used to achieve accuracy of X RF method. Measured values were found in agreements with certified values. The average elemental concentrations of K, Ca, Ti, Mn, Fe, Cu, Zn, Pb, Rb, Sr, and Zr were 5882.7, 20703.3, 6264.3, 460.97, 26713.3, 7.7, 43.4, 18.6, 28.6, 144.8, and 173.06, respectively. Correlation between elements was performed also cluster analysis was used to check the similarly between the samples result. The result of study were compared with previous studies and the concentrations of some elements found to be similar.(Author)

  14. Downsizing of Johansson spectrometer for X-ray fluorescence trace analysis with brilliant undulator source

    CERN Document Server

    Sakurai, K; Inoue, K; Yagi, N

    2001-01-01

    The downsizing of a Johansson-type X-ray fluorescence (XRF) spectrometer has been examined as a way of enhancing detection efficiency with a tolerable loss of energy resolution. A compact spectrometer equipped with a Ge(2 2 0) analyzing crystal with a Rowland radius of 120 mm has been tested with a highly brilliant helical undulator source at BL40XU, SPring-8. The energy resolution obtained for cobalt K alpha sub 1 (6930.32 eV) was 8.8 eV, which is 10-20 times better than that obtained using a Si(Li) detector, and effectively improved the signal-to-background ratio for XRF spectra. The combination of the present spectrometer and a third generation synchrotron source could provide new opportunities for trace analytical applications, which have been difficult so far by conventional synchrotron XRF experiments based on a Si(Li) detector system. The detection limit obtained for solid bulk samples has reached a level of several tens of ppb.

  15. Exploring Light’s Interactions with Bubbles and Light Absorbers in Photoelectrochemical Devices using Ray Tracing

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, John Colby [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). The Joint Center for Artificial Photosynthesis; Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering

    2012-12-01

    Ray tracing was used to perform optical optimization of arrays of photovoltaic microrods and explore the interaction between light and bubbles of oxygen gas on the surface of the microrods. The incident angle of light was varied over a wide range. The percent of incident light absorbed by the microrods and reflected by the bubbles was computed over this range. It was found that, for the 10 μm diameter, 100 μm tall SrTiO3 microrods simulated in the model, the optimal center-­to-­center spacing was 14 μm for a square grid. This geometry produced 75% average and 90% maximum absorbance. For a triangular grid using the same microrods, the optimal center-­to-­center spacing was 14 μm. This geometry produced 67% average and 85% maximum absorbance. For a randomly laid out grid of 5 μm diameter, 100 μm tall SrTiO3 microrods with an average center-­to-­center spacing of 20 μm, the average absorption was 23% and the maximum absorption was 43%. For a 50% areal coverage fraction of bubbles on the absorber surface, between 2%-­20% of the incident light energy was reflected away from the rods by the bubbles, depending upon incident angle and bubble morphology.

  16. Diffraction gratings metrology and ray-tracing results for an XUV Raman spectrometer at FLASH.

    Science.gov (United States)

    Dziarzhytski, Siarhei; Siewert, Frank; Sokolov, Andrey; Gwalt, Grzegorz; Seliger, Tino; Rübhausen, Michael; Weigelt, Holger; Brenner, Günter

    2018-01-01

    The extreme-ultraviolet double-stage imaging Raman spectrometer is a permanent experimental endstation at the plane-grating monochromator beamline branch PG1 at FLASH at DESY in Hamburg, Germany. This unique instrument covers the photon energy range from 20 to 200 eV with high energy resolution of about 2 to 20 meV (design values) featuring an efficient elastic line suppression as well as effective stray light rejection. Such a design enables studies of low-energy excitations like, for example, phonons in solids close to the vicinity of the elastic line. The Raman spectrometer effectively operates with four reflective off-axial parabolic mirrors and two plane-grating units. The optics quality and their precise alignment are crucial to guarantee best performance of the instrument. Here, results on a comprehensive investigation of the quality of the spectrometer diffraction gratings are presented. The gratings have been characterized by ex situ metrology at the BESSY-II Optics Laboratory, employing slope measuring deflectometry and interferometry as well as atomic force microscopy studies. The efficiency of these key optical elements has been measured at the at-wavelength metrology laboratory using the reflectometer at the BESSY-II Optics beamline. Also, the metrology results are discussed with respect to the expected resolving power of the instrument by including them in ray-tracing studies of the instrument.

  17. Metrology of variable-line-spacing x-ray gratings using the APS Long Trace Profiler

    Science.gov (United States)

    Sheung, Janet; Qian, Jun; Sullivan, Joseph; Thomasset, Muriel; Manton, Jonathan; Bean, Sunil; Takacs, Peter; Dvorak, Joseph; Assoufid, Lahsen

    2017-09-01

    As resolving power targets have increased with each generation of beamlines commissioned in synchrotron radiation facilities worldwide, diffraction gratings are quickly becoming crucial optical components for meeting performance targets. However, the metrology of variable-line-spacing (VLS) gratings for high resolution beamlines is not widespread; in particular, no metrology facility at any US DOE facility is currently equipped to fully characterize such gratings. To begin to address this issue, the Optics Group at the Advanced Photon Source at Argonne, in collaboration with SOLEIL and with support from Brookhaven National Laboratory (BNL), has developed an alternative beam path addition to the Long Trace Profiler (LTP) at Argonne's Advanced Photon Source. This significantly expands the functionality of the LTP not only to measure mirrors surface slope profile at normal incidence, but also to characterize the groove density of VLS diffraction gratings in the Littrow incidence up to 79°, which covers virtually all diffraction gratings used at synchrotrons in the first order. The LTP light source is a 20mW HeNe laser, which yields enough signal for diffraction measurements to be performed on low angle blazed gratings optimized for soft X-ray wavelengths. We will present the design of the beam path, technical requirements for the optomechanics, and our data analysis procedure. Finally, we discuss challenges still to be overcome and potential limitations with use of the LTP to perform metrology on diffraction gratings.

  18. Usage of CO2 microbubbles as flow-tracing contrast media in X-ray dynamic imaging of blood flows.

    Science.gov (United States)

    Lee, Sang Joon; Park, Han Wook; Jung, Sung Yong

    2014-09-01

    X-ray imaging techniques have been employed to visualize various biofluid flow phenomena in a non-destructive manner. X-ray particle image velocimetry (PIV) was developed to measure velocity fields of blood flows to obtain hemodynamic information. A time-resolved X-ray PIV technique that is capable of measuring the velocity fields of blood flows under real physiological conditions was recently developed. However, technical limitations still remained in the measurement of blood flows with high image contrast and sufficient biocapability. In this study, CO2 microbubbles as flow-tracing contrast media for X-ray PIV measurements of biofluid flows was developed. Human serum albumin and CO2 gas were mechanically agitated to fabricate CO2 microbubbles. The optimal fabricating conditions of CO2 microbubbles were found by comparing the size and amount of microbubbles fabricated under various operating conditions. The average size and quantity of CO2 microbubbles were measured by using a synchrotron X-ray imaging technique with a high spatial resolution. The quantity and size of the fabricated microbubbles decrease with increasing speed and operation time of the mechanical agitation. The feasibility of CO2 microbubbles as a flow-tracing contrast media was checked for a 40% hematocrit blood flow. Particle images of the blood flow were consecutively captured by the time-resolved X-ray PIV system to obtain velocity field information of the flow. The experimental results were compared with a theoretically amassed velocity profile. Results show that the CO2 microbubbles can be used as effective flow-tracing contrast media in X-ray PIV experiments.

  19. Mesospheric gravity waves observed near equatorial and low–middle latitude stations: wave characteristics and reverse ray tracing results

    Directory of Open Access Journals (Sweden)

    E. Achmad

    2006-12-01

    Full Text Available Gravity wave signatures were extracted from OH airglow observations using all-sky CCD imagers at four different stations: Cachoeira Paulista (CP (22.7° S, 45° W and São João do Cariri (7.4° S, 36.5° W, Brazil; Tanjungsari (TJS (6.9° S, 107.9° E, Indonesia and Shigaraki (34.9° N, 136° E, Japan. The gravity wave parameters are used as an input in a reverse ray tracing model to study the gravity wave vertical propagation trajectory and to estimate the wave source region. Gravity waves observed near the equator showed a shorter period and a larger phase velocity than those waves observed at low-middle latitudes. The waves ray traced down into the troposphere showed the largest horizontal wavelength and phase speed. The ray tracing results also showed that at CP, Cariri and Shigaraki the majority of the ray paths stopped in the mesosphere due to the condition of m2m2m|→∞, which suggests the presence of ducting waves and/or waves generated in-situ. In the troposphere, the possible gravity wave sources are related to meteorological front activities and cloud convections at CP, while at Cariri and TJS tropical cloud convections near the equator are the most probable gravity wave sources. The tropospheric jet stream and the orography are thought to be the major responsible sources for the waves observed at Shigaraki.

  20. Self-assembled iron oxide nanoparticle multilayer: x-ray and polarized neutron reflectivity.

    Science.gov (United States)

    Mishra, D; Benitez, M J; Petracic, O; Badini Confalonieri, G A; Szary, P; Brüssing, F; Theis-Bröhl, K; Devishvili, A; Vorobiev, A; Konovalov, O; Paulus, M; Sternemann, C; Toperverg, B P; Zabel, H

    2012-02-10

    We have investigated the structure and magnetism of self-assembled, 20 nm diameter iron oxide nanoparticles covered by an oleic acid shell for scrutinizing their structural and magnetic correlations. The nanoparticles were spin-coated on an Si substrate as a single monolayer and as a stack of 5 ML forming a multilayer. X-ray scattering (reflectivity and grazing incidence small-angle scattering) confirms high in-plane hexagonal correlation and a good layering property of the nanoparticles. Using polarized neutron reflectivity we have also determined the long range magnetic correlations parallel and perpendicular to the layers in addition to the structural ones. In a field of 5 kOe we determine a magnetization value of about 80% of the saturation value. At remanence the global magnetization is close to zero. However, polarized neutron reflectivity reveals the existence of regions in which magnetic moments of nanoparticles are well aligned, while losing order over longer distances. These findings confirm that in the nanoparticle assembly the magnetic dipole-dipole interaction is rather strong, dominating the collective magnetic properties at room temperature.

  1. Application of a portable total reflection x-ray fluorescence spectrometer to a trace elemental analysis of wines

    International Nuclear Information System (INIS)

    Kunimura, Shinsuke; Kawai, Jun

    2009-01-01

    A portable total reflection X-ray fluorescence (TXRF) spectrometer has been applied to a trace elemental analysis of wines. Sulfur, K, Mn, Fe, and Rb were detected. These five elements were quantified by using 1 ppm of Co as an internal standard. The quantified concentrations ranged from sub-ppm to several hundred ppm. Because of organic substances in wines, the scattering of the incident X-rays from the dry residues of wines becomes strong. Therefore, a high spectral background appears in TXRF spectra of wines. Because of this background, relative standard deviations of the quantified concentrations were from 4 to 28%. Although the high spectral background appeared in the TXRF spectra of the wines, a detection limit down to several tens of ppb was achieved. The present portable spectrometer can be applied to screening for trace elements in wines before an accurate and precise analysis using a large elemental analyzer. (author)

  2. A ray-tracing study of electron cyclotron resonance heating in Tokamak plasmas with a superthermal electron tail

    International Nuclear Information System (INIS)

    Montes, A.; Dendy, R.O.

    1987-09-01

    We consider a Tokamak plasma in which the distribution of electron velocities in the direction parallel to the magnetic field has a monotonically decreasing superthermal tail. A fully three-dimensional ray-tracing code, which includes a realistic antenna pattern, toroidal effects, and refaction, is used to calculate the absorption of the extraordinary mode in the nonrelativistic limit away from perpendicular incidence. The ray-tracing approach extends results previously obtained in slab geometry (3-8) to a more realistic configuration; it is also essential in dealing with strong refraction in high-density plasmas. Our analytical model for the tail makes available a wide range of tail shapes and parameters. At low densities small tails (tail fraction [pt

  3. A generalized ray-tracing procedure for an atmospheric Cherenkov imaging telescope and optical characteristics of the TACTIC light collector

    International Nuclear Information System (INIS)

    Tickoo, A.K.; Suthar, R.L.; Koul, R.; Sapru, M.L.; Kumar, N.; Kaul, C.L.; Yadav, K.K.; Thoudam, S.; Kaul, S.K.; Venugopal, K.; Kothari, M.; Goyal, H.C.; Chandra, P.; Dhar, V.K.; Rannot, R.C.; Koul, M.K.; Kaul, S.R.

    2005-01-01

    A generalized ray-tracing procedure has been developed, which facilitates the design of a multimirror-based light collector used in atmospheric Cherenkov telescopes. This procedure has been employed to study the optical characteristics of the 3.5 m diameter light collector of the TACTIC Imaging telescope. Comparison of the measured point-spread function of the light collector with the simulated performance of ideal Davies-Cotton and paraboloid designs has been made to determine an optimum arrangement of the 34 spherical mirror facets used in the telescope to obtain the best possible point-spread function. A description of the ray-tracing subroutine used for processing CORSIKA-generated Cherenkov data, required for carrying out Monte-Carlo simulation studies, is also discussed in the paper

  4. An analysis of options available for developing a common laser ray tracing package for Ares and Kull code frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Weeratunga, S K

    2008-11-06

    Ares and Kull are mature code frameworks that support ALE hydrodynamics for a variety of HEDP applications at LLNL, using two widely different meshing approaches. While Ares is based on a 2-D/3-D block-structured mesh data base, Kull is designed to support unstructured, arbitrary polygonal/polyhedral meshes. In addition, both frameworks are capable of running applications on large, distributed-memory parallel machines. Currently, both these frameworks separately support assorted collections of physics packages related to HEDP, including one for the energy deposition by laser/ion-beam ray tracing. This study analyzes the options available for developing a common laser/ion-beam ray tracing package that can be easily shared between these two code frameworks and concludes with a set of recommendations for its development.

  5. 3-D TECATE/BREW: Thermal, stress, and birefringent ray-tracing codes for solid-state laser design

    Science.gov (United States)

    Gelinas, R. J.; Doss, S. K.; Nelson, R. G.

    1994-07-01

    This report describes the physics, code formulations, and numerics that are used in the TECATE (totally Eulerian code for anisotropic thermo-elasticity) and BREW (birefringent ray-tracing of electromagnetic waves) codes for laser design. These codes resolve thermal, stress, and birefringent optical effects in 3-D stationary solid-state systems. This suite of three constituent codes is a package referred to as LASRPAK.

  6. (U) Second-Order Sensitivity Analysis of Uncollided Particle Contributions to Radiation Detector Responses Using Ray-Tracing

    Energy Technology Data Exchange (ETDEWEB)

    Favorite, Jeffrey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-30

    The Second-Level Adjoint Sensitivity System (2nd-LASS) that yields the second-order sensitivities of a response of uncollided particles with respect to isotope densities, cross sections, and source emission rates is derived in Refs. 1 and 2. In Ref. 2, we solved problems for the uncollided leakage from a homogeneous sphere and a multiregion cylinder using the PARTISN multigroup discrete-ordinates code. In this memo, we derive solutions of the 2nd-LASS for the particular case when the response is a flux or partial current density computed at a single point on the boundary, and the inner products are computed using ray-tracing. Both the PARTISN approach and the ray-tracing approach are implemented in a computer code, SENSPG. The next section of this report presents the equations of the 1st- and 2nd-LASS for uncollided particles and the first- and second-order sensitivities that use the solutions of the 1st- and 2nd-LASS. Section III presents solutions of the 1st- and 2nd-LASS equations for the case of ray-tracing from a detector point. Section IV presents specific solutions of the 2nd-LASS and derives the ray-trace form of the inner products needed for second-order sensitivities. Numerical results for the total leakage from a homogeneous sphere are presented in Sec. V and for the leakage from one side of a two-region slab in Sec. VI. Section VII is a summary and conclusions.

  7. Demonstration of polarization sensitivity of emulsion-based pair conversion telescope for cosmic gamma-ray polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ozaki, Keita, E-mail: ozaki@radix.h.kobe-u.ac.jp [Kobe University, 3-11, Tsurukabuto, Nada-ku, Kobe 657-8501 (Japan); Takahashi, Satoru, E-mail: satoru@radix.h.kobe-u.ac.jp [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Aoki, Shigeki; Kamada, Keiki; Kaneyama, Taichi; Nakagawa, Ryo; Rokujo, Hiroki [Kobe University, 3-11, Tsurukabuto, Nada-ku, Kobe 657-8501 (Japan)

    2016-10-11

    Linear polarization of high-energy gamma-rays (10MeV–100 GeV) can be detected by measuring the azimuthal angle of electron–positron pairs and observing the modulation of the azimuthal distribution. To demonstrate the gamma-ray polarization sensitivity of emulsion, we conducted a test using a polarized gamma-ray beam (0.8–2.4 GeV) at SPring-8/LEPS. Emulsion tracks were reconstructed using scanning data, and gamma-ray events were selected automatically. Using an optical microscope, out of the 2381 gamma-ray conversions that were observed, 1372 remained after event selection, on the azimuthal angle distribution of which we measured the modulation. From the distribution of the azimuthal angles of the selected events, a modulation factor of 0.21+0.11−0.09 was measured, from which the detection of a non-zero modulation was established with a significance of 3.06σ. This attractive polarimeter will be applied to the GRAINE project, a balloon-borne experiment that observes 10–100 GeV cosmic gamma-rays with an emulsion-based pair conversion telescope.

  8. Rotation of X-ray polarization in the glitches of a silicon crystal monochromator.

    Science.gov (United States)

    Sutter, John P; Boada, Roberto; Bowron, Daniel T; Stepanov, Sergey A; Díaz-Moreno, Sofía

    2016-08-01

    EXAFS studies on dilute samples are usually carried out by collecting the fluorescence yield using a large-area multi-element detector. This method is susceptible to the 'glitches' produced by all single-crystal monochromators. Glitches are sharp dips or spikes in the diffracted intensity at specific crystal orientations. If incorrectly compensated, they degrade the spectroscopic data. Normalization of the fluorescence signal by the incident flux alone is sometimes insufficient to compensate for the glitches. Measurements performed at the state-of-the-art wiggler beamline I20-scanning at Diamond Light Source have shown that the glitches alter the spatial distribution of the sample's quasi-elastic X-ray scattering. Because glitches result from additional Bragg reflections, multiple-beam dynamical diffraction theory is necessary to understand their effects. Here, the glitches of the Si(111) four-bounce monochromator of I20-scanning just above the Ni  K edge are associated with their Bragg reflections. A fitting procedure that treats coherent and Compton scattering is developed and applied to a sample of an extremely dilute (100 micromolal) aqueous solution of Ni(NO 3 ) 2 . The depolarization of the wiggler X-ray beam out of the electron orbit is modeled. The fits achieve good agreement with the sample's quasi-elastic scattering with just a few parameters. The X-ray polarization is rotated up to ±4.3° within the glitches, as predicted by dynamical diffraction. These results will help users normalize EXAFS data at glitches.

  9. Rotation of X-ray polarization in the glitches of a silicon crystal monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Sutter, John P.; Boada, Roberto; Bowron, Daniel T.; Stepanov, Sergey A.; Díaz-Moreno, Sofía

    2016-07-06

    EXAFS studies on dilute samples are usually carried out by collecting the fluorescence yield using a large-area multi-element detector. This method is susceptible to the `glitches' produced by all single-crystal monochromators. Glitches are sharp dips or spikes in the diffracted intensity at specific crystal orientations. If incorrectly compensated, they degrade the spectroscopic data. Normalization of the fluorescence signal by the incident flux alone is sometimes insufficient to compensate for the glitches. Measurements performed at the state-of-the-art wiggler beamline I20-scanning at Diamond Light Source have shown that the glitches alter the spatial distribution of the sample's quasi-elastic X-ray scattering. Because glitches result from additional Bragg reflections, multiple-beam dynamical diffraction theory is necessary to understand their effects. Here, the glitches of the Si(111) four-bounce monochromator of I20-scanning just above the Ni Kedge are associated with their Bragg reflections. A fitting procedure that treats coherent and Compton scattering is developed and applied to a sample of an extremely dilute (100 micromolal) aqueous solution of Ni(NO3)2. The depolarization of the wiggler X-ray beam out of the electron orbit is modeled. The fits achieve good agreement with the sample's quasi-elastic scattering with just a few parameters. The X-ray polarization is rotated up to ±4.3° within the glitches, as predicted by dynamical diffraction. These results will help users normalize EXAFS data at glitches.

  10. A comparative study of ray tracing and CIVA simulation for ultrasonic examination of anisotropic inhomogeneous austenitic welds

    Science.gov (United States)

    Kolkoori, S. R.; Shokouhi, P.; Hoehne, C.; Rahman, M.-U.; Kreutzbruck, M.; Prager, J.

    2013-01-01

    Ultrasonic examination of anisotropic inhomogeneous austenitic welds is challenging, because of the columnar grain structure of the weld leads to beam skewing and splitting. Modeling tools play an important role in understanding the ultrasound field propagation and optimization of experimental parameters during the ultrasonic testing of austenitic welds as well as the interpretation of the test results. In this contribution, an efficient theoretical model based on the ray tracing concepts is developed to calculate the ultrasonic fields in inhomogeneous austenitic welds quantitatively. The developed model determines the ultrasound fields by taking into account the directivity of the ray source, the inhomogenity of the weld as well as ray transmission coefficients. Directivity of the ray source in columnar grained austenitic materials (including layback orientation) is obtained in three dimensions based on Lamb's reciprocity theorem. Ray energy reflection and transmission coefficients at an interface between two general columnar grained austenitic materials are calculated in three dimensions. The ray tracing model predictions on inhomogeneous austenitic weld material are compared against those from CIVA, a commercial non-destructive modeling and simulation tool. The ultrasonic modeling tools in CIVA are based on semi-analytical solutions. For beam propagation simulation, a so-called "pencil method" is used, which involves modeling the probe as a set of individual source points, each radiating "a bundle" of diverging rays into the medium and integrating those elementary contributions. Inhomogenity in the weld region is approximated by mapping the grain orientations on weld macrograph. Simulation results for ultrasonic field profiles for an austenitic weld are shown to be in good agreement with the corresponding experimental results.

  11. Radiation parameters of the x-ray binary A 0535 + 26 = HDE 245770 based on polarization and photometric data

    International Nuclear Information System (INIS)

    Larionov, V.M.

    1988-01-01

    Analysis of the observations of Shakhovskaya et al. has led to the identification in the radiation of the x-ray binary system A 0535 + 26 = HDE 245770 of two components associated with an optical 09 III star and an accretion disk around a neutron star. The parameters of the interstellar polarization agree with Serkowski's formula and the observations of neighboring stars. The variability of the brightness of the system observed in the optical and infrared ranges can be explained by changes in the contribution of the accretion disk to the total emission of the system. The values obtained for the parameters of the intrinsic polarization, interpreted in the framework of the proposed model, suggest directions of the polarization vectors in the infrared and x-ray range

  12. Spin-polarized x-ray emission of 3d transition-metal ions : A comparison via K alpha and K beta detection

    NARCIS (Netherlands)

    Wang, Xin; deGroot, F.M.F.; Cramer, SP

    1997-01-01

    This paper demonstrates that spin-polarized x-ray-excitation spectra can be obtained using K alpha emission as well as K beta lines. A spin-polarized analysis of K alpha x-ray emission and the excitation spectra by K alpha detection on a Ni compound is reported. A systematic analysis of the

  13. Trace element characterization using a synchrotron radiation X-ray microprobe

    OpenAIRE

    早川, 慎二郎

    1996-01-01

    A scanning X-ray microprobe using synchrotron radiation was developed employing an X-ray focusing system with total reflection mirrors. Utilizing a Wolter mirror system, a hard X-ray microbeam was first realized. With an energy tunable X-ray microprobe, sensitivity in X-ray fluorescence (XRF) analysis can be optimized for the element of interest at less than 1 ppm in relative concentration. Moreover, small area X-ray absorption fine structure (XAFS) measurements with XRF detection can provide...

  14. Algorithms and interface for ocean acoustic ray-tracing (Developed in MATLAB)

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.; Rao, M.M.M.; Prakash, S.S.; Chandramouli, P.; Murthy, K.S.R.

    for Munk's canonical sound speed profile off Visakhapatnam waters are detailed as a case study. The simulated acoustic ray parameters of canonical ocean, off Visakhapatnam continental slope regions, reveals that the even very flat angle rays can scan entire...

  15. Trace elements determination in Syrian honey using x-ray fluorescence technique

    International Nuclear Information System (INIS)

    Khuder, A.; Ahmad, M.; Saour, G.

    2009-05-01

    Major and trace elements of S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr in 27 Syrian honey samples, which collected from different areas in the country, in addition to 3 imported honey samples, were determined by dry ashing method for XRF analysis. The samples were diluted and homogenized with a binder made from cellulose powder. The analyzed elements were divided into three groups, relating to the secondary targets used for X-ray excitation. The internal standard method for XRF analysis with a Mo secondary target was used for the determination of the first group of elements: Sr, Rb, Se, As, Zn, Cu, Ni, and Fe. While, the external standard method for XRF analysis with Cu and Ti secondary targets was used for the determination of the second: Mn, Cr, Ti, Ca, K, and third: Cl, and S group of elements, respectively. The results were accurate with a relative standard error less than 4.2 %. The problem of element loss was overcome by the complete drying of honey samples before their ashing. The moisture content was obtained using mass loss and refractive index methods. As a result, the lower limits of detection (LLD) obtained by Mo-XRF was in the range from 0.011 μg Sr/g to 0.064 μg Fe/g, resulting for samples containing 0.1 % ash and collecting live time 1000 s; while, LLD obtained by Cu-XRF was in the range 0.014 μg Mn/g to 0.057 μg K/g. LLD for S and Cl using Ti secondary target was with values of 0.503 μg/g and 1.96 μg/g, respectively. The enhancement factor obtained by drying method for XRF was in the range from 147 to 1667. Normal concentration of elements in Syrian honey was obtained. The concentration of elements was comparable to those obtained by other workers for honeys in different countries. Elements of K, Ca, and Cl were predominantly distributed in all Syrian honey samples. Elements of Sr, Zn, Cu, Fe, Ti, and S were well distributed in all honey samples. While, the concentrations of Rb, Ni, Mn, Cr elements in some honey samples were below the

  16. Determination of trace metals in sea waters of the albanian coast by energy-dispersive x-ray fluorescence

    International Nuclear Information System (INIS)

    Civici, N.

    1994-01-01

    Preconcentration of trace transition and heavy metal ions by precipitation with APDC has been combined with energy-dispersive X-ray fluorescence for environmental sea water analysis. The preconcentration procedure implies adding of 500 μg Mo ion and 10 ml of 1 % water solution of APDC to a 500 ml water sample at pH 4, filtering off on a Millipore filter and analyzing after drying. Realistic detection limits are at 1 μg * l -1 level and precision varies between 10 - 25% at about 5 μg * l -1 level, depending on the element. Eleven sea water samples, covering Albanian Adriatic and Ionian coast, are analyzed for trace metal ions. (author) 8 refs.; 2 figs.; 5 tabs

  17. Theoretical estimation of proton induced X-ray emission yield of the trace elements present in the lung and breast cancer

    International Nuclear Information System (INIS)

    Manjunatha, H.C.; Sowmya, N.

    2013-01-01

    X-rays may be produced following the excitation of target atoms induced by an energetic incident ion beam of protons. Proton induced X-ray emission (PIXE) analysis has been used for many years for the determination of elemental composition of materials using X-rays. Recent interest in the proton induced X-ray emission cross section has arisen due to their importance in the rapidly expanding field of PIXE analysis. One of the steps in the analysis is to fit the measured X-ray spectrum with theoretical spectrum. The theoretical cross section and yields are essential for the evaluation of spectrum. We have theoretically evaluated the PIXE cross sections for trace elements in the lung and breast cancer tissues such as Cl, K, Ca,Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, P, S, Sr, Hg and Pb. The estimated cross section is used in the evaluation of Proton induced X-ray emission spectrum for the given trace elements.We have also evaluated the Proton induced X-ray emission yields in the thin and thick target of the given trace elements. The evaluated Proton induced X-ray emission cross-section, spectrum and yields are graphically represented. Some of these values are also tabulated. Proton induced X-ray emission cross sections and a yield for the given trace elements varies with the energy. PIXE yield depends on a real density and does not on thickness of the target. (author)

  18. Ray Tracing through the Edge Focusing of Rectangular Benders and an Improved Model for the Los Alamos Proton Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Kolski, Jeffrey S. [Los Alamos National Laboratory; Barlow, David B. [Los Alamos National Laboratory; Macek, Robert J. [Los Alamos National Laboratory; McCrady, Rodney C. [Los Alamos National Laboratory

    2011-01-01

    Particle ray tracing through simulated 3D magnetic fields was executed to investigate the effective quadrupole strength of the edge focusing of the rectangular bending magnets in the Los Alamos Proton Storage Ring (PSR). The particle rays receive a kick in the edge field of the rectangular dipole. A focal length may be calculated from the particle tracking and related to the fringe field integral (FINT) model parameter. This tech note introduces the baseline lattice model of the PSR and motivates the need for an improvement in the baseline model's vertical tune prediction, which differs from measurement by .05. An improved model of the PSR is created by modifying the fringe field integral parameter to those suggested by the ray tracing investigation. This improved model is then verified against measurement at the nominal PSR operating set point and at set points far away from the nominal operating conditions. Lastly, Linear Optics from Closed Orbits (LOCO) is employed in an orbit response matrix method for model improvement to verify the quadrupole strengths of the improved model.

  19. Modeling UV Radiation Feedback from Massive Stars. I. Implementation of Adaptive Ray-tracing Method and Tests

    Science.gov (United States)

    Kim, Jeong-Gyu; Kim, Woong-Tae; Ostriker, Eve C.; Skinner, M. Aaron

    2017-12-01

    We present an implementation of an adaptive ray-tracing (ART) module in the Athena hydrodynamics code that accurately and efficiently handles the radiative transfer involving multiple point sources on a three-dimensional Cartesian grid. We adopt a recently proposed parallel algorithm that uses nonblocking, asynchronous MPI communications to accelerate transport of rays across the computational domain. We validate our implementation through several standard test problems, including the propagation of radiation in vacuum and the expansions of various types of H II regions. Additionally, scaling tests show that the cost of a full ray trace per source remains comparable to that of the hydrodynamics update on up to ∼ {10}3 processors. To demonstrate application of our ART implementation, we perform a simulation of star cluster formation in a marginally bound, turbulent cloud, finding that its star formation efficiency is 12% when both radiation pressure forces and photoionization by UV radiation are treated. We directly compare the radiation forces computed from the ART scheme with those from the M 1 closure relation. Although the ART and M 1 schemes yield similar results on large scales, the latter is unable to resolve the radiation field accurately near individual point sources.

  20. Ray Tracing for Dispersive Tsunamis and Source Amplitude Estimation Based on Green's Law: Application to the 2015 Volcanic Tsunami Earthquake Near Torishima, South of Japan

    Science.gov (United States)

    Sandanbata, Osamu; Watada, Shingo; Satake, Kenji; Fukao, Yoshio; Sugioka, Hiroko; Ito, Aki; Shiobara, Hajime

    2017-12-01

    Ray tracing, which has been widely used for seismic waves, was also applied to tsunamis to examine the bathymetry effects during propagation, but it was limited to linear shallow-water waves. Green's law, which is based on the conservation of energy flux, has been used to estimate tsunami amplitude on ray paths. In this study, we first propose a new ray tracing method extended to dispersive tsunamis. By using an iterative algorithm to map two-dimensional tsunami velocity fields at different frequencies, ray paths at each frequency can be traced. We then show that Green's law is valid only outside the source region and that extension of Green's law is needed for source amplitude estimation. As an application example, we analyzed tsunami waves generated by an earthquake that occurred at a submarine volcano, Smith Caldera, near Torishima, Japan, in 2015. The ray-tracing results reveal that the ray paths are very dependent on its frequency, particularly at deep oceans. The validity of our frequency-dependent ray tracing is confirmed by the comparison of arrival angles and travel times with those of observed tsunami waveforms at an array of ocean bottom pressure gauges. The tsunami amplitude at the source is nearly twice or more of that just outside the source estimated from the array tsunami data by Green's law.

  1. Spin dynamics modeling in the AGS based on a stepwise ray-tracing method

    Energy Technology Data Exchange (ETDEWEB)

    Dutheil, Yann [Univ. of Grenoble (France)

    2006-08-07

    The AGS provides a polarized proton beam to RHIC. The beam is accelerated in the AGS from Gγ= 4.5 to Gγ = 45.5 and the polarization transmission is critical to the RHIC spin program. In the recent years, various systems were implemented to improve the AGS polarization transmission. These upgrades include the double partial snakes configuration and the tune jumps system. However, 100% polarization transmission through the AGS acceleration cycle is not yet reached. The current efficiency of the polarization transmission is estimated to be around 85% in typical running conditions. Understanding the sources of depolarization in the AGS is critical to improve the AGS polarized proton performances. The complexity of beam and spin dynamics, which is in part due to the specialized Siberian snake magnets, drove a strong interest for original methods of simulations. For that, the Zgoubi code, capable of direct particle and spin tracking through field maps, was here used to model the AGS. A model of the AGS using the Zgoubi code was developed and interfaced with the current system through a simple command: the AgsFromSnapRampCmd. Interfacing with the machine control system allows for fast modelization using actual machine parameters. Those developments allowed the model to realistically reproduce the optics of the AGS along the acceleration ramp. Additional developments on the Zgoubi code, as well as on post-processing and pre-processing tools, granted long term multiturn beam tracking capabilities: the tracking of realistic beams along the complete AGS acceleration cycle. Beam multiturn tracking simulations in the AGS, using realistic beam and machine parameters, provided a unique insight into the mechanisms behind the evolution of the beam emittance and polarization during the acceleration cycle. Post-processing softwares were developed to allow the representation of the relevant quantities from the Zgoubi simulations data. The Zgoubi simulations proved particularly

  2. Energy and polarization dependence of resonant inelastic X-ray scattering in Nd2CuO4

    International Nuclear Information System (INIS)

    Hill, J.P.; Kao, C.C.; Haemaelaeinen, K.

    1998-01-01

    The authors report the energy and polarization dependence of resonant inelastic x-ray scattering from Nd 2 CuO 4 . An energy loss feature at ∼6 eV is observed in the vicinity of the Cu K-edge. Numerical calculations based on the Anderson impurity model identify this as a charge transfer excitation to the anti-bonding state. The incident polarization is shown to select the intermediate states participating in the resonance process. Resonances are observed at 8,990 eV and 9,000 eV with the incident polarization perpendicular and parallel to the CuO planes, respectively. In contrast to the single-site model calculations, no resonances are observed associated with the 1s3d 10 L intermediate states, suggesting non-local effects play a role

  3. Tracing Clusters to High Red-shift Ray P. Norris & the EMU Team

    Indian Academy of Sciences (India)

    To trace the evolution of massive black holes throughout the history of the. Universe, and understand their relationship to star formation. • To use the distribution of radio sources to explore the large-scale structure and cosmological parameters of the Universe, and to test fundamental physics. • To explore an uncharted ...

  4. Multi-element analysis of pyrite ores using polarized energy-dispersive X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ustuendag, Zafer [Department of Chemistry, Faculty of Science, Ankara University, Ankara (Turkey)]. E-mail: zustun@science.ankara.edu.tr; Ustuendag, Ilknur [Department of Physics Engineering, Faculty of Engineering, Hacettepe University, Ankara (Turkey); Kagan Kadioglu, Yusuf [Department of Geological Engineering, Faculty of Engineering, Ankara University, Ankara (Turkey)

    2007-07-15

    X-ray fluorescence (XRF) spectrometry is used worldwide in geological material analysis. This study, applies polarized energy-dispersive X-ray fluorescence (PEDXRF) Spectrometer and compares in the samples of Rize-Cayeli and Mardin pyrite ores. The samples of pyrite ore were collected from the Rize and Mardin in Turkey. The prepared samples were analyzed using a PEDXRF spectrometer. The result of the analysis shows the presence of many elements including rare-earth elements (from Na to Th). The accuracy and precision of the technique for chemical analysis is demonstrated by analyzing USGS standards, GEOL, GBW 7109 and GBW-7309 sediment.

  5. Plane polarized x-ray fluorescence system for the in vivo measurement of platinum in head and neck tumours

    Science.gov (United States)

    Ali, P. A.; Al-Hussany, A. F.; Bennett, C. A.; Hancock, D. A.; El-Sharkawi, A. M.

    1998-08-01

    A plane polarized x-ray fluorescence system based on an orthovoltage radiotherapy treatment unit, the Pantak DXT-300, has been developed and optimized to measure tumour platinum concentration. The platinum derives from platinum based chemotherapy agents, such as cisplatin and carboplatin used to treat tumours in the head and neck region. Photons from an x-ray tube are polarized by scattering through , and used to stimulate the emission of characteristic platinum x-rays from the tumour. Information about the drug in the tumour could be of use in establishing dose-response relationships, in order to optimize the treatment and reduce the toxicity of the drug. The performance of the system was optimized with respect to the applied x-ray tube voltage, the current and the filter material; the effect on the minimum detection limit (MDL) of the thickness of the overlying tissue surrounding the tumour was investigated in detail. The lowest MDL is achieved using 0.25 mm of tin filter and x-ray tube voltage of 220 kV. This is 5.6 ppm for a tumour surrounded with 20 mm of overlying tissue, a measurement time of 2000 s and an estimated skin dose of 3.0 mGy. This represents the most sensitive in vivo XRF system to date. We have embarked on a clinical pilot study to measure the platinum concentration in tumours of the head and neck, and expect initial results to be available in the near future.

  6. Polarization study of non-resonant X-ray magnetic scattering from spin-density-wave modulation in chromium

    International Nuclear Information System (INIS)

    Ohsumi, Hiroyuki; Takata, Masaki

    2007-01-01

    We present a polarization study of non-resonant X-ray magnetic scattering in pure chromium. Satellite reflections are observed at +/-Q and +/-2Q, where Q is the modulation wave vector of an itinerant spin-density-wave. The first and second harmonics are confirmed to have magnetic and charge origin, respectively, by means of polarimetry without using an analyzer crystal. This alternative technique eliminates intolerable intensity loss at an analyzer by utilizing the sample crystal also as an analyzer crystal

  7. Total reflection X-ray fluorescence as a convenient tool for determination of trace elements in microscale gasoline and diesel

    Science.gov (United States)

    Zhang, Airui; Jin, Axiang; Wang, Hai; Wang, Xiaokang; Zha, Pengfei; Wang, Meiling; Song, Xiaoping; Gao, Sitian

    2018-03-01

    Quantitative determination of trace elements like S, Fe, Cu, Mn and Pb in gasoline and S in diesel is of great importance due to the growing concerns over air pollution, human health and engine failure caused by utilization of gasoline and diesel with these harmful elements. A method of total reflection X-ray fluorescence (TXRF) was developed to measure these harmful trace elements in gasoline and diesel. A variety of factors to affect measurement results, including TXRF parameters, microwave-assisted digestion conditions and internal standard element and its addition, were examined to optimize these experimental procedures. The hydrophobic treatment of the surface of quartz reflectors to support the analyte with neutral silicone solutions could prepare thin films of gasoline and diesel digestion solutions for subsequent TXRF analysis. The proposed method shows good potential and reliability to determine the content of harmful trace elements in gasoline and diesel with high sensitivity and accuracy without drawing different standard calibration curves, and can be easily employed to screen gasoline and diesel in routine quality control and assurance.

  8. Trace metal analysis in sea grasses from Mexican Caribbean Coast by particle induced X-ray emission (PIXE)

    International Nuclear Information System (INIS)

    Solis, C.; Issac O, K.; Martinez, A.; Lavoisier, E.; Martinez, M. A.

    2008-01-01

    The growing urban and tourist activity in the Mexican Caribbean coasts has resulted in an increase of chemical substances, metals in particular, discharged to the coastal waters. In order to reach an adequate management and conservation of these marine ecosystems it is necessary to perform an inventory of the actual conditions that reflect the vulnerability and the level of damage. Sea-grasses are considered good biological indicators of heavy metal contamination in marine systems. The goal of this preliminary work is to evaluate the concentrations of trace metals such as Cr, Mn, Fe, Co, Cu, Zn, and Pb in Thalassia testudinum, a very common sea-grass in the Mexican Caribbean Sea. Samples were collected from several locations in the coasts of the Yucatan Peninsula: Holbox, Blanquizal and Punta Allen, areas virtually uninfluenced by anthropogenic activities. Trace elements in different part plants were determined by particle induced X-ray emission (PIXE). This is a very suitable technique since it offers a fast, accurate and multi-element analysis. Also, the analysis by PIXE can be performed directly on powdered leaves without a laborious sample preparation. The trace metal concentration determined in sea-grasses growing in Caribbean generally fall in the range of the lowest valuables reported for sea grasses from the Gulf of Mexico. The results indicate that the studied areas do not present contamination by heavy metals. (Author)

  9. Intelligent simultaneous quantitative online analysis of environmental trace heavy metals with total-reflection X-ray fluorescence.

    Science.gov (United States)

    Ma, Junjie; Wang, Yeyao; Yang, Qi; Liu, Yubing; Shi, Ping

    2015-05-06

    Total-reflection X-ray fluorescence (TXRF) has achieved remarkable success with the advantages of simultaneous multi-element analysis capability, decreased background noise, no matrix effects, wide dynamic range, ease of operation, and potential of trace analysis. Simultaneous quantitative online analysis of trace heavy metals is urgently required by dynamic environmental monitoring and management, and TXRF has potential in this application domain. However, it calls for an online analysis scheme based on TXRF as well as a robust and rapid quantification method, which have not been well explored yet. Besides, spectral overlapping and background effects may lead to loss of accuracy or even faulty results during practical quantitative TXRF analysis. This paper proposes an intelligent, multi-element quantification method according to the established online TXRF analysis platform. In the intelligent quantification method, collected characteristic curves of all existing elements and a pre-estimated background curve in the whole spectrum scope are used to approximate the measured spectrum. A novel hybrid algorithm, PSO-RBFN-SA, is designed to solve the curve-fitting problem, with offline global optimization and fast online computing. Experimental results verify that simultaneous quantification of trace heavy metals, including Cr, Mn, Fe, Co, Ni, Cu and Zn, is realized on the online TXRF analysis platform, and both high measurement precision and computational efficiency are obtained.

  10. Intelligent Simultaneous Quantitative Online Analysis of Environmental Trace Heavy Metals with Total-Reflection X-Ray Fluorescence

    Directory of Open Access Journals (Sweden)

    Junjie Ma

    2015-05-01

    Full Text Available Total-reflection X-ray fluorescence (TXRF has achieved remarkable success with the advantages of simultaneous multi-element analysis capability, decreased background noise, no matrix effects, wide dynamic range, ease of operation, and potential of trace analysis. Simultaneous quantitative online analysis of trace heavy metals is urgently required by dynamic environmental monitoring and management, and TXRF has potential in this application domain. However, it calls for an online analysis scheme based on TXRF as well as a robust and rapid quantification method, which have not been well explored yet. Besides, spectral overlapping and background effects may lead to loss of accuracy or even faulty results during practical quantitative TXRF analysis. This paper proposes an intelligent, multi-element quantification method according to the established online TXRF analysis platform. In the intelligent quantification method, collected characteristic curves of all existing elements and a pre-estimated background curve in the whole spectrum scope are used to approximate the measured spectrum. A novel hybrid algorithm, PSO-RBFN-SA, is designed to solve the curve-fitting problem, with offline global optimization and fast online computing. Experimental results verify that simultaneous quantification of trace heavy metals, including Cr, Mn, Fe, Co, Ni, Cu and Zn, is realized on the online TXRF analysis platform, and both high measurement precision and computational efficiency are obtained.

  11. Polarized high-brilliance and high-resolution soft x-ray source at ELETTRA: The performance of beamline BACH

    International Nuclear Information System (INIS)

    Zangrando, M.; Zacchigna, M.; Finazzi, M.; Cocco, D.; Rochow, R.; Parmigiani, F.

    2004-01-01

    BACH, a soft x-ray beamline for polarization-dependent experiments at the Italian synchrotron radiation facility ELETTRA, was recently completed and characterized. Its performance, in terms of energy resolution, flux and polarization, is presented. Based on two APPLE II undulators, BACH covers the energy range between 35 and 1600 eV with the control of the light polarization. The monochromator is equipped with four gratings and allows one to work either in a high resolution or in a high flux mode. After the monochromator, the beamline is split into two branches with different refocusing properties. One is optimized to exploit the performance of the soft x-ray spectrometer (ComIXS) available at the beamline. Resolving powers between 12000 at 90 eV photon energy and 6600 near 867 eV were achieved using the high-resolution gratings and the smallest available slit width (10 μm). For the high-brilliance grating, which works between 290 and 1600 eV, resolving powers between 7000 at 400 eV and 2200 at 867 eV were obtained. The flux in the experimental chamber, measured with the high-resolution gratings for linearly polarized light at the best achievable resolution, ranges between 4x10 11 photons/s at 125 eV and 2x10 10 photons/s between 900 and 1250 eV. In circularly polarized mode the flux is two times larger for energies up to 380 eV. A gain of nearly one order of magnitude is obtained for the high-brilliance grating, in accordance with theoretical predictions. Flux beyond 1.3x10 11 photons/s was measured up to 1300 eV, and thus over nearly the complete energy range covered by this high-brilliance grating, with a maximum of 1.6x10 11 photons/s between 800 and 1100 eV. First results from polarization measurements confirm a polarization above 99.7% for both linearly and circularly polarized modes at low energies. Circular dichroism experiments indicate a circular polarization beyond 90% at the Fe L 2 /L 3 edge near 720 eV

  12. Estimation of heterogeneous reaction rates for stratospheric trace gases with particular reference to the diffusional uptake of HCl and ClONO2 by polar stratospheric clouds

    Directory of Open Access Journals (Sweden)

    J. A. Pyle

    Full Text Available The stratosphere holds a variety of particulates like polar stratospheric clouds (PSCs and sulphate aerosols which catalyse chemical reactions. These reactions cause changes in the composition of the stratosphere, including the redistribution of active chlorine which might lead to ozone destruction. As a result during recent years a lot of effort has been directed towards the quantification of the uptake of trace gases like ClONO2, HCl, etc. into these particulates. However, it has been observed that many of the two and three dimensional models used in such studies are constrained by the lack of adequate rate constant data. This paper describes a theoretical approach to estimate the reaction rate constants for 23 gases on both types of polar stratospheric clouds (type I and II. It is found that for gases like N2O5, ClONO2 and HCl, diffusional uptake is important and contributes significantly to the heterogeneous reaction rate. A complete Lennard-Jones calculation is used to accurately compute the trace gas diffusion coefficients.

  13. Time-resolved non-sequential ray-tracing modelling of non-line-of-sight picosecond pulse LIDAR

    Science.gov (United States)

    Sroka, Adam; Chan, Susan; Warburton, Ryan; Gariepy, Genevieve; Henderson, Robert; Leach, Jonathan; Faccio, Daniele; Lee, Stephen T.

    2016-05-01

    The ability to detect motion and to track a moving object that is hidden around a corner or behind a wall provides a crucial advantage when physically going around the obstacle is impossible or dangerous. One recently demonstrated approach to achieving this goal makes use of non-line-of-sight picosecond pulse laser ranging. This approach has recently become interesting due to the availability of single-photon avalanche diode (SPAD) receivers with picosecond time resolution. We present a time-resolved non-sequential ray-tracing model and its application to indirect line-of-sight detection of moving targets. The model makes use of the Zemax optical design programme's capabilities in stray light analysis where it traces large numbers of rays through multiple random scattering events in a 3D non-sequential environment. Our model then reconstructs the generated multi-segment ray paths and adds temporal analysis. Validation of this model against experimental results is shown. We then exercise the model to explore the limits placed on system design by available laser sources and detectors. In particular we detail the requirements on the laser's pulse energy, duration and repetition rate, and on the receiver's temporal response and sensitivity. These are discussed in terms of the resulting implications for achievable range, resolution and measurement time while retaining eye-safety with this technique. Finally, the model is used to examine potential extensions to the experimental system that may allow for increased localisation of the position of the detected moving object, such as the inclusion of multiple detectors and/or multiple emitters.

  14. Trace elements in airborne particles in internal industrial environments: spectrometric analysis of x-ray fluorescence (XRF)

    International Nuclear Information System (INIS)

    Salazar Matarrita, Alfonso

    2001-01-01

    Fluorescence spectroscopy x-ray, is a technique of non-destructive analysis, that allows quantitative determination of the absolute concentration of chemical elements that make up a given matrix. The detected elements depend on atomic number and energy of the secondary target used for irradiation of samples. X-rays are detected and counted in a spectroscopy system based on a multichannel analyzer, that discriminates by energy and form a spectrum of independent photopeaks, whose energy identifies the element and its intensity is proportional to its concentration. The quantification requires the irradiation and counting of a set of pattern comparators, of the same elements identified in the samples. The x-ray emission shows only during the time that the selected sample is subjected to irradiation by x-ray tube. This irradiation does not change the structure nor the chemical composition of the matrix, so the sample remains unchanged, after irradiation. This condition non-destructive characterizes the fluorescence x-ray. The trace elements present in airborne particles, are determined and collected on a Nuclepore filter. The collection sites selected are: Taller de Mecanica de Precision de la Escuela de Fisica, Universidad de Costa Rica; Taller J. V. G. Precision, San Antonio de Coronado; Taller de Muflas, MUFLASA, Alto de Guadalupe; Industria Silvania S. A., Pavas. In addition, it is attached the service rendered to the enterprise Sellos Generales S. A. The working conditions and physical conditions of facilities were considered. An aerosol sampler with a temporal variation was used. Irradiation of samples and an evaluation of the concentrations have been made. (author) [es

  15. Application of the nudged elastic band method to the point-to-point radio wave ray tracing in IRI modeled ionosphere

    Science.gov (United States)

    Nosikov, I. A.; Klimenko, M. V.; Bessarab, P. F.; Zhbankov, G. A.

    2017-07-01

    Point-to-point ray tracing is an important problem in many fields of science. While direct variational methods where some trajectory is transformed to an optimal one are routinely used in calculations of pathways of seismic waves, chemical reactions, diffusion processes, etc., this approach is not widely known in ionospheric point-to-point ray tracing. We apply the Nudged Elastic Band (NEB) method to a radio wave propagation problem. In the NEB method, a chain of points which gives a discrete representation of the radio wave ray is adjusted iteratively to an optimal configuration satisfying the Fermat's principle, while the endpoints of the trajectory are kept fixed according to the boundary conditions. Transverse displacements define the radio ray trajectory, while springs between the points control their distribution along the ray. The method is applied to a study of point-to-point ionospheric ray tracing, where the propagation medium is obtained with the International Reference Ionosphere model taking into account traveling ionospheric disturbances. A 2-dimensional representation of the optical path functional is developed and used to gain insight into the fundamental difference between high and low rays. We conclude that high and low rays are minima and saddle points of the optical path functional, respectively.

  16. Computation of the Transmitted and Polarized Scattered Fluxes by the Exoplanet HD 189733b in X-Rays

    Energy Technology Data Exchange (ETDEWEB)

    Marin, Frédéric [Astronomical Institute of the Academy of Sciences, Boční II 1401, CZ-14100 Prague (Czech Republic); Grosso, Nicolas, E-mail: frederic.marin@astro.unistra.fr [Université de Strasbourg, CNRS, Observatoire astronomique de Strasbourg, UMR 7550, F-67000 Strasbourg (France)

    2017-02-01

    Thousands of exoplanets have been detected, but only one exoplanetary transit was potentially observed in X-rays from HD 189733A. What makes the detection of exoplanets so difficult in this band? To answer this question, we run Monte-Carlo radiative transfer simulations to estimate the amount of X-ray flux reprocessed by HD 189733b. Despite its extended evaporating atmosphere, we find that the X-ray absorption radius of HD 189733b at 0.7 keV, which is the mean energy of the photons detected in the 0.25–2 keV energy band by XMM-Newton , is ∼1.01 times the planetary radius for an atmosphere of atomic hydrogen and helium (including ions), and produces a maximum depth of ∼2.1% at ∼±46 minutes from the center of the planetary transit on the geometrically thick and optically thin corona. We compute numerically in the 0.25–2 keV energy band that this maximum depth is only of ∼1.6% at ∼±47 minutes from the transit center, and not very sensitive to the metal abundance, assuming that adding metals in the atmosphere would not dramatically change the density–temperature profile. Regarding a direct detection of HD 189733b in X-rays, we find that the amount of flux reprocessed by the exoplanetary atmosphere varies with the orbital phase, spanning between three and five orders of magnitude fainter than the flux of the primary star. Additionally, the degree of linear polarization emerging from HD 189733b is <0.003%, with maximums detected near planetary greatest elongations. This implies that both the modulation of the X-ray flux with the orbital phase and the scatter-induced continuum polarization cannot be observed with current X-ray facilities.

  17. Tracing euxinia by molybdenum concentrations in sediments using handheld X-ray fluorescence spectroscopy (HHXRF)

    DEFF Research Database (Denmark)

    Dahl, Tais W.; Ruhl, Micha; Hammarlund, Emma U.

    2013-01-01

    Elevated molybdenum (Mo) contents in organic-rich sediments are indicative of deposition from an anoxic and sulfide-rich (euxinic) water-column. This can be used for tracing past euxinic conditions in ancient oceans from sedimentary archives. Conventional analytical detection of elevated molybdenum...... obtained Mo concentrations from homogenous powders of the same rocks. Collectively, our data show that HHXRF as a quick and reliable method for the precise and accurate quantification of molybdenum concentrations in both rock powders and at fresh rock surfaces. The non-destructive nature of the HHXRF...

  18. Grazing exit versus grazing incidence geometry for x-ray absorption near edge structure analysis of arsenic traces

    International Nuclear Information System (INIS)

    Meirer, F.; Streli, C.; Wobrauschek, P.; Zoeger, N.; Pepponi, G.

    2009-01-01

    In the presented study the grazing exit x-ray fluorescence was tested for its applicability to x-ray absorption near edge structure analysis of arsenic in droplet samples. The experimental results have been compared to the findings of former analyses of the same samples using a grazing incidence (GI) setup to compare the performance of both geometries. Furthermore, the investigations were accomplished to gain a better understanding of the so called self-absorption effect, which was observed and investigated in previous studies using a GI geometry. It was suggested that a normal incidence-grazing-exit geometry would not suffer from self-absorption effects in x-ray absorption fine structure (XAFS) analysis due to the minimized path length of the incident beam through the sample. The results proved this assumption and in turn confirmed the occurrence of the self-absorption effect for GI geometry. Due to its lower sensitivity it is difficult to apply the GE geometry to XAFS analysis of trace amounts (few nanograms) of samples but the technique is well suited for the analysis of small amounts of concentrated samples

  19. Bright Linearly and Circularly Polarized Extreme Ultraviolet and Soft X-ray High Harmonics for Absorption Spectroscopy

    Science.gov (United States)

    Fan, Tingting

    High harmonic generation (HHG) is an extreme nonlinear optical process. When implemented in a phase-matched geometry, HHG coherent upconverts femtosecond laser light into coherent "X-ray laser" beams, while retaining excellent spatial and temporal coherence, as well as the polarization state of the driving laser. HHG has a tabletop footprint, with femtosecond to attosecond time resolution, combined with nanometer spatial resolution. As a consequence of these unique capabilities, HHG is now being widely adopted for use in molecular spectroscopy and imaging, materials science, as well as nanoimaging in general. In the first half of this thesis, I demonstrate high flux linearly polarized soft X-ray HHG, driven by a single-stage 10-mJ Ti:sapphire regenerative amplifier at a repetition rate of 1 kHz. I first down-converted the laser to 1.3 mum using an optical parametric amplifier, before up-converting it into the soft X-ray region using HHG in a high-pressure, phase-matched, hollow waveguide geometry. The resulting optimally phase-matched broadband spectrum extends to 200 eV, with a soft X-ray photon flux of > 106 photons/pulse/1% bandwidth at 1 kHz, corresponding to > 109 photons/s/1% bandwidth, or approximately a three orders-of-magnitude increase compared with past work. Using this broad bandwidth X-ray source, I demonstrated X-ray absorption spectroscopy of multiple elements and transitions in molecules in a single spectrum, with a spectral resolution of 0.25 eV, and with the ability to resolve the near edge fine structure. In the second half of this thesis, I discuss how to generate the first bright circularly polarized (CP) soft X-ray HHG and also use them to implement the first tabletop X-ray magnetic circular dichroism (XMCD) measurements. Using counter-rotating CP lasers at 1.3 mum and 0.79 mum, I generated CPHHG with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right CP peaks, with energies

  20. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T. [Physics Department, University of Nevada, Reno, Nevada 89557 (United States); Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2014-12-15

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a “double bun” structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  1. Precision gamma-ray polarimetry applied to studies of bremsstrahlung produced by polarized electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kovtun, Oleksiy

    2015-12-16

    The thesis reports on the measurement of bremsstrahlung linear polarization produced in collisions of longitudinally and transversely polarized electrons with gold atoms. The experiment was performed at the Mainzer Microtron MAMI in the Institut fuer Kernphysik of Johannes Gutenberg-Universitaet Mainz, Germany. Spin-oriented electrons with 2.15 MeV kinetic energy collided with a thin golden target and produced bremsstrahlung. Linear polarization of the emitted photons was measured by means of Compton polarimetry applied to a segmented high-purity germanium detector. Experimental results reveal a strong correlation between the electron spin orientation and bremsstrahlung linear polarization. This indicates a dominant role of the electron spin in atomic-field bremsstrahlung and Coulomb scattering.

  2. The influence of the positronium photoionization rate on the polar cap X-ray luminosity of radio pulsars

    Science.gov (United States)

    Barsukov, D. P.; Vorontsov, M. V.

    2017-12-01

    The influence of the positronium photoionization rate on the polar cap X-ray luminosity of old radio pulsars is considered. It is assumed that the polar cap is heated only by reverse positrons accelerated in the pulsar diode. It is supposed that the pulsar diode is in a stationary state with the lower plate located near the star surface (polar cap model) occupies all the pulsar tube cross section and operates in the regime of steady space charge by the limited electron flow. The influence of a small-scale magnetic field on the electric field inside the pulsar diode is taken into account. The reverse positron current is calculated in the framework of two models: rapid and gradual screening. To calculate the production rate of electron-positron pairs we take into account only the curvature radiation of primary electrons and its absorption in the magnetic field. It is assumed that some fraction of electron-positron pairs is created in a bound state (positronium). Later, such positroniums are photoionized by thermal photons from the polar cap.

  3. Trace analysis in the atmosphere, water bodies and uranium ores by means of X-ray fluorescence

    International Nuclear Information System (INIS)

    Perez Novara, A.M.

    1986-01-01

    Analysis with X-ray fluorescence is an instrumental method that evaluates concentrations, at trace levels, of elements in samples of all kinds. The applications of this method are broad, specially useful in the analysis of metals as contaminators in air and water, and as impurities in minerals. The preparation of the samples is very important to obtain good accuracy, and at the same time, you should make a series of standards of known concentrations so you can compare the counting of each sample against the standard, for each of the elements. You should make, depending on the nature of the sample, several corrections with respect to the background, interferences, overlaps, or for effects of a third element. (author)

  4. Theoretical simulation and analysis of large size BMP-LSC by 3D Monte Carlo ray tracing model

    International Nuclear Information System (INIS)

    Zhang Feng; Zhang Ning-Ning; Yan Sen; Song Sun; Jun Bao; Chen Gao; Zhang Yi

    2017-01-01

    Luminescent solar concentrators (LSC) can reduce the area of solar cells by collecting light from a large area and concentrating the captured light onto relatively small area photovoltaic (PV) cells, and thereby reducing the cost of PV electricity generation. LSCs with bottom-facing cells (BMP-LSC) can collect both direct light and indirect light, so further improving the efficiency of the PV cells. However, it is hard to analyze the effect of each parameter by experiment because there are too many parameters involved in the BMP-LSC. In this paper, all the physical processes of the light transmission and collection in the BMP-LSC were analyzed. A three-dimensional Monte Carlo ray tracing program was developed to study the transmission of photons in the LSC. A larger-size LSC was simulated, and the effects of dye concentration, the LSC thickness, the cell area, and the cell distance were systematically analyzed. (paper)

  5. Determination of trace chromium(VI) in drinking water using X-ray fluorescence spectrometry after solid-phase extraction

    Energy Technology Data Exchange (ETDEWEB)

    Aranda, Pedro R.; Moyano, Susana; Martinez, Luis D.; De Vito, Irma E. [Universidad Nacional de San Luis, Facultad de Quimica, Bioquimica y Farmacia, Area de Quimica Analitica, Instituto de Quimica de San Luis (INQUISAL - CONICET), San Luis (Argentina)

    2010-09-15

    A new, simple, and selective method for preconcentration and determination of Cr(VI) in aqueous samples. After adsorption in ''batch mode'' on Aliquat 336-AC, determinations were made directly on the solid by X-ray fluorescence spectrometry, which had the advantage of not requiring the step of elution of the chromium retained. The enrichment factor was calculated considering that the tablets obtained from 10 mL solution of Cr(VI) (1000 {mu}g L{sup -1}) had a final thickness of 0.64 mm and a diameter of 16.7 mm; the volume deposited on the pellet was 0.14 cm{sup 3}. The preconcentration factor obtained was 71-fold, which was highly satisfactory for chromium trace analysis by XRF. Finally, the method was successfully applied to the determination of Cr(VI) in drinking water samples. (orig.)

  6. Ray-tracing study on the post-scanner variable beam expansion optics in a two-photon microscopy system

    Science.gov (United States)

    Kim, Do-Hyun; Welle, Cristin; Krauthamer, Victor

    2012-03-01

    Due to the low signal levels typical of two-photon microscopy (TPM) in biological samples, optical design optimization is critical. One of the most important factors is overfilling of the back aperture of the objective lens. A variable beam expander is commonly placed before the scanning mirrors to achieve this goal, however, this may cause degradation of image quality due to increased dispersion. Additionally, scanning mirror size restricts the degree of expansion, which often prevents the overfilling of objective lens back aperture. We investigated the implementation of variable beam expansion optics after the scanning mirrors. Ray-tracing analyses confirmed that the post-scanner beam expansion has two key advantages over the conventional pre-scanner beam expansion approach: decreasing the number of optical elements reduces pulse dispersion and reducing the size of the scanning mirror enables faster scanning. Resolution and aberration of a TPM with post-scanner beam expansion optics were analysed.

  7. Seasonal variation in trace and minor elements in Brazilian honey by total reflection X-ray fluorescence.

    Science.gov (United States)

    de Oliveira Resende Ribeiro, Roberta; Mársico, Eliane Teixeira; da Silva Carneiro, Carla; Simoes, Julia Siqueira; da Silva Ferreira, Micheli; de Jesus, Edgar Francisco Oliveira; Almeida, Eduardo; Junior, Carlos Adam Conte

    2015-03-01

    Honey is used as an alternative medicine and is a constituent of a healthy diet worldwide. Its composition is associated with botanical origin and, to some extent, geographical origin because soil and climate characteristics determine the melliferous flora. Also, the elements content in honey samples could give an indication of environmental pollution or geographical origin. The main purpose of this study was to evaluate seasonal patterns of essential elements of Brazilian honey. Honey was collected during spring, summer, autumn, and winter for 2 years to quantify K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, and Sr using total reflection X-ray fluorescence spectroscopy (TXRF). Our results indicate no seasonal differences in concentration of Cr, Ni, Se, and Ti, although there were significant seasonal patterns in the composition of essential elements in honey, with higher concentrations of minor and trace elements, especially K and Ca of samples collected in spring and summer.

  8. Beta-Barrel Detection for Medium Resolution Cryo-Electron Microscopy Density Maps Using Genetic Algorithms and Ray Tracing.

    Science.gov (United States)

    Ng, Albert; Si, Dong

    2017-10-16

    Cryo-electron microscopy (cryo-EM) is a technique that produces three-dimensional density maps of large protein complexes. This allows for the study of the structure of these proteins. Identifying the secondary structures within proteins is vital to understanding the overall structure and function of the protein. The [Formula: see text]-barrel is one such secondary structure, commonly found in lipocalins and membrane proteins. In this article, we present a novel approach that utilizes genetic algorithms, kd-trees, and ray tracing to automatically detect and extract [Formula: see text]-barrels from cryo-EM density maps. This approach was tested on simulated and experimental density maps with zero, one, or multiple barrels in the density map. The results suggest that the proposed approach is capable of performing automatic detection of [Formula: see text]-barrels from medium resolution cryo-EM density maps.

  9. Towards modeling of random lasing in dye doped bio-organic based systems: ray-tracing and cellular automaton analysis

    Science.gov (United States)

    Mitus, A. C.; Stopa, P.; Zaklukiewicz, W.; Pawlik, G.; Mysliwiec, J.; Kajzar, F.; Rau, I.

    2015-08-01

    One of many photonic applications of biopolymers as functional materials is random lasing resulting from an incorporation of highly luminescent dyes into biopolymeric matrix, which leads to a random but coherent light scattering in amplifying medium. In spite of numerous theoretical and experimental studies the origin of the coherence is still not clear and various scenarios are discussed. In particular, inhomogeneity of biopolymeric layers can hypothetically promote the feedback in the scattering of the emitted light resulting in coherent and incoherent random lasing. In this paper we analyze the light scattering in a model system of scattering centers of circular shapes and various dimensions using ray-tracing techniques. In the second part, which has mostly a tutorial character, we present the approach to the study of random lasing using a cellular automaton model of Wiersma et al.

  10. Determination of heavy metals at traces level in leached samples by energy dispersive x-ray fluorescence technique

    International Nuclear Information System (INIS)

    Simabuco, Silvana M.; Nascimento Filho, Virgilio F. do; Inacio, Graziela R.; Navarro, Angela N.

    1996-01-01

    In landfill solid residues are disposed in the soil. When made based on technical criteria and specifically operation patterns a safe confinement is warranted according to environmental and public health protection. However, when the disposal is made by a random and unsuitable way serious problems can be caused as groundwater and superficial water contamination through leach action, indicating the usefulness of monitoring landfills. In this way energy dispersive X-ray fluorescence analysis with radioisotopic excitation was applied to evaluate the concentrations of heavy metals at trace levels in leached samples from the Americana City Landfill with pre-concentration of the elements by a non-specific precipitating agent, called ammonium pyrrolidine dithiocarbamate (APDC). (author)

  11. Ultra-Wideband Indoor Channel Modelling Using Ray-Tracing Software for through-the-Wall Imaging Radar

    Directory of Open Access Journals (Sweden)

    Christophe Lièbe

    2010-01-01

    Full Text Available This paper presents a new software for design of through-the-wall imaging radars. The first part describes the evolution of a ray tracing simulator, originally designed for propagation of narrowband signals, and then for ultra-wideband signals. This simulator allows to obtain temporal channel response to a wide-band emitter (3 GHz to 10 GHz. An experimental method is also described to identify the propagation paths. Simulation results are compared to propagation experiments under the same conditions. Different configurations are tested and then discussed. Finally, a configuration of through-the-wall imaging radar is proposed, with different antennas patterns and different targets. Simulated images will be helpful for understanding the experiment obtained images.

  12. Design of co-path scanning long trace profiler for measurement of x-ray space optical elements

    Science.gov (United States)

    Shun, Li; Yan, Gong; Wei, Zhang; Yang, Zhao

    2010-08-01

    The Long Trace Profiler (LTP) is a precision surface slope error measurement instrument used in synchrotron radiation optics for many years. By making some modifications to the LTP system, we developed a co-path scanning LTP (CSLTP) system to test the cylindrical aspherical surface which used in X-ray space optics. To reduce the mistake caused by air turbulence and manufacture faults of optical elements used, the CSLTP is designed with the least difference between the testing beam path and the reference beam path. Also, it uses multiple-beam interference but double beam interference to reduce the width of beam fringe. This improves the position precision of the beam fringe on the image plane.

  13. Electronic-structure origin of the anisotropic thermopower of nanolaminated Ti3SiC2 determined by polarized x-ray spectroscopy and Seebeck measurements

    DEFF Research Database (Denmark)

    Magnuson, Martin; Mattesini, Maurizio; Van Nong, Ngo

    2012-01-01

    Nanolaminated materials exhibit characteristic magnetic, mechanical, and thermoelectric properties, with large contemporary scientific and technological interest. Here we report on the anisotropic Seebeck coefficient in nanolaminated Ti3SiC2 single-crystal thin films and trace the origin...... value of 4–6 μV/K. Employing a combination of polarized angle-dependent x-ray spectroscopy and density functional theory we directly show electronic structure anisotropy in inherently nanolaminated Ti3SiC2 single-crystal thin films as a model system. The density of Ti 3d and C 2p states at the Fermi...... to anisotropies in element-specific electronic states. In bulk polycrystalline form, Ti3SiC2 has a virtually zero Seebeck coefficient over a wide temperature range. In contrast, we find that the in-plane (basal ab) Seebeck coefficient of Ti3SiC2, measured on single-crystal films, has a substantial and positive...

  14. Trace elemental analysis of drugs of abuse using synchrotron radiation total reflection X-ray fluorescence analysis (SR-TXRF).

    Science.gov (United States)

    Muratsu, Seiji; Ninomiya, Toshio; Kagoshima, Yasushi; Matsui, Junji

    2002-09-01

    Synchrotron radiation total reflection X-ray fluorescence spectroscopy (SR-TXRF) was utilized to analyze various trace elements in small amounts of drugs of abuse. Sample amounts of 1 microL solutions containing 10 microg of drugs (methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine, cocaine, and heroin) were spotted on silicon wafers for direct analysis. In addition, a leaflet of marijuana was set directly on a silicon wafer, and opium in the form of a soft lump was smeared on another silicon wafer for analysis. In these experiments, about 10 pg of contaminant elements could be detected. For example, in a seized methamphetamine sample, iodine was found, which could be indicative of synthetic route. In seized 3,4-methylenedioxymethamphetamine samples, variable amounts of phosphorus, calcium, sulfur, and potassium were found, which could not be detected in a control 3,4-methylenedioxymethamphetamine sample. For marijuana and opium, two spectral patterns were obtained that were far different from each other and could be easily discriminated. Using SR-TXRF, pg amounts of each trace element in 10 microg of various drugs can be easily detected, which is not the case either for a standard TXRF experimental system or for other elemental analysis techniques.

  15. Application of the Total Reflection X-ray Fluorescence technique to trace elements determination in tobacco

    International Nuclear Information System (INIS)

    Martinez, T.; Lartigue, J.; Zarazua, G.; Avila-Perez, P.; Navarrete, M.; Tejeda, S.

    2008-01-01

    Many studies have identified an important number of toxic elements along with organic carcinogen molecules and radioactive isotopes in tobacco. In this work we have analyzed by Total Reflection X-Ray Fluorescence 9 brands of cigarettes being manufactured and distributed in the Mexican market. Two National Institute of Standards and Technology standards and a blank were equally treated at the same time. Results show the presence of some toxic elements such as Pb and Ni. These results are compared with available data for some foreign brands, while their implications for health are discussed. It can be confirmed that the Total Reflection X-Ray Fluorescence method provides precise (reproducible) and accuracy (trueness) data for 15 elements concentration in tobacco samples

  16. Analysis of trace elements in medicinal plants with energy dispersive X-ray fluorescence

    International Nuclear Information System (INIS)

    Ekinci, N.; Polat, R.; Budak, G.; Ekinci, R.

    2004-01-01

    Mankind still depend on traditional herbal medicine for the treatment of various diseases and ailments. Elemental composition and concentration of medicinal plants have been investigated by energy dispersive X-ray fluorescence. The elements present in medicinal plants are P, Cl, K, Ca, S, Al, Ti, V, Rb, Sr, Zr, Nb, Mo, In, Sn, I and Ce. The physical basis of the used analytical method, the experimental set up and the procedure of sample preparation are presented. (author)

  17. Response of the polar atmosphere of the earth to variations of cosmic-ray intensity in the stratosphere

    Science.gov (United States)

    Ulianov, V. P.; Rudnev, Iu. F.; Novikov, A. M.

    The effect of cosmic-ray intensity variations in the polar stratosphere on the circulation in this region is investigated on the basis of data from the Tiksi and Murmansk stations. It is shown that an increase in solar activity manifested in Forbush effects at the end of February and the beginning of March leads in general to an earlier-than-usual spring reversal of stratospheric circulation. The reversal mechanism evidently has a complex character: a decrease in the intensity of the circumpolar vortex is observed three to five days after the Forbush effect; this decrease is succeeded by a significant increase eight to ten days after the effect.

  18. Natural circular dichroism of amino acid films observed in soft X-ray and VUV region using polarizing undulator

    International Nuclear Information System (INIS)

    Nakagawa, K.; Kaneko, F.; Ohta, Y.; Tanaka, M.; Kitada, T.; Agui, A.; Fujii, F.; Yokoya, A.; Yagi-Watanabe, K.; Yamada, T.

    2005-01-01

    We observed the natural circular dichroism NCD of amino acid films in the soft X-ray region for the first time [M. Tanaka, K. Nakagawa, A. Agui, K. Fujii, A. Yokoya, Physica Scripta, in press]. Based on the success, a new generation of detection system is now under preparation. Vacuum ultraviolet NCD of amino acid films was measured successfully using a polarizing undulator [H. Onuki, Nucl. Instrum. Meth. A 246 (1986) 94] installed at the TERAS electron storage ring at AIST, Tsukuba, Japan. A result of NCD measurement for alanine films is described in detail

  19. Strong disk winds traced throughout outbursts in black-hole X-ray binaries.

    Science.gov (United States)

    Tetarenko, B E; Lasota, J-P; Heinke, C O; Dubus, G; Sivakoff, G R

    2018-02-01

    Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1-0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2-1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

  20. Strong disk winds traced throughout outbursts in black-hole X-ray binaries

    Science.gov (United States)

    Tetarenko, B. E.; Lasota, J.-P.; Heinke, C. O.; Dubus, G.; Sivakoff, G. R.

    2018-02-01

    Recurring outbursts associated with matter flowing onto compact stellar remnants (such as black holes, neutron stars and white dwarfs) in close binary systems provide a way of constraining the poorly understood accretion process. The light curves of these outbursts are shaped by the efficiency of angular-momentum (and thus mass) transport in the accretion disks, which has traditionally been encoded in a viscosity parameter, α. Numerical simulations of the magneto-rotational instability that is believed to be the physical mechanism behind this transport yield values of α of roughly 0.1–0.2, consistent with values determined from observations of accreting white dwarfs. Equivalent viscosity parameters have hitherto not been estimated for disks around neutron stars or black holes. Here we report the results of an analysis of archival X-ray light curves of 21 outbursts in black-hole X-ray binaries. By applying a Bayesian approach to a model of accretion, we determine corresponding values of α of around 0.2–1.0. These high values may be interpreted as an indication either of a very high intrinsic rate of angular-momentum transport in the disk, which could be sustained by the magneto-rotational instability only if a large-scale magnetic field threads the disk, or that mass is being lost from the disk through substantial outflows, which strongly shape the outburst in the black-hole X-ray binary. The lack of correlation between our estimates of α and the accretion state of the binaries implies that such outflows can remove a substantial fraction of the disk mass in all accretion states and therefore suggests that the outflows correspond to magnetically driven disk winds rather than thermally driven ones, which require specific radiative conditions.

  1. Resolution enhanced 3D image reconstruction by use of ray tracing and auto-focus in computational integral imaging

    Science.gov (United States)

    Yuan, Ying; Yu, Shuo; Wang, Xiaorui; Zhang, Jianlei

    2017-12-01

    We propose a three-dimensional (3D) image reconstruction algorithm that can computationally reconstruct the light field image with enhanced resolution. This method is based on ray tracing and can reconstruct the elemental images from arbitrary viewpoints. In the conventional integral imaging reconstruction process, a plane needs to be selected to make the reconstructed image in focus, so prior knowledge is required. Auto-focus (AF) of the digital camera is applied in the integral imaging reconstruction process and the optimal reconstruction plane can be selected automatically without any prior knowledge. Thus, the integral imaging system can record the light field of 3D scene without focusing on them and image focusing will be completed in the computational post-processing process. To our knowledge, this is the first time to apply auto-focus method to 3D integral imaging reconstruction. Furthermore, the depth-of-field can be controlled by adjusting the transmission angle of light ray from the elemental images. Experimental results are presented to demonstrate the feasibility and effectiveness of the proposed method.

  2. Quantitative analysis of selected minor and trace elements through use of a computerized automatic x-ray spectrograph

    International Nuclear Information System (INIS)

    Fabbi, B.P.; Elsheimer, H.N.; Espos, L.F.

    1976-01-01

    Upgrading a manual X-ray spectrograph, interfacing with an 8K computer, and employment of interelement correction programs have resulted in a several-fold increase in productivity for routine quantitative analysis and an accompanying decrease in operator bias both in measurement procedures and in calculations. Factors such as dead time and self-absorption also are now computer corrected, resulting in improved accuracy. All conditions of analysis except for the X-ray tube voltage are controlled by the computer, which enhances precision of analysis. Elemental intensities are corrected for matrix effects, and from these the percent concentrations are calculated and printed via teletype. Interelement correction programs utilizing multiple linear regression are employed for the determination of the following minor and trace elements: K, S, Rb, Sr, Y, and Zr in silicate rocks, and Ba, As, Sb, and Zn in both silicate and carbonate rock samples. The last named elements use the same regression curves for both rock types. All these elements are determined in concentrations generally ranging from 0.0025 percent to 4.00 percent. The sensitivities obtainable range from 0.0001 percent for barium to 0.001 percent for antimony. The accuracy, as measured by the percent relative error for a variety of silicate and carbonate rocks, is on the order of 1-7 percent. The exception is yttrium

  3. Solar Ray Tracing Analysis to Determine Energy Availability in a CPC Designed for Use as a Residential Water Heater

    Directory of Open Access Journals (Sweden)

    Miguel Terrón-Hernández

    2018-01-01

    Full Text Available Compound parabolic concentrators are relevant systems used in solar thermal technology. With adequate tailoring, they can be used as an efficient and low-cost alternative in residential water heating applications. This work presents a simulation study using a ray tracing analysis. With this technique, we simulate the interaction between solar rays and solar concentrator to quantify the amount of energy that impinges on the receiver at a particular time. Energy availability is evaluated in a comparison of two configurations throughout the year: static setup at 21° and multi-position setup; tilted with respect to the horizontal, depending on three seasonal positions: 0° for summer, 16° for spring/autumn, and 32° for winter, with the aim to evaluate the amount of available energy in each season. The fact that a tracking system can be dispensed with also represents an economical option for the proposed application. The results showed that at 21°, the proposed solar Compound Parabolic Concentrator (CPC works satisfactorily; however, by carrying out the selected angular adjustments, the overall energy availability increased by 22%, resulting in a more efficient option. The most effective design was also built and analyzed outdoors. The obtained thermal efficiency was of ~43%. The optical design and its evaluation developed herein proved to be a valuable tool for prototype design and performance evaluation.

  4. X-ray fluorescence study of the concentration of selected trace and minor elements in human brain tumours

    Science.gov (United States)

    Wandzilak, Aleksandra; Czyzycki, Mateusz; Radwanska, Edyta; Adamek, Dariusz; Geraki, Kalotina; Lankosz, Marek

    2015-12-01

    Neoplastic and healthy brain tissues were analysed to discern the changes in the spatial distribution and overall concentration of elements using micro X-ray fluorescence spectroscopy. High-resolution distribution maps of minor and trace elements such as P, S, Cl, K, Ca, Fe, Cu and Zn made it possible to distinguish between homogeneous cancerous tissue and areas where some structures could be identified, such as blood vessels and calcifications. Concentrations of the elements in the selected homogeneous areas of brain tissue were compared between tumours with various malignancy grades and with the controls. The study showed a decrease in the average concentration of Fe, P, S and Ca in tissues with high grades of malignancy as compared to the control group, whereas the concentration of Zn in these tissues was increased. The changes in the concentration were found to be correlated with the tumour malignancy grade. The efficacy of micro X-ray fluorescence spectroscopy to distinguish between various types of cancer based on the concentrations of studied elements was confirmed by multivariate discriminant analysis. Our analysis showed that the most important elements for tissue classification are Cu, K, Fe, Ca, and Zn. This method made it possible to correctly classify histopathological types in 99.93% of the cases used to build the model and in as much as 99.16% of new cases.

  5. Determination of trace perchlorate concentrations by anion-selective membranes and total reflection X-ray fluorescence analysis.

    Science.gov (United States)

    Hatzistavros, Vasilios S; Kallithrakas-Kontos, Nikolaos G

    2011-05-01

    In the present work a method for the determination of perchlorate trace levels by total reflection X-ray fluorescence (TXRF) is introduced. Perchlorate anions were concentrated on anion-selective membranes that had been prepared on the surface of TXRF quartz reflectors. Various complexation substances were used in the membranes. The reflectors were immersed in water solutions containing nanogram per milliliter (ppb) concentrations of perchlorate. After this step, the reflectors were taken out of the solution and they were analyzed by TXRF, using a copper X-ray tube and helium flow on the target (to lower the argon peak which is present in the air). The effects of various experimental parameters were examined, and the possibility of discrimination between chloride and perchlorate anions was shown. Minimum detection limits lower than 1 ng/mL and good linearity at the concentration range of 1-50 ng/mL were achieved. The method is applicable for the analysis of perchlorate in drinking water samples.

  6. A Change in the Optical Polarization Associated with a Gamma-Ray Flare in the Blazar 3C 279

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A.A.

    2011-08-19

    It is widely accepted that strong and variable radiation detected over all accessible energy bands in a number of active galaxies arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. The size of the emitting zone and the location of this region relative to the central supermassive black hole are, however, poorly known, with estimates ranging from light-hours to a light-year or more. Here we report the coincidence of a gamma ({gamma})-ray flare with a dramatic change of optical polarization angle. This provides evidence for co-spatiality of optical and {gamma}-ray emission regions and indicates a highly ordered jet magnetic field. The results also require a non-axisymmetric structure of the emission zone, implying a curved trajectory for the emitting material within the jet, with the dissipation region located at a considerable distance from the black hole, at about 10{sup 5} gravitational radii.

  7. Estimation of viscoelastic attenuation of real seismic data by use of ray tracing software: Application to the detection of gas hydrates and free gas

    Czech Academy of Sciences Publication Activity Database

    Bouchaala, Fateh; Guennou, C.

    2012-01-01

    Roč. 344, č. 2 (2012), s. 57-66 ISSN 1631-0713 Institutional research plan: CEZ:AV0Z30120515 Keywords : viscoelastic attenuation * gas hydrates * free gas * ray tracing Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.401, year: 2012

  8. Architecture of the south-eastern Carpathians nappes and Focsani Basin (Romania) from 2D ray tracing of densely-spaced refraction data

    NARCIS (Netherlands)

    Bocin, A.; Stephenson, R.A.; Mocanu, V.I.; Matenco, L.C.

    2009-01-01

    A velocity model of the upper crust (maximum depth 10-15 km) of the earthquake-prone Vrancea area (Romania) from 2D forward ray tracing of densely-spaced refraction data is presented. The model is derived from more than 11,000 travel times recorded at stations 100 m apart picked from 42 shot gathers

  9. Simulating an extreme over-the-horizon optical propagation event over Lake Michigan using a coupled mesoscale modeling and ray tracing framework

    NARCIS (Netherlands)

    Basu, S.

    2017-01-01

    Accurate simulation and forecasting of over-the-horizon propagation events are essential for various civilian and defense applications. We demonstrate the prowess of a newly proposed coupled mesoscale modeling and ray tracing framework in reproducing such an event. Wherever possible, routinely

  10. Agreement between total corneal astigmatism calculated by vector summation and total corneal astigmatism measured by ray tracing using Galilei double Scheimpflug analyzer.

    Science.gov (United States)

    Feizi, Sepehr; Delfazayebaher, Siamak; Ownagh, Vahid; Sadeghpour, Fatemeh

    To evaluate the agreement between total corneal astigmatism calculated by vector summation of anterior and posterior corneal astigmatism (TCA Vec ) and total corneal astigmatism measured by ray tracing (TCA Ray ). This study enrolled a total of 204 right eyes of 204 normal subjects. The eyes were measured using a Galilei double Scheimpflug analyzer. The measured parameters included simulated keratometric astigmatism using the keratometric index, anterior corneal astigmatism using the corneal refractive index, posterior corneal astigmatism, and TCA Ray . TCA Vec was derived by vector summation of the astigmatism on the anterior and posterior corneal surfaces. The magnitudes and axes of TCA Vec and TCA Ray were compared. The Pearson correlation coefficient and Bland-Altman plots were used to assess the relationship and agreement between TCA Vec and TCA Ray , respectively. The mean TCA Vec and TCA Ray magnitudes were 0.76±0.57D and 1.00±0.78D, respectively (Pvector summation and ray tracing methods cannot be used interchangeably. There was a systematic error between the TCA Vec and TCA Ray magnitudes. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

  11. Simultaneous resonant x-ray diffraction measurement of polarization inversion and lattice strain in polycrystalline ferroelectrics

    DEFF Research Database (Denmark)

    Gorfman, S.; Simons, Hugh; Iamsasri, T.

    2016-01-01

    strain and, for the first time, polarization reversal during in-situ electrical perturbation. This technique is demonstrated for BaTiO3-BiZn0.5Ti0.5O3 (BT-BZT) polycrystalline ferroelectrics, a prototypical lead-free piezoelectric with an ambiguous switching mechanism. This combines the benefits...

  12. Trace-level determination of polar flavour compounds in butter by solid-phase extraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Adahchour, M; Vreuls, R J; van der Heijden, A; Brinkman, U A

    1999-06-04

    Volatile compounds are responsible for the aromas of butter. A simple technique for the determination of these components is described which is based on solid-phase extraction (SPE) after melting of the butter and separation of the aqueous phase from the fat. Volatile flavours present in the water fraction are collected by off-line SPE on cartidges packed with a copolymer sorbent. After desorption with 500 microliters of methyl acetate, 1-microliter aliquots are quantified and/or identified by gas chromatography-mass spectrometry. The procedure was tested with respect to recovery, linearity and limit of detection in real-life samples using five polar model analytes. It allows the characterisation of polar flavour compounds in butter prior to and after heat treatment at 170 degrees C. From the five model compounds, vanillin, traces of diacetyl and maltol were found to be present in the butter samples. After heat treatment 500-1000-fold increased concentration of maltol, and substantial amounts of furaneol were detected.

  13. Determination of trace metals in nuclear-grade uranium dioxide by X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Salvador, V.L.R.; Imakuma, K.

    1988-04-01

    A method is described for the simultaneous determination of low concentrations of Ca, Cr, Cu, Fe, Mn and Ni in nuclear-grade uranium dioxide by X-ray fluorescence spectrometry, without the use of chemical treatment. The lower limits of detection range from 2 μg g -1 for nickel and manganese to 5 μg g -1 for copper. Samples are prepared in the form of double-layer pellets with boric acid as a binding agent. Standards are prepared in a U 3 O 8 matrix, which is more chemically stable than UO 2 and has similar matrix behaviour. The correlation coefficients for calibration curves are better than 0.999. Erros range from 2.4 % for chromium to 6.8 % for nickel. (author) [pt

  14. X-ray fluorescence analysis of K, Al and trace elements in chloroaluminate melts

    Science.gov (United States)

    Shibitko, A. O.; Abramov, A. V.; Denisov, E. I.; Lisienko, D. G.; Rebrin, O. I.; Bunkov, G. M.; Rychkov, V. N.

    2017-09-01

    Energy dispersive x-ray fluorescence spectrometry was applied to quantitative determination of K, Al, Cr, Fe and Ni in chloroaluminate melts. To implement the external standard calibration method, an unconventional way of samples preparation was suggested. A mixture of metal chlorides was melted in a quartz cell at 350-450 °C under a slightly excessive pressure of purified argon (99.999 %). The composition of the calibration samples (CSs) prepared was controlled by means of the inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimal conditions for analytical lines excitation were determined, the analytes calibration curves were obtained. There was some influence of matrix effects in synthesized samples on the analytical signal of some elements. The CSs are to be stored in inert gas atmosphere. The precision, accuracy, and reproducibility factors of the quantitative chemical analysis were computed.

  15. Determination of trace element levels in leaves of Nerium oleander using X-Ray Fluorescence

    International Nuclear Information System (INIS)

    Santos, Ramon S.; Sanches, Francis A.C.R.A.; Neves, Arthur O.P.; Oliveira, Luis F.; Oliveira, Davi F.; Anjos, Marcelino J.

    2013-01-01

    The environmental pollution by human activity has been one of the most concerns in the last years, principally due to rapid urban growth in the cities and the industrialization process. The air pollution can be increased due to several different kinds of emissions: urban traffic, industrial activities, burning fuel, civil industry of construction/demolition, fires and natural phenomena. Many of these emissions move from long distances due to convections currents and finally tend to deposit mainly in the plants leaves and in the soil. Thus, the plants leaves works as a natural sampler by the emissions deposit in these ones. In this study Nerium oleander leaves were used to measure the environmental pollutions levels in different sampling urban regions in the city of Rio de Janeiro/RJ: Andarai, Benfica, Bonsucesso, Caju, Engenho de Dentro, Engenho Novo, Estacio, Grajau, Inhauma, Lins, Maracana, Maria da Graca, Meier, Praca da Bandeira, Riachuelo, Rio Comprido, Sao Cristovao, Tijuca, Vila Isabel and city Center. The control samples were collected in Campo Grande near of Parque Nacional da Pedra Branca/RJ (National Park of Pedra Branca/RJ). The leaves were collected from adult plants and after the collection the samples were cleaned and placed in the greenhouse for drying, then were mashed and pressed into tablets forms. The analyses were performed using the energy dispersion X-ray fluorescence (EDXRF), developed on the own laboratory and based in a SiPIN detector and a mini X ray tube. It was possible to detect 16 elements in the analyzed samples: K, Ca, Cr, Mn, Fe, Cu, Zn, Br, Rb, Sr, Ba and Pb. The results shows that, in the studied areas, the analysis of the Nerium oleander plant shows a low-cost option and with a substantial efficiency as an environmental pollution biomonitor. (author)

  16. Determination of trace element levels in leaves of Nerium oleander using X-Ray Fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Ramon S.; Sanches, Francis A.C.R.A.; Neves, Arthur O.P.; Oliveira, Luis F.; Oliveira, Davi F.; Anjos, Marcelino J. [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Inst. de Fisica Armando Dias Tavares. Dept. de Fisica Aplicada e Termodinamica

    2013-07-01

    The environmental pollution by human activity has been one of the most concerns in the last years, principally due to rapid urban growth in the cities and the industrialization process. The air pollution can be increased due to several different kinds of emissions: urban traffic, industrial activities, burning fuel, civil industry of construction/demolition, fires and natural phenomena. Many of these emissions move from long distances due to convections currents and finally tend to deposit mainly in the plants leaves and in the soil. Thus, the plants leaves works as a natural sampler by the emissions deposit in these ones. In this study Nerium oleander leaves were used to measure the environmental pollutions levels in different sampling urban regions in the city of Rio de Janeiro/RJ: Andarai, Benfica, Bonsucesso, Caju, Engenho de Dentro, Engenho Novo, Estacio, Grajau, Inhauma, Lins, Maracana, Maria da Graca, Meier, Praca da Bandeira, Riachuelo, Rio Comprido, Sao Cristovao, Tijuca, Vila Isabel and city Center. The control samples were collected in Campo Grande near of Parque Nacional da Pedra Branca/RJ (National Park of Pedra Branca/RJ). The leaves were collected from adult plants and after the collection the samples were cleaned and placed in the greenhouse for drying, then were mashed and pressed into tablets forms. The analyses were performed using the energy dispersion X-ray fluorescence (EDXRF), developed on the own laboratory and based in a SiPIN detector and a mini X ray tube. It was possible to detect 16 elements in the analyzed samples: K, Ca, Cr, Mn, Fe, Cu, Zn, Br, Rb, Sr, Ba and Pb. The results shows that, in the studied areas, the analysis of the Nerium oleander plant shows a low-cost option and with a substantial efficiency as an environmental pollution biomonitor. (author)

  17. Simulation of AZ-PN100 resist pattern fluctuation in X-ray lithography, including synchrotron beam polarization

    International Nuclear Information System (INIS)

    Scheckler, E.W.; Ogawa, Taro; Tanaka, Toshihiko; Takeda, Eiji; Oizumi, Hiroaki.

    1993-01-01

    A new simulation model for nanometer-scale pattern fluctuation in X-ray lithography is presented and applied to a study of AZ-PN100 negative chemical amplification resist. The exposure simulation considers polarized photons from a synchrotron radiation (SR) source. Monte Carlo simulation of Auger and photoelectron generation is followed by electron scattering simulation to determine the deposited energy distribution at the nanometer scale, including beam polarization effects. An acid-catalyst random walk model simulates the post-exposure bake (PEB) step. Fourier transform infrared (FTIR) spectroscopy and developed resist thickness measurements are used to fit PEB and rate models for AZ-PN100. A polymer removal model for development simulation predicts the macroscopic resist shape and pattern roughness. The simulated 3σ linewidth variation is in excess of 24 nm. Simulation also shows a detrimental effect if the beam polarization is perpendicular to the line. Simulation assuming a theoretical ideal exposure yields a 50 nm minimum line for standard process conditions. (author)

  18. The simultaneous measurement of energy and linear polarization of the scattered radiation in resonant inelastic soft x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Braicovich, L., E-mail: lucio.braicovich@polimi.it; Minola, M.; Dellea, G.; Ghiringhelli, G. [CNR-SPIN and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo Da Vinci 32, Milano I-20133 (Italy); Le Tacon, M. [Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Moretti Sala, M.; Morawe, C.; Peffen, J.-Ch.; Yakhou, F.; Brookes, N. B. [European Synchrotron Radiation Facility, 71 Avenue des Martyrs, Grenoble F-38043 (France); Supruangnet, R. [Synchrotron Light Research Institute, Nakhon Ratchasima (Thailand)

    2014-11-15

    Resonant Inelastic X-ray Scattering (RIXS) in the soft x-ray range is an element-specific energy-loss spectroscopy used to probe the electronic and magnetic excitations in strongly correlated solids. In the recent years, RIXS has been progressing very quickly in terms of energy resolution and understanding of the experimental results, but the interpretation of spectra could further improve, sometimes decisively, from a full knowledge of the polarization of incident and scattered photons. Here we present the first implementation, in a high resolution soft-RIXS spectrometer used to analyze the scattered radiation, of a device allowing the measurement of the degree of linear polarization. The system, based on a graded W/B{sub 4}C multilayer mirror installed in proximity of the CCD detector, has been installed on the AXES spectrometer at the ESRF (European Synchrotron Radiation Facility); it has been fully characterized and it has been used for a demonstration experiment at the Cu L{sub 3} edge on a high-T{sub c} superconducting cuprate. The loss in efficiency suffered by the spectrometer equipped with this test facility was a factor 17.5. We propose also a more advanced version, suitable for a routine use on the next generation of RIXS spectrometers and with an overall efficiency up to 10%.

  19. Interfacial mixing in as-deposited Si/Ni/Si layers analyzed by x-ray and polarized neutron reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Debarati, E-mail: debarati@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Basu, Saibal; Singh, Surendra [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Roy, Sumalay; Dev, Bhupendra Nath [Department of Materials Science, Indian Association for the Cultivation of Science, 2A and 2B Raja S.C. Mullick Road, Jadavpur, Kolkata 700032 (India)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Room temperature diffusion in Si/Ni/Si trilayer detected through complementary x-ray and polarized neutron reflectometry. Black-Right-Pointing-Pointer Analyses of XPNR data generated the construction of the layered structure in terms of physical parameters along with alloy layers created by diffusion. Black-Right-Pointing-Pointer Scattering length density information from XPNR provided quantitative assessment of the stoichiometry of alloys formed at the Si/Ni and Ni/Si interfaces. - Abstract: Interdiffusion occurring across the interfaces in a Si/Ni/Si layered system during deposition at room temperature was probed using x-ray reflectivity (XRR) and polarized neutron reflectivity (PNR). Exploiting the complementarity of these techniques, both structural and magnetic characterization with nanometer depth resolution could be achieved. Suitable model fitting of the reflectivity profiles identified the formation of Ni-Si mixed alloy layers at the Si/Ni and Ni/Si interfaces. The physical parameters of the layered structure, including quantitative assessment of the stoichiometry of interfacial alloys, were obtained from the analyses of XRR and PNR patterns. In addition, PNR provided magnetic moment density profile as a function of depth in the stratified medium.

  20. A new multi-gas constrained model of trace gas non-homogeneous transport in firn: evaluation and behaviour at eleven polar sites

    Directory of Open Access Journals (Sweden)

    E. Witrant

    2012-12-01

    Full Text Available Insoluble trace gases are trapped in polar ice at the firn-ice transition, at approximately 50 to 100 m below the surface, depending primarily on the site temperature and snow accumulation. Models of trace gas transport in polar firn are used to relate firn air and ice core records of trace gases to their atmospheric history. We propose a new model based on the following contributions. First, the firn air transport model is revised in a poromechanics framework with emphasis on the non-homogeneous properties and the treatment of gravitational settling. We then derive a nonlinear least square multi-gas optimisation scheme to calculate the effective firn diffusivity (automatic diffusivity tuning. The improvements gained by the multi-gas approach are investigated (up to ten gases for a single site are included in the optimisation process. We apply the model to four Arctic (Devon Island, NEEM, North GRIP, Summit and seven Antarctic (DE08, Berkner Island, Siple Dome, Dronning Maud Land, South Pole, Dome C, Vostok sites and calculate their respective depth-dependent diffusivity profiles. Among these different sites, a relationship is inferred between the snow accumulation rate and an increasing thickness of the lock-in zone defined from the isotopic composition of molecular nitrogen in firn air (denoted δ15N. It is associated with a reduced diffusivity value and an increased ratio of advective to diffusive flux in deep firn, which is particularly important at high accumulation rate sites. This has implications for the understanding of δ15N of N2 records in ice cores, in relation with past variations of the snow accumulation rate. As the snow accumulation rate is clearly a primary control on the thickness of the lock-in zone, our new approach that allows for the estimation of the lock-in zone width as a function of accumulation may lead to a better constraint on the age difference between the ice and entrapped gases.

  1. Determination of trace element and heavy metal in black tea and tea leaves using x-ray fluorescence

    International Nuclear Information System (INIS)

    Salih, Mohamed Abualgasim Abdalhakam

    2016-08-01

    The aim of this study was to provide information about the trace element and heavy metals concentrations in black tea and tea leaves. 23 different samples were collected from the Sudanese local market. The collected samples were characterized as the most common used items in Sudan. The concentration of trace and heavy elements were determined using x-ray fluorescence (X RF) technique. The standard reference materials (IAEA-V-10) and hay (powder) were used to evaluate the accuracy of the analytical result. The measured values were found in agreement with the certified values. The elements determined were K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Br, Rb, and Sr. The average concentration of the elements is black tea were 2277.43, 7245.71, 1.11, 1025.29, 334.29, 6.88, 11.24, 9.47, 1.02, 7.08, 97.4 and 63.21 respectively while the average concentration of the elements in leaves tea were 2644.44, 8805.56, 1.02, 571.81, 295.44, 6.19, 10.69, 9.26, 0.91, 13.42, 63.03 and 67.14 respectively. The results showed an increase in the concentration of some elements such as calcium, chromium, manganese, iron, nickel, copper, zinc, bromine, rubidium and strontium (22500, 6.75, 48.9, 194, 4.37, 9,77, 24.9, 8.23, 7.79, 40,9) ppm respectively compared to certified values. Correlation between concentration of certain element and cluster analysis were preformed and the results compared with values of literature and the concentrations of some elements found to be similar.(Author)

  2. Vapor phase treatment–total reflection X-ray fluorescence for trace elemental analysis of silicon wafer surface

    Energy Technology Data Exchange (ETDEWEB)

    Takahara, Hikari, E-mail: hikari@rigaku.co.jp [Rigaku Corp., 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146 (Japan); Mori, Yoshihiro [Horiba Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto 601-8510 (Japan); Shibata, Harumi [SUMCO Corporation, Seavance North, 1-2-1 Shibaura, Minato-ku, Tokyo 105-8634 (Japan); Shimazaki, Ayako [Toshiba Corporation, 8, Shinsugita-cho, Isogo-ku, Yokohama 235-8522 (Japan); Shabani, Mohammad B. [Mitsubishi Material Corporation, 1-297, Kitabukuro-cho, Omiya-ku, Saitama 330-8508 (Japan); Yamagami, Motoyuki [Rigaku Corp., 14-8 Akaoji-cho, Takatsuki, Osaka 569-1146 (Japan); Yabumoto, Norikuni [Analysis Atelier Co., 4-36-4, Yoyogi, Shibuya-ku, Tokyo 151-0053 (Japan); Nishihagi, Kazuo [Horiba Ltd., 2 Miyanohigashi, Kisshoin, Minami-ku, Kyoto 601-8510 (Japan); Gohshi, Yohichi [Tsukuba University, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8571 (Japan)

    2013-12-01

    Vapor phase treatment (VPT) was under investigation by the International Organization for Standardization/Technical Committee 201/Working Group 2 (ISO/TC201/WG2) to improve the detection limit of total reflection X-ray fluorescence spectroscopy (TXRF) for trace metal analysis of silicon wafers. Round robin test results have confirmed that TXRF intensity increased by VPT for intentional contamination with 5 × 10{sup 9} and 5 × 10{sup 10} atoms/cm{sup 2} Fe and Ni. The magnification of intensity enhancement varied greatly (1.2–4.7 in VPT factor) among the participating laboratories, though reproducible results could be obtained for average of mapping measurement. SEM observation results showed that various features, sizes, and surface densities of particles formed on the wafer after VPT. The particle morphology seems to have some impact on the VPT efficiency. High resolution SEM observation revealed that a certain number of dots with SiO{sub 2}, silicate and/or carbon gathered to form a particle and heavy metals, Ni and Fe in this study were segregated on it. The amount and shape of the residue should be important to control VPT factor. - Highlights: • This paper presents a summary of study results of VPT–TXRF using ISO/TC201/WG2. • Our goal is to analyze the trace metallic contamination on silicon wafer with concentrations below 1 × 10{sup 10} atoms/cm{sup 2}. • The efficiency and mechanism of VPT are discussed under several round robin tests and systematic studies.

  3. Analytical possibilities of total reflection X-ray spectrometry (TXRF) for trace selenium determination in soils.

    Science.gov (United States)

    Marguí, E; Floor, G H; Hidalgo, M; Kregsamer, P; Román-Ross, G; Streli, C; Queralt, I

    2010-09-15

    Selenium content of soils is an important issue due to the narrow range between the nutritious requirement and toxic effects upon Se exposure. However, its determination is challenging due to low concentrations within complex matrices that hamper the analysis in most spectroscopic techniques. In this study, we explored the possibilities of several analytical approaches combined with total reflection X-ray (TXRF) spectrometry for soil Se determinations. The direct analysis of a solid suspension using 20 mg of fine ground material (TXRF analysis of soil extracts due to the high Fe concentrations (∼700 mg/L). On the other hand, a dispersive liquid-liquid microextraction procedure (DLLME) before the TXRF analysis of the soil digest was also developed. The effects of various experimental parameters such as sample volume, effect of major elements present in the soil matrix (Fe), and Se concentration in the sample were investigated. The LOD using this analytical methodology (0.05 mg/kg of Se) was comparable to or lower than those obtained in previous works using other popular spectrometric techniques such as GFAAS, ICPMS, and AFS. The calculated Se concentration for JSAC-0411 ([Se] = 1.32 ± 0.27 mg/kg) using the combination of DLLME and TXRF ([Se] = 1.40 ± 0.23 mg/kg) was in agreement with the certified value.

  4. Ray tracing method for the description of radiation trapping in 3D plasma domains

    Science.gov (United States)

    Kalanov, D.; Golubovskii, Yu; Gortschakow, S.; Uhrlandt, D.

    2017-10-01

    A new approach for the solution of the Holstein-Biberman equation based on the advanced matrix method is developed. It allows for the consideration of radiation trapping in arbitrary finite 3D plasma domains for the various shapes of line contours and in a wide range of optical depths. Homogeneous and inhomogeneous distributions of absorbing atoms are considered. To solve the equation, an arbitrary plasma domain is discretized on a Cartesian voxel grid. The distances between the cells which are crossed by photons are computed by means of an efficient ray traversal algorithm. The algorithm is optimized for parallel computation on a graphical processing unit (GPU). For the Lorentzian shape of emission and absorption lines, the analytical expressions (which significantly decrease the computation time) have been derived. In the high opacity limit, the matrix is transformed to the universal form with an escape factor as a multiplier. The method is validated against a previously developed matrix approach by comparing the solutions for a finite cylinder geometry. The applicability range of the old method is specified. This range is defined by the asymptotics of Lorentz line wings at high optical depths. The capability of the method is illustrated with several complex geometries which are typical for various plasma sources. The effects related to the presence of photon blocking barriers are demonstrated. The proposed method allows for the demonstration of the fundamental differences between radiation and diffusion transport processes in the plasma domains of a complex shape. The method can be integrated into multi-component collisional-radiative models.

  5. Basic design of beamline and polarization control

    International Nuclear Information System (INIS)

    Watanabe, M.

    2006-01-01

    The basic concept of synchrotron radiation beamlines for' vacuum ultraviolet and X-ray experiments has been introduced to beginning users and designers of beamlines. The beamline defined here is composed of a front end, pre-mirrors, and a monochromator with refocusing mirrors, which are connected by beam pipes, providing monochromatic light for the experiments. Firstly, time characteristics of the synchrotron radiation are briefly reviewed. Secondly, the basic technology is introduced as the fundamental knowledge required to both users and designers. The topics are photoabsorption by air and solids, front ends and beam pipes, mirrors, monochromators, and filters. Thirdly, the design consideration is described mainly for the designers. The topics are design principle, principle of ray tracing, optical machinery and control, and vacuum. Fourthly, polarization control is considered. The topics are polarizers, polarization diagnosis of beamline, and circularly-polarized light generation. Finally, a brief summary is given introducing some references for further knowledge of the user's and the designers. (authors)

  6. Ray-tracing traveltime tomography versus wave-equation traveltime inversion for near-surface seismic land data

    KAUST Repository

    Fu, Lei

    2017-05-11

    Full-waveform inversion of land seismic data tends to get stuck in a local minimum associated with the waveform misfit function. This problem can be partly mitigated by using an initial velocity model that is close to the true velocity model. This initial starting model can be obtained by inverting traveltimes with ray-tracing traveltime tomography (RT) or wave-equation traveltime (WT) inversion. We have found that WT can provide a more accurate tomogram than RT by inverting the first-arrival traveltimes, and empirical tests suggest that RT is more sensitive to the additive noise in the input data than WT. We present two examples of applying WT and RT to land seismic data acquired in western Saudi Arabia. One of the seismic experiments investigated the water-table depth, and the other one attempted to detect the location of a buried fault. The seismic land data were inverted by WT and RT to generate the P-velocity tomograms, from which we can clearly identify the water table depth along the seismic survey line in the first example and the fault location in the second example.

  7. Spectrophotometric study of Saturn's main rings by means of Monte Carlo ray-tracing and Hapke's theory

    Science.gov (United States)

    Ciarniello, Mauro; Filacchione, Gianrico; D'Aversa, Emiliano; Cuzzi, Jeffrey N.; Capaccioni, Fabrizio; Hedman, Matthew M.; Dalle Ore, Cristina M.; Nicholson, Philip D.; Clark, Roger Nelson; Brown, Robert H.; Cerroni, Priscilla; Spilker, Linda

    2017-10-01

    This work is devoted to the investigation of the spectrophotometric properties of Saturn's rings from Cassini-VIMS (Visible and Infrared Mapping Spectrometer) observations. The dataset used for this analysis is represented by ten radial spectrograms of the rings which have been derived in Filacchione et al. (2014) by radial mosaics produced by VIMS. Spectrograms report the measured radiance factor of the main Saturn's rings as a function of both radial distance (from 73.500 to 141.375 km) and wavelength (0.35-5.1 µm) for different observation geometries (phase angle ranging in the 1.9°-132.2° interval). We take advantage of a Monte Carlo ray-tracing routine to characterize the photometric behavior of the rings at each wavelength and derive the spectral Bond albedo of rings particles. This quantity is used to infer the composition of the regolith covering rings particles by applying Hapke's theory. Four different regions, characterized by different optical depths, and respectively located in the C ring, inner B ring, mid B ring and A ring, have been investigated. Results from spectral modeling indicate that rings spectrum can be described by water ice with minimal inclusion of organic materials (tholin, exogenous material, which is more effective in the less dense regions of the rings because of their lower content of pure water ice.

  8. Calculation of the overlap factor for scanning LiDAR based on the tridimensional ray-tracing method.

    Science.gov (United States)

    Chen, Ruiqiang; Jiang, Yuesong; Wen, Luhong; Wen, Donghai

    2017-06-01

    The overlap factor is used to evaluate the LiDAR light collection ability. Ranging LiDAR is mainly determined by the optical configuration. However, scanning LiDAR, equipped with a scanning mechanism to acquire a 3D coordinate points cloud for a specified target, is essential in considering the scanning effect at the same time. Otherwise, scanning LiDAR will reduce the light collection ability and even cannot receive any echo. From this point of view, we propose a scanning LiDAR overlap factor calculation method based on the tridimensional ray-tracing method, which can be applied to scanning LiDAR with any special laser intensity distribution, any type of telescope (reflector, refractor, or mixed), and any shape obstruction (i.e., the reflector of a coaxial optical system). A case study for our LiDAR with a scanning mirror is carried out, and a MATLAB program is written to analyze the laser emission and reception process. Sensitivity analysis is carried out as a function of scanning mirror rotation speed and detector position, and the results guide how to optimize the overlap factor for our LiDAR. The results of this research will have a guiding significance in scanning LiDAR design and assembly.

  9. μX-ray fluorescence analysis of traces and calcium phosphate phases on tooth-tartar interfaces using synchrotron radiation

    International Nuclear Information System (INIS)

    Abraham, J.A.; Grenon, M.S.; Sanchez, H.J.; Valentinuzzi, M.C.; Perez, C.A.

    2007-01-01

    Hard dental tissues like dentine and cementum with calcified deposits (dental calculi) were studied in several human dental pieces of adult individuals from the same geographic region. A couple of cross cuts were performed at dental root level resulting in a planar slice with calculus and dental tissue exposed for analysis. The elemental content along a linear path crossing the dentine-cementum-tartar interfaces and also all over a surface was measured by X-ray fluorescence microanalysis using synchrotron radiation (μSRXRF). The concentration of elemental traces like K, V, Cu, Zn, As, Br and Sr showed different features on the analyzed regions. The possible connections with the dynamic of mineralization and biological implications are discussed. The concentrations of major elements Ca and P were also determined and the measured Ca/P molar ratio was used to estimate the average composition of calcium phosphate phases in the measured points. A deeper knowledge of the variations of the elemental compositions and the changes of the different phases will help to a better understanding of the scarcely known mechanism of calculus growing

  10. A novel total reflection X-ray fluorescence procedure for the direct determination of trace elements in petrochemical products

    Energy Technology Data Exchange (ETDEWEB)

    Cinosi, Amedeo [Sasol Italy SpA, Paderno Dugnano (Italy); GNR srl, Agrate Conturbia, Novara (Italy); Andriollo, Nunzio [Sasol Italy SpA, Paderno Dugnano (Italy); Pepponi, Giancarlo [Fondazione Bruno Kessler, Povo, Trento (Italy); Monticelli, Damiano [Universita degli Studi dell' Insubria - sede di Como, Dipartimento di Scienze Chimiche e Ambientali, Como, CO (Italy)

    2011-01-15

    A total reflection X-ray fluorescence (TXRF) procedure was developed for the determination of metal traces in petrochemical end products or intermediates for surfactant synthesis. The method combines a fast and straightforward sample preparation, i.e. deposition on the sample holder and evaporation of the sample matrix, with an efficient quantification method based on internal standardization (organic gallium standard). The method developed showed detection limits below 0.05 {mu}g g{sup -1} and in most cases below 0.005 {mu}g g{sup -1}. Fifteen elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rh, Sn, Sr, V and Zn) were determined in matrices such as paraffins, n-olefins, linear alkylbenzenes, long-chain alkyl alcohols and esters: typical metal contents were below 1 {mu}g g{sup -1}. The results were compared with the reference method ASTM D5708 (test method B) based on inductively coupled plasma optical emission spectroscopy: advantages and drawbacks of the two procedures were critically evaluated. The TXRF method developed showed comparable precision and absence of bias with respect to the reference method. A comparison of the performances of the two methods is presented. (orig.)

  11. A novel total reflection X-ray fluorescence procedure for the direct determination of trace elements in petrochemical products.

    Science.gov (United States)

    Cinosi, Amedeo; Andriollo, Nunzio; Pepponi, Giancarlo; Monticelli, Damiano

    2011-01-01

    A total reflection X-ray fluorescence (TXRF) procedure was developed for the determination of metal traces in petrochemical end products or intermediates for surfactant synthesis. The method combines a fast and straightforward sample preparation, i.e. deposition on the sample holder and evaporation of the sample matrix, with an efficient quantification method based on internal standardization (organic gallium standard). The method developed showed detection limits below 0.05 μg g(-1) and in most cases below 0.005 μg g(-1). Fifteen elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rh, Sn, Sr, V and Zn) were determined in matrices such as paraffins, n-olefins, linear alkylbenzenes, long-chain alkyl alcohols and esters: typical metal contents were below 1 μg g(-1). The results were compared with the reference method ASTM D5708 (test method B) based on inductively coupled plasma optical emission spectroscopy: advantages and drawbacks of the two procedures were critically evaluated. The TXRF method developed showed comparable precision and absence of bias with respect to the reference method. A comparison of the performances of the two methods is presented.

  12. Evidence for Intermediate Polars as the Origin of the Galactic Center Hard X-ray Emission

    DEFF Research Database (Denmark)

    Hailey, Charles J.; Mori, Kaya; Perez, Kerstin

    2016-01-01

    estimated white dwarf mass. Observations of the inner 10 pc can be accounted for by IPs with 〈MWD〉≈0.9M⊙, consistent with that of the CV population in general and the X-ray observed field IPs in particular. The lower mass derived by Chandra and XMM-Newton appears to be an artifact of narrow energy...

  13. Trace elements in natural azurite pigments found in illuminated manuscript leaves investigated by synchrotron x-ray fluorescence and diffraction mapping

    Energy Technology Data Exchange (ETDEWEB)

    Smieska, Louisa M.; Woll, Arthur R. [Cornell High Energy Synchrotron Source, Wilson Laboratory, Ithaca, NY (United States); Mullett, Ruth [Cornell University, Medieval Studies Program, Ithaca, NY (United States); Ferri, Laurent [Cornell University, Cornell Library Rare and Manuscript Collections, Ithaca, NY (United States)

    2017-07-15

    We present trace-element and composition analysis of azurite pigments in six illuminated manuscript leaves, dating from the thirteenth to sixteenth century, using synchrotron-based, large-area x-ray fluorescence (SR-XRF) and diffraction (SR-XRD) mapping. SR-XRF mapping reveals several trace elements correlated with azurite, including arsenic, zirconium, antimony, barium, and bismuth, that appear in multiple manuscripts but were not always detected by point XRF. Within some manuscript leaves, variations in the concentration of trace elements associated with azurite coincide with distinct regions of the illuminations, suggesting systematic differences in azurite preparation or purification. Variations of the trace element concentrations in azurite are greater among different manuscript leaves than the variations within each individual leaf, suggesting the possibility that such impurities reflect distinct mineralogical/geologic sources. SR-XRD maps collected simultaneously with the SR-XRF maps confirm the identification of azurite regions and are consistent with impurities found in natural mineral sources of azurite. In general, our results suggest the feasibility of using azurite trace element analysis for provenance studies of illuminated manuscript fragments, and demonstrate the value of XRF mapping in non-destructive determination of trace element concentrations within a single pigment. (orig.)

  14. Salting-out-enhanced ionic liquid microextraction with a dual-role solvent for simultaneous determination of trace pollutants with a wide polarity range in aqueous samples.

    Science.gov (United States)

    Gao, Man; Qu, Jingang; Chen, Kai; Jin, Lide; Dahlgren, Randy Alan; Wang, Huili; Tan, Chengxia; Wang, Xuedong

    2017-11-01

    In real aquatic environments, many occupational pollutants with a wide range of polarities coexist at nanogram to milligram per liter levels. Most reported microextraction methods focus on extracting compounds with similar properties (e.g., polarity or specific functional groups). Herein, we developed a salting-out-enhanced ionic liquid microextraction based on a dual-role solvent (SILM-DS) for simultaneous detection of tetracycline, doxycycline, bisphenol A, triclosan, and methyltriclosan, with log K ow ranging from -1.32 to 5.40 in complex milk and environmental water matrices. The disperser in the ionic-liquid-based dispersive liquid-liquid microextraction was converted to the extraction solvent in the subsequent salting-out-assisted microextraction procedures, and thus a single solvent performed a dual role as both extractant and disperser in the SILM-DS process. Acetonitrile was selected as the dual-role solvent because of its strong affinity for both ionic liquids and water, as well as the extractant in the salting-out step. Optimized experimental conditions were 115 μL [C 8 MIM][PF 6 ] as extractor, 1200 μL acetonitrile as dual-role solvent, pH 2.0, 5.0 min ultrasound extraction time, 3.0 g Na 2 SO 4 , and 3.0 min vortex extraction time. Under optimized conditions, the recoveries of the five pollutants ranged from 74.5 to 106.9%, and their LODs were 0.12-0.75 μg kg -1 in milk samples and 0.11-0.79 μg L -1 in environmental waters. Experimental precision based on relative standard deviation was 1.4-6.4% for intraday and 2.3-6.5% for interday analyses. Compared with previous methods, the prominent advantages of the newly developed method are simultaneous determination of pollutants with a wide range of polarities and a substantially reduced workload for ordinary environmental monitoring and food tests. Therefore, the new method has great application potential for simultaneous determination of trace pollutants with strongly contrasting polarities in several

  15. The backward ray tracing with effective solar brightness used to simulate the concentrated flux map of a solar tower concentrator

    Science.gov (United States)

    Guo, Minghuan; Sun, Feihu; Wang, Zhifeng

    2017-06-01

    The solar tower concentrator is mainly composed of the central receiver on the tower top and the heliostat field around the tower. The optical efficiencies of a solar tower concentrator are important to the whole thermal performance of the solar tower collector, and the aperture plane of a cavity receiver or the (inner or external) absorbing surface of any central receiver is a key interface of energy flux. So it is necessary to simulate and analyze the concentrated time-changing solar flux density distributions on the flat or curved receiving surface of the collector, with main optical errors considered. The transient concentrated solar flux on the receiving surface is the superimposition of the flux density distributions of all the normal working heliostats in the field. In this paper, we will mainly introduce a new backward ray tracing (BRT) method combined with the lumped effective solar cone, to simulate the flux density map on the receiving-surface. For BRT, bundles of rays are launched at the receiving-surface points of interest, strike directly on the valid cell centers among the uniformly sampled mirror cell centers in the mirror surface of the heliostats, and then direct to the effective solar cone around the incident sun beam direction after reflection. All the optical errors are convoluted into the effective solar cone. The brightness distribution of the effective solar cone is here supposed to be circular Gaussian type. The mirror curvature can be adequately formulated by certain number of local normal vectors at the mirror cell centers of a heliostat. The shading & blocking mirror region of a heliostat by neighbor heliostats and also the solar tower shading on the heliostat mirror are all computed on the flat-ground-plane platform, i.e., projecting the mirror contours and the envelope cylinder of the tower onto the horizontal ground plane along the sun-beam incident direction or along the reflection directions. If the shading projection of a sampled

  16. Quantitative evaluation of ultrasonic wave propagation in inhomogeneous anisotropic austenitic welds using 3D ray tracing method. Numerical and experimental validation

    International Nuclear Information System (INIS)

    Kolkoori, Sanjeevareddy

    2014-01-01

    Austenitic welds and dissimilar welds are extensively used in primary circuit pipes and pressure vessels in nuclear power plants, chemical industries and fossil fuelled power plants because of their high fracture toughness, resistance to corrosion and creep at elevated temperatures. However, cracks may initiate in these weld materials during fabrication process or stress operations in service. Thus, it is very important to evaluate the structural integrity of these materials using highly reliable non-destructive testing (NDT) methods. Ultrasonic non-destructive inspection of austenitic welds and dissimilar weld components is complicated because of anisotropic columnar grain structure leading to beam splitting and beam deflection. Simulation tools play an important role in developing advanced reliable ultrasonic testing (UT) techniques and optimizing experimental parameters for inspection of austenitic welds and dissimilar weld components. The main aim of the thesis is to develop a 3D ray tracing model for quantitative evaluation of ultrasonic wave propagation in an inhomogeneous anisotropic austenitic weld material. Inhomogenity in the anisotropic weld material is represented by discretizing into several homogeneous layers. According to ray tracing model, ultrasonic ray paths are traced during its energy propagation through various discretized layers of the material and at each interface the problem of reflection and transmission is solved. The influence of anisotropy on ultrasonic reflection and transmission behaviour in an anisotropic austenitic weld material are quantitatively analyzed in three dimensions. The ultrasonic beam directivity in columnar grained austenitic steel material is determined three dimensionally using Lamb's reciprocity theorem. The developed ray tracing model evaluates the transducer excited ultrasonic fields accurately by taking into account the directivity of the transducer, divergence of the ray bundle, density of rays and phase

  17. Quantitative evaluation of ultrasonic wave propagation in inhomogeneous anisotropic austenitic welds using 3D ray tracing method. Numerical and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Kolkoori, Sanjeevareddy

    2014-07-01

    Austenitic welds and dissimilar welds are extensively used in primary circuit pipes and pressure vessels in nuclear power plants, chemical industries and fossil fuelled power plants because of their high fracture toughness, resistance to corrosion and creep at elevated temperatures. However, cracks may initiate in these weld materials during fabrication process or stress operations in service. Thus, it is very important to evaluate the structural integrity of these materials using highly reliable non-destructive testing (NDT) methods. Ultrasonic non-destructive inspection of austenitic welds and dissimilar weld components is complicated because of anisotropic columnar grain structure leading to beam splitting and beam deflection. Simulation tools play an important role in developing advanced reliable ultrasonic testing (UT) techniques and optimizing experimental parameters for inspection of austenitic welds and dissimilar weld components. The main aim of the thesis is to develop a 3D ray tracing model for quantitative evaluation of ultrasonic wave propagation in an inhomogeneous anisotropic austenitic weld material. Inhomogenity in the anisotropic weld material is represented by discretizing into several homogeneous layers. According to ray tracing model, ultrasonic ray paths are traced during its energy propagation through various discretized layers of the material and at each interface the problem of reflection and transmission is solved. The influence of anisotropy on ultrasonic reflection and transmission behaviour in an anisotropic austenitic weld material are quantitatively analyzed in three dimensions. The ultrasonic beam directivity in columnar grained austenitic steel material is determined three dimensionally using Lamb's reciprocity theorem. The developed ray tracing model evaluates the transducer excited ultrasonic fields accurately by taking into account the directivity of the transducer, divergence of the ray bundle, density of rays and phase

  18. Electronic-structure origin of the anisotropic thermopower of nanolaminated Ti3SiC2 determined by polarized x-ray spectroscopy and Seebeck measurements

    Science.gov (United States)

    Magnuson, Martin; Mattesini, Maurizio; Nong, Ngo Van; Eklund, Per; Hultman, Lars

    2012-05-01

    Nanolaminated materials exhibit characteristic magnetic, mechanical, and thermoelectric properties, with large contemporary scientific and technological interest. Here we report on the anisotropic Seebeck coefficient in nanolaminated Ti3SiC2 single-crystal thin films and trace the origin to anisotropies in element-specific electronic states. In bulk polycrystalline form, Ti3SiC2 has a virtually zero Seebeck coefficient over a wide temperature range. In contrast, we find that the in-plane (basal ab) Seebeck coefficient of Ti3SiC2, measured on single-crystal films, has a substantial and positive value of 4-6 μV/K. Employing a combination of polarized angle-dependent x-ray spectroscopy and density functional theory we directly show electronic structure anisotropy in inherently nanolaminated Ti3SiC2 single-crystal thin films as a model system. The density of Ti 3d and C 2p states at the Fermi level in the basal ab plane is about 40% higher than along the c axis. The Seebeck coefficient is related to electron and hole-like bands close to the Fermi level, but in contrast to ground state density functional theory modeling, the electronic structure is also influenced by phonons that need to be taken into account. Positive contribution to the Seebeck coefficient of the element-specific electronic occupations in the basal plane is compensated by 73% enhanced Si 3d electronic states across the laminate plane that give rise to a negative Seebeck coefficient in that direction. Strong phonon vibration modes with three to four times higher frequency along the c axis than along the basal ab plane also influence the electronic population and the measured spectra by the asymmetric average displacements of the Si atoms. These results constitute experimental evidence explaining why the average Seebeck coefficient of Ti3SiC2 in polycrystals is negligible over a wide temperature range. This allows the origin of anisotropy in physical properties of nanolaminated materials to be traced

  19. Extended X-ray absorption fine structure of copper(II) complexes at the air-water interface by a polarized total-reflection X-ray absorption technique.

    Science.gov (United States)

    Nagatani, Hirohisa; Tanida, Hajime; Watanabe, Iwao; Sagara, Takamasa

    2009-04-01

    Copper(II) complexes spread on an aqueous solution surface were studied by a polarized total-reflection X-ray absorption fine structure (TR-XAFS) technique. The polarized TR-XAFS spectra at the Cu-K edge for copper(II) porphyrins and copper(II) chlorophyllin in a monolayer were measured in situ at the air-water interface. The polarization dependences of X-ray absorption near-edge structure (XANES) involving a 1s-->4p(z) transition allowed us to estimate the molecular orientation and the local coordination structure around the copper(II) atom in the polarization plane selectively. The extended X-ray absorption fine structure (EXAFS) region of the polarized TR-XAFS spectra for the metal complexes present at the air-water interface was successfully analyzed for the first time. The relative coordination number for the copper center evaluated from the EXAFS analysis indicated larger values in the vertical polarization than in the horizontal one, in agreement with the standing-up molecular orientation at the air-water interface estimated from the XANES region.

  20. Combined Application of QEM-SEM and Hard X-ray Microscopy to Determine Mineralogical Associations and Chemcial Speciation of Trace Metals

    Energy Technology Data Exchange (ETDEWEB)

    M Grafe; M Landers; R Tappero; P Austin; B Gan; A Grabsch; C Klauber

    2011-12-31

    We describe the application of quantitative evaluation of mineralogy by scanning electron microscopy in combination with techniques commonly available at hard X-ray microprobes to define the mineralogical environment of a bauxite residue core segment with the more specific aim of determining the speciation of trace metals (e.g., Ti, V, Cr, and Mn) within the mineral matrix. Successful trace metal speciation in heterogeneous matrices, such as those encountered in soils or mineral residues, relies on a combination of techniques including spectroscopy, microscopy, diffraction, and wet chemical and physical experiments. Of substantial interest is the ability to define the mineralogy of a sample to infer redox behavior, pH buffering, and mineral-water interfaces that are likely to interact with trace metals through adsorption, coprecipitation, dissolution, or electron transfer reactions. Quantitative evaluation of mineralogy by scanning electron microscopy coupled with micro-focused X-ray diffraction, micro-X-ray fluorescence, and micro-X-ray absorption near edge structure (mXANES) spectroscopy provided detailed insights into the composition of mineral assemblages and their effect on trace metal speciation during this investigation. In the sample investigated, titanium occurs as poorly ordered ilmenite, as rutile, and is substituted in iron oxides. Manganese's spatial correlation to Ti is closely linked to ilmenite, where it appears to substitute for Fe and Ti in the ilmenite structure based on its mXANES signature. Vanadium is associated with ilmenite and goethite but always assumes the +4 oxidation state, whereas chromium is predominantly in the +3 oxidation state and solely associated with iron oxides (goethite and hematite) and appears to substitute for Fe in the goethite structure.

  1. First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments

    Directory of Open Access Journals (Sweden)

    Maxime Deutsch

    2014-05-01

    Full Text Available Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment. However, a breakthrough was recently made by the development of a common model in order to combine information coming from all these different experiments. Here we report the first experimental determination of spin-resolved electron density obtained by a combined treatment of X-ray, neutron and polarized neutron diffraction data. These experimental spin up and spin down densities compare very well with density functional theory (DFT calculations and also confirm a theoretical prediction made in 1985 which claims that majority spin electrons should have a more contracted distribution around the nucleus than minority spin electrons. Topological analysis of the resulting experimental spin-resolved electron density is also briefly discussed.

  2. Sweet Pepper (Capsicum annuum L.) Canopy Photosynthesis Modeling Using 3D Plant Architecture and Light Ray-Tracing.

    Science.gov (United States)

    Kim, Jee Hoon; Lee, Joon Woo; Ahn, Tae In; Shin, Jong Hwa; Park, Kyung Sub; Son, Jung Eek

    2016-01-01

    Canopy photosynthesis has typically been estimated using mathematical models that have the following assumptions: the light interception inside the canopy exponentially declines with the canopy depth, and the photosynthetic capacity is affected by light interception as a result of acclimation. However, in actual situations, light interception in the canopy is quite heterogenous depending on environmental factors such as the location, microclimate, leaf area index, and canopy architecture. It is important to apply these factors in an analysis. The objective of the current study is to estimate the canopy photosynthesis of paprika (Capsicum annuum L.) with an analysis of by simulating the intercepted irradiation of the canopy using a 3D ray-tracing and photosynthetic capacity in each layer. By inputting the structural data of an actual plant, the 3D architecture of paprika was reconstructed using graphic software (Houdini FX, FX, Canada). The light curves and A/C i curve of each layer were measured to parameterize the Farquhar, von Caemmerer, and Berry (FvCB) model. The difference in photosynthetic capacity within the canopy was observed. With the intercepted irradiation data and photosynthetic parameters of each layer, the values of an entire plant's photosynthesis rate were estimated by integrating the calculated photosynthesis rate at each layer. The estimated photosynthesis rate of an entire plant showed good agreement with the measured plant using a closed chamber for validation. From the results, this method was considered as a reliable tool to predict canopy photosynthesis using light interception, and can be extended to analyze the canopy photosynthesis in actual greenhouse conditions.

  3. Contribution of a 3D ray tracing model in a complex medium to the localization of infra-sound sources

    International Nuclear Information System (INIS)

    Mialle, Pierrick

    2007-01-01

    Localisation of infra-sound sources is a difficult task due to large propagation distances at stake and because of the atmospheric complexity. In order to resolve this problem, one can seek as many necessary information as the comprehension of wave propagation, the role and influence of the atmosphere and its spatio-temporal variations, the knowledge of sources and detection parameters, but also the configuration of the stations and their global spreading. Two methods based on the construction of propagation tables depending on station, date and time are introduced. Those tables require a long range propagation tool to simulate the propagation through a complex medium, which are carried out by WASP-3D Sph a 3D paraxial ray tracing based-theory tool integrating both amplitude estimation and horizontal wind fields in space and time. Tables are centered on the receptor. They describe spatial variations of the main observation parameters and offer a snapshot of the atmospheric propagation depending on the range for every simulated phase. For each path, celerity, azimuth deviation, attenuation and return altitude are predicted and allow building the tables. The latter help to identify detected phases and are integrated in an accurate localization procedure. The procedure is tested on three case study, such as the explosion of gas-pipeline in Belgium 2004 near Ghislenghien, the explosion of a military facility in 2007 in Novaky, Slovakia and the explosion of the Buncefield oil depot in 2005 in the United Kingdom, where event specificities, propagation parameters and used configurations are introduced. The accuracy and optimization of the localization are discussed. A validation study is presented regarding International Monitoring System stations along a meridian - I18DK (Greenland, Denmark), I51UK (Bermuda, United Kingdom), I25FR (Guyane, France), I08BO (La Paz, Bolivia), I01AR (Paso Flores, Argentina), I02AR (Ushuaia, Argentina), I54US (Antarctica, U.S.A.) - to

  4. Generation of circularly polarized XUV and soft-x-ray high-order harmonics by homonuclear and heteronuclear diatomic molecules subject to bichromatic counter-rotating circularly polarized intense laser fields

    Science.gov (United States)

    Heslar, John; Telnov, Dmitry A.; Chu, Shih-I.

    2017-12-01

    Recently, studies of bright circularly polarized high-harmonic beams from atoms in the soft-x-ray region as a source for x-ray magnetic circular dichroism measurement in a tabletop-scale setup have received considerable attention. In this paper, we address the problem with molecular targets and perform a detailed quantum study of H2 +, CO, and N2 molecules in bichromatic counter-rotating circularly polarized laser fields where we adopt wavelengths (1300 and 790 nm) and intensities (2 ×1014W /cm2 ) reported in a recent experiment [Proc. Natl. Acad. Sci. USA 112, 14206 (2015), 10.1073/pnas.1519666112]. Our treatment of multiphoton processes in homonuclear and heteronuclear diatomic molecules is nonperturbative and based on the time-dependent density-functional theory for multielectron systems. The calculated radiation spectrum contains doublets of left and right circularly polarized harmonics with high-energy photons in the XUV and soft-x-ray ranges. Our results reveal intriguing and substantially different nonlinear optical responses for homonuclear and heteronuclear diatomic molecules subject to circularly polarized intense laser fields. We study in detail the below- and above-threshold harmonic regions and analyze the ellipticity and phase of the generated harmonic peaks.

  5. High-efficient rendering of the multi-view image for the three-dimensional display based on the backward ray-tracing technique

    Science.gov (United States)

    Pang, Bo; Sang, Xinzhu; Xing, Shujun; Yu, Xunbo; Chen, Duo; Yan, Binbin; Wang, Kuiru; Yu, Chongxiu; Liu, Boyang; Cui, Can; Guan, Yanxin; Xiang, Weikang; Ge, Lei

    2017-12-01

    Computer-generated multi-view (MV) image for the three-dimensional (3D) display with lenticular lens arrays based on the backward ray-tracing technique is presented. To overcome the limitations of the traditional ray-tracing technique, whose minimum operating unit is the pixel, the proposed method can be applied at the sub-pixel level. The quality of the generated 3D image is not reduced, in contrast to existing methods for converting 2D images to 3D. Compared to the previous each camera viewpoint independent rendering method, the backward ray-tracing technique directly renders the final MV image rather than all the single-viewpoint images. Accordingly, the total render time is substantially reduced. Experimental results show that our proposed method significantly increases the simplicity and efficiency of the rendering process, especially ensuring the resolution of the final MV 3D image. Experimental results for 3D display with the generated 32-viewpoint 3D images are presented.

  6. A fast and efficient adaptive parallel ray tracing based model for thermally coupled surface radiation in casting and heat treatment processes

    Science.gov (United States)

    Fainberg, J.; Schaefer, W.

    2015-06-01

    A new algorithm for heat exchange between thermally coupled diffusely radiating interfaces is presented, which can be applied for closed and half open transparent radiating cavities. Interfaces between opaque and transparent materials are automatically detected and subdivided into elementary radiation surfaces named tiles. Contrary to the classical view factor method, the fixed unit sphere area subdivision oriented along the normal tile direction is projected onto the surrounding radiation mesh and not vice versa. Then, the total incident radiating flux of the receiver is approximated as a direct sum of radiation intensities of representative “senders” with the same weight factor. A hierarchical scheme for the space angle subdivision is selected in order to minimize the total memory and the computational demands during thermal calculations. Direct visibility is tested by means of a voxel-based ray tracing method accelerated by means of the anisotropic Chebyshev distance method, which reuses the computational grid as a Chebyshev one. The ray tracing algorithm is fully parallelized using MPI and takes advantage of the balanced distribution of all available tiles among all CPU's. This approach allows tracing of each particular ray without any communication. The algorithm has been implemented in a commercial casting process simulation software. The accuracy and computational performance of the new radiation model for heat treatment, investment and ingot casting applications is illustrated using industrial examples.

  7. Non-destructive assessment of the polarity of GaN nanowire ensembles using low-energy electron diffraction and x-ray photoelectron diffraction

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Olexandr; Fernández-Garrido, S.; Jiříček, Petr; Bartoš, Igor; Geelhaar, L.; Brandt, O.; Paskova, T.

    2015-01-01

    Roč. 106, č. 2 (2015), "021602-1"-"021602-4" ISSN 0003-6951 Grant - others:AVČR(CZ) M100101201 Institutional support: RVO:68378271 Keywords : GaN nanowires * X-ray photoelectron diffraction * LEED I-V * GaN polarity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.142, year: 2015

  8. Quantitative evaluation of ultrasonic C-scan image in acoustically homogeneous and layered anisotropic materials using three dimensional ray tracing method.

    Science.gov (United States)

    Kolkoori, Sanjeevareddy; Hoehne, Christian; Prager, Jens; Rethmeier, Michael; Kreutzbruck, Marc

    2014-02-01

    Quantitative evaluation of ultrasonic C-scan images in homogeneous and layered anisotropic austenitic materials is of general importance for understanding the influence of anisotropy on wave fields during ultrasonic non-destructive testing and evaluation of these materials. In this contribution, a three dimensional ray tracing method is presented for evaluating ultrasonic C-scan images quantitatively in general homogeneous and layered anisotropic austenitic materials. The directivity of the ultrasonic ray source in general homogeneous columnar grained anisotropic austenitic steel material (including layback orientation) is obtained in three dimensions based on Lamb's reciprocity theorem. As a prerequisite for ray tracing model, the problem of ultrasonic ray energy reflection and transmission coefficients at an interface between (a) isotropic base material and anisotropic austenitic weld material (including layback orientation), (b) two adjacent anisotropic weld metals and (c) anisotropic weld metal and isotropic base material is solved in three dimensions. The influence of columnar grain orientation and layback orientation on ultrasonic C-scan image is quantitatively analyzed in the context of ultrasonic testing of homogeneous and layered austenitic steel materials. The presented quantitative results provide valuable information during ultrasonic characterization of homogeneous and layered anisotropic austenitic steel materials. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Detailed EXOSAT and optical observations of the intermediate polar 3A0729+103: discovery of two medium energy X-ray emission regions

    International Nuclear Information System (INIS)

    McHardy, I.M.; Pye, J.P.; Fairall, A.P.; Menzies, J.W.

    1987-01-01

    EXOSAT observations of the intermediate polar cataclysmic variable 3A0729+103 reveal a strong orbital modulation, with the 2-4KeV X-rays being significantly more modulated than the 4-6keV X-rays, indicative of photoelectric absorption. The 913 second modulation which is very prominent in the optical light curve, is weakly detected in the medium-energy X-ray light curve, confirming that it represents the white dwarf spin period. These observations are well explained by a combination of two sources of medium-energy X-ray emission. The presence of two emission regions is also clearly seen in the optical spectroscopy, particularly in the intensity of the He II4686 line which has two peaks during the orbit. The authors identify the two optical emission regions with the two X-ray emission regions. (author)

  10. Resonant inelastic X-ray spectroscopy of atoms and simple molecules: Satellite features and dependence on energy detuning and photon polarization

    Energy Technology Data Exchange (ETDEWEB)

    Žitnik, M., E-mail: matjaz.zitnik@ijs.si [Jožef Stefan Institute, P.O. Box 3000, SI-1001 Ljubljana (Slovenia); University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 21, SI-1000 Ljubljana (Slovenia); Kavčič, M.; Bohinc, R.; Bučar, K.; Mihelič, A. [Jožef Stefan Institute, P.O. Box 3000, SI-1001 Ljubljana (Slovenia); Cao, W. [Research Centre for Molecular Materials, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland); Guillemin, R.; Journel, L.; Marchenko, T.; Carniato, S.; Kawerk, E. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); Piancastelli, M.N. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala (Sweden); Simon, M. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France)

    2015-10-15

    We summarize recent results dealing with high resolution (resonant) X-ray spectroscopy of atomic and molecular targets in the tender X-ray energy region. We comment on advantages, new possibilities and problems related to RIXS spectroscopy with respect to the standard photoabsorption technique, where scanning the probe energy is the only option. In particular, three research areas are covered: X-ray emission mediated by energy dependent photoabsorption to multi-electron excited states, the Cl K core-hole clock studies exemplified by systematic study of chloro(fluoro)-hydrocarbon targets and the polarization dependent X-ray emission studies. Due to its spectral selectivity and simultaneous detection capability, high resolution wavelength dispersive X-ray spectroscopy has the capability to resolve structural and dynamical properties of matter within new instrumentation frontiers.

  11. Polarized Moessbauer transitions

    International Nuclear Information System (INIS)

    Barb, D.

    1975-01-01

    Theoretical aspects of the emission, absorption and scattering of polarized gamma rays are reviewed for a general case of combined magnetic and electric hyperfine interactions; various possibilities of obtaining polarized gamma sources are described and examples are given of the applications of Moessbauer spectroscopy with polarized gamma rays in solving problems of solid state physics. (A.K.)

  12. eXTP: Enhanced X-ray Timing and Polarization mission

    Science.gov (United States)

    Zhang, S. N.; Feroci, M.; Santangelo, A.; Dong, Y. W.; Feng, H.; Lu, F. J.; Nandra, K.; Wang, Z. S.; Zhang, S.; Bozzo, E.; Brandt, S.; De Rosa, A.; Gou, L. J.; Hernanz, M.; van der Klis, M.; Li, X. D.; Liu, Y.; Orleanski, P.; Pareschi, G.; Pohl, M.; Poutanen, J.; Qu, J. L.; Schanne, S.; Stella, L.; Uttley, P.; Watts, A.; Xu, R. X.; Yu, W. F.; in 't Zand, J. J. M.; Zane, S.; Alvarez, L.; Amati, L.; Baldini, L.; Bambi, C.; Basso, S.; Bhattacharyya S.; , Bellazzini, R.; Belloni, T.; Bellutti, P.; Bianchi, S.; Brez, A.; Bursa, M.; Burwitz, V.; Budtz-Jørgensen, C.; Caiazzo, I.; Campana, R.; Cao, X.; Casella, P.; Chen, C. Y.; Chen, L.; Chen, T.; Chen, Y.; Chen, Y.; Chen, Y. P.; Civitani, M.; Coti Zelati, F.; Cui, W.; Cui, W. W.; Dai, Z. G.; Del Monte, E.; de Martino, D.; Di Cosimo, S.; Diebold, S.; Dovciak, M.; Donnarumma, I.; Doroshenko, V.; Esposito, P.; Evangelista, Y.; Favre, Y.; Friedrich, P.; Fuschino, F.; Galvez, J. L.; Gao, Z. L.; Ge, M. Y.; Gevin, O.; Goetz, D.; Han, D. W.; Heyl, J.; Horak, J.; Hu, W.; Huang, F.; Huang, Q. S.; Hudec, R.; Huppenkothen, D.; Israel, G. L.; Ingram, A.; Karas, V.; Karelin, D.; Jenke, P. A.; Ji, L.; Korpela, S.; Kunneriath, D.; Labanti, C.; Li, G.; Li, X.; Li, Z. S.; Liang, E. W.; Limousin, O.; Lin, L.; Ling, Z. X.; Liu, H. B.; Liu, H. W.; Liu, Z.; Lu, B.; Lund, N.; Lai, D.; Luo, B.; Luo, T.; Ma, B.; Mahmoodifar, S.; Marisaldi, M.; Martindale, A.; Meidinger, N.; Men, Y.; Michalska, M.; Mignani, R.; Minuti, M.; Motta, S.; Muleri, F.; Neilsen, J.; Orlandini, M.; Pan, A. T.; Patruno, A.; Perinati, E.; Picciotto, A.; Piemonte, C.; Pinchera, M.; Rachevski A.; Rapisarda, M.; Rea, N.; Rossi, E. M. R.; Rubini, A.; Sala, G.; Shu, X. W.; Sgro, C.; Shen, Z. X.; Soffitta, P.; Song, L.; Spandre, G.; Stratta, G.; Strohmayer, T. E.; Sun, L.; Svoboda, J.; Tagliaferri, G.; Tenzer, G.; Hong, T.; Taverna, R.; Torok, G.; Turolla, R.; Vacchi, S.; Wang, J.; Walton, D.; Wang, K.; Wang, J. F.; Wang, R. J.; Wang, Y. F.; Weng, S. S.; Wilms, J.; Winter, B.; Wu, X.; Wu, X. F.; Xiong, S. L.; Xu, Y. P.; Xue, Y. Q.; Yan, Z.; Yang, S.; Yang, X.; Yang, Y. J.; Yuan, F.; Yuan, W. M.; Yuan, Y. F.; Zampa, G.; Zampa, N.; Zdziarski, A.; Zhang, C.; Zhang, C. L.; Zhang, L.; Zhang, X.; Zhang, Z.; Zhang, W. D.; Zheng, S. J.; Zhou, P.; Zhou X. L.

    2016-07-01

    eXTP is a science mission designed to study the state of matter under extreme conditions of density, gravity and magnetism. Primary goals are the determination of the equation of state of matter at supra-nuclear density, the measurement of QED effects in highly magnetized star, and the study of accretion in the strong-field regime of gravity. Primary targets include isolated and binary neutron stars, strong magnetic field systems like magnetars, and stellar-mass and supermassive black holes. The mission carries a unique and unprecedented suite of state-of-the-art scientific instruments enabling for the first time ever the simultaneous spectral-timing-polarimetry studies of cosmic sources in the energy range from 0.5-30 keV (and beyond). Key elements of the payload are: the Spectroscopic Focusing Array (SFA) - a set of 11 X-ray optics for a total effective area of ˜0.9 m2 and 0.6 m2 at 2 keV and 6 keV respectively, equipped with Silicon Drift Detectors offering units, equipped with position-sensitive Silicon Drift Detectors, each covering a 90 degrees x 90 degrees field of view. The eXTP international consortium includes major institutions of the Chinese Academy of Sciences and Universities in China, as well as major institutions in several European countries and the United States. The predecessor of eXTP, the XTP mission concept, has been selected and funded as one of the so-called background missions in the Strategic Priority Space Science Program of the Chinese Academy of Sciences since 2011. The strong European participation has significantly enhanced the scientific capabilities of eXTP. The planned launch date of the mission is earlier than 2025.

  13. Comparative study of trace element contents in human full-term placenta and fetal membranes by total reflection X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Kubala-Kukus, A. E-mail: aldona.kubala-kukus@pu.kielce.pl; Banas, D.; Braziewicz, J.; Majewska, U.; Pajek, M

    2003-04-18

    The total reflection X-ray fluorescence (TXRF) method was applied to study the influence of environmental pollution on the contents of trace elements in human full-term placenta and fetal membranes. The samples were collected from the donors living in two regions characterised by different levels of environmental pollution. In this comparative study, based on relatively large ({approx}100) populations, the concentrations of approximately 20 trace elements (P-Pb) were determined in the samples. In particular, the paper discusses the role of 'truncation' of measured concentration distribution by the detection limit of the TXRF method in context of comparative studies. First, the importance of the developed method of reconstruction of original concentration distribution, to derive the correct concentrations of trace elements, is described and demonstrated and, second, the statistical tests, which can be used to compare the truncated, or reconstructed, concentration distributions are discussed. Finally, the statistically significant differences of trace element concentrations found in both populations are presented and summarised.

  14. The small satellite NINA-MITA to study galactic and solar cosmic rays in low-altitude polar orbit

    Science.gov (United States)

    Furano, G.; Bidoli, V.; Casolino, M.; de Pascale, M. P.; Iannucci, A.; Morselli, A.; Picozza, P.; Reali, E.; Sparvoli, R.; Bakaldin, A.; Galper, A.; Koldashov, M.; Korotkov, M.; Leonov, A.; Mikhailov, V.; Murashov, A.; Voronov, S.; Mazzenga, G.; Ricci, M.; Castellini, G.; Barbiellini, M.; Boezio, M.; Bonvicini, V.; Cirami, R.; Vacchi, A.; Zampa, N.; Ambriola, M.; Bellotti, R.; Cafagna, F.; Ciacio, F.; Circella, M.; de Marzo, C.; Adriani, O.; Papini, P.; Piccardi, S.; Spillantini, P.

    The satellite MITA, carrying on board the scientific payload NINA-2, was launched on July the 15th, 2000 from the cosmodrome of Plesetsk (Russia) with a Cosmos-3M rocket. The satellite and the payload are currently operating within nominal parameters. NINA-2 is the first scientific payload for the technological flight of the Italian small satellite MITA. The detector used in this mission is identical to the one already flying on the Russian satellite Resurs-O1 n.4 in a 840-km sun-synchronous orbit, but makes use of the extensive computer and telemetry capabilities of MITA bus to improve the active data acquisition time. NINA physics objectives are to study cosmic nuclei from hydrogen to iron in the energy range between 10 MeV/n and 1 GeV/n during the years 2000-2003, that is the solar maximum period. The device is capable of charge identification up to iron with isotope sensitivity up to oxigen. The 87.3 degrees, 460 km altitude polar orbit allows investigations of cosmic rays of solar and galactic origin, so to study long and short term solar transient phenomena, and the study of the trapped radiation at higher geomagnetic cutoff.

  15. The polarized neutron reflectivity and X-ray reflectivity studies of the magnetic profiles of epitaxial Ni80Fe20/Ru multilayers

    International Nuclear Information System (INIS)

    Su, H.-C.; Peir, J.-J.; Lee, C.-H.; Lin, M.-Z.; Wu, P.-T.; Huang, J.C.A.; Tun Zin

    2005-01-01

    The depth profiles of the epitaxial Ni 80 Fe 20 (1 1 1)/Ru(0 0 0 1) multilayers were studied by polarized neutron reflectivity and X-ray reflectivity. At the Ru thickness that the anti-ferromagnetic coupling was found, the magnetic moments between two Ni 80 Fe 20 interlayers show a biquadratic coupling effect with a double unit cell at low applied fields. A magnetic dead layer of about 0.3 nm was also found at the interface boundaries. The maximal polarization effect applied to the Ru layer is less than 0.03μ B

  16. Quantification of trace arsenic in soils by field-portable X-ray fluorescence spectrometry: considerations for sample preparation and measurement conditions.

    Science.gov (United States)

    Parsons, Chris; Margui Grabulosa, Eva; Pili, Eric; Floor, Geerke H; Roman-Ross, Gabriela; Charlet, Laurent

    2013-11-15

    Recent technological improvements have led to the widespread adoption of field portable energy dispersive X-ray fluorescence (FP-XRF) by governmental agencies, environmental consultancies and research institutions. FP-XRF units often include analysis modes specifically designed for the quantification of trace elements in soils. Using these modes, X-ray tube based FP-XRF units can offer almost "point and shoot" ease of use and results comparable to those of laboratory based instruments. Nevertheless, FP-XRF analysis is sensitive to spectral interferences as well as physical and chemical matrix effects which can result in decreased precision and accuracy. In this study, an X-ray tube-based FP-XRF analyser was used to determine trace (low ppm) concentrations of As in a floodplain soil. The effect of different sample preparation and analysis conditions on precision and accuracy were systematically evaluated. We propose strategies to minimise sources of error and maximise data precision and accuracy, achieving in situ limits of detection and precision of 6.8 ppm and 14.4%RSD, respectively for arsenic. We demonstrate that soil moisture, even in relatively dry soils, dramatically affects analytical performance with a signal loss of 37% recorded for arsenic at 20 wt% soil moisture relative to dry soil. We also highlight the importance of the use of certified reference materials and independent measurement methods to ensure accurate correction of field values. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Rapid screening of heavy metals and trace elements in environmental samples using portable X-ray fluorescence spectrometer, A comparative study

    Science.gov (United States)

    McComb, Jacqueline Q.; Rogers, Christian; Han, Fengxiang X.; Tchounwou, Paul B.

    2014-01-01

    With industrialization, great amounts of trace elements and heavy metals have been excavated and released on the surface of the earth and dissipated into the environments. Rapid screening technology for detecting major and trace elements as well as heavy metals in variety of environmental samples is most desired. The objectives of this study were to determine the detection limits, accuracy, repeatability and efficiency of a X-ray fluorescence spectrometer (Niton XRF analyzer) in comparison with the traditional analytical methods, inductively coupled plasma optical emission spectrometer (ICP-OES) and inductively coupled plasma optical emission spectrometer (ICP-MS) in screening of major and trace elements of environmental samples including estuary soils and sediments, contaminated soils, and biological samples. XRF is a fast and non-destructive method in measuring the total concentration of multi--elements simultaneously. Contrary to ICP-OES and ICP-MS, XRF analyzer is characterized by the limited preparation required for solid samples, non-destructive analysis, increased total speed and high throughout, the decreased production of hazardous waste and the low running costs as well as multi-elemental determination and portability in the fields. The current comparative study demonstrates that XRF is a good rapid non-destructive method for contaminated soils, sediments and biological samples containing higher concentrations of major and trace elements. Unfortunately, XRF does not have sensitive detection limits of most major and trace elements as ICP-OES or ICP-MS but it may serve as a rapid screening tool for locating hot spots of uncontaminated field soils and sediments. PMID:25861136

  18. Determination of trace elements in small water samples by total reflexion X-ray fluorescence (TXRF) and by neutron activation analysis (NAA)

    Energy Technology Data Exchange (ETDEWEB)

    Lieser, K.H. (Fachbereich Chemie, Eduard Zintl-Inst., Technische Hochschule Darmstadt (Germany)); Flakowski, M. (Fachbereich Chemie, Eduard Zintl-Inst., Technische Hochschule Darmstadt (Germany)); Hoffmann, P. (Fachbereich Chemie, Eduard Zintl-Inst., Technische Hochschule Darmstadt (Germany))

    1994-09-01

    The problems encountered in the determination of trace elements in small sample volumes of the order of 1 to 10 [mu]l (e.g. in droplets of water) are discussed. Total reflexion X-ray fluorescence (TXRF) and neutron activation analysis (NAA) are applied for the determination of Na, Mg, K, Ca, Mn, Fe, Co, and Cu in concentrations of 0.01 to 10 mg/L in 1 to 10 [mu]L of water. The applied methods are described, the results are discussed and the advantages of TXRF are brought forward. (orig.)

  19. Automated solid-phase extraction for trace-metal analysis of seawater: sample preparation for total-reflection X-ray fluorescence measurements

    Science.gov (United States)

    Gerwinski, Wolfgang; Schmidt, Diether

    1998-08-01

    Solid-phase chromatography on silica gel columns can be used as a sample preparation technique for seawater, followed by total-reflection X-ray fluorescence analysis (TXRF). An automated extraction system (Zymark AutoTrace SPE Workstation) was studied for the analysis of blank solutions, seawater samples and certified reference materials. After replacing some stainless steel parts in the system, adequate blanks could be obtained to allow the analysis of seawater samples. Replicate analyses yielded low standard deviations and good recoveries for certified reference materials. Using a six-channel model and user-defined software, the time needed for a complete analytical run was about 100 min.

  20. Studies of trace elements in biological systems by energy dispersive x-ray fluorescence (EDXRF) and proton induced x-ray emission (PIXE) methods

    International Nuclear Information System (INIS)

    Lal, Madan; Choudhury, R.K.

    1991-01-01

    Applicability of EDXRF and PIXE techniques for trace elemental analysis in biology and medicine is demonstrated. Due to increasing importance of the need to determine the role of essential and toxic trace elements in human health and disease, the method of PIXE analysis has assumed great importance in recent years. This method has been found to be particularly useful for biological samples. EDXRF also offers a complimentary method particularly in the range of elements of Z=45 to 60 where the sensitivity of PIXE analysis is not quite adequate. EDXRF can also be usefully employed for other elements of the periodic chart with relatively lesser sensitivity. The work being presented here includes trace element analysis of normal and cancer bearing tissues of Swiss mice, trace element profiles in cancerous human oesophageal tissues, investigations on the effect of toxic metals such as Hg from Ayurvedic drugs on Wister rats, and investigations of blood lead levels of children admitted to Sion Hospital from Dharavi slums of Bombay. The results of these investigations are presented and discussed. (author). 21 refs., 8 figs., 3 tabs

  1. Quantification of trace elements in protein bands by synchrotron radiation x-ray fluorescence after isoelectric focusing separation of human hemoglobin

    International Nuclear Information System (INIS)

    Gao Yuxi; Chen Chunying; Li Bai; He Wei; Huang Yuying; Chai Zhifang

    2005-01-01

    The role and effects of a trace element in a particular organism strongly depend on its particular chemical forms in which the element is present. Therefore, the bulk content or concentration of an element in the organism of interest is often meaningless in judging its biological significance. To understand bioavailability, transportation, cell uptake, metabolism, toxicity, and other biological behaviors of trace elements in the body, information is needed about speciation of trace element, especially about distribution of metal-containing proteins. Development of appropriate methods for speciation analysis is therefore required. Synchrotron radiation x-ray fluorescence (SRXRF) is a sensitive method for multielemental analysis with detection limit of 10 ng/g. It has been successfully used for imaging and quantifying trace elements in various pathological and healthy tissues, even in a single cell, to help understand the mechanism of diseases and the biochemistry of elements. In our previous work, the technique was combined with electrophoresis to study distribution of metalloproteins in biological samples, but the quantitative analysis of trace elements in protein bands after electrophoresis was still unrealized. In this study, a procedure has been proposed for quantification of Fe, Cu, and Zn in protein bands with SRXRF analysis after isoelectric focusing (IEF) separation. Calibration standards were prepared by adding certain amounts of metal ions and free-metal proteins to electrophoresis gel. Human hemoglobin was separated with IEF, and Fe, Cu, and Zn in protein bands were analyzed by SRXRF. The calibration curves can be obtained in a range of 0-8 mg/kg metals and a linear relationship between dosage of metals and fluorescent intensity can be observed (r 2 > 0.99). The method provides the detection limits of 2.43, 1.12, and 0.96 mg/kg for Fe, Cu and Zn, and the recoveries of 90.4 and 115.7 % for Fe and Zn, respectively. The hyphenated technique of SRXRF and IEF

  2. Dipole and quadrupole contributions to polarized Cu K x-ray absorption near-edge structure spectra of CuO

    Czech Academy of Sciences Publication Activity Database

    Bocharov, S.; Kirchner, T.; Dräger, G.; Šipr, Ondřej; Šimůnek, Antonín

    2001-01-01

    Roč. 63, - (2001), s. 045104-1-045104-10 ISSN 0163-1829 R&D Projects: GA ČR GA202/99/0404; GA ČR GA203/99/0067 Institutional research plan: CEZ:AV0Z1010914 Keywords : high-Tc superconductots * polarized Cu K x-ray absorption * CuO Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.070, year: 2001

  3. Ray-Tracing-Based Modeling of Clad-Removed Step-Index Plastic Optical Fiber in Smart Textiles: Effect of Curvature in Plain Weave Fabric

    Directory of Open Access Journals (Sweden)

    Sun Hee Moon

    2018-01-01

    Full Text Available Plastic optical fiber was chosen for information delivery media in smart textile. Cladding layer was peeled off by chemical and mechanical methods to find optimal peeling conditions. Both radial side illumination and longitudinal end-tip illumination were measured for visible light of 627 µm wavelength. A half-cone-shaped jig was manufactured using 3D printing to give various curvature conditions to fibers. Also POFs were embedded in plain weave textile structure to measure the light dissipation effect. The waveguide phenomenon was modeled using discrete ray tracing technique and ray-to-interface collision detection algorithm. Results from the proposed modeling technique showed linear relationship with those from experiment.

  4. Application of neutron activation techniques and x-ray energy dispersion spectrometry, in analysis of metallic traces adsorbed by chelex-100 resin

    International Nuclear Information System (INIS)

    Fernandes, Jair C.; Amaral, Angela M.; Magalhaes, Jesus C.; Pereira, Jose S.J.; Silva, Juliana B. da; Auler, Lucia M.L.A.

    2000-01-01

    In this work, the authors have investigated optimal conditions of adsorption for several ion metallic groups (cations of heavy metals and transition metals, oxyanions metallics and metalloids and cations of rare earths), as traces (ppb), withdrawn and in mixture of groups, by chelex-100 resin. The experiments have been developed by bath techniques in ammonium acetate tamponade solution 40 mM pH 5,52 content 0,5 g of chelex-100 resin. After magnetic agitation for two hours, resins were dried and submitted to X-ray energy dispersion spectrometry, x-ray fluorescence spectrometry and neutron activation analysis. The results have demonstrated that chelex-100 resin adsorb quantitatively transition element groups and rare earth groups in two cases (withdrawn and simultaneously adsorption)

  5. Seasonal determination of trace and ultra-trace content in Macrocystis pyrifera from San Jorge Gulf (Patagonia) by Total Reflection X-ray Fluorescence

    Science.gov (United States)

    Salomone, Vanesa N.; Riera, Marina; Cerchietti, Luciana; Custo, Graciela; Muniain, Claudia

    2017-05-01

    Seaweed have a great capacity to accumulate heavy metals in their tissues. The chemical characterization of seaweed is important due to their use in environmental monitoring and human or animal food. The aim of the present study was to evaluate the multi-elemental composition of seaweed from San Jorge Gulf (Patagonia, Argentina) by Total Reflection X-ray Fluorescence (TXRF). The elements As, Br, Cu, Cr, Fe, Mn, Ni, Pb, Rb, Sr, V and Zn were seasonally analyzed and quantified in blades of Macrocystis pyrifera. TXRF showed to be a suitable technique for simultaneous multi-element analysis in this kind of samples. The results revealed seasonal variations in the chemical content for some elements; arsenic content was maximum in summer and autumn, iron concentration increased to the winter and zinc concentration was maximum in autumn. The sum of principal micronutrients (Fe + Zn + Mn + Cu) varied between 114 and 171 mg k- 1 g dw. The total As concentration ranged between 36 and 66 mg kg- 1. Lead, nickel and copper were not detected.

  6. Upgrade of long trace profiler for characterization of high-precision X-ray mirrors at SPring-8

    International Nuclear Information System (INIS)

    Senba, Y.; Kishimoto, H.; Ohashi, H.; Yumoto, H.; Zeschke, T.; Siewert, F.; Goto, S.; Ishikawa, T.

    2010-01-01

    The long trace profiler (LTP) at SPring-8 has been upgraded to improve stability and resolution of slope measurement. The performances of the upgraded LTP at SPring-8 are presented by cross-checking measurements on a flat mirror with data obtained using Nanometer Optical Component Measuring Machine (NOM) at the Helmholtz Zentrum Berlin/BESSY-II.

  7. Assessment of trace element concentration distribution in human placenta by wavelength dispersive X-ray fluorescence: Effect of neonate weight and maternal age

    International Nuclear Information System (INIS)

    Ozdemir, Yueksel; Boerekci, Buenyamin; Levet, Aytac; Kurudirek, Murat

    2009-01-01

    Trace element status in human placenta is dependent on maternal-neonatal characteristics. This work was undertaken to investigate the correlation between essential trace element concentrations in the placenta and maternal-neonatal characteristics. Placenta samples were collected from total 61 healthy mothers at gestation between 37 and 41 weeks. These samples were investigated with the restriction that the mother's age was 20-40 years old and the neonate's weight was 1-4 kg. Percent concentrations of trace elements were determined using wavelength dispersive X-ray fluorescence (WDXRF). The placenta samples were prepared and analyzed without exposure to any chemical treatment. Concentrations of Fe, Cu and Zn in placenta tissues were found statistically to vary corresponding to the age of the mother and weight of the neonate. In the subjects, the concentration of Fe and Cu were increased in heavier neonates (p<0.05) and the concentration of Zn was increased with increasing mother age (p<0.05). Consequently, the Fe, Cu and Zn elements appear to have interactive connections in human placenta.

  8. Study of trace element correlations with drought tolerance in different sorghum genotypes using Energy Dispersive X-Rays Fluorescence (EDXRF) technique

    International Nuclear Information System (INIS)

    Abu Assar, A.H.; Joseph, Daisy; Choudhury, R.K.; Saxena, A.; Suprasanna, P.; Bapat, V.A.

    2000-01-01

    Drought tolerant and susceptible genotypes of sorghum plants were analysed by Energy Dispersive X-Ray Fluorescence (EDXRF) technique to study the correlation of trace elements with drought tolerance capacities for sorghum plants. Samples prepared from mature seeds, young seedlings and old plants were analyzed using 109 Cd radioisotope source and a Si(Li) semiconductor detector of resolution 170 eV for 5.9 keV Mn K α X-ray. The elements such as K, Fe, Cu, Zn, Rb and Sr and Y were seen to be present in varying concentrations in different samples. The trace element profile in the seeds of 11 genotypes and in seedlings (young and old) of four sorghum genotypes that were studied exhibited considerable variation in their concentrations. Some seed genotypes showed the presence of Hg in small amounts. It was observed that in most of the genotypes (seeds), K and Fe concentrations were more in the tolerant genotype as compared to the susceptible type. Concentration of Fe decreased with maturity in the tolerant group while it increased with maturity in the susceptible group. The genotype Arfa Gadamak (AG) showed a distinct abnormality in its young seedling with high level of Zn. (author)

  9. Trace metal analysis by laser ablation-inductively coupled plasmamass spectrometry and x-ray K-edge densitometry of forensic samples

    Energy Technology Data Exchange (ETDEWEB)

    Berry, Jonna Elizabeth [Iowa State Univ., Ames, IA (United States)

    2016-10-25

    This dissertation describes a variety of studies on the determination of trace elements in samples with forensic importance. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to determine the trace element composition of numerous lipstick samples. Lipstick samples were determined to be homogeneous. Most lipstick samples of similar colors were readily distinguishable at a 95% confidence interval based on trace element composition. Numerous strands of a multi-strand speaker cable were analyzed by LA-ICP-MS. The strands in this study are spatially heterogeneous in trace element composition. In actual forensic applications, the possibility of spatial heterogeneity must be considered, especially in cases where only small samples (e.g., copper wire fragments after an explosion) are available. The effects of many unpredictable variables, such as weather, temperature, and human activity, on the retention of gunshot residue (GSR) around projectile wounds were assessed with LAICP- MS. Skin samples around gunshot and stab wounds and larvae feeding in and around the wounds on decomposing pig carcasses were analyzed for elements consistent with GSR (Sb, Pb, Ba, and Cu). These elements were detected at higher levels in skin and larvae samples around the gunshot wounds compared to the stab wounds for an extended period of time throughout decomposition in both a winter and summer study. After decomposition, radiographic images of the pig bones containing possible damage from bullets revealed metallic particles embedded within a number of bones. Metallic particles within the bones were analyzed with x-ray, K-edge densitometry and determined to contain lead, indicating that bullet residue can be retained throughout decomposition and detected within bones containing projectile trauma.

  10. Application of Differential Geometry to Acoustics: Development of a Generalized Paraxial Ray-Trace Procedure from Geodesic Deviation

    National Research Council Canada - National Science Library

    Bergman, David R

    2005-01-01

    .... The geodesic deviation vector is used to model beam deformation and provides one with an all-purpose tool for measuring geometric transmission loss and locating caustics within a ray skeleton without...

  11. Tracing the Mass-Dependent Star Formation History of Late-Type Galaxies using X-ray Emission: Results from the CHANDRA Deep Fields

    Science.gov (United States)

    Lehmer, B.D; Brandt, W.N.; Schneider, D.P.; Steffen, A.T.; Alexander, D.M.; Bell, E.F.; Hornschemeier, A.E.; McIntosh, D.H.; Bauer, F.E.; Gilli, R.; hide

    2008-01-01

    We report on the X-ray evolution over the last approx.9 Gyr of cosmic history (i.e., since z = 1.4) of late-type galaxy populations in the Chandra Deep Field-North and Extended Chandra Deep Field-South (CDF-N and E-CDF-S. respectively; jointly CDFs) survey fields. Our late-type galaxy sample consists of 2568 galaxies. which were identified using rest-frame optical colors and HST morphologies. We utilized X-ray stacking analyses to investigate the X-ray emission from these galaxies, emphasizing the contributions from normal galaxies that are not dominated by active galactic nuclei (AGNs). Over this redshift range, we find significant increases (factors of approx. 5-10) in the X-ray-to-optical mean luminosity ratio (L(sub x)/L(sub B)) and the X-ray-to-stellar-mass mean ratio (L(sub x)/M(sub *)) for galaxy populations selected by L(sub B) and M(sub *), respectively. When analyzing galaxy samples selected via SFR, we find that the mean X-ray-to-SFR ratio (L(sub x)/SFR) is consistent with being constant over the entire redshift range for galaxies with SFR = 1-100 Solar Mass/yr, thus demonstrating that X-ray emission can be used as a robust indicator of star-formation activity out to z approx. 1.4. We find that the star-formation activity (as traced by X-ray luminosity) per unit stellar mass in a given redshift bin increases with decreasing stellar mass over the redshift range z = 0.2-1, which is consistent with previous studies of how star-formation activity depends on stellar mass. Finally, we extend our X-ray analyses to Lyman break galaxies at z approx. 3 and estimate that L(sub x)/L(sub B) at z approx. 3 is similar to its value at z = 1.4.

  12. New ray tracing method to investigate the various effects on wave propagation in medical scenario: an application of wireless body area network.

    Science.gov (United States)

    Islam, M J; Reza, A W; Kausar, A S M Z; Ramiah, H

    2014-01-01

    The advent of technology with the increasing use of wireless network has led to the development of Wireless Body Area Network (WBAN) to continuously monitor the change of physiological data in a cost efficient manner. As numerous researches on wave propagation characterization have been done in intrabody communication, this study has given emphasis on the wave propagation characterization between the control units (CUs) and wireless access point (AP) in a hospital scenario. Ray tracing is a tool to predict the rays to characterize the wave propagation. It takes huge simulation time, especially when multiple transmitters are involved to transmit physiological data in a realistic hospital environment. Therefore, this study has developed an accelerated ray tracing method based on the nearest neighbor cell and prior knowledge of intersection techniques. Beside this, Red-Black tree is used to store and provide a faster retrieval mechanism of objects in the hospital environment. To prove the superiority, detailed complexity analysis and calculations of reflection and transmission coefficients are also presented in this paper. The results show that the proposed method is about 1.51, 2.1, and 2.9 times faster than the Object Distribution Technique (ODT), Space Volumetric Partitioning (SVP), and Angular Z-Buffer (AZB) methods, respectively. To show the various effects on received power in 60 GHz frequency, few comparisons are made and it is found that on average -9.44 dBm, -8.23 dBm, and -9.27 dBm received power attenuations should be considered when human, AP, and CU move in a given hospital scenario.

  13. Analysis of trace elements in ceramic prints on automobile glasses for forensic examination using high-energy synchrotron radiation x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Nishiwaki, Yoshinori; Takatsu, Masahisa; Miyamoto, Naoki; Watanabe, Seiya; Shimoda, Osamu; Muratsu, Seiji; Nakanishi, Toshio; Nakai, Izumi

    2007-01-01

    This study revealed that high-energy SRXRF (synchrotron radiation X-ray fluorescence spectrometry) utilizing 75.5 keV X-rays of SPring-8 is a powerful technique for trace elemental analysis of ceramic prints on automotive glasses for forensic examination. Fragments of 99 ceramic prints were collected from automobiles of various manufacturers, types and model years. Their major heavy element-components were found to be either Pb or Bi. Because of recent environment protection movement for lead-free material, there was a tendency of the shift of material from the Pb Type to the Bi Type with years of the production. A utilization of 75.5 keV X-rays as excitation source allowed us to detect trace heavy-elements, such as Sb, La, Ce, Hf and W, as well as relatively light-elements, such as V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr and Mo, in samples using K series of XRF emission lines. XRF intensities of these elements normalized by those of the major heavy-elements (Pb or Bi) became characteristic finger prints, showing the identity of each sample with a size of less than 0.5x0.5 mm 2 . The mean relative standard deviations of the normalized XRF intensities measured for the three fragments of each sample were less than 9.3%. These results show that the ceramic prints on automobile glasses contain rich elemental information for discrimination, and therefore the materials can be important evidence for practical forensic examinations. (author)

  14. Ultra-trace-level determination of polar pesticides and their transformation products in surface and estuarine water samples using column liquid chromatography electrospray-tandem mass spectrometry

    NARCIS (Netherlands)

    Steen, R.J.C.A.; Hogenboom, A.C.; Leonards, P.E.G.; Peerboom, R.A.L.; Cofino, W.P.; Brinkman, U.A.T.

    1999-01-01

    A method is developed for the determination of polar pesticides and their transformation products [atrazine, deethylatrazine, deisopropylatrazine, hydroxyatrazine, diuron, 3,4-dichlorophenylmethylurea, 3,4-dichlorophenylurea (DPU), monuron, bentazone, anthranil-isopropylamide, chloridazon,

  15. Study of the polarization dependence of the photoelectric effect in the soft X-ray band - A focal plane photoelectric stellar X-ray polarimeter for the Spectrum-X-Gamma mission

    International Nuclear Information System (INIS)

    Heckler, A.; Blaer, A.; Kaaret, P.; Novick, R.

    1989-01-01

    An experimental study of the polarization dependence of the photoelectric effect in cesium iodide in the soft X-ray band was started (Heckler et al., 1989). At a grazing angle of 10 degrees and a photon energy of 2.6 keV, it is found that the photoelectric yield from a thin layer of evaporated cesium iodide varies by 12.4 percent as the polarization vector of the incident X-ray beam is rotated about the line-of-sight. The rotation angle corresponding to the maximum photoyield is displaced by 16 degrees from the normal to the photocathode. This modulation and phase shift are in good agreement with the results recently reported by Fraser, et al. (1989) It is shown that a focal plane stellar X-ray polarimeter based on this photoelectric effect will be substantially more efficient than convential X-ray polarimeters such as those based on either Bragg reflection or scattering from low atomic number targets. 7 refs

  16. Generation of circularly polarized radiation from a compact plasma-based extreme ultraviolet light source for tabletop X-ray magnetic circular dichroism studies

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Daniel; Rudolf, Denis, E-mail: d.rudolf@fz-juelich.de; Juschkin, Larissa [RWTH Aachen University, Experimental Physics of EUV, Steinbachstraße 15, 52074 Aachen (Germany); Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-9), JARA-FIT, 52425 Jülich (Germany); Weier, Christian; Adam, Roman; Schneider, Claus M. [Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), JARA-FIT, 52425 Jülich (Germany); Winkler, Gerrit; Frömter, Robert [Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg (Germany); Danylyuk, Serhiy [RWTH Aachen University, Chair for Technology of Optical Systems, JARA-FIT, Steinbachstraße 15, 52074 Aachen (Germany); Bergmann, Klaus [Fraunhofer Institute for Laser Technology, Steinbachstrasse 15, 52074 Aachen (Germany); Grützmacher, Detlev [Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-9), JARA-FIT, 52425 Jülich (Germany)

    2014-10-15

    Generation of circularly polarized light in the extreme ultraviolet (EUV) spectral region (about 25 eV–250 eV) is highly desirable for applications in spectroscopy and microscopy but very challenging to achieve in a small-scale laboratory. We present a compact apparatus for generation of linearly and circularly polarized EUV radiation from a gas-discharge plasma light source between 50 eV and 70 eV photon energy. In this spectral range, the 3p absorption edges of Fe (54 eV), Co (60 eV), and Ni (67 eV) offer a high magnetic contrast often employed for magneto-optical and electron spectroscopy as well as for magnetic imaging. We simulated and designed an instrument for generation of linearly and circularly polarized EUV radiation and performed polarimetric measurements of the degree of linear and circular polarization. Furthermore, we demonstrate first measurements of the X-ray magnetic circular dichroism at the Co 3p absorption edge with a plasma-based EUV light source. Our approach opens the door for laboratory-based, element-selective spectroscopy of magnetic materials and spectro-microscopy of ferromagnetic domains.

  17. Wavelength-dispersive total-reflection X-ray fluorescence with an efficient Johansson spectrometer and an undulator X-ray source: detection of 10-16 g-level trace metals.

    Science.gov (United States)

    Sakurai, Kenji; Eba, Hiromi; Inoue, Katsuaki; Yagi, Naoto

    2002-09-01

    The present paper reports significant enhancement of the detection power for total-reflection X-ray fluorescence (TXRF). The employment of an efficient wavelength-dispersive spectrometer rather than a conventional Si(Li) detector, as well as the use of a quasi-monochromatic undulator X-ray source, completely changed the quality of X-ray florescence spectra. The energy resolution is 20 times better, which effectively contributes to reducing the low-energy tail of the scattering background and to separating neighboring X-ray florescence peaks. Another advantage is its capability with respect to high-counting-rate measurements, which ensure the detection of weak signals from trace materials. The absolute and relative detection limit for nickel are 3.1 x 10(-16) g and 3.1 ppt (pg/g) for a 0.1-microL droplet of pure water, respectively, which is nearly 50 times better than the current best data achieved by conventional energy-dispersive TXRF using a Si(Li) detector system.

  18. Polarization transfer in x-ray transitions due to photoionization in highly charged copper-like ions

    Science.gov (United States)

    Ma, Kun; Chen, Zhan-Bin; Xie, Lu-You; Dong, Chen-Zhong

    2018-02-01

    Using the density matrix theory and the multi-configuration Dirac-Fock method, the 3{d}3/2 subshell photoionization of highly charged ions is studied, together with their subsequent radiative decay. The effects of polarization transfer on the linear polarization and angular distribution of the 3{d}94{s}2{}2{D}3/2\\to 3{d}104p{}2{P}1/2 characteristic line photoemission for selected Cu-like Zn+, Ba27+, {{{W}}}45+, and {{{U}}}63+ ions are investigated. Our results show that the polarization transfer, arising from the originally polarized incident light, may lead to a considerable change in the alignment parameters and the polarization properties of the radiation, the character of which is highly sensitive to the initial photon polarization, yet virtually independent of the photon energy. These characteristics are very similar to those of the electron bremsstrahlung process reported by Märtin et al (2012 Phys. Rev. Lett. 108 264801). The present results are compared with available experimental results and show a good quantitative agreement.

  19. Procedures for the determination of trace elements in milk by energy dispersive x-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Langhorst, A.L.; Bonner, N.A.; Bazan, F.; McIntyre, D.R.

    1976-01-01

    A procedure for the simultaneous determination of K, Ca, Fe, Cu, Zn, Br, Rb, Sr, and Pb in milk by x-ray fluorescence spectrometry is described. Comparison of molybdenum-tube excitation and cadmium-109 isotopic excitation is discussed, and results of over 500 milk samples are summarized

  20. Development and characterization of a portable total reflection X-ray fluorescence system using a waveguide for trace elements analysis.

    Science.gov (United States)

    da Costa, Ana Cristina M; de Araújo, Ubiratan B; de Jesus, Edgar F O; Anjos, Marcelino J; Lopes, Ricardo T

    2014-01-01

    This paper presents a portable total reflection X-ray fluorescence system composed of a 15 W X-ray tube, with a gold anode, a waveguide constituted by two Perspex(®) parallel plates, a Si PIN detector and a quartz optical flat. The critical angle of the total reflection system was experimentally determined by measuring a zinc solution (100 mg/L). The accuracy of the system was checked using SRM 1577b Bovine Liver by NIST as standard reference material. We obtained the absolute detection limits of the following elements: P (450 ± 40 ng), S (200 ± 31 ng), K (30 ± 2.5 ng), Ca (19 ± 3.5 ng), Mn (4.1 ± 0.5 ng), Fe (3.6 ± 0.9 ng), Cu (3.3 ± 0.4 ng) and Zn (3.5 ± 0.3 ng). This paper shows that it is possible to produce total reflection X-ray fluorescence with very compact, efficient, low-cost and easy-to-handle instrumentation using a low-power X-ray tube and a Si PIN compact detector.

  1. Vectorial field propagation through high NA objectives using polarized Gaussian beam decomposition

    Science.gov (United States)

    Worku, N.; Gross, H.

    2017-08-01

    Scalar fields can be propagated through non-paraxial systems using the Gaussian beam decomposition method. However, for high NA objectives, this scalar treatment is not sufficient to correctly describe the electromagnetic fields inside the focal region due to high ray bendings, which result in a significant change in the polarization state of light. To model these vectorial effects, the Gaussian beam decomposition method has to be extended to include the polarization state of light. In this work we have combined it with the three dimensional polarization ray tracing in order to propagate vectorial fields through high NA optical systems. During the Gaussian beam decomposition, the polarization state of each individual beamlet is represented by a polarization vector [𝐸𝑥, 𝐸𝑦, 𝐸𝑧 ] associated with its central ray. Individual Gaussian beams are then propagated through the system using the complex ray tracing method. The effect of the optical system on the polarization state of each beam is computed by applying the three dimensional polarization ray tracing of the corresponding central rays. Finally the individual beams are superposed coherently in the plane of interest resulting in the complete vectorial field. We apply the proposed method to compute the vectorial field inside the focal region of a high NA microscope objective lens and compare our result to the vectorial Debye integral method. We find that the Gaussian beam decomposition method overcomes serious limitations of algorithms relying on Fourier transforms, i.e. the field sampling requirements are less critical in high NA focusing and in the presence of large aberrations. However, sharp edges in the amplitude profile are difficult to handle as they should be replaced with smooth Gaussian edge.

  2. Correction of the spectral calibration of the Joint European Torus core light detecting and ranging Thomson scattering diagnostic using ray tracing

    Energy Technology Data Exchange (ETDEWEB)

    Hawke, J. [FOM Institute DIFFER – Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, 3430 BE Nieuwegein (Netherlands); Scannell, R.; Maslov, M. [EURATOM-CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Migozzi, J. B. [JBM Optique, 4 Rue du Calvaire Bâtiment 11, 92210 Saint Cloud (France); Collaboration: JET-EFDA Contributors

    2013-10-15

    This work isolated the cause of the observed discrepancy between the electron temperature (T{sub e}) measurements before and after the JET Core LIDAR Thomson Scattering (TS) diagnostic was upgraded. In the upgrade process, stray light filters positioned just before the detectors were removed from the system. Modelling showed that the shift imposed on the stray light filters transmission functions due to the variations in the incidence angles of the collected photons impacted plasma measurements. To correct for this identified source of error, correction factors were developed using ray tracing models for the calibration and operational states of the diagnostic. The application of these correction factors resulted in an increase in the observed T{sub e}, resulting in the partial if not complete removal of the observed discrepancy in the measured T{sub e} between the JET core LIDAR TS diagnostic, High Resolution Thomson Scattering, and the Electron Cyclotron Emission diagnostics.

  3. Determination of trace elements in honey from different regions in Rio de Janeiro State (Brazil) by total reflection X-ray fluorescence.

    Science.gov (United States)

    Ribeiro, Roberta de Oliveira Resende; Mársico, Eliane Teixeira; de Jesus, Edgar Francisco Oliveira; da Silva Carneiro, Carla; Júnior, Carlos Adam Conte; de Almeida, Eduardo; Filho, Virgílio Franco do Nascimento

    2014-04-01

    Trace and minor elements in Brazilian honey were analyzed by total reflection X-ray fluorescence spectroscopy. Up to 12 elements (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, and Sr) were detected in 160 samples of honey from 4 regions of Rio de Janeiro State (Barra Mansa, Teresópolis, northern and southern Nova Friburgo). The results showed the samples from Teresópolis had higher rates of essential and nonessential elements than samples from the other regions, except for Ni. K and Ca were the most abundant elements in all samples, in the range of 116.5 to 987.0 μg g(-1) . Ni, Cu, Zn, Se, and Sr were identified in small concentrations (0.01 to 12.08 μg g(-1) ) in all samples, indicating a low level of contamination in all the regions. © 2014 Institute of Food Technologists®

  4. A New Method for Simulating Power Flow Density Focused by a Silicon Lens Antenna Irradiated with Linearly Polarized THz Wave

    Directory of Open Access Journals (Sweden)

    Catur Apriono

    2015-08-01

    Full Text Available A terahertz system uses dielectric lens antennas for focusing and collimating beams of terahertz wave radiation. Linearly polarized terahertz wave radiation has been widely applied in the terahertz system. Therefore, an accurate method for analyzing the power flow density in the dielectric lens antenna irradiated with the linearly polarized terahertz wave radiation is important to design the terahertz systems. In optics, ray-tracing method has been used to calculate the power flow density by a number density of rays. In this study, we propose a method of ray-tracing combined with Fresnel’s transmission, including transmittance and polarization of the terahertz wave radiation to calculate power flow density in a Silicon lens antenna. We compare power flow density calculated by the proposed method with the regular ray-tracing method. When the Silicon lens antenna is irradiated with linearly polarized terahertz wave radiation, the proposed method calculates the power flow density more accurately than the regular ray-tracing.

  5. Localization of the Trace Elements Iron, Zinc and Selenium in Relation to Anatomical Structures in Bovine Ovaries by X-Ray Fluorescence Imaging.

    Science.gov (United States)

    Ceko, Melanie J; Hummitzsch, Katja; Bonner, Wendy M; Aitken, Jade B; Spiers, Kathryn M; Rodgers, Raymond J; Harris, Hugh H

    2015-06-01

    X-ray fluorescence (XRF) was used to image 40 histological cross-sections of bovine ovaries (n=19), focusing on structures including: antral follicles at different stages of growth or atresia, corpora lutea at three stages of development (II-IV), and capillaries, arterioles, and other blood vessels. This method identified three key trace elements [iron (Fe), zinc (Zn), and selenium (Se)] within the ovarian tissue which appeared to be localized to specific structures. Owing to minimal preprocessing of the ovaries, important high-resolution information regarding the spatial distribution of these elements was obtained with elemental trends and colocalizations of Fe and Zn apparent, as well as the infrequent appearance of Se surrounding the antrum of large follicles, as previously reported. The ability to use synchrotron radiation to measure trace element distributions in bovine ovaries at such high resolution and over such large areas could have a significant impact on understanding the mechanisms of ovarian development. This research is intended to form a baseline study of healthy ovaries which can later be extended to disease states, thereby improving our current understanding of infertility and endocrine diseases involving the ovary.

  6. Two-dimensional micro-beam imaging of trace elements in a single plankton measured by a synchrotron radiation X-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Ezoe, Masako; Sasaki, Miho; Hokura, Akiko; Nakai, Izumi; Terada, Yasuko; Yoshinaga, Tatsuki; Tukamoto, Katsumi; Hagiwara, Atsushi

    2002-01-01

    Two-dimensional imaging and a quantitative analysis of trace elements in rotifer, Brachionus plicatilis, belonging to zooplankton, were carried out by a synchrotron radiation X-ray fluorescence analysis (SR-XRF). The XRF imaging revealed that female rotifers accumulated Fe and Zn in the digestive organ and Fe, Zn, Cu, and Ca in the sexual organs, while the Mn level was high in the head. From a quantitative analysis by inductively coupled plasma mass spectrometry (ICP-MS), we found that rotifers eat the chlorella and accumulate the above elements in the body. The result of quantitative analyses of Mn, Cu, and Zn by SR-XRF in a single sample is in fair agreement with the average values determined by ICP-MS analyses, which were obtained by measuring a large number of rotifers, digested by nitric acid. The present study has demonstrated that SR-XRF is an effective tool for the trace element analysis of a single individual of rotifer. (author)

  7. X-ray fluorescence analysis of high purity rare earth oxides for common trace rare earth impurities

    International Nuclear Information System (INIS)

    Chandola, L.C.; Dixit, R.M.; Khanna, P.P.; Deshpande, S.S.; Machado, I.J.; Kapoor, S.K.

    1990-01-01

    Methods for the determination of individual trace common rare earth (RE) elements have been developed for fifteen RE oxide matrices viz. La 2 O 3 to Lu 2 O 3 and Y 2 O 3 . In general, for each matrix, two or three neighbouring elements on both sides of the matrix element are determined. The minimum determination limit (MDL) achieved is 0.002% for most of the elements. Special efforts were made to use a small amount of sample (as low as 400 mg) for the analysis by the use of double layer pellet technique and critical thickness studies. Practical experiences with 15 RE matrices, most of which are investigated for the first time, are discussed. Details of selection of instrumental parameters and analysis lines, precision and accuracy and preparation of samples and synthetic standards are given. Theoretical minimum detection limit (TMDL) for each analyte element is calculated in all the 15 matrices. (author). 50 tabs., 2 figs

  8. When combined X-ray and polarized neutron diffraction data challenge high-level calculations: spin-resolved electron density of an organic radical.

    Science.gov (United States)

    Voufack, Ariste Bolivard; Claiser, Nicolas; Lecomte, Claude; Pillet, Sébastien; Pontillon, Yves; Gillon, Béatrice; Yan, Zeyin; Gillet, Jean Michel; Marazzi, Marco; Genoni, Alessandro; Souhassou, Mohamed

    2017-08-01

    Joint refinement of X-ray and polarized neutron diffraction data has been carried out in order to determine charge and spin density distributions simultaneously in the nitronyl nitroxide (NN) free radical Nit(SMe)Ph. For comparison purposes, density functional theory (DFT) and complete active-space self-consistent field (CASSCF) theoretical calculations were also performed. Experimentally derived charge and spin densities show significant differences between the two NO groups of the NN function that are not observed from DFT theoretical calculations. On the contrary, CASSCF calculations exhibit the same fine details as observed in spin-resolved joint refinement and a clear asymmetry between the two NO groups.

  9. Trace element analysis of mineral and tap water samples using total reflection x-ray fluorescence (TXRF)

    International Nuclear Information System (INIS)

    Mangala, M.J.; Korir, K.A.; Maina, D.M.; Kinyua, A.M.

    2000-01-01

    Results of trace element analysis by TXRF of tap water and various brands of bottled mineral water samples which are representative of local and imported brands sold in Nairobi are reported. The variation in elemental concentrations in water samples analyzed were as follows: potassium (K) 0.2 to 28.9 μg/ml; calcium (Ca) 2.2 to 120 μg/ml; titanium (Ti) 11 to 60 μg/l; manganese (Mn) 8 to 670 μg/l; iron (Fe) 31 to 540 μg/l; copper (Cu) 8 to 30 μg/l; zinc (Zn) 8 to 4730 μg/l; bromine (Br) 9 to 248 μg/l; rubidium (Rb) 10 to 40 μg/l and strontium (Sr) 10 to 1000 μg/l. Local mineral water samples contain higher levels of trace elements; manganese (Mn), zinc (Zn), bromine (Br), rubidium (Rb) and strontium (Sr) as compared to the imported brands. Principal component analysis of the results revealed three component loading factors clusters for: rubidium (Rb), strontium (Sr) and calcium (Ca); titanium (Ti), iron (Fe), bromine (Br), and zinc (Zn); zinc (Zn), manganese (Mn) and potassium (K) respectively. The percentage of total variance explained by the components was 31.4, 27.3, and 14.8 respectively. In this study, we also found that a limited spread of 5-6 mm for a 10 μl sample was achieved when the quartz sample carrier was dried in a low pressure (300 mbar) oven at 70 o C for 10 hours. (author)

  10. Trace element analysis in geochemistry using a nuclear microprobe. Ionoluminescence and particle induced X-ray emission

    International Nuclear Information System (INIS)

    Homman, P.

    1994-01-01

    In PIXE analysis of geological specimens based on X-ray detection with Si(Li) detectors, effects of detector tailing, pulse pileup, and gamma-ray production are pronounced. In this work the tailing effect has been addressed through characterization of the response function of a Si(Li) detector using an absorber technique. The pileup interval, in the pulse forming electronics of a PIXE detection system, has been improved to 100 ns X-ray energies above 8 keV by means of pulse shape analysis. Pulses due to tailing effects were also isolated but no major improvement was obtained. A means of reducing the increased background in the PIXE spectrum due to Compton scattering of high energetic gamma-rays in the Si(Li) crystal has been investigated by installation of an anti-Compton shield consisting of an organic scintillator mounted inside the detector cryostat and read out by a photomultiplier. Ionoluminescence, a new analytical technique for the nuclear microprobe, has shown to be a technique that can be employed as a fast diagnostic tool in imaging applications. The technique is based on analysis of the light that often can be observed when an ion beam impinges on a geological specimen. This light, luminescence, can often be associated with impurities in the crystal lattice or other structural defects. It can therefore be employed for revealing some chemical information about the specimens in contradiction to PIXE which is rather insensitive to chemical variations. The potential of the method is demonstrated and discussed both as an imaging tool and for spectroscopic studies. 19 refs, 10 figs

  11. Ultrashort x-ray pulse generation by nonlinear Thomson scattering of a relativistic electron with an intense circularly polarized laser pulse

    Directory of Open Access Journals (Sweden)

    F. Liu

    2012-07-01

    Full Text Available The nonlinear Thomson scattering of a relativistic electron with an intense laser pulse is calculated numerically. The results show that an ultrashort x-ray pulse can be generated by an electron with an initial energy of 5 MeV propagating across a circularly polarized laser pulse with a duration of 8 femtosecond and an intensity of about 1.1×10^{21}  W/cm^{2}, when the detection direction is perpendicular to the propagation directions of both the electron and the laser beam. The optimal values of the carrier-envelop phase and the intensity of the laser pulse for the generation of a single ultrashort x-ray pulse are obtained and verified by our calculations of the radiation characteristics.

  12. Direct rapid analysis of trace bioavailable soil macronutrients by chemometrics-assisted energy dispersive X-ray fluorescence and scattering spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Kaniu, M.I., E-mail: ikaniu@uonbi.ac.ke [Institute of Nuclear Science and Technology, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya); Angeyo, K.H. [Department of Physics, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya); Mwala, A.K. [Department of Land Resource Management and Agricultural Technology, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya); Mangala, M.J. [Institute of Nuclear Science and Technology, University of Nairobi, P.O. Box 30197-00100 Nairobi (Kenya)

    2012-06-04

    Highlights: Black-Right-Pointing-Pointer Chemometrics-assisted EDXRFS spectroscopy realizes direct, rapid and accurate analysis of trace bioavailable macronutrients in soils. Black-Right-Pointing-Pointer The method is minimally invasive, involves little sample preparation, short analysis times and is relatively insensitive to matrix effects. Black-Right-Pointing-Pointer This opens up the ability to rapidly characterize large number of samples/matrices with this method. - Abstract: Precision agriculture depends on the knowledge and management of soil quality (SQ), which calls for affordable, simple and rapid but accurate analysis of bioavailable soil nutrients. Conventional SQ analysis methods are tedious and expensive. We demonstrate the utility of a new chemometrics-assisted energy dispersive X-ray fluorescence and scattering (EDXRFS) spectroscopy method we have developed for direct rapid analysis of trace 'bioavailable' macronutrients (i.e. C, N, Na, Mg, P) in soils. The method exploits, in addition to X-ray fluorescence, the scatter peaks detected from soil pellets to develop a model for SQ analysis. Spectra were acquired from soil samples held in a Teflon holder analyzed using {sup 109}Cd isotope source EDXRF spectrometer for 200 s. Chemometric techniques namely principal component analysis (PCA), partial least squares (PLS) and artificial neural networks (ANNs) were utilized for pattern recognition based on fluorescence and Compton scatter peaks regions, and to develop multivariate quantitative calibration models based on Compton scatter peak respectively. SQ analyses were realized with high CMD (R{sup 2} > 0.9) and low SEP (0.01% for N and Na, 0.05% for C, 0.08% for Mg and 1.98 {mu}g g{sup -1} for P). Comparison of predicted macronutrients with reference standards using a one-way ANOVA test showed no statistical difference at 95% confidence level. To the best of the authors' knowledge, this is the first time that an XRF method has demonstrated

  13. Radioisotope x-ray fluorescence and neutron activation analyses of the trace element concentrations of the rainbow trout

    International Nuclear Information System (INIS)

    Akyuz, T.; Bassari, A.; Bolcal, C.; Sener, E.; Yildiz, M.; Kucer, R.; Kaplan, Z.; Dogan, G.; Akyuz, S.

    1999-01-01

    The muscles and livers of the ten rainbow trouts (Oncorhynchus mykiss; N, 1752) obtained from Sapanca, Aquaculture Facility of Aquatic Products Faculty, The University of Istanbul (Turkey), have been analysed quantitatively for some minor elements using the radioisotope energy dispersive X-ray fluorescence (EDXRF) and neutron activation analysis (NAA) methods. It was found that samples contain Na, K, Ca, Sc, Cs, Fe, Co, Cu, Zn, Se, Br, Rb, Sr, Au, La and Ce in different amounts. Comparison of the results with those of reference river fish samples indicated that agricultural rainbow trout samples from Sapanca region have higher Fe level. (author)

  14. Radioisotope X-ray fluorescence and neutron activation analyses of the trace element concentrations of the rainbow trout

    Science.gov (United States)

    Akyuz, T.; Bassari, A.; Bolcal, C.; Sener, E.; Yildiz, M.; Kucer, R.; Kaplan, Z.; Dogan, G.; Akyuz, S.

    1999-01-01

    The muscles and livers of the ten rainbow trouts ( Oncorhynchus mykiss; N, 1752) obtained from Sapanca, Aquaculture Facility of Aquatic Products Faculty, The University of Istanbul (Turkey), have been analysed quantitatively for some minor elements using the radioisotope energy dispersive X-ray fluorescence (EDXRF) and neutron activation analysis (NAA) methods. It was found that samples contain Na, K, Ca, Sc, Cs, Fe, Co, Cu, Zn, Se, Br, Rb, Sr, Au, La and Ce in different amounts. Comparison of the results with those of reference river fish samples indicated that agricultural rainbow trout samples from Sapanca region have higher Fe level.

  15. Radiation heat transfer model using Monte Carlo ray tracing method on hierarchical ortho-Cartesian meshes and non-uniform rational basis spline surfaces for description of boundaries

    Directory of Open Access Journals (Sweden)

    Kuczyński Paweł

    2014-06-01

    Full Text Available The paper deals with a solution of radiation heat transfer problems in enclosures filled with nonparticipating medium using ray tracing on hierarchical ortho-Cartesian meshes. The idea behind the approach is that radiative heat transfer problems can be solved on much coarser grids than their counterparts from computational fluid dynamics (CFD. The resulting code is designed as an add-on to OpenFOAM, an open-source CFD program. Ortho-Cartesian mesh involving boundary elements is created based upon CFD mesh. Parametric non-uniform rational basis spline (NURBS surfaces are used to define boundaries of the enclosure, allowing for dealing with domains of complex shapes. Algorithm for determining random, uniformly distributed locations of rays leaving NURBS surfaces is described. The paper presents results of test cases assuming gray diffusive walls. In the current version of the model the radiation is not absorbed within gases. However, the ultimate aim of the work is to upgrade the functionality of the model, to problems in absorbing, emitting and scattering medium projecting iteratively the results of radiative analysis on CFD mesh and CFD solution on radiative mesh.

  16. Interpretation of polarized Cu K x-ray absorption near-edge-structure spectra of CuO

    Czech Academy of Sciences Publication Activity Database

    Šipr, Ondřej; Šimůnek, Antonín

    2001-01-01

    Roč. 13, - (2001), s. 8519-8525 ISSN 0953-8984 Institutional research plan: CEZ:AV0Z1010914 Keywords : polarized Cu K-edge spectra * CuO * band-structure calculations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.611, year: 2001

  17. Worldwide Open Proficiency Test for X ray Fluorescence Laboratories PTXRFIAEA08: Determination of Minor and Trace Elements in Natural Soil

    International Nuclear Information System (INIS)

    2014-01-01

    The IAEA assists Member State laboratories to maintain their readiness by producing reference materials, developing standardized analytical methods, and conducting interlaboratory comparisons and proficiency tests as tools for quality control. To ensure a reliable, worldwide, rapid and consistent response, the IAEA Nuclear Spectrometry and Applications Laboratory organizes tests for Member State laboratories. This publication presents the results of the worldwide proficiency test PTXRFIAEA08 on the determination of minor and trace elements in natural soil. Methodologies, a data evaluation approach, a summary evaluation of each element and individual evaluation reports for each laboratory are also described. The test was carried out within the IAEA project Nuclear Spectrometry for Analytical Applications, under the Nuclear Science Programme. The main objective of the project was to enhance the capability of interested Member States in effective utilization of nuclear spectrometries and analytical services in industry, human health and agriculture, and in monitoring and evaluating environmental pollution. This proficiency test was designed to identify analytical problems and to support Member State laboratories in improving the quality of their analytical results, maintaining their accreditation and providing a regular forum for discussion and technology transfer in this area. The type of sample and the concentration levels of the analytes were designed to enable the identification of potential analytical problems

  18. Monte-Carlo RAY tracing simulation of a falling particle receiver in connection with a central receiver field

    Energy Technology Data Exchange (ETDEWEB)

    Alxneit, I. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The program RAY was developed to perform Monte-Carlo simulations of the flux distribution in solar reactors in connection with an arbitrary heliostat field. The code accounts for the shading of the incoming rays from the sun due to the reactor supporting tower as well as for full blocking and shading of the heliostats among themselves. A simplified falling particle reactor (FPR) was evaluated. A central receiver field was used with a total area of 311 m{sup 2} composed of 176 round, focusing heliostats. No attempt was undertaken to optimise either the geometry of the heliostat field nor the aiming strategy of the heliostats. The FPR was evaluated at two different geographic latitudes (-8.23W/47.542N; PSI and -8.23W/20.0N) and during the course of a day (May 30{sup th}). The incident power passing through the reactor aperture and the flux density distribution within the FPR was calculated. (author) 3 figs., 1 tab., 3 refs.

  19. Polarized X-ray absorption spectroscopy of single-crystal Mn(V) complexes relevant to the oxygen-evolving complex of photosystem II

    DEFF Research Database (Denmark)

    Yano, Junko; Robblee, John; Pushkar, Yulia

    2007-01-01

    High-valent Mn-oxo species have been suggested to have a catalytically important role in the water splitting reaction which occurs in the Photosystem II membrane protein. In this study, five- and six-coordinate mononuclear Mn(V) compounds were investigated by polarized X-ray absorption spectroscopy...... structure of the metal site was then studied by measuring the polarization dependence of X-ray absorption near-edge spectroscopy (XANES) pre-edge spectra (1s to 3d transition) and comparing with the results of density functional theory (DFT) calculations. The Mn(V)-nitrido compound, in which the manganese......-edge peak. This component was interpreted as a 1s to 3d(xz,yz) transition with 4px,y mixing, due to the displacement of the Mn atom out of the equatorial plane. The XANES results have been correlated to DFT calculations, and the spectra have been simulated using a TD (time-dependent)-DFT approach...

  20. X-Ray and Optical Study of the Gamma-ray Source 3FGL J0838.8–2829: Identification of a Candidate Millisecond Pulsar Binary and an Asynchronous Polar

    Energy Technology Data Exchange (ETDEWEB)

    Halpern, Jules P.; Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027-6601 (United States); Thorstensen, John R., E-mail: jules@astro.columbia.edu [Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755-3528 (United States)

    2017-04-01

    We observed the field of the Fermi source 3FGL J0838.8−2829 in optical and X-rays, initially motivated by the cataclysmic variable (CV) 1RXS J083842.1−282723 that lies within its error circle. Several X-ray sources first classified as CVs have turned out to be γ -ray emitting millisecond pulsars (MSPs). We find that 1RXS J083842.1−282723 is in fact an unusual CV, a stream-fed asynchronous polar in which accretion switches between magnetic poles (that are ≈120° apart) when the accretion rate is at minimum. High-amplitude X-ray modulation at periods of 94.8 ± 0.4 minutes and 14.7 ± 1.2 hr are seen. The former appears to be the spin period, while the latter is inferred to be one-third of the beat period between the spin and the orbit, implying an orbital period of 98.3 ± 0.5 minutes. We also measure an optical emission-line spectroscopic period of 98.413 ± 0.004 minutes, which is consistent with the orbital period inferred from the X-rays. In any case, this system is unlikely to be the γ -ray source. Instead, we find a fainter variable X-ray and optical source, XMMU J083850.38−282756.8, that is modulated on a timescale of hours in addition to exhibiting occasional sharp flares. It resembles the black widow or redback pulsars that have been discovered as counterparts of Fermi sources, with the optical modulation due to heating of the photosphere of a low-mass companion star by, in this case, an as-yet undetected MSP. We propose XMMU J083850.38−282756.8 as the MSP counterpart of 3FGL J0838.8−2829.

  1. Trace elemental analysis of school chalk using energy dispersive X-ray florescence spectroscopy (ED-XRF)

    Science.gov (United States)

    Maruthi, Y. A.; Das, N. Lakshmana; Ramprasad, S.; Ram, S. S.; Sudarshan, M.

    2015-08-01

    The present studies focus the quantitative analysis of elements in school chalk to ensure the safety of its use. The elements like Calcium (Ca), Aluminum (Al), Iron (Fe), Silicon (Si) and Chromium (Cr) were analyzed from settled chalk dust samples collected from five classrooms (CD-1) and also from another set of unused chalk samples collected from local market (CD-2) using Energy Dispersive X-Ray florescence(ED-XRF) spectroscopy. Presence of these elements in significant concentrations in school chalk confirmed that, it is an irritant and occupational hazard. It is suggested to use protective equipments like filtered mask for mouth, nose and chalk holders. This study also suggested using the advanced mode of techniques like Digital boards, marker boards and power point presentations to mitigate the occupational hazard for classroom chalk

  2. The simulation of three-dimensional ray tracing and parameters optimization in DPL lens duct coupling system

    Science.gov (United States)

    Fan, Shuwei; Zhang, Yan; Shen, Yuting

    2010-06-01

    DPL coupling system was researched in this paper. First, the mathematic model of 3D and 2D light transmission in hollow duct was analyzed and compared. Then the 3D simulation software for all rays of the coupling system -lens duct was developed. The influence of various structural parameters of the hollow lens duct to the energy and the beam distribution were discussed with the help of developed software. The structural parameters such as the duct length, the lens radius, the size of the input and output ends were researched and were optimized to get higher efficiency and better beam distribution. Finally, the energy conversion efficiency and the beam spatial distribution of before and after optimization were compared. The results showed that the efficiency and the distribution of energy were well improved after the optimization.

  3. Trace Elemental Determination Using a Portable Total Reflection X-Ray Fluorescence Spectrometer with a Collodion Film Sample Holder.

    Science.gov (United States)

    Kunimura, Shinsuke; Shinkai, Tomoki

    2017-01-01

    Using a portable total-reflection X-ray fluorescence (TXRF) spectrometer with a collodion film sample holder, a spectrum of an analyte containing 50 ng of aluminum was measured. The Al Kα line (1.49 keV) that partially overlaps with the Si Kα line (1.74 keV) from a quartz glass substrate usually used as a sample holder for TXRF analysis, was clearly detected when using the collodion film sample holder. To investigate the quantitative performance of the portable spectrometer with a collodion film sample holder, the concentrations of Cr, Mn, and Fe in a certified reference material of river water (JSAC 0302-3b), whose certified values are 10.0, 5.1, and 59.6 μg/L, respectively, were determined by the internal-standard method. We showed that approximate concentrations of these elements were determined.

  4. Quantitative analysis of trace palladium contamination in solution using electrochemical X-ray fluorescence (EC-XRF).

    Science.gov (United States)

    Ayres, Zoë J; Newton, Mark E; Macpherson, Julie V

    2016-06-07

    The application of electrochemical X-ray fluorescence (EC-XRF), for the detection of palladium (Pd) contamination in a range of solutions containing electrochemically active compounds, present in excess and relevant to the pharmaceutical and food industries, is reported. In EC-XRF, EC is used to electrochemically pre-concentrate metal on an electrode under forced convection conditions, whilst XRF is employed to spectroscopically quantify the amount of metal deposited, which quantitatively correlates with the original metal concentration in solution. Boron doped diamond is used as the electrode due to its very wide cathodic window and the fact that B and C are non-interfering elements for XRF analysis. The effect of several parameters on the Pd XRF signal intensity are explored including: deposition potential (Edep), deposition time (tdep) and Pd(2+) concentration, [Pd(2+)]. Under high deposition potentials (Edep = -1.5 V), the Pd XRF peak intensity varies linearly with both tdep and [Pd(2+)]. Quantification of [Pd(2+)] is demonstrated in the presence of excess acetaminophen (ACM), l-ascorbic acid, caffeine and riboflavin. We show the same Pd XRF signal intensity (for [Pd(2+)] = 1.1 μM and tdep = 325 s) is observed, i.e. same amount of Pd is deposited on the electrode surface, irrespective of whether these redox active molecules are present or absent. For tdep = 900 s we report a limit of detection for [Pd(2+)] of 3.6 ppb (34 nM). Even lower LODs are possible by increasing tdep or by optimising the X-ray source specifically for Pd. The work presented for Pd detection in the presence of ACM, achieves the required detection sensitivity stipulated by international pharmacopeia guidelines.

  5. Using portable X-ray fluorescence spectrometry and GIS to assess environmental risk and identify sources of trace metals in soils of peri-urban areas in the Yangtze Delta region, China.

    Science.gov (United States)

    Ran, Jing; Wang, Dejian; Wang, Can; Zhang, Gang; Yao, Lipeng

    2014-08-01

    Portable X-ray fluorescence (PXRF) spectrometry may be very suitable for a fast and effective environmental assessment and source identification of trace metals in soils. In this study, topsoils (0-10 cm) at 139 sites were in situ scanned for total trace metals (Cr, Cu, Ni, Pb and Zn) and arsenic concentrations by PXRF in a typical town in Yangtze Delta region of Jiangsu province, China. To validate the utility of PXRF, 53 samples were collected from the scanning sites for the determination of selected trace metals using conventional methods. Based on trace metal concentrations detected by in situ PXRF, the contamination extent and sources of trace metals were studied via geo-accumulation index, multivariate analysis and geostatistics. The trace metal concentrations determined by PXRF were similar to those obtained via conventional chemical analysis. The median concentration of As, Cr, Cu, Ni, Pb and Zn in soils were 10.8, 56.4, 41.5, 43.5, 33.5, and 77.7 mg kg(-1), respectively. The distribution patterns of Cr, Cu, Ni, Pb, and Zn were mostly affected by anthropogenic sources, while As was mainly derived from lithogenic sources. Overall, PXRF has been successfully applied to contamination assessment and source identification of trace metals in soils.

  6. Determination of trace elements in calcium rich carbonate rocks by Wavelength Dispersive X-ray Fluorescence Spectrometry for environmental and geological studies.

    Science.gov (United States)

    Cherkashina, T Yu; Shtel'makh, S I; Pashkova, G V

    2017-12-01

    A simple, rapid and non destructive Wavelength Dispersive X-ray Fluorescence Spectrometry (WDXRFS) was developed for the determination of trace elements such as V, Cr, Co, Ni, Cu, Zn, Pb, Ba, La, Ce, Nd, Rb, Sr, Y, Zr, and Nb in carbonate rocks with high calcium content. Samples of marble, limestone, fluorite ore and carbonatite-like rocks were chosen as objects under investigation. These samples have wide ranges of major and trace element contents, and high concentration of calcite (70-98%) in calcium rich carbonates. The sample mass required for infinite thickness was calculated for each element. In order to determine V, Cr, Co, Ni, Cu, Zn, Ba, La, Nd, Ce, sample weighting 1g was pressed with a pressure of 100kN. For the determination of Rb, Sr, Y, Zr, Nb, Pb, the sample mass was increased up to 5g. The calibration curves were constructed by employing the International Certified reference materials (ICRMs) and in-house standard reference materials (HSRMs) of various types of rocks and sediments, and the matrix effects were taken into account using the influence coefficients (α-correction equations). Analytical figures of merit have also been assessed. The calculated values of the instrumental limit of the detection were within the interval from 0.5 to 4.0mgkg -1 . The repeatability and reproducibility were found to be satisfactory with the relative standard deviations lower than 5%. The accuracy was evaluated by the analysis of two reference materials and the comparison with the ICP-MS results. A good agreement was achieved between the reference and measured values with recoveries ranging from 85% to 115%. The relative disagreements between the XRF and ICP-MS results were less than 10%. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Worldwide proficiency test for X ray fluorescence laboratories PTXRFIAEA/05 determination of minor and trace elements in marine sediment

    International Nuclear Information System (INIS)

    2009-01-01

    The proficiency test (code PTXRFIAEA05) was the fifth worldwide exercise organized by the IAEA Seibersdorf Laboratories in order to assist X ray fluorescence laboratories in assessment and improvement of their analytical performance. The test was carried out within the IAEA Project 1.4.3.4 (D.3.03) on Nuclear Spectrometry for Analytical Applications, under the Nuclear Science Programme. The main objective of the project was to enhance capability of interested Member States in effective utilization of nuclear spectrometries and analytical services in industry, human health, agriculture, and in monitoring and evaluation of environmental pollution. Marine sediment test samples with established homogeneity and well characterized known target values of the mass fractions of analytes were distributed to participating laboratories. The laboratories were requested to analyze the sample using established techniques following their analytical procedures. Based on the results of the proficiency test presented in the report each participating laboratory should assess its analytical performance results by using the specified criteria and, if appropriate, to identify discrepancies, and to correct relevant analytical procedures. The next proficiency test exercise will be executed in 2009

  8. The trace element analysis of ancient Indian coins using proton induced x-ray emission (PIXE) technique

    International Nuclear Information System (INIS)

    PURI, N.K.; HAJIVALIEI, M.; BEDI, S.C.; SINGH, N.; GOVIL, I.M.; GARG, M.L.; HANDA, D.K.; GOVIL, K.L.; ROUT, B.; VIJAYAN, V.

    2004-01-01

    Elemental analysis of ancient Indian coins viz. thirty-three punched marked coins (6 th century B.C.), fifty-nine coins belonging to Kusanas (78-250 A.D) and twenty-five coins belonging to medieval period (11 th -14 th century A.D), from India have been analysed using Proton Induced X-ray Emission (PIXE) technique. The elements namely S, Ca, Fe, Ag, Cu, Ni and Pb were detected in most of the punch-marked coins while elements namely S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, As and Zn were detected in most of the Kusanas coins and the S, Ca, Fe, Cu, Ag, Sn, Pb were detected in 11 th -14 th century A.D. coins. Based on the elemental analysis different hypotheses put forward in the earlier literature were examined. This is the first attempt where reasonable number of ancient coins belonging to different periods were analysed by modern non destructive multi-elemental technique such as PIXE and has put the importance of the elemental analysis of ancient Indian coins in the proper perspective

  9. Trace elemental analysis of commercial bottled drinking water by a portable total reflection X-ray fluorescence spectrometer.

    Science.gov (United States)

    Kunimura, Shinsuke; Kawai, Jun

    2007-10-01

    A portable total reflection X-ray fluorescence spectrometer was applied to commercial bottled drinking water containing 62 ppb (microg/L) V, 7.5 ppm (mg/L) Ca, and 1 ppm K. A dry residue, prepared by repeated pipetting and drying a 20 microL portion of drinking water on a sample holder six times, and another dry residue, prepared by pipetting and drying a 120 microL portion of the drinking water, were measured. The size of the dry residue of the drinking water was reduced by repeating the pipetting and drying. Calcium and potassium were easily detected in these two dry residues. Vanadium was detected in the dry residue prepared by repeated pipetting and drying. Vanadium, calcium, and potassium were quantified by using an internal standard, and the average quantified concentrations of V, Ca, and K were 91 ppb, 8.2 ppm, and 1.5 ppm, respectively. Although these quantified concentrations deviated from the certified concentrations (62 ppb of V, 7.5 ppm of Ca, and 1 ppm of K), it was possible for this portable spectrometer to estimate approximate concentrations.

  10. Influence of spatial curvature of a liquid jet on the rainbow positions: Ray tracing and experimental study

    Science.gov (United States)

    Duan, Qingwei; Zhong, Ruliang; Han, Xiang'e.; Ren, Kuan Fang

    2017-07-01

    Rainbow refractometry is largely used in optical metrology of particles thanks to its advantages of being non-intrusive, precise and fast. Many authors have contributed to its development and the application in the characterization of liquid jets/droplets. The researches reported in the literature are mainly for the spherical droplets or the liquid jets which can be considered as a cylinder of constant section. However, the section of a real liquid jet, even in the simplest configuration, varies with distance from the exit. The influence of the spatial curvature of the jets must, therefore, be taken into account. In this paper, we report experimental measurements of the shifts of the rainbow positions in the horizontal and vertical directions of a liquid jet and the theoretical investigation with the vectorial complex ray model. It is shown that the shifts of rainbow positions are very sensitive to the spatial curvature of the jets. This work is hoped to provide a new approach to characterizing the structure and the instability of liquid jets.

  11. Use of neutron and synchrotron X-ray diffraction for evaluation of residual stresses in a 2024-T351 aluminum alloy variable-polarity plasma-arc weld

    Science.gov (United States)

    Ganguly, S.; Fitzpatrick, M. E.; Edwards, L.

    2006-02-01

    The residual stress fields associated with variable-polarity plasma-arc (VPPA) welds in 2024-T351 aluminum alloy plates have been measured nondestructively using neutron and synchrotron X-ray diffraction. Neutron diffraction allows in-depth measurements of the full strain tensor to be made in thick components; synchrotron X-rays allow for rapid measurements of strains inside components, although their penetration is less than that of the neutrons and constraints arising from the diffraction geometry generally lead to only two strain components being easily measurable. Hence, a combination of the two techniques, applied as described herein, is ideal for a detailed nondestructive evaluation of residual stresses in plates. The residual stresses in a 12-mm-thick VPPA-welded aluminum 2024-T351 alloy plate have been measured using neutron diffraction. The stresses were then remeasured by a combination of neutron and synchrotron X-ray diffraction after the plate had been reduced in thickness (or, skimmed) to 7 mm by machining both sides of the weld, mimicking the likely manufacturing operation, should such welds be used in aerospace structures. A strong tensile residual stress field was measured in the longitudinal direction, parallel to the weld, in both the as-welded and skimmed specimens. There was only a slight modification of the residual stress state on skimming.

  12. Determination of trace elements in freshwater rotifers and ciliates by total reflection X-ray fluorescence spectrometry

    Science.gov (United States)

    Woelfl, S.; Óvári, M.; Nimptsch, J.; Neu, T. R.; Mages, M.

    2016-02-01

    Element determination in plankton is important for the assessment of metal contamination of aquatic environments. Until recently, it has been difficult to determine elemental content in rotifers or ciliates derived from natural plankton samples because of the difficulty in handling and separation of these fragile organisms. The aim of this study was to evaluate methods for separation of rotifers and large ciliates from natural plankton samples (μg range dry weight) and subsequent analysis of their elemental content using total-reflection X-ray fluorescence spectrometry (TXRF). Plankton samples were collected from different aquatic environments (three lakes, one river) in Chile, Argentina and Hungary. From one to eighty specimens of five rotifer species (Brachionus calyciflorus, Brachionus falcatus, Asplanchna sieboldii, Asplanchna sp., Philodina sp.) and four to twelve specimens of one large ciliate (Stentor amethystinus) were prepared according to the dry method originally developed for microcrustaceans, and analysed by TRXF following in situ microdigestion. Our results demonstrated that it possible to process these small and fragile organisms (individual dry mass: 0.17-9.39 μg ind- 1) via careful washing and preparation procedures. We found species-dependent differences of the element mass fractions for some of the elements studied (Cr, Mn, Fe, Ni, Cu, Zn, As, Pb), especially for Cu, Fe and Mn. One large rotifer species (A. sieboldii) also showed a negative correlation between individual dry weight and the element content for Pb, Ni and Cr. We conclude that our application of the in situ microdigestion-TRXF method is suitable even for rotifers and ciliates, greatly expanding the possibilities for use of plankton in biomonitoring of metal contamination in aquatic environments.

  13. Tracing the accretion history of supermassive black holes through X-ray variability: results from the ChandraDeep Field-South

    Science.gov (United States)

    Paolillo, M.; Papadakis, I.; Brandt, W. N.; Luo, B.; Xue, Y. Q.; Tozzi, P.; Shemmer, O.; Allevato, V.; Bauer, F. E.; Comastri, A.; Gilli, R.; Koekemoer, A. M.; Liu, T.; Vignali, C.; Vito, F.; Yang, G.; Wang, J. X.; Zheng, X. C.

    2017-11-01

    We study the X-ray variability properties of distant active galactic nuclei (AGNs) in the ChandraDeep Field-South region over 17 yr, up to z ˜ 4, and compare them with those predicted by models based on local samples. We use the results of Monte Carlo simulations to account for the biases introduced by the discontinuous sampling and the low-count regime. We confirm that variability is a ubiquitous property of AGNs, with no clear dependence on the density of the environment. The variability properties of high-z AGNs, over different temporal time-scales, are most consistent with a power spectral density (PSD) described by a broken (or bending) power law, similar to nearby AGNs. We confirm the presence of an anticorrelation between luminosity and variability, resulting from the dependence of variability on black hole (BH) mass and accretion rate. We explore different models, finding that our acceptable solutions predict that BH mass influences the value of the PSD break frequency, while the Eddington ratio λEdd affects the PSD break frequency and, possibly, the PSD amplitude as well. We derive the evolution of the average λEdd as a function of redshift, finding results in agreement with measurements based on different estimators. The large statistical uncertainties make our results consistent with a constant Eddington ratio, although one of our models suggest a possible increase of λEdd with lookback time up to z ˜ 2-3. We conclude that variability is a viable mean to trace the accretion history of supermassive BHs, whose usefulness will increase with future, wide-field/large effective area X-ray missions.

  14. Analysis of nutrition-relevant trace elements in human blood and serum by means of total reflection X-ray fluorescence (TXRF) spectroscopy

    International Nuclear Information System (INIS)

    Stosnach, Hagen; Mages, Margarete

    2009-01-01

    In clinical service laboratories, one of the most common analytical tasks with regard to inorganic traces is the determination of the nutrition-relevant elements Fe, Cu, Zn, and Se. Because of the high numbers of samples and the commercial character of these analyses, a time-consuming sample preparation must be avoided. In this presentation, the results of total reflection X-ray fluorescence measurements with a low-power system and different sample preparation procedures are compared with those derived from analysis with common methods like Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The results of these investigations indicate that the optimal total reflection X-ray fluorescence analysis of the nutrition-relevant elements Fe, Cu, Zn, and Se can be performed by preparing whole blood and serum samples after dilution with ultrapure water and transferring 10 μl of internally standardized sample to an unsiliconized quartz glass sample carrier with subsequent drying in a laboratory oven. Suitable measurement time was found to be 600 s. The enhanced sample preparation by means of microwave or open digestion, in parts combined with cold plasma ashing, led to an improvement of detection limits by a factor of 2 for serum samples while for whole blood samples an improvement was only observed for samples prepared by means of microwave digestion. As the matrix elements P, S, Cl, and for whole blood Fe have a major influence on the detection limits, most probably a further enhancement of analytical quality requires the removal of the organic matrix. However, for the routine analysis of the nutrition-relevant elements, the dilution preparation was found to be sufficient.

  15. Rapid determination of trace phosphorus, sulfur, chlorine, bromine and iodine by energy dispersive X-ray fluorescence analysis with monochromatic excitations

    International Nuclear Information System (INIS)

    Wakisaka, Tatsushi; Morita, Naoki; Hirabayashi, Tadashi; Nakahara, Taketoshi

    1998-01-01

    A useful and rapid procedure is described for the determination of trace phosphorus, sulfur, chlorine, bromine, and iodine by means of an energy dispersive X-ray fluorescence spectrometer (EDXRF) with monochromatic excitations. Using monochromatic excitations, the detection limits for phosphorus, sulfur, chlorine (Cr-Kα, 5.41 keV), bromine (Mo-Kα, 17.44 keV), and iodine (W-continuum, 40 keV) were found to be 4.6, 1.7, 0.7, 0.09 and 0.5 μg g -1 , respectively. The relative standard deviations in five replicate measurements were 0.9-1.3%. The proposed method was applied to the direct determination of sulfur in the NIST Residual Fuel Oil, and others. The results obtained by the proposed method were in good agreement with the certified values. Bromine in a seawater sample, as well as iodine and bromine in a brine sample were determined by the proposed method. The obtained results were in good agreement with those obtained by ion chromatography. (author)

  16. General relativistic ray-tracing algorithm for the determination of the electron-positron energy deposition rate from neutrino pair annihilation around rotating neutron and quark stars

    Science.gov (United States)

    Kovács, Z.; Harko, T.

    2011-11-01

    We present a full general relativistic numerical code for estimating the energy-momentum deposition rate (EMDR) from neutrino pair annihilation (?). The source of the neutrinos is assumed to be a neutrino-cooled accretion disc around neutron and quark stars. We calculate the neutrino trajectories by using a ray-tracing algorithm with the general relativistic Hamilton's equations for neutrinos and derive the spatial distribution of the EMDR due to the annihilations of neutrinos and antineutrinos around rotating neutron and quark stars. We obtain the EMDR for several classes of rotating neutron stars, described by different equations of state of the neutron matter, and for quark stars, described by the Massachusetts Institute of Technology (MIT) bag model equation of state and in the colour-flavour-locked (CFL) phase. The distribution of the total annihilation rate of the neutrino-antineutrino pairs around rotating neutron and quark stars is studied for isothermal discs and accretion discs in thermodynamical equilibrium. We demonstrate both the differences in the equations of state for neutron and quark matter and rotation with the general relativistic effects significantly modify the EMDR of the electrons and positrons generated by the neutrino-antineutrino pair annihilation around compact stellar objects, as measured at infinity.

  17. Combined NanoSIMS and synchrotron X-ray fluorescence reveal distinct cellular and subcellular distribution patterns of trace elements in rice tissues.

    Science.gov (United States)

    Moore, Katie L; Chen, Yi; van de Meene, Allison M L; Hughes, Louise; Liu, Wenju; Geraki, Tina; Mosselmans, Fred; McGrath, Steve P; Grovenor, Chris; Zhao, Fang-Jie

    2014-01-01

    The cellular and subcellular distributions of trace elements can provide important clues to understanding how the elements are transported and stored in plant cells, but mapping their distributions is a challenging task. The distributions of arsenic, iron, zinc, manganese and copper, as well as physiologically related macro-elements, were mapped in the node, internode and leaf sheath of rice (Oryza sativa) using synchrotron X-ray fluorescence (S-XRF) and high-resolution secondary ion mass spectrometry (NanoSIMS). Although copper and silicon generally showed cell wall localization, arsenic, iron and zinc were strongly localized in the vacuoles of specific cell types. Arsenic was highly localized in the companion cell vacuoles of the phloem in all vascular bundles, showing a strong co-localization with sulfur, consistent with As(III)-thiol complexation. Within the node, zinc was localized in the vacuoles of the parenchyma cell bridge bordering the enlarged and diffuse vascular bundles, whereas iron and manganese were localized in the fundamental parenchyma cells, with iron being strongly co-localized with phosphorus in the vacuoles. The highly heterogeneous and contrasting distribution patterns of these elements imply different transport activities and/or storage capacities among different cell types. Sequestration of arsenic in companion cell vacuoles may explain the limited phloem mobility of arsenite. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  18. Determination of trace elements in planktonic microcrustaceans using total reflection X-ray fluorescence (TXRF): First results from two Chilean lakes

    Energy Technology Data Exchange (ETDEWEB)

    Woelfl, Stefan; Mercado, Susana; Villalobos, Lorena [Instituto de Zoologia, Universidad Austral de Chile, Casilla 567, Valdivia (Chile); Mages, Margarete; Ovari, Mihaly [Department of Inland Water Research Magdeburg, UFZ Centre for Environmental Research Leipzig-Halle, Brueckstrasse 3a, 39114, Magdeburg (Germany); Encina, Francisco [Escuela de Ciencias Ambientales, Facultad de Ciencias, Universidad Catolica de Temuco, Montt 056, Temuco (Chile)

    2004-02-01

    First results are described from the application of a recently developed dry method for determination of elements in single specimens of freshwater microcrustaceans, using total reflection X-ray fluorescence spectrometry (TXRF). This method is a powerful, non-destructive technique for quantifying the trace element content of minute biological samples with a dry weight of 3-50 {mu}g. Three different freshwater microcrustaceans were sampled, from the natural, uncontaminated Lake Laja and from the artificial Rapel reservoir which is slightly contaminated by drainage water from a copper mine. Single specimens of Daphnia pulex, Bosmina chilensis, and Ceriodaphnia dubia were prepared using a modification of the dry method and measured by TXRF. The results showed that both As, Mn, Fe, Ni, Zn, and Cu content and the bioaccumulation of these metals were usually significantly different between the microcrustaceans from the two lakes. The largest difference was found for Cu which was eight times more concentrated in the two microcrustaceans from Rapel reservoir than it was in D. pulex from Lake Laja. (orig.)

  19. Determination of trace elements in planktonic microcrustaceans using total reflection X-ray fluorescence (TXRF): first results from two Chilean lakes.

    Science.gov (United States)

    Woelfl, Stefan; Mages, Margarete; Mercado, Susana; Villalobos, Lorena; Ovári, Mihály; Encina, Francisco

    2004-02-01

    First results are described from the application of a recently developed dry method for determination of elements in single specimens of freshwater microcrustaceans, using total reflection X-ray fluorescence spectrometry (TXRF). This method is a powerful, non-destructive technique for quantifying the trace element content of minute biological samples with a dry weight of 3-50 microg. Three different freshwater microcrustaceans were sampled, from the natural, uncontaminated Lake Laja and from the artificial Rapel reservoir which is slightly contaminated by drainage water from a copper mine. Single specimens of Daphnia pulex, Bosmina chilensis, and Ceriodaphnia dubia were prepared using a modification of the dry method and measured by TXRF. The results showed that both As, Mn, Fe, Ni, Zn, and Cu content and the bioaccumulation of these metals were usually significantly different between the microcrustaceans from the two lakes. The largest difference was found for Cu which was eight times more concentrated in the two microcrustaceans from Rapel reservoir than it was in D. pulex from Lake Laja.

  20. Portable ultrahigh-vacuum sample storage system for polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo; Beniya, Atsushi; Isomura, Noritake [Toyota Central R& D Labs., Inc., Yokomichi 41-1, Nagakute, Aichi 480-1192 (Japan); Uehara, Hiromitsu; Asakura, Kiyotaka; Takakusagi, Satoru [Catalysis Research Center, Hokkaido University, Kita 21-10, Sapporo, Hokkaido 001-0021 (Japan); Nimura, Tomoyuki [AVC Co., Ltd., Inada 1450-6, Hitachinaka, Ibaraki 312-0061 (Japan)

    2016-03-15

    A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstrated by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.

  1. K-edge x-ray dichroism investigation of Fe1-xCoxSi: Experimental evidence for spin polarization crossover

    Science.gov (United States)

    Hearne, G. R.; Diguet, G.; Baudelet, F.; Itié, J.-P.; Manyala, N.

    2015-04-01

    Both Fe and Co K-edge x-ray magnetic circular dichroism (XMCD) have been employed as element-specific probes of the magnetic moments in the composition series of the disordered ferromagnet Fe1-xCoxSi (for x=0.2, 0.3, 0.4, 0.5). A definitive single peaked XMCD profile occurs for all compositions at both Fe and Co K-edges. The Fe 4p orbital moment, deduced from the integral of the XMCD signal, has a steep dependence on x at low doping levels and evolves to a different (weaker) dependence at x≥0.3, similar to the behavior of the magnetization in the Co composition range studied here. It is systematically higher, by at least a factor of two, than the corresponding Co orbital moment for most of the composition series. Fine structure beyond the K-edge absorption (limited range EXAFS) suggests that the local order (atomic environment) is very similar across the series, from the perspective of both the Fe and Co absorbing atom. The variation in the XMCD integral across the Co composition range has two regimes, that which occurs below x=0.3 and then evolves to different behavior at higher doping levels. This is more conspicuously present in the Fe contribution. This is rationalized as the evolution from a half-metallic ferromagnet at low Co doping to that of a strong ferromagnet at x>0.3 and as such, spin polarization crossover occurs. The Fermi level is tuned from the majority spin band for x<0.3 where a strongly polarized majority spin electron gas prevails, to a regime where minority spin carriers dominate at higher doping. The evolution of the Fe-derived spin polarized (3d) bands, indirectly probed here via the 4p states, is the primary determinant of the doping dependence of the magnetism in this alloy series.

  2. Comprehension of direct extraction of hydrophilic antioxidants using vegetable oils by polar paradox theory and small angle X-ray scattering analysis.

    Science.gov (United States)

    Li, Ying; Fabiano-Tixier, Anne Sylvie; Ruiz, Karine; Rossignol Castera, Anne; Bauduin, Pierre; Diat, Olivier; Chemat, Farid

    2015-04-15

    Since the polar paradox theory rationalised the fact that polar antioxidants are more effective in nonpolar media, extractions of phenolic compounds in vegetable oils were inspired and achieved in this study for obtaining oils enriched in phenolic compounds. Moreover, the influence of surfactants on the extractability of phenolic compounds was experimentally studied first, followed by the small angle X-ray scattering analysis for the oil structural observation before and after extraction so as to better understand the dissolving mechanism underpinning the extraction. The results showed a significant difference on the extraction yield of phenolic compounds among oils, which was mainly dependent on their composition instead of the unsaturation of fatty acids. Appropriate surfactant additions could significantly improve extraction yield for refined sunflower oils, which 1% w/w addition of glyceryl oleate was determined as the optimal. Besides, 5% w/w addition of lecithin performed the best in oil enrichments compared with mono- and di-glycerides. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Study of the ultrafast polarization dynamics in lithium borohydride by means of femtosecond X-ray diffraction

    International Nuclear Information System (INIS)

    Stingl, Johannes

    2013-01-01

    In this thesis the ultrafast electronic polarisation in the crystalline material lithium borohydride (LiBH 4 ) is examined. The material is excited by a femtosecond long optical pulse and scanned by a likewise short X-ray pulse. Using X-ray scattering the optically induced spatial rearrangement of electronic charge can be directly mapped with atomic spatial resolution. Copper K-alpha X-rays for the experiment are produced in a laboratory table-top laserplasma source with 1 kHz repetition rate. This radiation is then focused on a powdered sample. Debye-Scherrer rings produced from powder diffraction are collected on a large area detector and processed to yield intensity profiles. Using pump-probe technique the change in diffracted intensity, triggered by excitation with a femtosecond optical pulse is examined. The temporal resolution is given by the delay between pump and probe pulse. This way insight is gained into the dynamic electronic evolution of the system. Intensity changes can be correlated to changes in charge density in the relevant material to elucidate structural dynamics on the femtosecond time scale. Lithium borohydride was chosen since it displays necessary characteristics for the exploration of ultrafast electronic polarisation. Up to date there has been no spatially resolved research in the femtosecond regime elucidating this electronic phenomenon. This work presents the ultrafast resonse in Lithiumborhydrid (LiBH 4 ) to strong electronic fields with optical frequencies, which leads to charge relocation accompanied by electronic polarisation.

  4. Unoccupied density of states of La2–xSrxNiO4+δ studied by polarization-dependent x-ray-absorption spectroscopy and bremsstrahlung isochromat spectroscopy

    NARCIS (Netherlands)

    Kuiper, P.; Elp, J. van; Sawatzky, G.A.; Fujimori, A.; Hosoya, S.; Leeuw, D.M. de

    1991-01-01

    Oxygen 1s x-ray-absorption measurements of La2–xSrxNiO4+δ (0≤x≤1.15) are presented, together with O 1s polarization-dependent x-ray absorption on single-crystal La1.85Sr0.15NiO4. It is concluded that the charge-compensating holes have mainly oxygen 2p character. The Ni 3d9 final states reached

  5. Relationship of college student characteristics and inquiry-based geometrical optics instruction to knowledge of image formation with light-ray tracing

    Science.gov (United States)

    Isik, Hakan

    This study is premised on the fact that student conceptions of optics appear to be unrelated to student characteristics of gender, age, years since high school graduation, or previous academic experiences. This study investigated the relationships between student characteristics and student performance on image formation test items and the changes in student conceptions of optics after an introductory inquiry-based physics course. Data was collected from 39 college students who were involved in an inquiry-based physics course teaching topics of geometrical optics. Student data concerning characteristics and previous experiences with optics and mathematics were collected. Assessment of student understanding of optics knowledge for pinholes, plane mirrors, refraction, and convex lenses was collected with, the Test of Image Formation with Light-Ray Tracing instrument. Total scale and subscale scores representing the optics instrument content were derived from student pretest and posttest responses. The types of knowledge, needed to answer each optics item correctly, were categorized as situational, conceptual, procedural, and strategic knowledge. These types of knowledge were associated with student correct and incorrect responses to each item to explain the existences and changes in student scientific and naive conceptions. Correlation and stepwise multiple regression analyses were conducted to identify the student characteristics and academic experiences that significantly predicted scores on the subscales of the test. The results showed that student experience with calculus was a significant predictor of student performance on the total scale as well as on the refraction subscale of the Test of Image Formation with Light-Ray Tracing. A combination of student age and previous academic experience with precalculus was a significant predictor of student performance on the pretest pinhole subscale. Student characteristic of years since high school graduation

  6. Essential trace elements content in a sudanese meal of cooked Hibiscus Sp. leaves as determined by both X-ray florescence and atomic absorption spectroscopy techniques

    International Nuclear Information System (INIS)

    Mohamed, S.M; Taha, M.H.

    2003-01-01

    Essential trace elements content of a Sudanese meal of cooked Karkadi plant leaves (Hibiscus Sp)was determined and found to be several folds higher than the average trace element content of Sudanese food as determined in twenty nine daily consumed mixed diets. Therefore, this plant can act as a promising natural supplement in cases of deficiency provided it is grown in a trace element rich soil. (Author)

  7. Comparison of slope and height profiles for flat synchrotron x-ray mirrors measured with a long trace profiler and a Fizeau interferometer

    International Nuclear Information System (INIS)

    Qian, J.; Assoufid, L.; Macrander, A.

    2007-01-01

    Long trace profilers (LTPS) have been used at many synchrotron radiation laboratories worldwide for over a decade to measure surface slope profiles of long grazing incidence x-ray mirrors. Phase measuring interferometers (PMIs) of the Fizeau type, on the other hand, are being used by most mirror manufacturers to accomplish the same task. However, large mirrors whose dimensions exceed the aperture of the Fizeau interferometer require measurements to be carried out at grazing incidence, and aspheric optics require the use of a null lens. While an LTP provides a direct measurement of ID slope profiles, PMIs measure area height profiles from which the slope can be obtained by a differentiation algorithm. Measurements of the two types of instruments have been found by us to be in good agreement, but to our knowledge there is no published work directly comparing the two instruments. This paper documents that comparison. We measured two different nominally flat mirrors with both the LTP in operation at the Advanced Photon Source (a type-II LTP) and a Fizeau-type PMI interferometer (Wyko model 6000). One mirror was 500 mm long and made of Zerodur, and the other mirror was 350 mm long and made of silicon. Slope error results with these instruments agree within nearly 100% (3.11 ± 0.15 (micro)rad for the LTP, and 3.11 ± 0.02 (micro)rad for the Fizeau PMI interferometer) for the medium quality Zerodur mirror with 3 (micro)rad rms nominal slope error. A significant difference was observed with the much higher quality silicon mirror. For the Si mirror, slope error data is 0.39 ± 0.08 (micro)rad from LTP measurements but it is 0.35 ± 0.01 (micro)rad from PMI interferometer measurements. The standard deviations show that the Fizeau PMI interferometer has much better measurement repeatability.

  8. Full-sky Ray-tracing Simulation of Weak Lensing Using ELUCID Simulations: Exploring Galaxy Intrinsic Alignment and Cosmic Shear Correlations

    Science.gov (United States)

    Wei, Chengliang; Li, Guoliang; Kang, Xi; Luo, Yu; Xia, Qianli; Wang, Peng; Yang, Xiaohu; Wang, Huiyuan; Jing, Yipeng; Mo, Houjun; Lin, Weipeng; Wang, Yang; Li, Shijie; Lu, Yi; Zhang, Youcai; Lim, S. H.; Tweed, Dylan; Cui, Weiguang

    2018-01-01

    The intrinsic alignment of galaxies is an important systematic effect in weak-lensing surveys, which can affect the derived cosmological parameters. One direct way to distinguish different alignment models and quantify their effects on the measurement is to produce mock weak-lensing surveys. In this work, we use the full-sky ray-tracing technique to produce mock images of galaxies from the ELUCID N-body simulation run with WMAP9 cosmology. In our model, we assume that the shape of the central elliptical galaxy follows that of the dark matter halo, and that of the spiral galaxy follows the halo spin. Using the mock galaxy images, a combination of galaxy intrinsic shape and the gravitational shear, we compare the predicted tomographic shear correlations to the results of the Kilo-Degree Survey (KiDS) and Deep Lens Survey (DLS). We find that our predictions stay between the KiDS and DLS results. We rule out a model in which the satellite galaxies are radially aligned with the center galaxy; otherwise, the shear correlations on small scales are too high. Most importantly, we find that although the intrinsic alignment of spiral galaxies is very weak, they induce a positive correlation between the gravitational shear signal and the intrinsic galaxy orientation (GI). This is because the spiral galaxy is tangentially aligned with the nearby large-scale overdensity, contrary to the radial alignment of the elliptical galaxy. Our results explain the origin of the detected positive GI term in the weak-lensing surveys. We conclude that in future analyses, the GI model must include the dependence on galaxy types in more detail.

  9. The use of x-ray fluorescence technique (XRF) in the determination of trace elements in environmental study: a case study for sediments and soils

    International Nuclear Information System (INIS)

    Hamzah Mohamad

    1997-01-01

    A specific X-ray fluorescence technique (XRF) was developed to determine the concentrations of nine common and significant trace elements in sediments and soils, i.e. two of the common materials used in environmental studies. The elements are Ba, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn. A total of 22 international reference materials of rocks, soils, minerals, ores and sediments were employed to construct nine calibration curves, all of which depict linear correlation of concentration-intensity, with correlation coefficients of 0.9 or better. The accuracy of determination is implied from the relative differences between the observed and suggested values in four reference materials: USGS SCO-1, shale; CCRMP SO-1, soil; CCRMP CO-2, soil; and SARM 42, soil. The determinations of four elements are considered as accurate, with relative errors of smaller than 10%; they are Fe (5%), Mn (6%), Cr (8%), and Cu (9%). Only a moderate accuracy has been achieved in the determinations of Ba (13%), Zn (18%) and V (21 %). Ni and Ph results are associated with larger errors. The developed technique is considered rapid, whereby nine elements in 30 samples in the form of pressed powder briquettes can be analysed in 8 hours. Without extrapolating the calibration curves, the method is suitable to analyse elements in soils and sediments in the following ranges of concentrations: Ba, 0-1500 ppm; Cr, 0-3000 ppm; Cu, 0-300 ppm; Fe, 0.7%; Mn, 0-1000 ppm; Ni, 0-300 ppm; Pb, 0-70 ppm; V, 0-300 ppm and Zn, 0-270 ppm

  10. Exploration of parameters influencing the self-absorption losses in luminescent solar concentrators with an experimentally validated combined ray-tracing/Monte-Carlo model

    Science.gov (United States)

    Krumer, Zachar; van Sark, Wilfried G. J. H. M.; de Mello Donegá, Celso; Schropp, Ruud E. I.

    2013-09-01

    Luminescent solar concentrators (LSCs) are low cost photovoltaic devices, which reduce the amount of necessary semiconductor material per unit area of a photovoltaic solar energy converter by means of concentration. The device is comprised of a thin plastic plate in which luminescent species (fluorophores) have been incorporated.The fluorophores absorb the solar light and radiatively re-emit a part of the energy. Total internal reflection traps most of the emitted light inside the plate and wave-guides it to a narrow side facet with a solar cell attached, where conversion into electricity occurs. The eciency of such devices is as yet rather low, due to several loss mechanisms, of which self-absorption is of high importance. Combined ray-tracing and Monte-Carlosimulations is a widely used tool for efficiency estimations of LSC-devices prior to manufacturing. We have applied this method to a model experiment, in which we analysed the impact of self-absorption onto LSC-efficiency of fluorophores with different absorption/emission-spectral overlap (Stokes-shift): several organic dyes and semiconductor quantum dots (single compound and core/shell of type-II). These results are compared with the ones obtained experimentally demonstrating a good agreement. The validated model is used to investigate systematically the influence of spectral separation and luminescence quantum efficiency on the intensity loss inconsequence of increased self-absorption. The results are used to adopt a quantity called the self-absorption cross-section and establish it as reliable criterion for self-absorption properties of materials that can be obtained from fundamental data and has a more universal scope of application, than the currently used Stokes-shift.

  11. Trace analysis by TXRF

    International Nuclear Information System (INIS)

    Hockett, R.S.

    1995-01-01

    Total reflection X-Ray Fluorescence (TXRF) originally was developed for trace analysis of small residues but has become a widespread method for measuring trace surface metal contamination an semiconductor substrates. It is estimated that approximately 100 TXRF instruments are in se in the semiconductor industry worldwide, and approximately half that for residue analysis x analytical laboratories. TXRF instrumentation is available today for reaching detection limits d the order of 10 9 atoms/cm 2 . This review emphasizes some of the more recent developments in TXRF for trace analysis, in particular with the use of synchrotron x-ray sources (SR-TXRF). There is some promise of reaching 10 7 atoms/cm 2 detection limits for surface analysis of semi-conductor substrates. 19 refs

  12. Polarization Optics

    OpenAIRE

    Fressengeas, Nicolas

    2010-01-01

    The physics of polarization optics *Polarized light propagation *Partially polarized light; DEA; After a brief introduction to polarization optics, this lecture reviews the basic formalisms for dealing with it: Jones Calculus for totally polarized light and Stokes parameters associated to Mueller Calculus for partially polarized light.

  13. In Situ Ambient Pressure X-ray Photoelectron Spectroscopy of Cobalt Perovskite Surfaces under Cathodic Polarization at High Temperatures

    KAUST Repository

    Crumlin, Ethan J.

    2013-08-08

    Heterostructured oxide interfaces have demonstrated enhanced oxygen reduction reaction rates at elevated temperatures (∼500-800 C); however, the physical origin underlying this enhancement is not well understood. By using synchrotron-based in situ ambient pressure X-ray photoelectron spectroscopy (APXPS), we focus on understanding the surface electronic structure, elemental composition, and chemical nature of epitaxial La0.8Sr 0.2CoO3-δ (LSC113), (La 0.5Sr0.5)2CoO4±δ (LSC214), and LSC214-decorated LSC113 (LSC 113/214) thin films as a function of applied electrical potentials (0 to -800 mV) at 520 C and p(O2) of 1 × 10-3 atm. Shifts in the top of the valence band binding energy and changes in the Sr 3d and O 1s spectral components under applied bias reveal key differences among the film chemistries, most notably in the degree of Sr segregation to the surface and quantity of active oxygen sites in the perovskite termination layer. These differences help to identify important factors governing the enhanced activity of oxygen electrocatalysis observed for the LSC113/214 heterostructured surface. © 2013 American Chemical Society.

  14. Application of neutron activation and high resolution X-ray spectrometry to the development of analytical methods suitable for the assay of trace elements in biological materials. Part of a coordinated programme on comparative methods for the study of trace elements in human nutrition

    International Nuclear Information System (INIS)

    Mantel, J.

    1980-12-01

    A new method for determining trace elements in biological materials by instrumental neutron activation analysis (INAA) has been investigated. This method is based on the measurement of low-energy X-rays emitted by the sample after appropriate activation with thermal neutrons. The X-rays were detected by a Si(Li) diode connected to a multichannel analyser. The background in the energy region of interest was reduced by means of an electromagnet which deflects high-energy beta-particles away from the detector. This method of measurement has been evaluated by application to a number of different biological reference materials. The use of the electromagnet for background reduction was shown to be extremely effective for several radionuclides that are common sources of disturbance in INAA. For 32 P the background was only 0.8% of its original value. For real samples the background reduction depends somewhat on the matrix and therefore varies from one material to another. Practical detection limits for typical biological materials were derived for 18 different trace elements. The use of a perspex absorber was also considered as an alternative to magnetic deflection of the beta rays. In practice, magnetic deflection is preferable for the lower-energy X-ray emitters such as the activation products of Co, Cr, Cu and Zn

  15. SU-E-T-587: Monte Carlo Versus Ray-Tracing for Treatment Planning Involving CNS Tumors On the MultiPlan System for CyberKnife Radiosurgery

    International Nuclear Information System (INIS)

    Forbang, R Teboh

    2014-01-01

    Purpose: MultiPlan, the treatment planning system for the CyberKnife Robotic Radiosurgery system offers two approaches to dose computation, namely Ray-Tracing (RT), the default technique and Monte Carlo (MC), an option. RT is deterministic, however it accounts for primary heterogeneity only. MC on the other hand has an uncertainty associated with the calculation results. The advantage is that in addition, it accounts for heterogeneity effects on the scattered dose. Not all sites will benefit from MC. The goal of this work was to focus on central nervous system (CNS) tumors and compare dosimetrically, treatment plans computed with RT versus MC. Methods: Treatment plans were computed using both RT and MC for sites covering (a) the brain (b) C-spine (c) upper T-spine (d) lower T-spine (e) L-spine and (f) sacrum. RT was first used to compute clinically valid treatment plans. Then the same treatment parameters, monitor units, beam weights, etc., were used in the MC algorithm to compute the dose distribution. The plans were then compared for tumor coverage to illustrate the difference if any. All MC calculations were performed at a 1% uncertainty. Results: Using the RT technique, the tumor coverage for the brain, C-spine (C3–C7), upper T-spine (T4–T6), lower T-spine (T10), Lspine (L2) and sacrum were 96.8%, 93.1%, 97.2%, 87.3%, 91.1%, and 95.3%. The corresponding tumor coverage based on the MC approach was 98.2%, 95.3%, 87.55%, 88.2%, 92.5%, and 95.3%. It should be noted that the acceptable planning target coverage for our clinical practice is >95%. The coverage can be compromised for spine tumors to spare normal tissues such as the spinal cord. Conclusion: For treatment planning involving the CNS, RT and MC appear to be similar for most sites but for the T-spine area where most of the beams traverse lung tissue. In this case, MC is highly recommended

  16. [Review] Polarization and Polarimetry

    Science.gov (United States)

    Trippe, Sascha

    2014-02-01

    Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/γ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation.

  17. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    Science.gov (United States)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-01

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from 235U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 × 10-5. The upper limit for the asymmetry coefficient has been set to | D n | fission correlation coefficient D α = (170±20) × 10-5. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5° to the fission axis, the correlation coefficient was found to be (1.57 ± 0.20) × 10-4, while at the angle of 67.5° it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt γ-rays.

  18. Effects of high-intensity pulse irradiation with linear polarized near-infrared rays and stretching on muscle tone in patients with cerebrovascular disease: a randomized controlled trial.

    Science.gov (United States)

    Takeuchi, Nobuyuki; Takezako, Nobuhiro; Shimonishi, Yuko; Usuda, Shigeru

    2017-08-01

    [Purpose] The purpose of this study was to clarify the influence of high-intensity pulse irradiation with linear polarized near-infrared rays (HI-LPNR) and stretching on hypertonia in cerebrovascular disease patients. [Subjects and Methods] The subjects were 40 cerebrovascular disease patients with hypertonia of the ankle joint plantar flexor muscle. The subjects were randomly allocated to groups undergoing treatment with HI-LPNR irradiation (HI-LPNR group), stretching (stretching group), HI-LPNR irradiation followed by stretching (combination group), and control group (10 subjects each). In all groups, the passive range of motion of ankle dorsiflexion and passive resistive joint torque of ankle dorsiflexion were measured before and after the specified intervention. [Results] The changes in passive range of motion, significant increase in the stretching and combination groups compared with that in the control group. The changes in passive resistive joint torque, significant decrease in HI-LPNR, stretching, and combination groups compared with that in the control group. [Conclusion] HI-LPNR irradiation and stretching has effect of decrease muscle tone. However, combination of HI-LPNR irradiation and stretching has no multiplier effect.

  19. Angular Distribution and Linear Polarization of X-ray Radiation Resulting from Electron Impact Excitation of Highly Charged Ions in Debye Plasmas

    Science.gov (United States)

    Chen, Zhanbin

    2018-05-01

    Plasma-screening effects on the 1s _{1/2} → 2l (l = s , p ) and 1s _{1/2} → 3d _{3/2} electron-impact excitation of highly charged ions are investigated, together with their subsequent radiative decay. The analysis is performed based on the multi-configuration Dirac-Fock method and the fully relativistic distorted-wave method incorporating the Debye-Hückel potential. To explore the nature of the effects, calculations are carried out based on detailed analyses of the integrated total and magnetic sublevel cross sections, the alignment parameters, the linear polarizations, and the angular distribution of the X-ray photoemission, as well as on corresponding data calculated in various Debye lengths/environments, taking the 2p _{3/2}→ 1s _{1/2} and 3d _{3/2}→ 1s _{1/2} characteristic lines of H-like Fe^{25+} ion as an example. The present results are compared with experimental data and other theoretical predictions where available.

  20. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    Science.gov (United States)

    Sutter, John P.; Dolbnya, Igor P.; Collins, Stephen P.; Harris, Kenneth D. M.; Edwards-Gau, Gregory R.; Palmer, Benjamin A.

    2015-04-01

    In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal monochromator is used upstream from the sample to select the appropriate photon energy, and a horizontally deflecting X-ray polarization analyzer, consisting of a perfect single crystal with a Bragg reflection at Bragg angle of approximately 45°, is placed downstream from the sample to measure the resulting rotation of the X-ray polarization. However, if the experiment is performed on a synchrotron bending-magnet beamline, then the elliptical polarization of the X-rays out of the electron orbit plane affects the shape of the output beam. Also, because the monochromator introduces a correlation between vertical position and photon energy to the X-ray beam, the polarization analyzer does not select the entire beam, but instead selects a diagonal stripe, the slope of which depends on the Bragg angles of the monochromator and the polarization analyzer. In the present work, the final background intensity distribution is calculated analytically because the phase space sampling methods normally used in ray traces are too inefficient for this setup. X-ray Birefringence Imaging data measured at the Diamond Light Source beamline B16 agree well with the theory developed here.

  1. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sutter, John P., E-mail: john.sutter@diamond.ac.uk; Dolbnya, Igor P.; Collins, Stephen P. [Diamond Light Source Ltd., Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom); Harris, Kenneth D. M.; Edwards-Gau, Gregory R. [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales (United Kingdom); Palmer, Benjamin A. [Department of Structural Biology, Weizmann Institute of Science, 234 Herzl St., Rehovot 7610001 (Israel)

    2015-04-28

    In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal monochromator is used upstream from the sample to select the appropriate photon energy, and a horizontally deflecting X-ray polarization analyzer, consisting of a perfect single crystal with a Bragg reflection at Bragg angle of approximately 45°, is placed downstream from the sample to measure the resulting rotation of the X-ray polarization. However, if the experiment is performed on a synchrotron bending-magnet beamline, then the elliptical polarization of the X-rays out of the electron orbit plane affects the shape of the output beam. Also, because the monochromator introduces a correlation between vertical position and photon energy to the X-ray beam, the polarization analyzer does not select the entire beam, but instead selects a diagonal stripe, the slope of which depends on the Bragg angles of the monochromator and the polarization analyzer. In the present work, the final background intensity distribution is calculated analytically because the phase space sampling methods normally used in ray traces are too inefficient for this setup. X-ray Birefringence Imaging data measured at the Diamond Light Source beamline B16 agree well with the theory developed here.

  2. A Proposal to the Department of Energy for The Fabrication of a Very High Energy Polarized Gama Ray Beam Facility and A Program of Medium Energy Physics Research at The National Synchrotron Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Sandorfi, A.M.; LeVine, M.J.; Thorn, C.E.; Giordano, G.; Matone, G.

    1982-09-01

    This proposal requests support for the fabrication and operation of a modest facility that would provide relatively intense beams of monochromatic and polarized photons with energies in the range of several hundreds of MeV. These {gamma} rays would be produced by Compton backscattering laser light from the electrons circulating in the 2.5-3.0 GeV 'X-RAY' storage ring of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The excellent emittance, phase space, and high current of this state-of-the-art storage ring will allow the production of 2 x 10{sup 7} {gamma} rays per second. These photons would be tagged by detecting the scattered electrons, thereby determining the energy to 2.7 MeV for all {gamma}-ray energies. The efficiency of this tagging procedure is 100% and the {gamma}-ray beam would be essentially background free. Tagging will also allow the flexibility of operating with a dynamic range as large as 200 MeV in photon energy while still preserving high resolution and polarization. These beams will permit a fruitful study of important questions in medium-energy nuclear physics. The initial goals of this program are to reach reliable operation with photon energies up to 300 MeV and to develop {gamma}-ray beams with energies up to about 500 MeV. To demonstrate reliable operation, a modest physics program is planned that, for the most part, utilizes existing magnets and detector systems but nonetheless addresses several important outstanding problems. Gamma ray beams of the versatility, intensity, energy, and resolution that can be achieved at this facility are not currently available at any other world facility either existing or under construction. Furthermore, the proposed program would produce the first intense source of medium-energy {gamma} rays that are polarized. Because of the difficulties in producing such polarized beams, it is very unlikely that viable alternate sources can be developed in the near future; at

  3. Sub-basalt Imaging of Hydrocarbon-Bearing Mesozoic Sediments Using Ray-Trace Inversion of First-Arrival Seismic Data and Elastic Finite-Difference Full-Wave Modeling Along Sinor-Valod Profile of Deccan Syneclise, India

    Science.gov (United States)

    Talukdar, Karabi; Behera, Laxmidhar

    2018-03-01

    Imaging below the basalt for hydrocarbon exploration is a global problem because of poor penetration and significant loss of seismic energy due to scattering, attenuation, absorption and mode-conversion when the seismic waves encounter a highly heterogeneous and rugose basalt layer. The conventional (short offset) seismic data acquisition, processing and modeling techniques adopted by the oil industry generally fails to image hydrocarbon-bearing sub-trappean Mesozoic sediments hidden below the basalt and is considered as a serious problem for hydrocarbon exploration in the world. To overcome this difficulty of sub-basalt imaging, we have generated dense synthetic seismic data with the help of elastic finite-difference full-wave modeling using staggered-grid scheme for the model derived from ray-trace inversion using sparse wide-angle seismic data acquired along Sinor-Valod profile in the Deccan Volcanic Province of India. The full-wave synthetic seismic data generated have been processed and imaged using conventional seismic data processing technique with Kirchhoff pre-stack time and depth migrations. The seismic image obtained correlates with all the structural features of the model obtained through ray-trace inversion of wide-angle seismic data, validating the effectiveness of robust elastic finite-difference full-wave modeling approach for imaging below thick basalts. Using the full-wave modeling also allows us to decipher small-scale heterogeneities imposed in the model as a measure of the rugose basalt interfaces, which could not be dealt with ray-trace inversion. Furthermore, we were able to accurately image thin low-velocity hydrocarbon-bearing Mesozoic sediments sandwiched between and hidden below two thick sequences of high-velocity basalt layers lying above the basement.

  4. Full-Field Calcium K-Edge X-ray Absorption Near-Edge Structure Spectroscopy on Cortical Bone at the Micron-Scale: Polarization Effects Reveal Mineral Orientation.

    Science.gov (United States)

    Hesse, Bernhard; Salome, Murielle; Castillo-Michel, Hiram; Cotte, Marine; Fayard, Barbara; Sahle, Christoph J; De Nolf, Wout; Hradilova, Jana; Masic, Admir; Kanngießer, Birgit; Bohner, Marc; Varga, Peter; Raum, Kay; Schrof, Susanne

    2016-04-05

    Here, we show results on X-ray absorption near edge structure spectroscopy in both transmission and X-ray fluorescence full-field mode (FF-XANES) at the calcium K-edge on human bone tissue in healthy and diseased conditions and for different tissue maturation stages. We observe that the dominating spectral differences originating from different tissue regions, which are well pronounced in the white line and postedge structures are associated with polarization effects. These polarization effects dominate the spectral variance and must be well understood and modeled before analyzing the very subtle spectral variations related to the bone tissue variations itself. However, these modulations in the fine structure of the spectra can potentially be of high interest to quantify orientations of the apatite crystals in highly structured tissue matrices such as bone. Due to the extremely short wavelengths of X-rays, FF-XANES overcomes the limited spatial resolution of other optical and spectroscopic techniques exploiting visible light. Since the field of view in FF-XANES is rather large the acquisition times for analyzing the same region are short compared to, for example, X-ray diffraction techniques. Our results on the angular absorption dependence were verified by both site-matched polarized Raman spectroscopy, which has been shown to be sensitive to the orientation of bone building blocks and by mathematical simulations of the angular absorbance dependence. As an outlook we further demonstrate the polarization based assessment of calcium-containing crystal orientation and specification of calcium in a beta-tricalcium phosphate (β-Ca3(PO4)2 scaffold implanted into ovine bone. Regarding the use of XANES to assess chemical properties of Ca in human bone tissue our data suggest that neither the anatomical site (tibia vs jaw) nor pathology (healthy vs necrotic jaw bone tissue) affected the averaged spectral shape of the XANES spectra.

  5. A nested multivariate chemometrics based calibration strategy for direct trace biometal analysis in soft tissue utilizing Energy Dispersive X-Ray Fluorescence (EDXRF) and scattering spectrometry.

    Science.gov (United States)

    Okonda, J J; Angeyo, K H; Mangala, J M; Kisia, S M

    2017-11-01

    Compton scatter-modulated fluorescence and multivariate chemometric (artificial neural network (ANN) and principal component regression (PCR)) calibration strategy was explored for direct rapid trace biometals (Mn, Fe, Cu, Zn, Se) analysis in "complex" matrices (model soft tissues). This involved spectral feature selection (multiple fluorescence signatures) normalized to or in conjunction with Compton scatter. ANN model resulted in more accurate trace biometal determination (R 2 >0.9) compared to PCR. Hybrid nested (ANN and PCR) approach led to optimized accurate biometals' concentrations in Oyster tissue (≤ ± 10%). Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Trace Element Mapping of a Biological Specimen by a Full-Field X-ray Fluorescence Imaging Microscope with a Wolter Mirror

    International Nuclear Information System (INIS)

    Hoshino, Masato; Yamada, Norimitsu; Ishino, Toyoaki; Namiki, Takashi; Watanabe, Norio; Aoki, Sadao

    2007-01-01

    A full-field X-ray fluorescence imaging microscope with a Wolter mirror was applied to the element mapping of alfalfa seeds. The X-ray fluorescence microscope was built at the Photon Factory BL3C2 (KEK). X-ray fluorescence images of several growing stages of the alfalfa seeds were obtained. X-ray fluorescence energy spectra were measured with either a solid state detector or a CCD photon counting method. The element distributions of iron and zinc which were included in the seeds were obtained using a photon counting method

  7. Development of an approach for qualitative and quantitative analysis of trace elements present in canine breast tumors by energy dispersive X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Cozer, Thamara C.; Conceicao, Andre L.C.; Paschuk, Sergei A.; Rocha, Anna S.S. da; Fagundes, Alana C.F.; Maciel, Karla F.R.; Pimentel, Gustavo R.O.; Badelli, Juliana C., E-mail: thamara.cozer@gmail.com, E-mail: alconceicao@utfpr.edu.br, E-mail: sergei@utfpr.edu.br, E-mail: anna@utfpr.edu.br, E-mail: alanacarolinef@gmail.com, E-mail: karla_rimanski@hotmail.com, E-mail: g_rop@hotmail.com, E-mail: jubadellin@gmail.com [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Lab. de Espectroscopia de Raio-X

    2015-07-01

    Studies performed with canines indicate that one of the main neoplasia which affect these animals are the breast tumors, representing from 25% to 50% of all kinds of tumors. Moreover, half of them are classified as malignant. In this sense, recent researches on humans have been associated the presence of certain trace elements with the development of breast neoplasia in those individuals. Then, as the breast tissue composition in canines is very similar to the humans, it is expected the same behavior. In this direction, a very effective technique to identify and to determinate trace elements concentration is the EDXRF. However, studies on this area are scarce in the literature. Therefore, in this work it was developed an approach to quantify the main trace elements present into these tumors with high sensitivity. For this purpose, it was determined calibration curves of standards samples diluted in water, with concentrations of Ca, Fe, Cu and Zn, ranging from 400mg/kg to 35mg/kg, from 20mg/kg to 2mg/kg, from 10mg/kg to 1mg/kg and from 100mg/kg to 10mg/kg, respectively. All calibration curves were linearly fitted and on basis in this behavior it was determined the sensitivity of our approach to quantify the concentration of the trace elements mentioned above. In addition, it is important to mention that studies in this area are of great potential, because EDXRF represents a quickly practical and non-destructive alternative to quantify trace elements. (author)

  8. Development of an approach for qualitative and quantitative analysis of trace elements present in canine breast tumors by energy dispersive X-ray fluorescence

    International Nuclear Information System (INIS)

    Cozer, Thamara C.; Conceicao, Andre L.C.; Paschuk, Sergei A.; Rocha, Anna S.S. da; Fagundes, Alana C.F.; Maciel, Karla F.R.; Pimentel, Gustavo R.O.; Badelli, Juliana C.

    2015-01-01

    Studies performed with canines indicate that one of the main neoplasia which affect these animals are the breast tumors, representing from 25% to 50% of all kinds of tumors. Moreover, half of them are classified as malignant. In this sense, recent researches on humans have been associated the presence of certain trace elements with the development of breast neoplasia in those individuals. Then, as the breast tissue composition in canines is very similar to the humans, it is expected the same behavior. In this direction, a very effective technique to identify and to determinate trace elements concentration is the EDXRF. However, studies on this area are scarce in the literature. Therefore, in this work it was developed an approach to quantify the main trace elements present into these tumors with high sensitivity. For this purpose, it was determined calibration curves of standards samples diluted in water, with concentrations of Ca, Fe, Cu and Zn, ranging from 400mg/kg to 35mg/kg, from 20mg/kg to 2mg/kg, from 10mg/kg to 1mg/kg and from 100mg/kg to 10mg/kg, respectively. All calibration curves were linearly fitted and on basis in this behavior it was determined the sensitivity of our approach to quantify the concentration of the trace elements mentioned above. In addition, it is important to mention that studies in this area are of great potential, because EDXRF represents a quickly practical and non-destructive alternative to quantify trace elements. (author)

  9. Determination of some main elements and traces by x-ray fluorescence analysis in silicate rocks: a comparative study of two analytical techniques

    International Nuclear Information System (INIS)

    Andrade, M.D. de.

    1977-01-01

    The determinations of silicon, magnesium, iron, potassium, calcium, titanium, manganese, barium, strontium, rubidium, zirconium and scandium in felsic and mafic rocks, by X ray fluorescence analysis are presented. (author)

  10. Polarization-dependent X-ray-absorption spectroscopy of $RNi_{2} B_{2}$ C (R=Er $\\to$ Lu) Reduced Ni-3d occupancy in $YbNi_{2} B_{2} C$

    CERN Document Server

    Mazumdar, C; Von Lips, H; Golden, M S; Fink, J; Canfield, P C; Kaindl, G

    2001-01-01

    We present here the results of polarization-dependent X-ray- absorption near-edge structure (XANES) studies at the B-K, C-K, and Ni-L/sub 3/ thresholds of single-crystalline borocarbide compounds RNi/sub 2/B/sub 2/C (with R=Er to Lu) using bulk-sensitive fluorescence yield technique. The Ni-L/sub 3/ XANES spectrum for YbNi /sub 2/B/sub 2/C with photon polarization parallel to the ab plane is significantly more intense than in analogous spectra of other members of this series. This indicates a reduced Ni-3d occupancy in the Ni /sub 2/B/sub 2/ layer in YbNi/sub 2/B/sub 2/C, a fact that might be responsible for the absence of superconductivity in this material. (26 refs).

  11. Worldwide Open Proficiency Test for X Ray Fluorescence Laboratories PTXRFIAEA09: Determination of Major, Minor and Trace Elements in a River Clay

    International Nuclear Information System (INIS)

    2014-01-01

    This publication presents the results of the worldwide proficiency test PTXRFIAEA09 on the determination of major, minor and trace elements in river clay. Methodologies, a data evaluation approach, a summary evaluation of each element and individual evaluation reports for each laboratory are also described. The test was carried out within the IAEA project Nuclear Spectrometry for Analytical Applications, under the Nuclear Science Programme. The main objective of the project was to enhance the capability of interest Member States in effective utilization of nuclear spectrometries and analytical services in industry, human health and agriculture, and in monitoring and evaluating environmental pollution

  12. Proton Induced X-Ray Emission (PIXE) Analysis to Measure Trace Metals in Soil Along the East River in Queens, New York

    Science.gov (United States)

    Chalise, Sajju; Conlan, Skye; Porat, Zachary; Labrake, Scott; Vineyard, Michael

    2017-09-01

    The Union College Ion-Beam Analysis Lab's 1.1 MV tandem Pelletron accelerator is used to determine the presence of heavy trace metals in Queens, NY between Astoria Park and 3.5 miles south to Gantry State Park. A PIXE analysis was performed on 0.5 g pelletized soil samples with a 2.2 MeV proton beam. The results show the presence of elements ranging from Ti to Pb with the concentration of Pb in Astoria Park (2200 +/-200 ppm) approximately ten times that of the Gantry State Park. We hypothesize that the high lead concentration at Astoria Park is due to the nearby Hell Gate Bridge, painted in 1916 with lead based paint, then sandblasted and repainted in the '90s. If the lead is from the repair of the bridge, then we should see the concentration decrease as we go further from the bridge. To test this, soil samples were collected and analyzed from seven different locations north and south of the bridge. The concentrations of lead decreased drastically within a 500 m radius and were approximately constant at greater distances. More soil samples need to be collected within the 500 m radius from bridge to identify the potential source of Pb. We will describe the experimental procedure, the PIXE analysis of soil samples, and present preliminary results on the distribution of heavy trace metals.

  13. Polarized photon transport through fog

    Science.gov (United States)

    Farmer, Jonathan; Persons, Christopher M.; DeSilva, Robert; Kirkland, James H.; Finney, Greg A.; Fuller, Kirk A.; Hokr, Brett H.

    2017-09-01

    Anyone who has driven through fog understands the detrimental effect scattering can have on your ability to see. When light interacts with a scattering center, in this case a fog droplet, it is scattered into a new direction, ultimately turning the world around you into a dull gray haze. In some fogs, visibility can be less than 100 meters. It would be possible to see through turbid media like fog if you can separate the scattered light from the unscattered, or ballistic, light; however, we must understand the light transport properties of the atmosphere to determine the optimum scheme. Here, we present an end-to-end simulation for polarized light transport through fog. Our approach can be summarized in three steps: compute the Mueller matrix for a single scattering interaction, ensemble average a distribution of sizes and shapes, and solve the light transport using a Monte Carlo simulation. For small spherical particles, such as fog, we use Mie theory to calculate the single scattering Mueller matrix, but this approach can be generalized to non-spherical particles using ray tracing for large particles or a T-matrix approach for smaller particles. Through this simulation, we are able to determine a backscattering Mueller matrix and a forward scattering Mueller matrix response function for the atmosphere as a function of position and detection angle.

  14. Polarization Characteristics Inferred From the Radio Receiver Instrument on the Enhanced Polar Outflow Probe

    Science.gov (United States)

    Danskin, Donald W.; Hussey, Glenn C.; Gillies, Robert G.; James, H. Gordon; Fairbairn, David T.; Yau, Andrew W.

    2018-02-01

    The Radio Receiver Instrument (RRI) on the CAScade, Smallsat, and Ionospheric Polar Explorer/enhanced Polar Outflow Probe (CASSIOPE/e-POP) satellite was used to receive continuous wave and binary phase shift keyed transmissions from a high-frequency transmitter located in Ottawa, ON, Canada during April 2016 to investigate how the ionosphere affects the polarization characteristics of transionospheric high-frequency radio waves. The spacecraft orientation was continuously slewed to maintain the dipole orientation in a plane perpendicular to the direction toward the transmitter, enabling the first in situ planar polarization determination for continuous wave and binary phase shift keyed modulated radio waves from space at times when the wave frequency is at least 1.58 times the plasma frequency. The Stokes parameters and polarization characteristics were derived from the measured data and interpreted using an existing ray tracing model. For the southern part of the passes, the power was observed to oscillate between the two dipoles of RRI, which was attributed to Faraday rotation of the radio waves. For the first time, a reversal in the rate of change of orientation angle was observed where the minimum in modeled Faraday rotation occurred. The reversal point was poleward of the point of closest approach between the satellite and transmitter; this was explained by the variations of total electron content and component of magnetic field along the direction of propagation. The received signals show both quasi-longitudinal (QL) and quasi-transverse characteristics. South of the transmitter the QL regime is dominant. Around the reversal point, a combination of QL and quasi-transverse nature was observed.

  15. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    Science.gov (United States)

    Bahadir, Z.; Bulut, V. N.; Hidalgo, M.; Soylak, M.; Marguí, E.

    2015-05-01

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L- 1. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101-108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples.

  16. Ray tracing through the liquid crystal point diffraction interferometer. 1998 summer research program for high school juniors at the University of Rochester's Laboratory for Laser Energetics. Student research reports

    International Nuclear Information System (INIS)

    Turner, A.

    1999-03-01

    The Omega laser is a system with many different parts that may cause imperfections. There are a multitude of lenses and mirrors, for example, that may not be polished correctly and can cause the laser wave front to have aberrations. The Liquid Crystal Point Diffraction Interferometer (L.C.P.D.I.) is a device whose main purpose is to read the wave front of the laser and measure any aberrations that may be on it. The way the L.C.P.D.I. reads the laser wave front and measures these aberrations is very complicated and has yet to be perfected. A ray-tracing model of the L.C.P.D.I. has been built, which calculates and models the ray trajectories, the optical paths of the rays, the O.P.D. between the object and reference beams, the absorption of the rays in the liquid crystal, and the intensities of each beam. It can predict an actual experiment by manipulating the different parameters of the program. It will be useful in optimization and further development of the L.C.P.D.I. Evidently, it is necessary to develop a liquid crystal solution with an O.D. greater than 0.3, and possibly as high as 2.0. This new solution would be able to reduce the intensity of the object beam sufficiently to make it comparable with the reference beam intensity. If this were achieved, the contrast, or visibility of the fringes would be better, and the interferogram could be used to diagnose the aberrations in the laser beam front. Then the cause of the aberrations could be fixed. This would result in a near-perfect laser front. If this were achieved, then it is possible that laser fusion could be made more efficient and possibly used as an energy source

  17. Monitoring environmental pollution of trace elements in tree-rings by synchrotron radiation total reflection X-ray fluorescence analysis (SR-TXRF)

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Silvana [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Civil, Arquitetura e Urbanismo]. E-mail: Silvana@fec.unicamp.br; Vives, Ana Elisa S. de [Universidade Metodista de Piracicaba (UNIMEP), Santa Barbara D' Oeste, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo]. E-mail: aesvives@unimep.br; Brienza, Sandra Maria B. [Universidade Metodista de Piracicaba (UNIMEP), Santa Barbara D' Oeste, SP (Brazil) Faculdade de Ciencias Matematicas, da Natureza e de Tecnologia da Informacao]. E-mail: sbrienza@unimep.br; Medeiros, Jean Gabriel S.; Tomazello Filho, Mario [Sao Paulo Univ., Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz]. E-mail: jeangm@esalq.usp.br; mtomazel@esalq.usp.br; Zucchi, Orgheda L.A.D. [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas]. E-mail: olzucchi@fcfrp.usp.br; Nascimento Filho, Virgilio F. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Instrumentacao Nuclear]. E-mail: virgilio@cena.usp.br

    2005-07-01

    This paper aims to study the environmental pollution in the tree development, as a manner to evaluate its use as bioindicator in urban and country sides. The sample collecting was carry out in Piracicaba city, Sao Paulo State, that presents high level of environmental contamination of the water, soil and air, due industrial activities, vehicles combustion, sugar-cane leaves burning in the harvesting, etc. It was selected the Caesalpinia peltophoroides ('Sibipiruna') specie because its very used in urban arborization. It was employed the analytical technique named total reflection X-ray fluorescence (TXRF) to identify and quantify the elements and metals of nutritional and toxicological importance in the wood samples. The analysis was done in the Brazilian Synchrotron Light Laboratory, using a white beam for excitation and a Si(Li) detector for characteristic X-ray detection. It was quantified the P, K, Ca, Ti, Fe, Sr, Ba e Pb elements. (author)

  18. Monitoring environmental pollution of trace elements in tree-rings by synchrotron radiation total reflection X-ray fluorescence analysis (SR-TXRF)

    International Nuclear Information System (INIS)

    Moreira, Silvana; Vives, Ana Elisa S. de; Brienza, Sandra Maria B.; Medeiros, Jean Gabriel S.; Tomazello Filho, Mario; Zucchi, Orgheda L.A.D.; Nascimento Filho, Virgilio F.

    2005-01-01

    This paper aims to study the environmental pollution in the tree development, as a manner to evaluate its use as bioindicator in urban and country sides. The sample collecting was carry out in Piracicaba city, Sao Paulo State, that presents high level of environmental contamination of the water, soil and air, due industrial activities, vehicles combustion, sugar-cane leaves burning in the harvesting, etc. It was selected the Caesalpinia peltophoroides ('Sibipiruna') specie because its very used in urban arborization. It was employed the analytical technique named total reflection X-ray fluorescence (TXRF) to identify and quantify the elements and metals of nutritional and toxicological importance in the wood samples. The analysis was done in the Brazilian Synchrotron Light Laboratory, using a white beam for excitation and a Si(Li) detector for characteristic X-ray detection. It was quantified the P, K, Ca, Ti, Fe, Sr, Ba e Pb elements. (author)

  19. Polarized Moessbauer transitions in mixed hyperfine interactions

    International Nuclear Information System (INIS)

    Barb, D.; Tarina, D.

    1975-01-01

    A contribution to the theory of elliptical polarization in the Moessbauer effect for transitions between mixed nuclear states is reported. A relation between the two-dimensional complex vector parameterization and the photon polarization density matrix was used in describing changes in the polarization of the gamma-ray involved. (A.K.)

  20. Determination of ultra trace contaminants on silicon wafer surfaces using total-reflection X-ray fluorescence TXRF 'state-of-the-art'

    Science.gov (United States)

    Pahlke, S.; Fabry, L.; Kotz, L.; Mantler, C.; Ehmann, T.

    2001-11-01

    In a well balanced system of highly motivated, well trained personnel and automated equipment, pure reagents and bulk media, cleanrooms and integrated data management, total-reflection X-ray fluorescence (TXRF) can and must contribute to quality assurance and process stability, support and canalize creative engineering by continuous learning about materials and processes. TXRF has the advantage of controlled one-point calibration, a linear dynamic range of three orders of magnitude, high grade of automation in operation and data management, high up-time, and a simple control of data plausibility.

  1. Trace element analysis of water using radioisotope induced X-ray fluorescence (Cd-109) and a preconcentration-internal standard method

    International Nuclear Information System (INIS)

    Alvarez, M.; Cano, W.

    1986-10-01

    Radioisotope induced X-ray fluorescence using Cd-109 was used for the determination of iron, nickel, copper, zinc, lead and mercury in water. These metals were concentrated by precipitation with the chelating agent APDC. The precipitated formed was filtered using a membrane filter. Cobalt was added as an internal standard. Minimum detection limit, sensitivities and calibration curves linearities have been obtained to find the limits of the method. The usefulness of the method is illustrated analysing synthetic standard solutions. As an application analytical results are given for water of a highly polluted river area. (Author)

  2. Polarization developments

    International Nuclear Information System (INIS)

    Prescott, C.Y.

    1993-07-01

    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist

  3. Algorithms and Programs for Strong Gravitational Lensing In Kerr Space-time Including Polarization

    Science.gov (United States)

    Chen, Bin; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie; Maddumage, Prasad

    2015-05-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  4. ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

    International Nuclear Information System (INIS)

    Chen, Bin; Maddumage, Prasad; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie

    2015-01-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python

  5. IPOLE - semi-analytic scheme for relativistic polarized radiative transport

    Science.gov (United States)

    Mościbrodzka, M.; Gammie, C. F.

    2018-03-01

    We describe IPOLE, a new public ray-tracing code for covariant, polarized radiative transport. The code extends the IBOTHROS scheme for covariant, unpolarized transport using two representations of the polarized radiation field: In the coordinate frame, it parallel transports the coherency tensor; in the frame of the plasma it evolves the Stokes parameters under emission, absorption, and Faraday conversion. The transport step is implemented to be as spacetime- and coordinate- independent as possible. The emission, absorption, and Faraday conversion step is implemented using an analytic solution to the polarized transport equation with constant coefficients. As a result, IPOLE is stable, efficient, and produces a physically reasonable solution even for a step with high optical depth and Faraday depth. We show that the code matches analytic results in flat space, and that it produces results that converge to those produced by Dexter's GRTRANS polarized transport code on a complicated model problem. We expect IPOLE will mainly find applications in modelling Event Horizon Telescope sources, but it may also be useful in other relativistic transport problems such as modelling for the IXPE mission.

  6. Analysis of trace in Rhododendron ferrigineum leaves for monitoring of urban atmospheric pollution by x-ray fluorescence with Synchrotron Radiation Excitation technique

    International Nuclear Information System (INIS)

    Pinto, Jefferson F.; Simabuco, Silvana M.; Jesus, E.F.O. de

    2000-01-01

    The purpose of this work was perform the biomonitoring of the atmospheric pollution in Campinas City (SP), applying the Energy Dispersive X-ray Fluorescence with Synchrotron Radiation Excitation technique. For this were performed the elemental analysis of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se and Pb in Rhododendron ferrigineum leaves, employed here as bioindicator from environmental pollution in order to evaluate the effects of spatial and climatic contribution on the elemental concentration on the vegetable. Urban and rural sites were sampling in different seasons. The collected leaves were divided in two parts, one of them was washed by detergent and deionized water, in order to quantify the losses due the washing, and the second one was not washed, following the both parts of material were dried in stove, crushed and so the samples were submitted to an nitric-perchloric digestion. The samples were preconcentrated with ammonium pyrrolidinedithiocarbamate (APDC), and the suspension was separated by filtration in cellulose membrane, then the samples were analyzed with X-ray tube and synchrotron radiation excitations. The results obtained shown that the vehicle flow can be associated to the distribution of the elements in the Rhododendrom ferrigineum leaves therefore the climatic contribution was not conclusive. (author)

  7. Electron-positron pair production by gamma-rays in an anisotropic flux of soft photons, and application to pulsar polar caps

    Science.gov (United States)

    Voisin, Guillaume; Mottez, Fabrice; Bonazzola, Silvano

    2018-02-01

    Electron-positron pair production by collision of photons is investigated in view of application to pulsar physics. We compute the absorption rate of individual gamma-ray photons by an arbitrary anisotropic distribution of softer photons, and the energy and angular spectrum of the outgoing leptons. We work analytically within the approximation that 1 ≫ mc2/E > ɛ/E, with E and ɛ the gamma-ray and soft-photon maximum energy and mc2 the electron mass energy. We give results at leading order in these small parameters. For practical purposes, we provide expressions in the form of Laurent series which give correct reaction rates in the isotropic case within an average error of ˜ 7 per cent. We apply this formalism to gamma-rays flying downward or upward from a hot neutron star thermally radiating at a uniform temperature of 106 K. Other temperatures can be easily deduced using the relevant scaling laws. We find differences in absorption between these two extreme directions of almost two orders of magnitude, much larger than our error estimate. The magnetosphere appears completely opaque to downward gamma-rays while there are up to ˜ 10 per cent chances of absorbing an upward gamma-ray. We provide energy and angular spectra for both upward and downward gamma-rays. Energy spectra show a typical double peak, with larger separation at larger gamma-ray energies. Angular spectra are very narrow, with an opening angle ranging from 10-3 to 10-7 radians with increasing gamma-ray energies.

  8. Polarization Techniques for Mitigation of Low Grazing Angle Sea Clutter

    Science.gov (United States)

    2017-01-01

    standard CFAR false alarm rate while maintaining detections on objects of interest. Moreover, PCL is elegant : It exploits fundamental characteristics of both...cannot measure polarization. Polarization is defined by the path traced by the tip of an EM wave’s electric field vector over one period of propagation...vector phasor propagating in the +z direction. Polarization is defined by the path traced by the tip of this electric field vector phasor over one

  9. Determination of trace elements in mine soil samples using portable X-ray fluorescence spectrometer: A comparative study with ICP-OES

    Directory of Open Access Journals (Sweden)

    Hamdi Sahraoui

    2016-08-01

    Full Text Available Lead (Pb, Zinc (Zn and Cadmium (Cd levels on soils surrounding of Lakhouat mine (North-West of Tunisia were measured. The total concentration of these elements in the soil samples was determined by portable X-ray fluorescence (XRF in situ and compared to the traditional digestion method using inductively coupled-plasma optical emission spectroscopy (ICP-OES. Statistical analyses were performed to determine if significant differences existed between the instrumental techniques, which included simple correlations by the regression lines and t-test for mean comparison. The statistical analysis demonstrated that no statistically significant differences were observed for the Pb concentrations; however, for the Zn and Cd concentrations, t-test showed significant differences between the inst

  10. Polarization, political

    NARCIS (Netherlands)

    Wojcieszak, M.; Mazzoleni, G.; Barnhurst, K.G.; Ikeda, K.; Maia, R.C.M.; Wessler, H.

    2015-01-01

    Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass

  11. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  12. Determination of trace amounts of hexavalent chromium in drinking waters by dispersive microsolid-phase extraction using modified multiwalled carbon nanotubes combined with total reflection X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bahadir, Z. [Department of Chemistry, Giresun University, Giresun (Turkey); Bulut, V.N. [Macka Vocational School, Karadeniz Technical University, Macka, Trabzon (Turkey); Hidalgo, M. [Department of Chemistry, Faculty of Sciences, University of Girona, Girona (Spain); Soylak, M. [Department of Chemistry, Faculty of Sciences, Erciyes University, Kayseri (Turkey); Marguí, E., E-mail: eva.margui@udg.edu [Department of Chemistry, Faculty of Sciences, University of Girona, Girona (Spain)

    2015-05-01

    A methodology based on the combination of dispersive microsolid-phase extraction (DMSPE) with total reflection X-ray fluorescence (TXRF) spectrometry is proposed for the determination of hexavalent chromium in drinking waters. Multiwalled carbon nanotubes (MWCNTs) modified with the anionic exchanger tricaprylmethylammonium chloride (Aliquat 336) were used as solid sorbents. After the sorption process of Cr(VI) on the modified MWCNTs, the aqueous sample was separated by centrifugation and the loaded MWCNTs were suspended using a small volume of an internal standard solution and analyzed directly by a benchtop TXRF spectrometer, without any elution step. Parameters affecting the extraction process (pH and volume of the aqueous sample, amount of MWCNTs, extraction time) and TXRF analysis (volume of internal standard, volume of deposited suspension on the reflector, drying mode, and instrumental parameters) have been carefully evaluated to test the real capability of the developed methodology for the determination of Cr(VI) at trace levels. Using the best analytical conditions, it was found that the minimum Cr(VI) content that can be detected in an aqueous solution was 3 μg L{sup −1}. This value is almost 20 times lower than the maximum hexavalent chromium content permissible in drinking waters, according to the World Health Organization (WHO). Recoveries for spiked tap and mineral water samples were, in most cases, in the range of 101–108% which demonstrates the suitability of the TXRF methodology for monitoring Cr(VI) at trace levels in drinking water samples. - Highlights: • A method using DMSPE and TXRF is proposed for Cr(VI) determination in water. • CNTs modified with a commercial anionic exchanger are used for the DMSPE. • The detection limit for hexavalent chromium is 3 μg L{sup −1}. • Accuracy and precision are suitable for the analysis of tap and mineral waters.

  13. Study on trace elements behaviour in cancerous and healthy tissues of colon, breast and stomach: Total reflection X-ray fluorescence applications

    Science.gov (United States)

    Magalhães, T.; Carvalho, M. L.; Von Bohlen, A.; Becker, M.

    2010-06-01

    In this work Total-reflection X-ray fluorescence (TXRF) was used to analyse healthy and cancerous tissues of the same individual along several contiguous thin sections of each tissue. Thirty two samples (16 pairs) of breast tissue, 30 samples (15 pairs) of intestine tissue and 10 samples (5 pairs) of stomach tissue were analysed. The samples were obtained in Civil Hospitals of Germany (Dortmund) and Portugal (Lisbon). The elemental distribution of P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr and Pb in these samples was studied. Descriptive statistics based on bar graphics and hypotheses tests and also an automatic classification based on hierarchical grouping analysis was used for the several analysed tissues. It was shown that the behaviour of the elements is tissue dependent. Some elements, like P and K exhibit the same behaviour in all the analysed tissue types. They have increased concentrations in all cancerous tissues. Unlike, other elements like Br show completely different behaviour depending on the tissue: similar concentration in healthy and cancerous stomach, decreased levels in colon cancerous tissues and enhanced concentrations in breast was observed. Moreover cancer tissues present decreased Se concentrations on colon and increased on breast.

  14. Polar Bears

    Science.gov (United States)

    Amstrup, Steven C.; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.

    2002-01-01

    Polar bears (Ursus maritimus) are hunted throughout most of their range. In addition to hunting polar bears of the Beaufort Sea region are exposed to mineral and petroleum extraction and related human activities such as shipping road-building, and seismic testing (Stirling 1990).Little was known at the start of this project about how polar bears move about in their environment, and although it was understood that many bears travel across political borders, the boundaries of populations had not been delineated (Amstrup 1986, Amstrup et al. 1986, Amstrup and DeMaster 1988, Garner et al. 1994, Amstrup 1995, Amstrup et al. 1995, Amstrup 2000).As human populations increase and demands for polar bears and other arctic resources escalate, managers must know the sizes and distributions of the polar bear populations. Resource managers also need reliable estimates of breeding rates, reproductive intervals, litter sizes, and survival of young and adults.Our objectives for this research were 1) to determine the seasonal and annual movements of polar bears in the Beaufort Sea, 2) to define the boundaries of the population(s) using this region, 3) to determine the size and status of the Beaufort Sea polar bear population, and 4) to establish reproduction and survival rates (Amstrup 2000).

  15. Polarization Observations of the Fermi blazars

    Science.gov (United States)

    Rani, Bindu; S. Jorstad, A. P. Marscher (BU, USA), K. Sokolovsky (IAASARS, Greece), I. Agudo (CSIC, Spain)

    2018-01-01

    Ever since the revolutionary discovery by the Fermi mission that active galactic nuclei (AGN) produce copious amounts of high-energy emission, its origin has remained elusive. Using high-frequency radio interferometry (VLBI) polarization imaging, we could probe the magnetic field topology of the compact high-energy emission regions in blazars. A case study for blazar 3C 279 reveals presence of multiple gamma-ray emission regions. The observed anti-correlation between gamma-ray flux and percentage polarization at optical bands challenges the current high-energy emission models. In addition to the turbulent component responsible for gamma-ray flares, our analysis suggests the presence of a steady polarized component having with its polarization direction aligned along the jet axis. The steady polarized component could possibly be the toroidal component of the helical magnetic field. To better understand the acceleration processes in jets, high-energy polarization missions are of great importance.

  16. The relation between the long-term X-ray and optical activity of the polar AM Her (RX J1816.2+4952)

    Czech Academy of Sciences Publication Activity Database

    Šimon, Vojtěch

    2011-01-01

    Roč. 16, č. 6 (2011), s. 405-411 ISSN 1384-1076 Institutional research plan: CEZ:AV0Z10030501 Keywords : radiation mechanisms * cataclysmic variables * X-rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.411, year: 2011

  17. Solid-phase arsenic speciation in aquifer sediments: A micro-X-ray absorption spectroscopy approach for quantifying trace-level speciation

    Science.gov (United States)

    Nicholas, Sarah L.; Erickson, Melinda L.; Woodruff, Laurel G.; Knaeble, Alan R.; Marcus, Matthew A.; Lynch, Joshua K.; Toner, Brandy M.

    2017-08-01

    Arsenic (As) is a geogenic contaminant affecting groundwater in geologically diverse systems globally. Arsenic release from aquifer sediments to groundwater is favored when biogeochemical conditions, especially oxidation-reduction (redox) potential, in aquifers fluctuate. The specific objective of this research is to identify the solid-phase sources and geochemical mechanisms of release of As in aquifers of the Des Moines Lobe glacial advance. The overarching concept is that conditions present at the aquifer-aquitard interfaces promote a suite of geochemical reactions leading to mineral alteration and release of As to groundwater. A microprobe X-ray absorption spectroscopy (μXAS) approach is developed and applied to rotosonic drill core samples to identify the solid-phase speciation of As in aquifer, aquitard, and aquifer-aquitard interface sediments. This approach addresses the low solid-phase As concentrations, as well as the fine-scale physical and chemical heterogeneity of the sediments. The spectroscopy data are analyzed using novel cosine-distance and correlation-distance hierarchical clustering for Fe 1s and As 1s μXAS datasets. The solid-phase Fe and As speciation is then interpreted using sediment and well-water chemical data to propose solid-phase As reservoirs and release mechanisms. The results confirm that in two of the three locations studied, the glacial sediment forming the aquitard is the source of As to the aquifer sediments. The results are consistent with three different As release mechanisms: (1) desorption from Fe (oxyhydr)oxides, (2) reductive dissolution of Fe (oxyhydr)oxides, and (3) oxidative dissolution of Fe sulfides. The findings confirm that glacial sediments at the interface between aquifer and aquitard are geochemically active zones for As. The diversity of As release mechanisms is consistent with the geographic heterogeneity observed in the distribution of elevated-As wells.

  18. Ab Initio Molecular Dynamics of Uranium Incorporated in Goethite (α-FeOOH): Interpretation of X-ray Absorption Spectroscopy of Trace Polyvalent Metals.

    Science.gov (United States)

    Kerisit, Sebastien; Bylaska, Eric J; Massey, Michael S; McBriarty, Martin E; Ilton, Eugene S

    2016-11-21

    Incorporation of economically or environmentally consequential polyvalent metals into iron (oxyhydr)oxides has applications in environmental chemistry, remediation, and materials science. A primary tool for characterizing the local coordination environment of such metals, and therefore building models to predict their behavior, is extended X-ray absorption fine structure spectroscopy (EXAFS). Accurate structural information can be lacking yet is required to constrain and inform data interpretation. In this regard, ab initio molecular dynamics (AIMD) was used to calculate the local coordination environment of minor amounts of U incorporated in the structure of goethite (α-FeOOH). U oxidation states (VI, V, and IV) and charge compensation schemes were varied. Simulated trajectories were used to calculate the U L III -edge EXAFS function and fit experimental EXAFS data for U incorporated into goethite under reducing conditions. Calculations that closely matched the U EXAFS of the well-characterized mineral uraninite (UO 2 ), and constrained the S 0 2 parameter to be 0.909, validated the approach. The results for the U-goethite system indicated that U(V) substituted for structural Fe(III) in octahedral uranate coordination. Charge balance was achieved by the loss of one structural proton coupled to addition of one electron into the solid (-1 H + , +1 e - ). The ability of AIMD to model higher energy states thermally accessible at room temperature is particularly relevant for protonated systems such as goethite, where proton transfers between adjacent octahedra had a dramatic effect on the calculated EXAFS. Vibrational effects as a function of temperature were also estimated using AIMD, allowing separate quantification of thermal and configurational disorder. In summary, coupling AIMD structural modeling and EXAFS experiments enables modeling of the redox behavior of polyvalent metals that are incorporated in conductive materials such as iron (oxyhydr)oxides, with

  19. Two different preparation techniques for trace element determination of single Daphnia specimen using total reflection x-ray fluorescence analysis (TXRF)

    International Nuclear Information System (INIS)

    Woelfl, S.; Mages, M.

    2000-01-01

    Bio accumulation gives first information about the bio-availability of elements in waters and becomes more and more important for the characterization of the water quality. The use of common analytical techniques like ICP-MS and AAS requires large quantities of biologic sample material. Single preparation for example of Daphnia, a common species for bio-test experiments, are hardly possible with these procedures. Therefore alternatively quantitative TXRF element determination of individually prepared Daphnia was developed. Two preparation techniques for single freshwater crustacean specimen from a eutrophic branch of the river Elbe in the 'Rothehorn Park', Magdeburg (Daphnia: dry weight: 10 - 50 μg individuum -1 ) had been tested: (1) Wet preparation: the single Daphnia specimen had been washed with 0.45 μm filtered lake water and put onto quartz sample carriers. After air drying, the body length were determined in order to calculate the dry weight according to previously established body lengths-dry weight relationships. (2) Dry preparation: after collection specimen were washed with 0.45 μm filtered lake water and frozen in liquid nitrogen. The individual lyophilisated dried Daphnia were weighted using an ultrafine micro-balance and put onto quartz sample carriers. After preparation, addition of some μl Gallium standard solution and air drying the individual Daphnia were digested at the quartz sample carriers with 10 μl HNO 3 on a hot plate and dried once more. Finally the element concentrations were determined using a EXTRA IIA total-reflection x-ray fluorescence spectrometer. As a result of these investigations we can conclude that both, the 'dry' and 'wet' preparation method can be used for the element determination in small single crustaceans using TXRF spectrometry. It seems that the 'dry' method yields more precise results, but the wet method is easier to handle in field when samples cannot be fixed with liquid nitrogen. (author)

  20. Information-theoretical feature selection using data obtained by scanning electron microscopy coupled with and energy dispersive X-ray spectrometer for the classification of glass traces.

    Science.gov (United States)

    Ramos, Daniel; Zadora, Grzegorz

    2011-10-31

    In this work, a selection of the best features for multivariate forensic glass classification using Scanning Electron Microscopy coupled with an Energy Dispersive X-ray spectrometer (SEM-EDX) has been performed. This has been motivated by the fact that the databases available for forensic glass classification are sparse nowadays, and the acquisition of SEM-EDX data is both costly and time-consuming for forensic laboratories. The database used for this work consists of 278 glass objects for which 7 variables, based on their elemental compositions obtained with SEM-EDX, are available. Two categories are considered for the classification task, namely containers and car/building windows, both of them typical in forensic casework. A multivariate model is proposed for the computation of the likelihood ratios. The feature selection process is carried out by means of an exhaustive search, with an Empirical Cross-Entropy (ECE) objective function. The ECE metric takes into account not only the discriminating power of the model in use, but also its calibration, which indicates whether or not the likelihood ratios are interpretable in a probabilistic way. Thus, the proposed model is applied to all the 63 possible univariate, bivariate and trivariate combinations taken from the 7 variables in the database, and its performance is ranked by its ECE. Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows (from cars or buildings) or containers, obtaining high (almost perfect) discriminating power and good calibration. This allows the proposed models to be used in casework. We also present an in-depth analysis which reveals the benefits of the proposed ECE metric as an assessment tool for classification models based on likelihood ratios. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Theoretical predictions for the polarization of the J = 0 - 1 neonlike germanium X-ray laser line in the presence of a directed beam of hot electrons

    International Nuclear Information System (INIS)

    Inal, M.K.; Dubau, J.; Cornille, M.

    1998-01-01

    The polarization of the neonlike germanium J = 0 - 1 laser line, which would arise from the existence of a directed beam of hot electrons in the amplifying plasma, is theoretically investigated. The relative populations of the magnetic sublevels in the lower J = 1 laser level have been determined by allowing for the processes of direct excitation from the 2p 6 ground level and collisional de-excitation from the upper J = 0 laser level. Elastic collisions leading to transitions between the M J = 0 and M J =1 sublevels within the lower level of the lasing line have also been taken into account. The required elastic and inelastic collision strengths for transitions between magnetic sublevels have been computed in a semi-relativistic distorted-wave approximation, for incident electron energies up to 15 keV. Our calculations predict a rather low degree of polarization for the J = 0 - 1 line, although the elastic collisions are found to play a negligibly small role in the redistribution of magnetic sublevel populations. (author)

  2. Polarized Light Microscopy

    Science.gov (United States)

    Frandsen, Athela F.

    2016-01-01

    Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

  3. Information-theoretical feature selection using data obtained by Scanning Electron Microscopy coupled with and Energy Dispersive X-ray spectrometer for the classification of glass traces

    International Nuclear Information System (INIS)

    Ramos, Daniel; Zadora, Grzegorz

    2011-01-01

    Highlights: → A selection of the best features for multivariate forensic glass classification using SEM-EDX was performed. → The feature selection process was carried out by means of an exhaustive search, with an Empirical Cross-Entropy objective function. → Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows or containers. - Abstract: In this work, a selection of the best features for multivariate forensic glass classification using Scanning Electron Microscopy coupled with an Energy Dispersive X-ray spectrometer (SEM-EDX) has been performed. This has been motivated by the fact that the databases available for forensic glass classification are sparse nowadays, and the acquisition of SEM-EDX data is both costly and time-consuming for forensic laboratories. The database used for this work consists of 278 glass objects for which 7 variables, based on their elemental compositions obtained with SEM-EDX, are available. Two categories are considered for the classification task, namely containers and car/building windows, both of them typical in forensic casework. A multivariate model is proposed for the computation of the likelihood ratios. The feature selection process is carried out by means of an exhaustive search, with an Empirical Cross-Entropy (ECE) objective function. The ECE metric takes into account not only the discriminating power of the model in use, but also its calibration, which indicates whether or not the likelihood ratios are interpretable in a probabilistic way. Thus, the proposed model is applied to all the 63 possible univariate, bivariate and trivariate combinations taken from the 7 variables in the database, and its performance is ranked by its ECE. Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows (from cars or buildings) or containers

  4. New insights into nucleation. Pressure trace measurements and the first small angle X-ray scattering experiments in a supersonic laval nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, D.

    2007-07-01

    Homogeneous nucleation rates of the n-alcohols and the n-alkanes have been determined by combining information from two sets of supersonic Laval nozzle expansion experiments under identical conditions. The nucleation rates J=N/{delta}t{sub Jmax} for the n-alcohols are in the range of 1.10{sup 17}ray Scattering experiments are conducted to determine the particle number density for both substance classes. Particle number densities in the range of 1.10{sup 12}

  5. New insights into nucleation. Pressure trace measurements and the first small angle X-ray scattering experiments in a supersonic laval nozzle

    International Nuclear Information System (INIS)

    Ghosh, D.

    2007-01-01

    Homogeneous nucleation rates of the n-alcohols and the n-alkanes have been determined by combining information from two sets of supersonic Laval nozzle expansion experiments under identical conditions. The nucleation rates J=N/Δt Jmax for the n-alcohols are in the range of 1.10 17 -3 s -1 17 for the temperatures 207≤T/K≤249, the nucleation rates for the n-alkanes lie in the range of 5.10 15 -3 s -1 18 for the temperatures 143 ≤T/K≤215. For the first time it is shown that the nucleation rate is not only a function of the supersaturation and temperature but clearly also sensitive to the expansion rate during supersonic nozzle expansion. A good agreement between the experimental results and those available in literature is found by applying Hale's scaling formalism [Hale, B., Phys. Rev. A 33, 4256 (1986); Hale, B., Metall. Trans. A 23, 1863 (1992)]. The scaling parameters from this work are also in good agreement with those shown by Rusyniak et al. [Rusyniak, M., M. S. El-Shall, J. Phys. Chem. B 105, 11873 (2001)] and Brus et al. [Brus, D., V. Zdimal F. Stratmann, J. Chem Phys. 124, 164306 (2006)]. In the first experiment static pressure measurements were conducted for the n-alkanes to determine the condensible partial pressure, temperature, supersaturation, characteristic time, and the expansion rate corresponding to the maximum nucleation rate. Characteristic times in the range of 13≤Δt Jmax /μs≤34 were found. In the second set of experiments, the first flow rate resolved Small Angle X-ray Scattering experiments are conducted to determine the particle number density for both substance classes. Particle number densities in the range of 1.10 12 -3 12 and 1.10 11 -3 12 for the n-alcohols and n-alkanes are found, respectively. Additionally, by analyzing the radially averaged scattering spectrum, information on the mean radius and the width of the size distribution of the aerosols is obtained. Mean radii for the n-alcohols in the range of 4< left angle r

  6. STUDIES OF THE ORIGIN OF HIGH-FREQUENCY QUASI-PERIODIC OSCILLATIONS OF MASS-ACCRETING BLACK HOLES IN X-RAY BINARIES WITH NEXT-GENERATION X-RAY TELESCOPES

    Energy Technology Data Exchange (ETDEWEB)

    Beheshtipour, Banafsheh; Hoormann, Janie K.; Krawczynski, Henric, E-mail: b.beheshtipour@wustl.edu [Physics Department and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, CB 1105, St. Louis, MO 63130 (United States)

    2016-08-01

    Observations with RXTE ( Rossi X-ray Timing Explorer ) revealed the presence of high-frequency quasi-periodic oscillations (HFQPOs) of the X-ray flux from several accreting stellar-mass black holes. HFQPOs (and their counterparts at lower frequencies) may allow us to study general relativity in the regime of strong gravity. However, the observational evidence today does not yet allow us to distinguish between different HFQPO models. In this paper we use a general-relativistic ray-tracing code to investigate X-ray timing spectroscopy and polarization properties of HFQPOs in the orbiting Hotspot model. We study observational signatures for the particular case of the 166 Hz quasi-periodic oscillation (QPO) in the galactic binary GRS 1915+105. We conclude with a discussion of the observability of spectral signatures with a timing-spectroscopy experiment such as the LOFT ( Large Observatory for X-ray Timing ) and polarization signatures with space-borne X-ray polarimeters such as IXPE ( Imaging X-ray Polarimetry Explorer ), PolSTAR ( Polarization Spectroscopic Telescope Array ), PRAXyS ( Polarimetry of Relativistic X-ray Sources ), or XIPE ( X-ray Imaging Polarimetry Explorer ). A mission with high count rate such as LOFT would make it possible to get a QPO phase for each photon, enabling the study of the QPO-phase-resolved spectral shape and the correlation between this and the flux level. Owing to the short periods of the HFQPOs, first-generation X-ray polarimeters would not be able to assign a QPO phase to each photon. The study of QPO-phase-resolved polarization energy spectra would thus require simultaneous observations with a first-generation X-ray polarimeter and a LOFT -type mission.

  7. Diagnostics method of interplanetary disturbances according to investigation of cosmic ray fluctuations and its realization in an automation system of science studies at the polar geocosmophysical Tiksi observatory

    International Nuclear Information System (INIS)

    Kozlov, V.I.; Borisov, D.Z.; Tugolukov, N.N.

    1984-01-01

    Diagnostics method of interplanetary disturbances (ID) according to investigation of galactic cosmic ray (GCR) fluctuations is under discussion. Experimental results on early ID diagnostics on April 1984 obtained under real time conditions are presented. Hourly magnitudes of GCR intensity from 20.04 up to 2.05 1984 and, respectively, indexes of GCR scintillations are presented. Short-term increases of indexes with the same decay are observed before the beginning of the main forbush decrease on 26.04 1984, this means the early ID diagnostics

  8. From single-site tantalum complexes to nanoparticles of TaxNy and TaOxNy supported on silica: elucidation of synthesis chemistry by dynamic nuclear polarization surface enhanced NMR spectroscopy and X-ray absorption spectroscopy

    KAUST Repository

    Mohandas, Janet Chakkamadathil

    2017-06-08

    Air-stable catalysts consisting of tantalum nitride nanoparticles represented as a mixture of TaxNy and TaOxNy with diameters in the range of 0.5 to 3 nm supported on highly dehydroxylated silica were synthesized from TaMe5 (Me = methyl) and dimeric Ta-2(OMe)(10) with guidance by the principles of surface organometallic chemistry (SOMC). Characterization of the supported precursors and the supported nanoparticles formed from them was carried out by IR, NMR, UV-Vis, extended X-ray absorption fine structure, and X-ray photoelectron spectroscopies complemented with XRD and high-resolution TEM, with dynamic nuclear polarization surface enhanced NMR spectroscopy being especially helpful by providing enhanced intensities of the signals of H-1, C-13, Si-29, and N-15 at their natural abundances. The characterization data provide details of the synthesis chemistry, including evidence of (a) O-2 insertion into Ta-CH3 species on the support and (b) a binuclear to mononuclear transformation of species formed from Ta-2(OMe)(10) on the support. A catalytic test reaction, cyclooctene epoxidation, was used to probe the supported nanoparticles, with 30% H2O2 serving as the oxidant. The catalysts gave selectivities up to 98% for the epoxide at conversions as high as 99% with a 3.4 wt% loading of Ta present as TaxNy/TaOxNy.

  9. Political polarization

    OpenAIRE

    Dixit, Avinash K.; Weibull, Jörgen W.

    2007-01-01

    Failures of government policies often provoke opposite reactions from citizens; some call for a reversal of the policy, whereas others favor its continuation in stronger form. We offer an explanation of such polarization, based on a natural bimodality of preferences in political and economic contexts and consistent with Bayesian rationality.

  10. Political polarization.

    Science.gov (United States)

    Dixit, Avinash K; Weibull, Jörgen W

    2007-05-01

    Failures of government policies often provoke opposite reactions from citizens; some call for a reversal of the policy, whereas others favor its continuation in stronger form. We offer an explanation of such polarization, based on a natural bimodality of preferences in political and economic contexts and consistent with Bayesian rationality.

  11. The Effect of an Offset Polar Cap Dipolar Magnetic Field on the Modeling of the Vela Pulsar’s γ-Ray Light Curves

    Science.gov (United States)

    Barnard, M.; Venter, C.; Harding, A. K.

    2016-12-01

    We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole B-fields (the latter is characterized by a parameter ɛ), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. The offset-PC dipole B-field mimics deviations from the static dipole (which corresponds to ɛ =0). In addition to constant-emissivity geometric models, we also considered a slot gap (SG) E-field associated with the offset-PC dipole B-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low E-field. Therefore, particles do not always attain the radiation-reaction limit. Our overall optimal light curve fit is for the retarded vacuum dipole field and OG model, at an inclination angle α ={78}-1+{1^\\circ } and observer angle \\zeta ={69}-1+{2^\\circ }. For this B-field, the TPC model is statistically disfavored compared to the OG model. For the static dipole field, neither model is significantly preferred. We found that smaller values of ɛ are favored for the offset-PC dipole field when assuming constant emissivity, and larger ɛ values favored for variable emissivity, but not significantly so. When multiplying the SG E-field by a factor of 100, we found improved light curve fits, with α and ζ being closer to best fits from independent studies, as well as curvature radiation reaction at lower altitudes.

  12. The Effect of an Offset Polar Cap Dipolar Magnetic Field on the Modeling of the Vela Pulsar's Gamma-Ray Light Curves

    Science.gov (United States)

    Barnard, M.; Venter, C.; Harding, A. K.

    2016-01-01

    We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole B-fields (the latter is characterized by a parameter epsilon), in conjunction with standard two-pole caustic (TPC) and outer gap (OG) emission geometries. The offset-PC dipole B-field mimics deviations from the static dipole (which corresponds to epsilon equals 0). In addition to constant-emissivity geometric models, we also considered a slot gap (SG) E-field associated with the offset-PC dipole B-field and found that its inclusion leads to qualitatively different light curves. Solving the particle transport equation shows that the particle energy only becomes large enough to yield significant curvature radiation at large altitudes above the stellar surface, given this relatively low E-field. Therefore, particles do not always attain the radiation-reaction limit. Our overall optimal light curve fit is for the retarded vacuum dipole field and OG model, at an inclination angle alpha equals 78 plus or minus 1 degree and observer angle zeta equals 69 plus 2 degrees or minus 1 degree. For this B-field, the TPC model is statistically disfavored compared to the OG model. For the static dipole field, neither model is significantly preferred. We found that smaller values of epsilon are favored for the offset-PC dipole field when assuming constant emissivity, and larger epsilon values favored for variable emissivity, but not significantly so. When multiplying the SG E-field by a factor of 100, we found improved light curve fits, with alpha and zeta being closer to best fits from independent studies, as well as curvature radiation reaction at lower altitudes.

  13. Final Scientific/Technical Report, USDOE Award DE-FG-02ER54684, Recipient: CompX, Project Title: Fokker-Planck/Ray Tracing for Electron Bernstein and Fast Wave Modeling in Support of NSTX

    International Nuclear Information System (INIS)

    Harvey, R.W.

    2009-01-01

    This DOE grant supported fusion energy research, a potential long-term solution to the world's energy needs. Magnetic fusion, exemplified by confinement of very hot ionized gases, i.e., plasmas, in donut-shaped tokamak vessels is a leading approach for this energy source. Thus far, a mixture of hydrogen isotopes has produced 10's of megawatts of fusion power for seconds in a tokamak reactor at Princeton Plasma Physics Laboratory in New Jersey. The research grant under consideration, ER54684, uses computer models to aid in understanding and projecting efficacy of heating and current drive sources in the National Spherical Torus Experiment, a tokamak variant, at PPPL. The NSTX experiment explores the physics of very tight aspect ratio, almost spherical tokamaks, aiming at producing steady-state fusion plasmas. The current drive is an integral part of the steady-state concept, maintaining the magnetic geometry in the steady-state tokamak. CompX further developed and applied models for radiofrequency (rf) heating and current drive for applications to NSTX. These models build on a 30 year development of rf ray tracing (the all-frequencies GENRAY code) and higher dimensional Fokker-Planck rf-collisional modeling (the 3D collisional-quasilinear CQL3D code) at CompX. Two mainline current-drive rf modes are proposed for injection into NSTX: (1) electron Bernstein wave (EBW), and (2) high harmonic fast wave (HHFW) modes. Both these current drive systems provide a means for the rf to access the especially high density plasma--termed high beta plasma--compared to the strength of the required magnetic fields. The CompX studies entailed detailed modeling of the EBW to calculate the efficiency of the current drive system, and to determine its range of flexibility for driving current at spatial locations in the plasma cross-section. The ray tracing showed penetration into NSTX bulk plasma, relatively efficient current drive, but a limited ability to produce current over the whole

  14. The polarization and beaming effect for GRBs

    OpenAIRE

    Cheng, K. S.; Fan, J. H.; Dai, Z. G.

    1999-01-01

    Both observations and theoretical models suggest that the emissions in gamma-ray bursts (GRBs) and the afterglows are beamed. We argue that the recent polarization measured in the afterglows gives further evidence of beaming in GRBs. In this approach, we adopted the polarization-magnitude relation of BL Lacertae objects to 4 GRBs with available polarization measurements and found that the data of the 4 GRBs are consistent with the relation of BL Lacertae objects. This result suggests that the...

  15. Past lessons and future importance of polarization

    International Nuclear Information System (INIS)

    Lipkin, H.J.

    1980-01-01

    Polarization and spin effects have traditionally brought surprises to physicists particularly to those who thought that such effects were unimportant. In hadron physics, large unexplained effects keep turning up and are still unresolved puzzles. A good measurement of the uninteresting beta ray polarization could have discovered parity nonconservation many years before its prediction by Lee and Yang. Nobody knows whether there are further exciting discoveries of this kind waiting for polarization experiments

  16. Epidemic contact tracing via communication traces.

    Science.gov (United States)

    Farrahi, Katayoun; Emonet, Rémi; Cebrian, Manuel

    2014-01-01

    Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

  17. Epidemic contact tracing via communication traces.

    Directory of Open Access Journals (Sweden)

    Katayoun Farrahi

    Full Text Available Traditional contact tracing relies on knowledge of the interpersonal network of physical interactions, where contagious outbreaks propagate. However, due to privacy constraints and noisy data assimilation, this network is generally difficult to reconstruct accurately. Communication traces obtained by mobile phones are known to be good proxies for the physical interaction network, and they may provide a valuable tool for contact tracing. Motivated by this assumption, we propose a model for contact tracing, where an infection is spreading in the physical interpersonal network, which can never be fully recovered; and contact tracing is occurring in a communication network which acts as a proxy for the first. We apply this dual model to a dataset covering 72 students over a 9 month period, for which both the physical interactions as well as the mobile communication traces are known. Our results suggest that a wide range of contact tracing strategies may significantly reduce the final size of the epidemic, by mainly affecting its peak of incidence. However, we find that for low overlap between the face-to-face and communication interaction network, contact tracing is only efficient at the beginning of the outbreak, due to rapidly increasing costs as the epidemic evolves. Overall, contact tracing via mobile phone communication traces may be a viable option to arrest contagious outbreaks.

  18. Real ray tracing in anisotropic viscoelastic media

    Czech Academy of Sciences Publication Activity Database

    Vavryčuk, Václav

    2008-01-01

    Roč. 175, č. 2 (2008), s. 617-626 ISSN 0956-540X R&D Projects: GA AV ČR IAA300120801 Grant - others:EC(XE) MTKI-CT-2004-517242 Institutional research plan: CEZ:AV0Z30120515 Keywords : elasticity and anelasticity * body waves * seismic anisotropy * seismic attenuation * wave propagation Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.219, year: 2008

  19. Tracing the X-Ray Trail

    Science.gov (United States)

    ... en otro establecimiento. de su médico, especificando el tipo de examen necesario, la razón para el examen y ... el examen, el radiólogo, médico entrenado para la lectura de imágenes para diagnóstico, examina las películas. El radiólogo ...

  20. Parametric Trace Slicing

    Science.gov (United States)

    Rosu, Grigore (Inventor); Chen, Feng (Inventor); Chen, Guo-fang; Wu, Yamei; Meredith, Patrick O. (Inventor)

    2014-01-01

    A program trace is obtained and events of the program trace are traversed. For each event identified in traversing the program trace, a trace slice of which the identified event is a part is identified based on the parameter instance of the identified event. For each trace slice of which the identified event is a part, the identified event is added to an end of a record of the trace slice. These parametric trace slices can be used in a variety of different manners, such as for monitoring, mining, and predicting.