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Sample records for ray-trace mc simulations

  1. Novel applications of the x-ray tracing software package McXtrace

    DEFF Research Database (Denmark)

    Bergbäck Knudsen, Erik; Nielsen, Martin Meedom; Haldrup, Kristoffer

    2014-01-01

    We will present examples of applying the X-ray tracing software package McXtrace to different kinds of X-ray scattering experiments. In particular we will be focusing on time-resolved type experiments. Simulations of full scale experiments are particularly useful for this kind, especially when...... some of the issues encountered. Generally more than one or all of these effects are present at once. Simulations can in these cases be used to identify distinct footprints of such distortions and thus give the experimenter a means of deconvoluting them from the signal. We will present a study...... of this kind along with the newest developments of the McXtrace software package....

  2. 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)

  3. Patient-specific scatter correction in clinical cone beam computed tomography imaging made possible by the combination of Monte Carlo simulations and a ray tracing algorithm

    International Nuclear Information System (INIS)

    Thing, Rune S.; Bernchou, Uffe; Brink, Carsten; Mainegra-Hing, Ernesto

    2013-01-01

    Purpose: Cone beam computed tomography (CBCT) image quality is limited by scattered photons. Monte Carlo (MC) simulations provide the ability of predicting the patient-specific scatter contamination in clinical CBCT imaging. Lengthy simulations prevent MC-based scatter correction from being fully implemented in a clinical setting. This study investigates the combination of using fast MC simulations to predict scatter distributions with a ray tracing algorithm to allow calibration between simulated and clinical CBCT images. Material and methods: An EGSnrc-based user code (egs c bct), was used to perform MC simulations of an Elekta XVI CBCT imaging system. A 60keV x-ray source was used, and air kerma scored at the detector plane. Several variance reduction techniques (VRTs) were used to increase the scatter calculation efficiency. Three patient phantoms based on CT scans were simulated, namely a brain, a thorax and a pelvis scan. A ray tracing algorithm was used to calculate the detector signal due to primary photons. A total of 288 projections were simulated, one for each thread on the computer cluster used for the investigation. Results: Scatter distributions for the brain, thorax and pelvis scan were simulated within 2 % statistical uncertainty in two hours per scan. Within the same time, the ray tracing algorithm provided the primary signal for each of the projections. Thus, all the data needed for MC-based scatter correction in clinical CBCT imaging was obtained within two hours per patient, using a full simulation of the clinical CBCT geometry. Conclusions: This study shows that use of MC-based scatter corrections in CBCT imaging has a great potential to improve CBCT image quality. By use of powerful VRTs to predict scatter distributions and a ray tracing algorithm to calculate the primary signal, it is possible to obtain the necessary data for patient specific MC scatter correction within two hours per patient

  4. MC ray-tracing optimization of lobster-eye focusing devices with RESTRAX

    International Nuclear Information System (INIS)

    Saroun, Jan; Kulda, Jiri

    2006-01-01

    The enhanced functionalities of the latest version of the RESTRAX software, providing a high-speed Monte Carlo (MC) ray-tracing code to represent a virtual three-axis neutron spectrometer, include representation of parabolic and elliptic guide profiles and facilities for numerical optimization of parameter values, characterizing the instrument components. As examples, we present simulations of a doubly focusing monochromator in combination with cold neutron guides and lobster-eye supermirror devices, concentrating a monochromatic beam to small sample volumes. A Levenberg-Marquardt minimization algorithm is used to optimize simultaneously several parameters of the monochromator and lobster-eye guides. We compare the performance of optimized configurations in terms of monochromatic neutron flux and energy spread and demonstrate the effect of lobster-eye optics on beam transformations in real and momentum subspaces

  5. McStas 1.1. A freeware package for neutron Monte Carlo ray-tracing simulations

    International Nuclear Information System (INIS)

    Lefmann, K.; Nielsen, K.

    1999-01-01

    Neutron simulation is becoming an indispensable tool for neutron instrument design. At Risoe National Laboratory, a user-friendly, versatile, and fast simulation package, McStas has been developed, which may be freely downloaded from our website. An instrument is described in the McStas meta-language and is composed of elements from the McStas component library, which is under constant development and debugging by both the users and us. The McStas front- and back-ends take care of performing the simulations and displaying their results, respectively. McStas 1.1 facilities detailed simulations of complicated triple-axis instruments like the Riso RITA spectrometer, and it is equally well equipped for time-of flight spectrometers. At ECNS'99, a brief tutorial of McStas including a few on-line demonstrations is presented. Further, results from the latest simulation work in the growing McStas user group are presented and the future of this project is discussed. (author)

  6. MCViNE – An object oriented Monte Carlo neutron ray tracing simulation package

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jiao Y.Y., E-mail: linjiao@ornl.gov [Caltech Center for Advanced Computing Research, California Institute of Technology (United States); Department of Applied Physics and Materials Science, California Institute of Technology (United States); Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory (United States); Smith, Hillary L. [Department of Applied Physics and Materials Science, California Institute of Technology (United States); Granroth, Garrett E., E-mail: granrothge@ornl.gov [Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory (United States); Abernathy, Douglas L.; Lumsden, Mark D.; Winn, Barry; Aczel, Adam A. [Quantum Condensed Matter Division, Oak Ridge National Laboratory (United States); Aivazis, Michael [Caltech Center for Advanced Computing Research, California Institute of Technology (United States); Fultz, Brent, E-mail: btf@caltech.edu [Department of Applied Physics and Materials Science, California Institute of Technology (United States)

    2016-02-21

    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.

  7. New challenges in ray tracing simulations of X-ray optics

    International Nuclear Information System (INIS)

    Río, M Sánchez del

    2013-01-01

    The construction of new synchrotron sources and the refurbishment and upgrade of existing ones has boosted in the last years the interest in X-ray optics simulations for beamline design and optimization. In the last years we conducted a full renewal of the well established SHADOW ray tracing code, ending with a modular version SHADOW3 interfaced to multiple programming languages (C, C++, IDL, Python). Some of the new features of SHADOW3 are presented. From the physics point of view, SHADOW3 has been upgraded for dealing with lens systems. X-ray partial coherence applications demand an extension of traditional ray tracing methods into a hybrid ray-tracing wave-optics approach. The software development is essential for fulfilling the requests of the ESRF Upgrade Programme, and some examples of calculations are also presented.

  8. McStas

    DEFF Research Database (Denmark)

    Willendrup, Peter Kjær; Farhi, Emmanuel; Bergbäck Knudsen, Erik

    2014-01-01

    experiments. McStas is being actively used for the design-update of the European Spallation Source (ESS) in Lund. This paper includes an introduction to the McStas package, recent and ongoing simulation projects. Further, new features in releases McStas 1.12c and 2.0 are discussed.......The McStas neutron ray-tracing simulation package is a collaboration between Risø DTU, ILL, University of Copenhagen and the PSI. During its lifetime, McStas has evolved to become the world leading software in the area of neutron scattering simulations for instrument design, optimisation, virtual...

  9. Interfacing MCNPX and McStas for simulation of neutron transport

    DEFF Research Database (Denmark)

    Klinkby, Esben Bryndt; Lauritzen, Bent; Nonbøl, Erik

    2013-01-01

    Stas[4, 5, 6, 7]. The coupling between the two simulation suites typically consists of providing analytical fits of MCNPX neutron spectra to McStas. This method is generally successful but has limitations, as it e.g. does not allow for re-entry of neutrons into the MCNPX regime. Previous work to resolve......Simulations of target-moderator-reflector system at spallation sources are conventionally carried out using Monte Carlo codes such as MCNPX[1] or FLUKA[2, 3] whereas simulations of neutron transport from the moderator and the instrument response are performed by neutron ray tracing codes such as Mc...... geometries, backgrounds, interference between beam-lines as well as shielding requirements along the neutron guides....

  10. Developing an interface between MCNP and McStas for simulation of neutron moderators

    DEFF Research Database (Denmark)

    Klinkby, Esben Bryndt; Lauritzen, Bent; Nonbøl, Erik

    2012-01-01

    Simulations of target-moderator-reflector system at spallation sources are conventionally carried out using MCNP/X whereas simulations of neutron transport and instrument performance are carried out by neutron ray tracing codes such as McStas. The coupling between the two simulations suites...... typically consists of providing analytical fits from MCNP/X neutron spectra to McStas. This method is generally successful, but as will be discussed in the this paper, there are limitations and a more direct coupling between MCNP/X andMcStas could allow for more accurate simulations of e.g. complex...... moderator geometries, interference between beamlines as well as shielding requirements along the neutron guides. In this paper different possible interfaces between McStas and MCNP/X are discussed and first preliminary performance results are shown....

  11. New developments in the McStas neutron instrument simulation package

    International Nuclear Information System (INIS)

    Willendrup, P K; Knudsen, E B; Klinkby, E; Nielsen, T; Farhi, E; Filges, U; Lefmann, K

    2014-01-01

    The McStas neutron ray-tracing software package is a versatile tool for building accurate simulators of neutron scattering instruments at reactors, short- and long-pulsed spallation sources such as the European Spallation Source. McStas is extensively used for design and optimization of instruments, virtual experiments, data analysis and user training. McStas was founded as a scientific, open-source collaborative code in 1997. This contribution presents the project at its current state and gives an overview of the main new developments in McStas 2.0 (December 2012) and McStas 2.1 (expected fall 2013), including many new components, component parameter uniformisation, partial loss of backward compatibility, updated source brilliance descriptions, developments toward new tools and user interfaces, web interfaces and a new method for estimating beam losses and background from neutron optics.

  12. Quantitative trace element analysis of individual fly ash particles by means of X-ray microfluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Vincze, L.; Somogyi, A.; Osan, J.; Vekemans, B.; Torok, S.; Janssens, K.; Adams, F. [Universitaire of Instelling Antwerp, Wilrijk (Belgium). Dept. of Chemistry

    2002-07-01

    A new quantification procedure was developed for the evaluation of X-ray microfluorescence (XRF) data sets obtained from individual particles, based on iterative Monte Carlo (MC) simulation. Combined with the high sensitivity of synchrotron radiation-induced XRF spectroscopy, the method was used to obtain quantitative information down to trace-level concentrations from micrometer-sized particulate matter. The detailed XRF simulation model was validated by comparison of calculated and experimental XRF spectra obtained for glass microsphere standards, resulting in uncertainties in the range of 3-10% for the calculated elemental sensitivities. The simulation model was applied for the quantitative analysis of X-ray tube and synchrotron radiation-induced scanning micro-XRF spectra of individual coal and wood fly ash particles originating from different Hungarian power plants. By measuring the same particles by both methods the major, minor, and trace element compositions of the particles were determined. The uncertainty of the MC based quantitative analysis scheme is estimated to be in the range of 5-30%.

  13. Ray tracing the Wigner distribution function for optical simulations

    NARCIS (Netherlands)

    Mout, B.M.; Wick, Michael; Bociort, F.; Petschulat, Joerg; Urbach, Paul

    2018-01-01

    We study a simulation method that uses the Wigner distribution function to incorporate wave optical effects in an established framework based on geometrical optics, i.e., a ray tracing engine. We use the method to calculate point spread functions and show that it is accurate for paraxial systems

  14. 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.

  15. 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

  16. 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.

  17. Solar proton exposure of an ICRU sphere within a complex structure part II: Ray-trace geometry.

    Science.gov (United States)

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

    2016-06-01

    A computationally efficient 3DHZETRN code with enhanced neutron and light ion (Z ≤ 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. Published by Elsevier Ltd.

  18. Ray Tracing for Real-time Games

    NARCIS (Netherlands)

    Bikker, J.

    2012-01-01

    This thesis describes efficient rendering algorithms based on ray tracing, and the application of these algorithms to real-time games. Compared to rasterizationbased approaches, rendering based on ray tracing allows elegant and correct simulation of important global effects, such as shadows,

  19. 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...

  20. Ray tracing the Wigner distribution function for optical simulations

    Science.gov (United States)

    Mout, Marco; Wick, Michael; Bociort, Florian; Petschulat, Joerg; Urbach, Paul

    2018-01-01

    We study a simulation method that uses the Wigner distribution function to incorporate wave optical effects in an established framework based on geometrical optics, i.e., a ray tracing engine. We use the method to calculate point spread functions and show that it is accurate for paraxial systems but produces unphysical results in the presence of aberrations. The cause of these anomalies is explained using an analytical model.

  1. Numerical simulation and comparison of nonlinear self-focusing based on iteration and ray tracing

    Science.gov (United States)

    Li, Xiaotong; Chen, Hao; Wang, Weiwei; Ruan, Wangchao; Zhang, Luwei; Cen, Zhaofeng

    2017-05-01

    Self-focusing is observed in nonlinear materials owing to the interaction between laser and matter when laser beam propagates. Some of numerical simulation strategies such as the beam propagation method (BPM) based on nonlinear Schrödinger equation and ray tracing method based on Fermat's principle have applied to simulate the self-focusing process. In this paper we present an iteration nonlinear ray tracing method in that the nonlinear material is also cut into massive slices just like the existing approaches, but instead of paraxial approximation and split-step Fourier transform, a large quantity of sampled real rays are traced step by step through the system with changing refractive index and laser intensity by iteration. In this process a smooth treatment is employed to generate a laser density distribution at each slice to decrease the error caused by the under-sampling. The characteristics of this method is that the nonlinear refractive indices of the points on current slice are calculated by iteration so as to solve the problem of unknown parameters in the material caused by the causal relationship between laser intensity and nonlinear refractive index. Compared with the beam propagation method, this algorithm is more suitable for engineering application with lower time complexity, and has the calculation capacity for numerical simulation of self-focusing process in the systems including both of linear and nonlinear optical media. If the sampled rays are traced with their complex amplitudes and light paths or phases, it will be possible to simulate the superposition effects of different beam. At the end of the paper, the advantages and disadvantages of this algorithm are discussed.

  2. The Alba ray tracing code: ART

    Science.gov (United States)

    Nicolas, Josep; Barla, Alessandro; Juanhuix, Jordi

    2013-09-01

    The Alba ray tracing code (ART) is a suite of Matlab functions and tools for the ray tracing simulation of x-ray beamlines. The code is structured in different layers, which allow its usage as part of optimization routines as well as an easy control from a graphical user interface. Additional tools for slope error handling and for grating efficiency calculations are also included. Generic characteristics of ART include the accumulation of rays to improve statistics without memory limitations, and still providing normalized values of flux and resolution in physically meaningful units.

  3. Multiscale optical simulation settings: challenging applications handled with an iterative ray-tracing FDTD interface method.

    Science.gov (United States)

    Leiner, Claude; Nemitz, Wolfgang; Schweitzer, Susanne; Kuna, Ladislav; Wenzl, Franz P; Hartmann, Paul; Satzinger, Valentin; Sommer, Christian

    2016-03-20

    We show that with an appropriate combination of two optical simulation techniques-classical ray-tracing and the finite difference time domain method-an optical device containing multiple diffractive and refractive optical elements can be accurately simulated in an iterative simulation approach. We compare the simulation results with experimental measurements of the device to discuss the applicability and accuracy of our iterative simulation procedure.

  4. Simulation of Satellite, Airborne and Terrestrial LiDAR with DART (I):Waveform Simulation with Quasi-Monte Carlo Ray Tracing

    Science.gov (United States)

    Gastellu-Etchegorry, Jean-Philippe; Yin, Tiangang; Lauret, Nicolas; Grau, Eloi; Rubio, Jeremy; Cook, Bruce D.; Morton, Douglas C.; Sun, Guoqing

    2016-01-01

    Light Detection And Ranging (LiDAR) provides unique data on the 3-D structure of atmosphere constituents and the Earth's surface. Simulating LiDAR returns for different laser technologies and Earth scenes is fundamental for evaluating and interpreting signal and noise in LiDAR data. Different types of models are capable of simulating LiDAR waveforms of Earth surfaces. Semi-empirical and geometric models can be imprecise because they rely on simplified simulations of Earth surfaces and light interaction mechanisms. On the other hand, Monte Carlo ray tracing (MCRT) models are potentially accurate but require long computational time. Here, we present a new LiDAR waveform simulation tool that is based on the introduction of a quasi-Monte Carlo ray tracing approach in the Discrete Anisotropic Radiative Transfer (DART) model. Two new approaches, the so-called "box method" and "Ray Carlo method", are implemented to provide robust and accurate simulations of LiDAR waveforms for any landscape, atmosphere and LiDAR sensor configuration (view direction, footprint size, pulse characteristics, etc.). The box method accelerates the selection of the scattering direction of a photon in the presence of scatterers with non-invertible phase function. The Ray Carlo method brings traditional ray-tracking into MCRT simulation, which makes computational time independent of LiDAR field of view (FOV) and reception solid angle. Both methods are fast enough for simulating multi-pulse acquisition. Sensitivity studies with various landscapes and atmosphere constituents are presented, and the simulated LiDAR signals compare favorably with their associated reflectance images and Laser Vegetation Imaging Sensor (LVIS) waveforms. The LiDAR module is fully integrated into DART, enabling more detailed simulations of LiDAR sensitivity to specific scene elements (e.g., atmospheric aerosols, leaf area, branches, or topography) and sensor configuration for airborne or satellite LiDAR sensors.

  5. Real time ray tracing based on shader

    Science.gov (United States)

    Gui, JiangHeng; Li, Min

    2017-07-01

    Ray tracing is a rendering algorithm for generating an image through tracing lights into an image plane, it can simulate complicate optical phenomenon like refraction, depth of field and motion blur. Compared with rasterization, ray tracing can achieve more realistic rendering result, however with greater computational cost, simple scene rendering can consume tons of time. With the GPU's performance improvement and the advent of programmable rendering pipeline, complicated algorithm can also be implemented directly on shader. So, this paper proposes a new method that implement ray tracing directly on fragment shader, mainly include: surface intersection, importance sampling and progressive rendering. With the help of GPU's powerful throughput capability, it can implement real time rendering of simple scene.

  6. A Computer Library for Ray Tracing in Analytical Media

    International Nuclear Information System (INIS)

    Miqueles, Eduardo; Coimbra, Tiago A; Figueiredo, J J S de

    2013-01-01

    Ray tracing technique is an important tool not only for forward but also for inverse problems in Geophysics, which most of the seismic processing steps depends on. However, implementing ray tracing codes can be very time consuming. This article presents a computer library to trace rays in 2.5D media composed by stack of layers. The velocity profile inside each layer is such that the eikonal equation can be analitically solved. Therefore, the ray tracing within such profile is made fast and accurately. The great advantage of an analytical ray tracing library is the numerical precision of the quantities computed and the fast execution of the implemented codes. Although ray tracing programs already exist for a long time, for example the seis package by Cervený, with a numerical approach to compute the ray. Regardless of the fact that numerical methods can solve more general problems, the analytical ones could be part of a more sofisticated simulation process, where the ray tracing time is completely relevant. We demonstrate the feasibility of our codes using numerical examples.

  7. Ray tracing reconstruction investigation for C-arm tomosynthesis

    Science.gov (United States)

    Malalla, Nuhad A. Y.; Chen, Ying

    2016-04-01

    C-arm tomosynthesis is a three dimensional imaging technique. Both x-ray source and the detector are mounted on a C-arm wheeled structure to provide wide variety of movement around the object. In this paper, C-arm tomosynthesis was introduced to provide three dimensional information over a limited view angle (less than 180o) to reduce radiation exposure and examination time. Reconstruction algorithms based on ray tracing method such as ray tracing back projection (BP), simultaneous algebraic reconstruction technique (SART) and maximum likelihood expectation maximization (MLEM) were developed for C-arm tomosynthesis. C-arm tomosynthesis projection images of simulated spherical object were simulated with a virtual geometric configuration with a total view angle of 40 degrees. This study demonstrated the sharpness of in-plane reconstructed structure and effectiveness of removing out-of-plane blur for each reconstruction algorithms. Results showed the ability of ray tracing based reconstruction algorithms to provide three dimensional information with limited angle C-arm tomosynthesis.

  8. Development of ray tracing visualization program by Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Kenji; Otani, Takayuki [Japan Atomic Energy Research Inst., Tokyo (Japan); Hasegawa, Yukihiro

    1997-09-01

    Ray tracing algorithm is a powerful method to synthesize three dimensional computer graphics. In conventional ray tracing algorithms, a view point is used as a starting point of ray tracing, from which the rays are tracked up to the light sources through center points of pixels on the view screen to calculate the intensities of the pixels. This manner, however, makes it difficult to define the configuration of light source as well as to strictly simulate the reflections of the rays. To resolve these problems, we have developed a new ray tracing means which traces rays from a light source, not from a view point, with use of Monte Carlo method which is widely applied in nuclear fields. Moreover, we adopt the variance reduction techniques to the program with use of the specialized machine (Monte-4) for particle transport Monte Carlo so that the computational time could be successfully reduced. (author)

  9. Evaluation of simulation alternatives for the brute-force ray-tracing approach used in backlight design

    Science.gov (United States)

    Desnijder, Karel; Hanselaer, Peter; Meuret, Youri

    2016-04-01

    A key requirement to obtain a uniform luminance for a side-lit LED backlight is the optimised spatial pattern of structures on the light guide that extract the light. The generation of such a scatter pattern is usually performed by applying an iterative approach. In each iteration, the luminance distribution of the backlight with a particular scatter pattern is analysed. This is typically performed with a brute-force ray-tracing algorithm, although this approach results in a time-consuming optimisation process. In this study, the Adding-Doubling method is explored as an alternative way for evaluating the luminance of a backlight. Due to the similarities between light propagating in a backlight with extraction structures and light scattering in a cloud of light scatterers, the Adding-Doubling method which is used to model the latter could also be used to model the light distribution in a backlight. The backlight problem is translated to a form upon which the Adding-Doubling method is directly applicable. The calculated luminance for a simple uniform extraction pattern with the Adding-Doubling method matches the luminance generated by a commercial raytracer very well. Although successful, no clear computational advantage over ray tracers is realised. However, the dynamics of light propagation in a light guide as used the Adding-Doubling method, also allow to enhance the efficiency of brute-force ray-tracing algorithms. The performance of this enhanced ray-tracing approach for the simulation of backlights is also evaluated against a typical brute-force ray-tracing approach.

  10. Infant word recognition: Insights from TRACE simulations.

    Science.gov (United States)

    Mayor, Julien; Plunkett, Kim

    2014-02-01

    The TRACE model of speech perception (McClelland & Elman, 1986) is used to simulate results from the infant word recognition literature, to provide a unified, theoretical framework for interpreting these findings. In a first set of simulations, we demonstrate how TRACE can reconcile apparently conflicting findings suggesting, on the one hand, that consonants play a pre-eminent role in lexical acquisition (Nespor, Peña & Mehler, 2003; Nazzi, 2005), and on the other, that there is a symmetry in infant sensitivity to vowel and consonant mispronunciations of familiar words (Mani & Plunkett, 2007). In a second series of simulations, we use TRACE to simulate infants' graded sensitivity to mispronunciations of familiar words as reported by White and Morgan (2008). An unexpected outcome is that TRACE fails to demonstrate graded sensitivity for White and Morgan's stimuli unless the inhibitory parameters in TRACE are substantially reduced. We explore the ramifications of this finding for theories of lexical development. Finally, TRACE mimics the impact of phonological neighbourhoods on early word learning reported by Swingley and Aslin (2007). TRACE offers an alternative explanation of these findings in terms of mispronunciations of lexical items rather than imputing word learning to infants. Together these simulations provide an evaluation of Developmental (Jusczyk, 1993) and Familiarity (Metsala, 1999) accounts of word recognition by infants and young children. The findings point to a role for both theoretical approaches whereby vocabulary structure and content constrain infant word recognition in an experience-dependent fashion, and highlight the continuity in the processes and representations involved in lexical development during the second year of life.

  11. User and programmers guide to the neutron ray-tracing package McStas, version 1.2

    DEFF Research Database (Denmark)

    Nielsen, K.; Lefmann, K.

    2000-01-01

    to handle more unusual needs. This report constitutes the reference manual for McStas, and contains full documentation for all ascpects of the program. Itcovers the various ways to compile and run simulations; a description of the metalanguage used to define simulations; a full description of all algorithms...

  12. New features in McStas, version 1.5

    DEFF Research Database (Denmark)

    Åstrand, P.O.; Lefmann, K.; Farhi, E.

    2002-01-01

    The neutron ray-tracing simulation package McStas has attracted numerous users, and the development of the package continues with version 1.5 released at the ICNS 2001 conference. New features include: support for neutron polarisation, labelling of neutrons, realistic source and sample components......, and interface to the Riso instrument-control software TASCOM. We give a general introduction to McStas and present the latest developments. In particular, we give an example of how the neutron-label option has been used to locate the origin of a spurious side-peak, observed in an experiment with RITA-1 at Riso....

  13. New features in McStas, version 1.5

    International Nuclear Information System (INIS)

    Aastrand, P.O.; Lefmann, K.; Nielsen, K.; Skaarup, P.; Farhi, E.

    2002-01-01

    The neutron ray-tracing simulation package McStas has attracted numerous users, and the development of the package continues with version 1.5 released at the ICNS 2001 conference. New features include: support for neutron polarisation, labelling of neutrons, realistic source and sample components, and interface to the Riso instrument-control software TASCOM. We give a general introduction to McStas and present the latest developments. In particular, we give an example of how the neutron-label option has been used to locate the origin of a spurious side-peak, observed in an experiment with RITA-1 at Riso. (orig.)

  14. Simulation tools for scattering corrections in spectrally resolved x-ray computed tomography using McXtrace

    Science.gov (United States)

    Busi, Matteo; Olsen, Ulrik L.; Knudsen, Erik B.; Frisvad, Jeppe R.; Kehres, Jan; Dreier, Erik S.; Khalil, Mohamad; Haldrup, Kristoffer

    2018-03-01

    Spectral computed tomography is an emerging imaging method that involves using recently developed energy discriminating photon-counting detectors (PCDs). This technique enables measurements at isolated high-energy ranges, in which the dominating undergoing interaction between the x-ray and the sample is the incoherent scattering. The scattered radiation causes a loss of contrast in the results, and its correction has proven to be a complex problem, due to its dependence on energy, material composition, and geometry. Monte Carlo simulations can utilize a physical model to estimate the scattering contribution to the signal, at the cost of high computational time. We present a fast Monte Carlo simulation tool, based on McXtrace, to predict the energy resolved radiation being scattered and absorbed by objects of complex shapes. We validate the tool through measurements using a CdTe single PCD (Multix ME-100) and use it for scattering correction in a simulation of a spectral CT. We found the correction to account for up to 7% relative amplification in the reconstructed linear attenuation. It is a useful tool for x-ray CT to obtain a more accurate material discrimination, especially in the high-energy range, where the incoherent scattering interactions become prevailing (>50 keV).

  15. Computer ray tracing speeds.

    Science.gov (United States)

    Robb, P; Pawlowski, B

    1990-05-01

    The results of measuring the ray trace speed and compilation speed of thirty-nine computers in fifty-seven configurations, ranging from personal computers to super computers, are described. A correlation of ray trace speed has been made with the LINPACK benchmark which allows the ray trace speed to be estimated using LINPACK performance data. The results indicate that the latest generation of workstations, using CPUs based on RISC (Reduced Instruction Set Computer) technology, are as fast or faster than mainframe computers in compute-bound situations.

  16. 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...

  17. 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.

  18. 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

  19. Usage of ray tracing transfer matrix to mitigate the stray light for ITER spectroscopy

    International Nuclear Information System (INIS)

    Kajita, S.; Veshchev, E.; Barnsley, R.; Walsh, M.

    2016-01-01

    Stray light formed by the reflection of photons on inner wall from a bright divertor region can be a serious issue in spectroscopic measurement systems in ITER. In this study, we propose a method to mitigate the influence of stray light using a ray tracing analysis. Usually, a ray tracing simulation requires a time consuming runs. We constructed transfer matrices based on the ray tracing simulation results and used them to demonstrate the influence of stray light. It is shown that the transfer matrix can be used to reconstruct the emission profile by considering the influence of the stray light without any additional ray tracing runs. Mitigation of the stray light in ITER divertor impurity monitor was demonstrated, and a method of prediction of the stray light level for the scrape off layer spectroscopy from divertor region was proposed. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Simulation of transmitted X-rays in a polycapillary X-ray lens

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Shiqi [The Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Liu, Zhiguo, E-mail: liuzhiguo512@126.com [The Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi; Wang, Kai; Yi, Longtao; Yang, Kui; Chen, Man; Wang, Jinbang [The Key Laboratory of Beam Technology and Material Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2015-09-21

    The geometrical description of capillary systems adjusted for the controlled guiding of X-rays and the basic theory of the transmission of X-rays are presented. A method of numerical calculation, based on Ray-Tracing theory, is developed to simulate the transmission efficiency of an X-ray parallel lens and the shape and size of the light spot gain from it. The simulation results for two half-lenses are in good agreement with the experimental results.

  1. Application of the MCNPX-McStas interface for shielding calculations and guide design at ESS

    DEFF Research Database (Denmark)

    Klinkby, Esben Bryndt; Bergbäck Knudsen, Erik; Willendrup, Peter Kjær

    2013-01-01

    . The generation and moderation of neutrons is simulated using a full scale MCNPX model of the ESS target monolith. Upon entering the beam extraction region, the individual neutron states are handed to McStas via the MCNPX-McStas interface. McStas transports the neutrons through the beam guide and by using newly......Recently, an interface between the Monte Carlo code MCNPX and the neutron ray-tracing code MCNPX was developed[1]. Based on the expected neutronic performance and guide geometries relevant for the ESS, the combined MCNPX-McStas code is used to calculate dose rates along neutron beam guides...... developed event logging capability, the neutron state parameters corresponding to un-reflected neutrons are recorded at each scattering. This information is handed back to MCNPX where it serves as neutron source input for a second MCNPX simulation. This simulation enables calculation of dose rates...

  2. Advanced 3D tools used in reverse engineering and ray tracing simulation of phased array inspection of turbine components with complex geometry

    International Nuclear Information System (INIS)

    Daks, W.; Kovacshazy, C.; Mair, D.; Ciorau, P.

    2002-01-01

    This paper outlines the practical aspects of reverse engineering and the integration of multiple pieces of software (Drafting, CNC Machining, Ray Tracing, Inspection Simulation Scenario and Phased Array UT Analysis), in order to inspect turbine components comprised of complex geometry. The CNC software, Mastercam, and design software, CADKEY/FastSURF, were used to validate the phased-array automated and manual inspection of blade root, rotor steeples and disk-blade rim attachment. The integration of a 3D part in the software engine, Imagine 3D and SimScan, as well as Tomoview analysis (specimen feature) is based on CADKEY Developer Kit - IGES/SAT file format. A generic Ray Tracing simulation for multi-probe beam was integrated into Imagine 3D. Representative examples of reference blocks and mock-ups, UT simulation and phased-array data comparison are presented. (author)

  3. 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.

  4. Ray tracing study of rising tone EMIC-triggered emissions

    Science.gov (United States)

    Hanzelka, Miroslav; Santolík, Ondřej; Grison, Benjamin; Cornilleau-Wehrlin, Nicole

    2017-04-01

    ElectroMagnetic Ion Cyclotron (EMIC) triggered emissions have been subject of extensive theoretical and experimental research in last years. These emissions are characterized by high coherence values and a frequency range of 0.5 - 2.0 Hz, close to local helium gyrofrequency. We perform ray tracing case studies of rising tone EMIC-triggered emissions observed by the Cluster spacecraft in both nightside and dayside regions off the equatorial plane. By comparison of simulated and measured wave properties, namely wave vector orientation, group velocity, dispersion and ellipticity of polarization, we determine possible source locations. Diffusive equilibrium density model and other, semi-empirical models are used with ion composition inferred from cross-over frequencies. Ray tracing simulations are done in cold plasma approximation with inclusion of Landau and cyclotron damping. Various widths, locations and profiles of plasmapause are tested.

  5. McStas event logger

    DEFF Research Database (Denmark)

    Bergbäck Knudsen, Erik; Willendrup, Peter Kjær; Klinkby, Esben Bryndt

    2014-01-01

    Functionality is added to the McStas neutron ray-tracing code, which allows individual neutron states before and after a scattering to be temporarily stored, and analysed. This logging mechanism has multiple uses, including studies of longitudinal intensity loss in neutron guides and guide coatin...

  6. Monte Carlo Simulation of Complete X-Ray Spectra for Use in Scanning Electron Microscopy Analysis

    International Nuclear Information System (INIS)

    Roet, David; Van Espen, Piet

    2003-01-01

    Full Text: The interactions of keV electrons and photons with matter can be simulated accurately with the aid of the Monte Carlo (MC) technique. In scanning electron microscopy x-ray analysis (SEM-EDX) such simulations can be used to perform quantitative analysis using a Reverse Monte Carlo method even if the samples have irregular geometry. Alternatively the MC technique can generate spectra of standards for use in quantization with partial least squares regression. The feasibility of these alternatives to the more classical ZAF or phi-rho-Z quantification methods has been proven already. In order to be applicable for these purposes the MC-code needs to generate accurately only the characteristic K and L x-ray lines, but also the Bremsstrahlung continuum, i.e. the complete x-ray spectrum need to be simulated. Currently two types of MC simulation codes are available. Programs like Electron Flight Simulator and CASINO simulate characteristic x-rays due to electron interaction in a fast and efficient way but lack provision for the simulation of the continuum. On the other hand, programs like EGS4, MCNP4 and PENELOPE, originally developed for high energy (MeV- GeV) applications, are more complete but difficult to use and still slow, even on todays fastest computers. We therefore started the development of a dedicated MC simulation code for use in quantitative SEM-EDX work. The selection of the most appropriate cross section for the different interactions will be discussed and the results obtained will be compared with those obtained with existing MC programs. Examples of the application of MC simulations for quantitative analysis of samples with various composition will be given

  7. 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.

  8. 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

  9. 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.

  10. Using McStas for modelling complex optics, using simple building bricks

    International Nuclear Information System (INIS)

    Willendrup, Peter K.; Udby, Linda; Knudsen, Erik; Farhi, Emmanuel; Lefmann, Kim

    2011-01-01

    The McStas neutron ray-tracing simulation package is a versatile tool for producing accurate neutron simulations, extensively used for design and optimization of instruments, virtual experiments, data analysis and user training. In McStas, component organization and simulation flow is intrinsically linear: the neutron interacts with the beamline components in a sequential order, one by one. Historically, a beamline component with several parts had to be implemented with a complete, internal description of all these parts, e.g. a guide component including all four mirror plates and required logic to allow scattering between the mirrors. For quite a while, users have requested the ability to allow 'components inside components' or meta-components, allowing to combine functionality of several simple components to achieve more complex behaviour, i.e. four single mirror plates together defining a guide. We will here show that it is now possible to define meta-components in McStas, and present a set of detailed, validated examples including a guide with an embedded, wedged, polarizing mirror system of the Helmholtz-Zentrum Berlin type.

  11. 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)

  12. Improved backward ray tracing with stochastic sampling

    Science.gov (United States)

    Ryu, Seung Taek; Yoon, Kyung-Hyun

    1999-03-01

    This paper presents a new technique that enhances the diffuse interreflection with the concepts of backward ray tracing. In this research, we have modeled the diffuse rays with the following conditions. First, as the reflection from the diffuse surfaces occurs in all directions, it is impossible to trace all of the reflected rays. We confined the diffuse rays by sampling the spherical angle out of the reflected rays around the normal vector. Second, the traveled distance of reflected energy from the diffuse surface differs according to the object's property, and has a comparatively short reflection distance. Considering the fact that the rays created on the diffuse surfaces affect relatively small area, it is very inefficient to trace all of the sampled diffused rays. Therefore, we set a fixed distance as the critical distance and all the rays beyond this distance are ignored. The result of this research is that as the improved backward ray tracing can model the illumination effects such as the color bleeding effects, we can replace the radiosity algorithm under the limited environment.

  13. SOLFAST, a Ray-Tracing Monte-Carlo software for solar concentrating facilities

    International Nuclear Information System (INIS)

    Roccia, J P; Piaud, B; Coustet, C; Caliot, C; Guillot, E; Flamant, G; Delatorre, J

    2012-01-01

    In this communication, the software SOLFAST is presented. It is a simulation tool based on the Monte-Carlo method and accelerated Ray-Tracing techniques to evaluate efficiently the energy flux in concentrated solar installations.

  14. RAY TRACING IMPLEMENTATION IN JAVA PROGRAMMING LANGUAGE

    OpenAIRE

    Aybars UĞUR; Mustafa TÜRKSEVER

    2002-01-01

    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 ...

  15. Technical Note: A direct ray-tracing method to compute integral depth dose in pencil beam proton radiography with a multilayer ionization chamber.

    Science.gov (United States)

    Farace, Paolo; Righetto, Roberto; Deffet, Sylvain; Meijers, Arturs; Vander Stappen, Francois

    2016-12-01

    To introduce a fast ray-tracing algorithm in pencil proton radiography (PR) with a multilayer ionization chamber (MLIC) for in vivo range error mapping. Pencil beam PR was obtained by delivering spots uniformly positioned in a square (45 × 45 mm 2 field-of-view) of 9 × 9 spots capable of crossing the phantoms (210 MeV). The exit beam was collected by a MLIC to sample the integral depth dose (IDD MLIC ). PRs of an electron-density and of a head phantom were acquired by moving the couch to obtain multiple 45 × 45 mm 2 frames. To map the corresponding range errors, the two-dimensional set of IDD MLIC was compared with (i) the integral depth dose computed by the treatment planning system (TPS) by both analytic (IDD TPS ) and Monte Carlo (IDD MC ) algorithms in a volume of water simulating the MLIC at the CT, and (ii) the integral depth dose directly computed by a simple ray-tracing algorithm (IDD direct ) through the same CT data. The exact spatial position of the spot pattern was numerically adjusted testing different in-plane positions and selecting the one that minimized the range differences between IDD direct and IDD MLIC . Range error mapping was feasible by both the TPS and the ray-tracing methods, but very sensitive to even small misalignments. In homogeneous regions, the range errors computed by the direct ray-tracing algorithm matched the results obtained by both the analytic and the Monte Carlo algorithms. In both phantoms, lateral heterogeneities were better modeled by the ray-tracing and the Monte Carlo algorithms than by the analytic TPS computation. Accordingly, when the pencil beam crossed lateral heterogeneities, the range errors mapped by the direct algorithm matched better the Monte Carlo maps than those obtained by the analytic algorithm. Finally, the simplicity of the ray-tracing algorithm allowed to implement a prototype procedure for automated spatial alignment. The ray-tracing algorithm can reliably replace the TPS method in MLIC PR for in

  16. 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

  17. 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.

  18. Ray-tracing of shape metrology data of grazing incidence x-ray astronomy mirrors

    Science.gov (United States)

    Zocchi, Fabio E.; Vernani, Dervis

    2008-07-01

    A number of future X-ray astronomy missions (e.g. Simbol-X, eROSITA) plan to utilize high throughput grazing incidence optics with very lightweight mirrors. The severe mass specifications require a further optimization of the existing technology with the consequent need of proper optical numerical modeling capabilities for both the masters and the mirrors. A ray tracing code has been developed for the simulation of the optical performance of type I Wolter masters and mirrors starting from 2D and 3D metrology data. In particular, in the case of 2D measurements, a 3D data set is reconstructed on the basis of dimensional references and used for the optical analysis by ray tracing. In this approach, the actual 3D shape is used for the optical analysis, thus avoiding the need of combining the separate contributions of different 2D measurements that require the knowledge of their interactions which is not normally available. The paper describes the proposed approach and presents examples of application on a prototype engineering master in the frame of ongoing activities carried out for present and future X-ray missions.

  19. 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.

  20. Computer program for optical systems ray tracing

    Science.gov (United States)

    Ferguson, T. J.; Konn, H.

    1967-01-01

    Program traces rays of light through optical systems consisting of up to 65 different optical surfaces and computes the aberrations. For design purposes, paraxial tracings with astigmation and third order tracings are provided.

  1. 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.

  2. 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).

  3. Fast estimation of first-order scattering in a medical x-ray computed tomography scanner using a ray-tracing technique.

    Science.gov (United States)

    Liu, Xin

    2014-01-01

    This study describes a deterministic method for simulating the first-order scattering in a medical computed tomography scanner. The method was developed based on a physics model of x-ray photon interactions with matter and a ray tracing technique. The results from simulated scattering were compared to the ones from an actual scattering measurement. Two phantoms with homogeneous and heterogeneous material distributions were used in the scattering simulation and measurement. It was found that the simulated scatter profile was in agreement with the measurement result, with an average difference of 25% or less. Finally, tomographic images with artifacts caused by scatter were corrected based on the simulated scatter profiles. The image quality improved significantly.

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

    KAUST Repository

    Masmoudi, Nabil; Pšenčí k, Ivan

    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.

  5. Software for simulation and design of neutron scattering instrumentation

    DEFF Research Database (Denmark)

    Bertelsen, Mads

    designed using the software. The Union components uses a new approach to simulation of samples in McStas. The properties of a sample are split into geometrical and material, simplifying user input, and allowing the construction of complicated geometries such as sample environments. Multiple scattering...... from conventional choices. Simulation of neutron scattering instrumentation is used when designing instrumentation, but also to understand instrumental effects on the measured scattering data. The Monte Carlo ray-tracing package McStas is among the most popular, capable of simulating the path of each...... neutron through the instrument using an easy to learn language. The subject of the defended thesis is contributions to the McStas language in the form of the software package guide_bot and the Union components.The guide_bot package simplifies the process of optimizing neutron guides by writing the Mc...

  6. Application of the MCNPX-McStas interface for shielding calculations and guide design at ESS

    DEFF Research Database (Denmark)

    Klinkby, Esben Bryndt; Bergbäck Knudsen, Erik; Willendrup, Peter Kjær

    2014-01-01

    Recently, an interface between the Monte Carlo code MCNPX and the neutron ray-tracing code MCNPX was developed [1, 2]. Based on the expected neutronic performance and guide geometries relevant for the ESS, the combined MCNPX-McStas code is used to calculate dose rates along neutron beam guides......, and by using newly developed event logging capability, the neutron state parameters corresponding to un-reflected neutrons are recorded at each scattering. This information is handed back to MCNPX where it serves as neutron source input for a second MCNPX simulation. This simulation enables calculation of dose...

  7. 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.

  8. 3D Laser Imprint Using a Smoother Ray-Traced Power Deposition Method

    Science.gov (United States)

    Schmitt, Andrew J.

    2017-10-01

    Imprinting of laser nonuniformities in directly-driven icf targets is a challenging problem to accurately simulate with large radiation-hydro codes. One of the most challenging aspects is the proper construction of the complex and rapidly changing laser interference structure driving the imprint using the reduced laser propagation models (usually ray-tracing) found in these codes. We have upgraded the modelling capability in our massively-parallel fastrad3d code by adding a more realistic EM-wave interference structure. This interference model adds an axial laser speckle to the previous transverse-only laser structure, and can be impressed on our improved smoothed 3D raytrace package. This latter package, which connects rays to form bundles and performs power deposition calculations on the bundles, is intended to decrease ray-trace noise (which can mask or add to imprint) while using fewer rays. We apply this improved model to 3D simulations of recent imprint experiments performed on the Omega-EP laser and the Nike laser that examined the reduction of imprinting due to very thin high-Z target coatings. We report on the conditions in which this new model makes a significant impact on the development of laser imprint. Supported by US DoE/NNSA.

  9. 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...

  10. AXAF FITS standard for ray trace interchange

    Science.gov (United States)

    Hsieh, Paul F.

    1993-07-01

    A standard data format for the archival and transport of x-ray events generated by ray trace models is described. Upon review and acceptance by the Advanced X-ray Astrophysics Facility (AXAF) Software Systems Working Group (SSWG), this standard shall become the official AXAF data format for ray trace events. The Flexible Image Transport System (FITS) is well suited for the purposes of the standard and was selected to be the basis of the standard. FITS is both flexible and efficient and is also widely used within the astronomical community for storage and transfer of data. In addition, software to read and write FITS format files are widely available. In selecting quantities to be included within the ray trace standard, the AXAF Mission Support team, Science Instruments team, and the other contractor teams were surveyed. From the results of this survey, the following requirements were established: (1) for the scientific needs, each photon should have associated with it: position, direction, energy, and statistical weight; the standard must also accommodate path length (relative phase), and polarization. (2) a unique photon identifier is necessary for bookkeeping purposes; (3) a log of individuals, organizations, and software packages that have modified the data must be maintained in order to create an audit trail; (4) a mechanism for extensions to the basic kernel should be provided; and (5) the ray trace standard should integrate with future AXAF data product standards.

  11. McXtrace

    DEFF Research Database (Denmark)

    Bergbäck Knudsen, Erik; Prodi, Andrea; Baltser, Jana

    2013-01-01

    to the standard X-ray simulation software SHADOW. McXtrace is open source, licensed under the General Public License, and does not require the user to have access to any proprietary software for its operation. The structure of the software is described in detail, and various examples are given to showcase...

  12. A comparison of ray-tracing software for the design of quadrupole microbeam systems

    International Nuclear Information System (INIS)

    Incerti, S.; Smith, R.W.; Merchant, M.; Grime, G.W.; Meot, F.; Serani, L.; Moretto, Ph.; Touzeau, C.; Barberet, Ph.; Habchi, C.; Nguyen, D.T.

    2005-01-01

    For many years the only ray-tracing software available with sufficient precision for the design of quadrupole microbeam focusing systems has been OXRAY and its successor TRAX, developed at Oxford in the 1980s. With the current interest in pushing the beam diameter into the nanometre region, this software has become dated and more importantly the precision at small displacements may not be sufficient and new simulation tools are required. Two candidates for this are Zgoubi, developed at CEA as a general beam line design tool and the CERN simulation program Geant in its latest version Geant4. In order to use Geant4 new quadrupole field modules have been developed and implemented. In this paper the capabilities of the three codes TRAX, Zgoubi and Geant4 are reviewed. Comparisons of ray-tracing calculations in a high demagnification quadrupole probe-forming system for the sub-micron region are presented

  13. X-Ray Outburst from Young Star in McNeil's Nebula

    Science.gov (United States)

    2004-07-01

    Observations with NASA's Chandra X-ray Observatory captured an X-ray outburst from a young star, revealing a probable scenario for the intermittent brightening of the recently discovered McNeil's Nebula. It appears the interaction between the young star's magnetic field and an orbiting disk of gas can cause dramatic, episodic increases in the light from the star and disk, illuminating the surrounding gas. "The story of McNeil's Nebula is a wonderful example of the importance of serendipity in science," said Joel Kastner of the Rochester Institute of Technology in Rochester, New York, lead author of a paper in the July 22 issue of Nature describing the X-ray results. "Visible-light images were made of this region several months before Jay McNeil made his discovery, so it could be determined approximately when and by how much the star flared up to produce McNeil's Nebula." The small nebula, which lies in the constellation Orion about 1300 light years from Earth, was discovered with a 3-inch telescope by McNeil, an amateur astronomer from Paducah, Kentucky, in January 2004. In November 2002, a team led by Ted Simon of the Institute for Astronomy in Hawaii had observed the star-rich region with Chandra in search of young, X-ray emitting stars, and had detected several objects. Optical and infrared astronomers had, as part of independent surveys, also observed the region about a year later, in 2003. After the announcement of McNeil's discovery, optical, infrared and X-ray astronomers rushed to observe the region again. They found that a young star buried in the nebula had flared up, and was illuminating the nebula. This star was coincident with one of the X-ray sources discovered earlier by Simon. Chandra observations obtained by Kastner's group just after the optical outburst showed that the source had brightened fifty-fold in X-rays when compared to Simon's earlier observation. The visible-light eruption provides evidence that the cause of the X-ray outburst is the

  14. X-ray fluorescence method for trace analysis and imaging

    International Nuclear Information System (INIS)

    Hayakawa, Shinjiro

    2000-01-01

    X-ray fluorescence analysis has a long history as 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 tace 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 instruments for trace characterization with a scanning x-ray microprobe are described. (author)

  15. The vectorization of a ray tracing program for image generation

    Science.gov (United States)

    Plunkett, D. J.; Cychosz, J. M.; Bailey, M. J.

    1984-01-01

    Ray tracing is a widely used method for producing realistic computer generated images. Ray tracing involves firing an imaginary ray from a view point, through a point on an image plane, into a three dimensional scene. The intersections of the ray with the objects in the scene determines what is visible at the point on the image plane. This process must be repeated many times, once for each point (commonly called a pixel) in the image plane. A typical image contains more than a million pixels making this process computationally expensive. A traditional ray tracing program processes one ray at a time. In such a serial approach, as much as ninety percent of the execution time is spent computing the intersection of a ray with the surface in the scene. With the CYBER 205, many rays can be intersected with all the bodies im the scene with a single series of vector operations. Vectorization of this intersection process results in large decreases in computation time. The CADLAB's interest in ray tracing stems from the need to produce realistic images of mechanical parts. A high quality image of a part during the design process can increase the productivity of the designer by helping him visualize the results of his work. To be useful in the design process, these images must be produced in a reasonable amount of time. This discussion will explain how the ray tracing process was vectorized and gives examples of the images obtained.

  16. Comparison between ray-tracing and physical optics for the computation of light absorption in capillaries--the influence of diffraction and interference.

    Science.gov (United States)

    Qin, Yuan; Michalowski, Andreas; Weber, Rudolf; Yang, Sen; Graf, Thomas; Ni, Xiaowu

    2012-11-19

    Ray-tracing is the commonly used technique to calculate the absorption of light in laser deep-penetration welding or drilling. Since new lasers with high brilliance enable small capillaries with high aspect ratios, diffraction might become important. To examine the applicability of the ray-tracing method, we studied the total absorptance and the absorbed intensity of polarized beams in several capillary geometries. The ray-tracing results are compared with more sophisticated simulations based on physical optics. The comparison shows that the simple ray-tracing is applicable to calculate the total absorptance in triangular grooves and in conical capillaries but not in rectangular grooves. To calculate the distribution of the absorbed intensity ray-tracing fails due to the neglected interference, diffraction, and the effects of beam propagation in the capillaries with sub-wavelength diameter. If diffraction is avoided e.g. with beams smaller than the entrance pupil of the capillary or with very shallow capillaries, the distribution of the absorbed intensity calculated by ray-tracing corresponds to the local average of the interference pattern found by physical optics.

  17. Simulation of high-resolution X-ray microscopic images for improved alignment

    International Nuclear Information System (INIS)

    Song Xiangxia; Zhang Xiaobo; Liu Gang; Cheng Xianchao; Li Wenjie; Guan Yong; Liu Ying; Xiong Ying; Tian Yangchao

    2011-01-01

    The introduction of precision optical elements to X-ray microscopes necessitates fine realignment to achieve optimal high-resolution imaging. In this paper, we demonstrate a numerical method for simulating image formation that facilitates alignment of the source, condenser, objective lens, and CCD camera. This algorithm, based on ray-tracing and Rayleigh-Sommerfeld diffraction theory, is applied to simulate the X-ray microscope beamline U7A of National Synchrotron Radiation Laboratory (NSRL). The simulations and imaging experiments show that the algorithm is useful for guiding experimental adjustments. Our alignment simulation method is an essential tool for the transmission X-ray microscope (TXM) with optical elements and may also be useful for the alignment of optical components in other modes of microscopy.

  18. Application of ray-traced tropospheric slant delays to geodetic VLBI analysis

    Science.gov (United States)

    Hofmeister, Armin; Böhm, Johannes

    2017-08-01

    The correction of tropospheric influences via so-called path delays is critical for the analysis of observations from space geodetic techniques like the very long baseline interferometry (VLBI). In standard VLBI analysis, the a priori slant path delays are determined using the concept of zenith delays, mapping functions and gradients. The a priori use of ray-traced delays, i.e., tropospheric slant path delays determined with the technique of ray-tracing through the meteorological data of numerical weather models (NWM), serves as an alternative way of correcting the influences of the troposphere on the VLBI observations within the analysis. In the presented research, the application of ray-traced delays to the VLBI analysis of sessions in a time span of 16.5 years is investigated. Ray-traced delays have been determined with program RADIATE (see Hofmeister in Ph.D. thesis, Department of Geodesy and Geophysics, Faculty of Mathematics and Geoinformation, Technische Universität Wien. http://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-3444, 2016) utilizing meteorological data provided by NWM of the European Centre for Medium-Range Weather Forecasts (ECMWF). In comparison with a standard VLBI analysis, which includes the tropospheric gradient estimation, the application of the ray-traced delays to an analysis, which uses the same parameterization except for the a priori slant path delay handling and the used wet mapping factors for the zenith wet delay (ZWD) estimation, improves the baseline length repeatability (BLR) at 55.9% of the baselines at sub-mm level. If no tropospheric gradients are estimated within the compared analyses, 90.6% of all baselines benefit from the application of the ray-traced delays, which leads to an average improvement of the BLR of 1 mm. The effects of the ray-traced delays on the terrestrial reference frame are also investigated. A separate assessment of the RADIATE ray-traced delays is carried out by comparison to the ray-traced delays from the

  19. 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 ...

  20. Mathematic models for a ray tracing method and its applications in wireless optical communications.

    Science.gov (United States)

    Zhang, Minglun; Zhang, Yangan; Yuan, Xueguang; Zhang, Jinnan

    2010-08-16

    This paper presents a new ray tracing method, which contains a whole set of mathematic models, and its validity is verified by simulations. In addition, both theoretical analysis and simulation results show that the computational complexity of the method is much lower than that of previous ones. Therefore, the method can be used to rapidly calculate the impulse response of wireless optical channels for complicated systems.

  1. Simulations and experiments on RITA-2 at PSI

    International Nuclear Information System (INIS)

    Klausen, S.N.; Lefmann, K.; McMorrow, D.F.; Altorfer, F.; Janssen, S.; Luethy, M.

    2002-01-01

    The cold-neutron triple-axis spectrometer RITA-2 designed and built at Riso National Laboratory was installed at the neutron source SINQ at Paul Scherrer Institute in April/May 2001. In connection with the installation of RITA-2, computer simulations were performed using the neutron ray-tracing package McStas. The simulation results are compared to real experimental results obtained with a powder sample. Especially, the flux at the sample position and the resolution function of the spectrometer are investigated. (orig.)

  2. Simulations and experiments on RITA-2 at PSI

    Science.gov (United States)

    Klausen, S. N.; Lefmann, K.; McMorrow, D. F.; Altorfer, F.; Janssen, S.; Lüthy, M.

    The cold-neutron triple-axis spectrometer RITA-2 designed and built at Riso National Laboratory was installed at the neutron source SINQ at Paul Scherrer Institute in April/May 2001. In connection with the installation of RITA-2, computer simulations were performed using the neutron ray-tracing package McStas. The simulation results are compared to real experimental results obtained with a powder sample. Especially, the flux at the sample position and the resolution function of the spectrometer are investigated.

  3. McXtrace 1.4: latest developments in the new release

    DEFF Research Database (Denmark)

    Knudsen, Erik B.; Willendrup, Peter Kjær; Garde, Jakob

    2017-01-01

    This paper presents details on some of the important new features in the newly released version of the x-ray tracing software package McXtrace. Although many developments have been made, this presentation is focused on the features that were required to meet the challenges posed for accurate simu...

  4. Construction of a catalog of X-ray spectra for mammography simulations

    International Nuclear Information System (INIS)

    Santos, L.C.S.; Vieira, J.W.

    2017-01-01

    Computational Exposure Models (MCEs) allow the simulation of the interaction of radiation with matter by means of Monte Carlo (MC) techniques. Generally, MCEs are composed of phantom, simulator algorithms of radioactive sources and an MC code to simulate the transport, interaction of the radiation with matter and to evaluate the energy deposited in regions of interest. To compose an MCE for simulations in mammography, the construction of a catalog of X-ray spectra was started, based on the catalog model constructed and using until then in MCEs by the Group of Research in Numerical Dosimetry and by the Group of Research in Computational Dosimetry & Embedded Systems (both referenced in this work as GDN). Potential of 25 kV and 35 kV and used target / filter were applied to the tube: Mo / Mo. The file containing the spectra was read correctly by EGSnrc

  5. 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

  6. 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

  7. GPU-accelerated ray-tracing for real-time treatment planning

    International Nuclear Information System (INIS)

    Heinrich, H; Ziegenhein, P; Kamerling, C P; Oelfke, U; Froening, H

    2014-01-01

    Dose calculation methods in radiotherapy treatment planning require the radiological depth information of the voxels that represent the patient volume to correct for tissue inhomogeneities. This information is acquired by time consuming ray-tracing-based calculations. For treatment planning scenarios with changing geometries and real-time constraints this is a severe bottleneck. We implemented an algorithm for the graphics processing unit (GPU) which implements a ray-matrix approach to reduce the number of rays to trace. Furthermore, we investigated the impact of different strategies of accessing memory in kernel implementations as well as strategies for rapid data transfers between main memory and memory of the graphics device. Our study included the overlapping of computations and memory transfers to reduce the overall runtime using Hyper-Q. We tested our approach on a prostate case (9 beams, coplanar). The measured execution times for a complete ray-tracing range from 28 msec for the computations on the GPU to 99 msec when considering data transfers to and from the graphics device. Our GPU-based algorithm performed the ray-tracing in real-time. The strategies efficiently reduce the time consumption of memory accesses and data transfer overhead. The achieved runtimes demonstrate the viability of this approach and allow improved real-time performance for dose calculation methods in clinical routine.

  8. Fast scattering simulation tool for multi-energy x-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sossin, A., E-mail: artur.sossin@cea.fr [CEA-LETI MINATEC Grenoble, F-38054 Grenoble (France); Tabary, J.; Rebuffel, V. [CEA-LETI MINATEC Grenoble, F-38054 Grenoble (France); Létang, J.M.; Freud, N. [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Claude Bernard Lyon 1, Centre Léon Bérard (France); Verger, L. [CEA-LETI MINATEC Grenoble, F-38054 Grenoble (France)

    2015-12-01

    A combination of Monte Carlo (MC) and deterministic approaches was employed as a means of creating a simulation tool capable of providing energy resolved x-ray primary and scatter images within a reasonable time interval. Libraries of Sindbad, a previously developed x-ray simulation software, were used in the development. The scatter simulation capabilities of the tool were validated through simulation with the aid of GATE and through experimentation by using a spectrometric CdTe detector. A simple cylindrical phantom with cavities and an aluminum insert was used. Cross-validation with GATE showed good agreement with a global spatial error of 1.5% and a maximum scatter spectrum error of around 6%. Experimental validation also supported the accuracy of the simulations obtained from the developed software with a global spatial error of 1.8% and a maximum error of around 8.5% in the scatter spectra.

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

    African Journals Online (AJOL)

    NIJOTECH

    Abstract. 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, ...

  10. CAD-based Monte Carlo program for integrated simulation of nuclear system SuperMC

    International Nuclear Information System (INIS)

    Wu, Yican; Song, Jing; Zheng, Huaqing; Sun, Guangyao; Hao, Lijuan; Long, Pengcheng; Hu, Liqin

    2015-01-01

    Highlights: • The new developed CAD-based Monte Carlo program named SuperMC for integrated simulation of nuclear system makes use of hybrid MC-deterministic method and advanced computer technologies. SuperMC is designed to perform transport calculation of various types of particles, depletion and activation calculation including isotope burn-up, material activation and shutdown dose, and multi-physics coupling calculation including thermo-hydraulics, fuel performance and structural mechanics. The bi-directional automatic conversion between general CAD models and physical settings and calculation models can be well performed. Results and process of simulation can be visualized with dynamical 3D dataset and geometry model. Continuous-energy cross section, burnup, activation, irradiation damage and material data etc. are used to support the multi-process simulation. Advanced cloud computing framework makes the computation and storage extremely intensive simulation more attractive just as a network service to support design optimization and assessment. The modular design and generic interface promotes its flexible manipulation and coupling of external solvers. • The new developed and incorporated advanced methods in SuperMC was introduced including hybrid MC-deterministic transport method, particle physical interaction treatment method, multi-physics coupling calculation method, geometry automatic modeling and processing method, intelligent data analysis and visualization method, elastic cloud computing technology and parallel calculation method. • The functions of SuperMC2.1 integrating automatic modeling, neutron and photon transport calculation, results and process visualization was introduced. It has been validated by using a series of benchmarking cases such as the fusion reactor ITER model and the fast reactor BN-600 model. - Abstract: Monte Carlo (MC) method has distinct advantages to simulate complicated nuclear systems and is envisioned as a routine

  11. Virtual X-ray imaging techniques in an immersive casting simulation environment

    International Nuclear Information System (INIS)

    Li, Ning; Kim, Sung-Hee; Suh, Ji-Hyun; Cho, Sang-Hyun; Choi, Jung-Gil; Kim, Myoung-Hee

    2007-01-01

    A computer code was developed to simulate radiograph of complex casting products in a CAVE TM -like environment. The simulation is based on the deterministic algorithms and ray tracing techniques. The aim of this study is to examine CAD/CAE/CAM models at the design stage, to optimize the design and inspect predicted defective regions with fast speed, good accuracy and small numerical expense. The present work discusses the algorithms for the radiography simulation of CAD/CAM model and proposes algorithmic solutions adapted from ray-box intersection algorithm and octree data structure specifically for radiographic simulation of CAE model. The stereoscopic visualization of full-size of product in the immersive casting simulation environment as well as the virtual X-ray images of castings provides an effective tool for design and evaluation of foundry processes by engineers and metallurgists

  12. Ray-tracing analysis of electron-cyclotron-resonance heating in straight stellarators

    International Nuclear Information System (INIS)

    Kato, K.

    1983-05-01

    A ray-tracing computer code is developed and implemented to simulate electron cyclotron resonance heating (ECRH) in stellarators. A straight stellarator model is developed to simulate the confinement geometry. Following a review of ECRH, a cold plasma model is used to define the dispersion relation. To calculate the wave power deposition, a finite temperature damping approximation is used. 3-D ray equations in cylindrical coordinates are derived and put into suitable forms for computation. The three computer codes, MAC, HERA, and GROUT, developed for this research, are described next. ECRH simulation is then carried out for three models including Heliotron E and Wendelstein VII A. Investigated aspects include launching position and mode scan, frequency detuning, helical effects, start-up, and toroidal effects. Results indicate: (1) an elliptical waveguide radiation pattern, with its long axis oriented half-way between the toroidal axis and the saddle point line, is more efficient than a circular one; and (2) mid-plane, high field side launch is favored for both O- and X-waves

  13. Thermal radiation characteristics of nonisothermal cylindrical enclosures using a numerical ray tracing technique

    Science.gov (United States)

    Baumeister, Joseph F.

    1990-01-01

    Analysis of energy emitted from simple or complex cavity designs can lead to intricate solutions due to nonuniform radiosity and irradiation within a cavity. A numerical ray tracing technique was applied to simulate radiation propagating within and from various cavity designs. To obtain the energy balance relationships between isothermal and nonisothermal cavity surfaces and space, the computer code NEVADA was utilized for its statistical technique applied to numerical ray tracing. The analysis method was validated by comparing results with known theoretical and limiting solutions, and the electrical resistance network method. In general, for nonisothermal cavities the performance (apparent emissivity) is a function of cylinder length-to-diameter ratio, surface emissivity, and cylinder surface temperatures. The extent of nonisothermal conditions in a cylindrical cavity significantly affects the overall cavity performance. Results are presented over a wide range of parametric variables for use as a possible design reference.

  14. Biasing transition rate method based on direct MC simulation for probabilistic safety assessment

    Institute of Scientific and Technical Information of China (English)

    Xiao-Lei Pan; Jia-Qun Wang; Run Yuan; Fang Wang; Han-Qing Lin; Li-Qin Hu; Jin Wang

    2017-01-01

    Direct Monte Carlo (MC) simulation is a powerful probabilistic safety assessment method for accounting dynamics of the system.But it is not efficient at simulating rare events.A biasing transition rate method based on direct MC simulation is proposed to solve the problem in this paper.This method biases transition rates of the components by adding virtual components to them in series to increase the occurrence probability of the rare event,hence the decrease in the variance of MC estimator.Several cases are used to benchmark this method.The results show that the method is effective at modeling system failure and is more efficient at collecting evidence of rare events than the direct MC simulation.The performance is greatly improved by the biasing transition rate method.

  15. 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

  16. 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)

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

    Institute of Scientific and Technical Information of China (English)

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

    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.

  18. 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

  19. Analysis of the KROTOS KFC test by coupling X-Ray image analysis and MC3D calculations

    Energy Technology Data Exchange (ETDEWEB)

    Brayer, C.; Charton, A.; Grishchenko, D.; Fouquart, P.; Bullado, Y.; Compagnon, F.; Correggio, P.; Cassiaut-Louis, N.; Piluso, P. [Commissariat a l' Energie Atomique et Aux Energies Alternatives, CEA Cadarache, DEN, F-13108 Saint-Paul-Les-Durance (France)

    2012-07-01

    During a hypothetical severe accident sequence in a Pressurized Water Reactor (PWR), the hot molten materials (corium) issuing from the degraded reactor core may generate a steam explosion if they come in contact with water and may damage the structures and threaten the reactor integrity. The SERENA program is an international OECD project that aims at helping the understanding of this phenomenon also called Fuel Coolant Interaction (FCI) by providing data. CEA takes part in this program by performing tests in its KROTOS facility where steam explosions using prototypic corium can be triggered. Data about the different phases in the premixing are extracted from the KROTOS X-Ray radioscopy images by using KIWI software (KROTOS Image analysis of Water-corium Interaction) currently developed by CEA. The MC3D code, developed by IRSN, is a thermal-hydraulic multiphase code mainly dedicated to FCI studies. It is composed of two applications: premixing and explosion. An overall FCI calculation with MC3D requires a premixing calculation followed by an explosion calculation. The present paper proposes an alternative approach in which all the features of the premixing are extracted from the X-Ray pictures using the KIWI software and transferred to an MC3D dataset for a direct simulation of the explosion. The main hypothesis are discussed as well as the first explosion results obtained with MC3D for the KROTOS KFC test. These results are rather encouraging and are analyzed on the basis of comparisons with the experimental data. (authors)

  20. Analysis of the KROTOS KFC test by coupling X-Ray image analysis and MC3D calculations

    International Nuclear Information System (INIS)

    Brayer, C.; Charton, A.; Grishchenko, D.; Fouquart, P.; Bullado, Y.; Compagnon, F.; Correggio, P.; Cassiaut-Louis, N.; Piluso, P.

    2012-01-01

    During a hypothetical severe accident sequence in a Pressurized Water Reactor (PWR), the hot molten materials (corium) issuing from the degraded reactor core may generate a steam explosion if they come in contact with water and may damage the structures and threaten the reactor integrity. The SERENA program is an international OECD project that aims at helping the understanding of this phenomenon also called Fuel Coolant Interaction (FCI) by providing data. CEA takes part in this program by performing tests in its KROTOS facility where steam explosions using prototypic corium can be triggered. Data about the different phases in the premixing are extracted from the KROTOS X-Ray radioscopy images by using KIWI software (KROTOS Image analysis of Water-corium Interaction) currently developed by CEA. The MC3D code, developed by IRSN, is a thermal-hydraulic multiphase code mainly dedicated to FCI studies. It is composed of two applications: premixing and explosion. An overall FCI calculation with MC3D requires a premixing calculation followed by an explosion calculation. The present paper proposes an alternative approach in which all the features of the premixing are extracted from the X-Ray pictures using the KIWI software and transferred to an MC3D dataset for a direct simulation of the explosion. The main hypothesis are discussed as well as the first explosion results obtained with MC3D for the KROTOS KFC test. These results are rather encouraging and are analyzed on the basis of comparisons with the experimental data. (authors)

  1. Electron ray tracing with high accuracy

    International Nuclear Information System (INIS)

    Saito, K.; Okubo, T.; Takamoto, K.; Uno, Y.; Kondo, M.

    1986-01-01

    An electron ray tracing program is developed to investigate the overall geometrical and chromatic aberrations in electron optical systems. The program also computes aberrations due to manufacturing errors in lenses and deflectors. Computation accuracy is improved by (1) calculating electrostatic and magnetic scalar potentials using the finite element method with third-order isoparametric elements, and (2) solving the modified ray equation which the aberrations satisfy. Computation accuracy of 4 nm is achieved for calculating optical properties of the system with an electrostatic lens

  2. Study on efficiency of time computation in x-ray imaging simulation base on Monte Carlo algorithm using graphics processing unit

    International Nuclear Information System (INIS)

    Setiani, Tia Dwi; Suprijadi; Haryanto, Freddy

    2016-01-01

    Monte Carlo (MC) is one of the powerful techniques for simulation in x-ray imaging. MC method can simulate the radiation transport within matter with high accuracy and provides a natural way to simulate radiation transport in complex systems. One of the codes based on MC algorithm that are widely used for radiographic images simulation is MC-GPU, a codes developed by Andrea Basal. This study was aimed to investigate the time computation of x-ray imaging simulation in GPU (Graphics Processing Unit) compared to a standard CPU (Central Processing Unit). Furthermore, the effect of physical parameters to the quality of radiographic images and the comparison of image quality resulted from simulation in the GPU and CPU are evaluated in this paper. The simulations were run in CPU which was simulated in serial condition, and in two GPU with 384 cores and 2304 cores. In simulation using GPU, each cores calculates one photon, so, a large number of photon were calculated simultaneously. Results show that the time simulations on GPU were significantly accelerated compared to CPU. The simulations on the 2304 core of GPU were performed about 64 -114 times faster than on CPU, while the simulation on the 384 core of GPU were performed about 20 – 31 times faster than in a single core of CPU. Another result shows that optimum quality of images from the simulation was gained at the history start from 10"8 and the energy from 60 Kev to 90 Kev. Analyzed by statistical approach, the quality of GPU and CPU images are relatively the same.

  3. Study on efficiency of time computation in x-ray imaging simulation base on Monte Carlo algorithm using graphics processing unit

    Energy Technology Data Exchange (ETDEWEB)

    Setiani, Tia Dwi, E-mail: tiadwisetiani@gmail.com [Computational Science, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jalan Ganesha 10 Bandung, 40132 (Indonesia); Suprijadi [Computational Science, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jalan Ganesha 10 Bandung, 40132 (Indonesia); Nuclear Physics and Biophysics Reaserch Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jalan Ganesha 10 Bandung, 40132 (Indonesia); Haryanto, Freddy [Nuclear Physics and Biophysics Reaserch Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jalan Ganesha 10 Bandung, 40132 (Indonesia)

    2016-03-11

    Monte Carlo (MC) is one of the powerful techniques for simulation in x-ray imaging. MC method can simulate the radiation transport within matter with high accuracy and provides a natural way to simulate radiation transport in complex systems. One of the codes based on MC algorithm that are widely used for radiographic images simulation is MC-GPU, a codes developed by Andrea Basal. This study was aimed to investigate the time computation of x-ray imaging simulation in GPU (Graphics Processing Unit) compared to a standard CPU (Central Processing Unit). Furthermore, the effect of physical parameters to the quality of radiographic images and the comparison of image quality resulted from simulation in the GPU and CPU are evaluated in this paper. The simulations were run in CPU which was simulated in serial condition, and in two GPU with 384 cores and 2304 cores. In simulation using GPU, each cores calculates one photon, so, a large number of photon were calculated simultaneously. Results show that the time simulations on GPU were significantly accelerated compared to CPU. The simulations on the 2304 core of GPU were performed about 64 -114 times faster than on CPU, while the simulation on the 384 core of GPU were performed about 20 – 31 times faster than in a single core of CPU. Another result shows that optimum quality of images from the simulation was gained at the history start from 10{sup 8} and the energy from 60 Kev to 90 Kev. Analyzed by statistical approach, the quality of GPU and CPU images are relatively the same.

  4. CloudMC: a cloud computing application for Monte Carlo simulation

    International Nuclear Information System (INIS)

    Miras, H; Jiménez, R; Miras, C; Gomà, C

    2013-01-01

    This work presents CloudMC, a cloud computing application—developed in Windows Azure®, the platform of the Microsoft® cloud—for the parallelization of Monte Carlo simulations in a dynamic virtual cluster. CloudMC is a web application designed to be independent of the Monte Carlo code in which the simulations are based—the simulations just need to be of the form: input files → executable → output files. To study the performance of CloudMC in Windows Azure®, Monte Carlo simulations with penelope were performed on different instance (virtual machine) sizes, and for different number of instances. The instance size was found to have no effect on the simulation runtime. It was also found that the decrease in time with the number of instances followed Amdahl's law, with a slight deviation due to the increase in the fraction of non-parallelizable time with increasing number of instances. A simulation that would have required 30 h of CPU on a single instance was completed in 48.6 min when executed on 64 instances in parallel (speedup of 37 ×). Furthermore, the use of cloud computing for parallel computing offers some advantages over conventional clusters: high accessibility, scalability and pay per usage. Therefore, it is strongly believed that cloud computing will play an important role in making Monte Carlo dose calculation a reality in future clinical practice. (note)

  5. CloudMC: a cloud computing application for Monte Carlo simulation.

    Science.gov (United States)

    Miras, H; Jiménez, R; Miras, C; Gomà, C

    2013-04-21

    This work presents CloudMC, a cloud computing application-developed in Windows Azure®, the platform of the Microsoft® cloud-for the parallelization of Monte Carlo simulations in a dynamic virtual cluster. CloudMC is a web application designed to be independent of the Monte Carlo code in which the simulations are based-the simulations just need to be of the form: input files → executable → output files. To study the performance of CloudMC in Windows Azure®, Monte Carlo simulations with penelope were performed on different instance (virtual machine) sizes, and for different number of instances. The instance size was found to have no effect on the simulation runtime. It was also found that the decrease in time with the number of instances followed Amdahl's law, with a slight deviation due to the increase in the fraction of non-parallelizable time with increasing number of instances. A simulation that would have required 30 h of CPU on a single instance was completed in 48.6 min when executed on 64 instances in parallel (speedup of 37 ×). Furthermore, the use of cloud computing for parallel computing offers some advantages over conventional clusters: high accessibility, scalability and pay per usage. Therefore, it is strongly believed that cloud computing will play an important role in making Monte Carlo dose calculation a reality in future clinical practice.

  6. 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.

  7. Virtual Ray Tracing as a Conceptual Tool for Image Formation in Mirrors and Lenses

    Science.gov (United States)

    Heikkinen, Lasse; Savinainen, Antti; Saarelainen, Markku

    2016-01-01

    The ray tracing method is widely used in teaching geometrical optics at the upper secondary and university levels. However, using simple and straightforward examples may lead to a situation in which students use the model of ray tracing too narrowly. Previous studies show that students seem to use the ray tracing method too concretely instead of…

  8. A manual to the MAXRAY program library for reflective and dispersive ray tracing

    International Nuclear Information System (INIS)

    Svensson, S.; Nyholm, R.

    1985-07-01

    A general ray tracing program package for reflective and dispersive X-ray optics is described. The package consists of a number of subroutines written in FORTRAN 77 code giving the necessary tools for ray tracing. The program package is available on request from the authors. (authors)

  9. Capturing sunlight into a photobioreactor: Ray tracing simulations of the propagation of light from capture to distribution into the reactor

    NARCIS (Netherlands)

    Zijffers, J.F.; Janssen, M.G.J.; Tramper, J.; Wijffels, R.H.; Salim, S.

    2008-01-01

    The Green Solar Collector (GSC), a photobioreactor designed for area efficient outdoor cultivation of microalgae uses Fresnel lenses and light guides to focus, transport and distribute direct light into the algae suspension. Calculating the path of rays of light, so-called ray tracing, is used to

  10. Patient-specific scatter correction in clinical cone beam computed tomography imaging made possible by the combination of Monte Carlo simulations and a ray tracing algorithm

    DEFF Research Database (Denmark)

    Slot Thing, Rune; Bernchou, Uffe; Mainegra-Hing, Ernesto

    2013-01-01

    Abstract Purpose. Cone beam computed tomography (CBCT) image quality is limited by scattered photons. Monte Carlo (MC) simulations provide the ability of predicting the patient-specific scatter contamination in clinical CBCT imaging. Lengthy simulations prevent MC-based scatter correction from...

  11. Study of Propagation Mechanisms in Dynamical Railway Environment to Reduce Computation Time of 3D Ray Tracing Simulator

    Directory of Open Access Journals (Sweden)

    Siham Hairoud

    2013-01-01

    Full Text Available In order to better assess the behaviours of the propagation channel in a confined environment such as a railway tunnel for subway application, we present an optimization method for a deterministic channel simulator based on 3D ray tracing associated to the geometrical optics laws and the uniform theory of diffraction. This tool requires a detailed description of the environment. Thus, the complexity of this model is directly bound to the complexity of the environment and specifically to the number of facets that compose it. In this paper, we propose an algorithm to identify facets that have no significant impact on the wave propagation. This allows us to simplify the description of the geometry of the modelled environment by removing them and by this way, to reduce the complexity of our model and therefore its computation time. A comparative study between full and simplified environment is led and shows the impact of this proposed method on the characteristic parameters of the propagation channel. Thus computation time obtained from the simplified environment is 6 times lower than the one of the full model without significant degradation of simulation accuracy.

  12. Ray tracing for optimization of compound parabolic concentrators for solar collectors of enclosed design

    OpenAIRE

    YURCHENKO, VLADIMIR; YURCHENKO, EDUARD; ÇİYDEM, MEHMET; TOTUK, ONAT

    2015-01-01

    We present our developments in computer simulations and optimization of compound parabolic concentrators (CPCs) for solar heat collectors. Issues of both the optical and thermal optimization of CPC collectors of enclosed design are discussed. Ray tracing results for a CPC with a V-shaped absorber are presented. A range of optimal values for the apex angle of a V-shaped absorber is proposed for a CPC collector of typical design.

  13. Simulating polarized light scattering in terrestrial snow based on bicontinuous random medium and Monte Carlo ray tracing

    International Nuclear Information System (INIS)

    Xiong, Chuan; Shi, Jiancheng

    2014-01-01

    To date, the light scattering models of snow consider very little about the real snow microstructures. The ideal spherical or other single shaped particle assumptions in previous snow light scattering models can cause error in light scattering modeling of snow and further cause errors in remote sensing inversion algorithms. This paper tries to build up a snow polarized reflectance model based on bicontinuous medium, with which the real snow microstructure is considered. The accurate specific surface area of bicontinuous medium can be analytically derived. The polarized Monte Carlo ray tracing technique is applied to the computer generated bicontinuous medium. With proper algorithms, the snow surface albedo, bidirectional reflectance distribution function (BRDF) and polarized BRDF can be simulated. The validation of model predicted spectral albedo and bidirectional reflectance factor (BRF) using experiment data shows good results. The relationship between snow surface albedo and snow specific surface area (SSA) were predicted, and this relationship can be used for future improvement of snow specific surface area (SSA) inversion algorithms. The model predicted polarized reflectance is validated and proved accurate, which can be further applied in polarized remote sensing. -- Highlights: • Bicontinuous random medium were used for real snow microstructure modeling. • Photon tracing technique with polarization status tracking ability was applied. • SSA–albedo relationship of snow is close to that of sphere based medium. • Validation of albedo and BRDF showed good results. • Validation of polarized reflectance showed good agreement with experiment data

  14. Simulation and application of micro X-ray fluorescence based on an ellipsoidal capillary

    Science.gov (United States)

    Yang, Jing; Li, Yude; Wang, Xingyi; Zhang, Xiaoyun; Lin, Xiaoyan

    2017-06-01

    A micro X-ray fluorescence setup was presented, based on an ellipsoidal capillary and a traditional laboratorial X-ray source. Using Ray-tracing principle, we have simulated the transmission path of X-ray beam in the ellipsoidal capillary and designed the optimal parameters of the ellipsoidal capillary for the micro X-ray fluorescence setup. We demonstrate that ellipsoidal capillary is well suited as condenser for the micro X-ray fluorescence based on traditional laboratorial X-ray source. Furthermore, we obtain the 2D mapping image of the leaf blade sample by using the ellipsoidal capillary we designed.

  15. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kroon-Batenburg, Loes M. J., E-mail: l.m.j.kroon-batenburg@uu.nl; Schreurs, Antoine M. M. [Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands); Ravelli, Raimond B. G. [Maastricht University, PO Box 616, 6200 MD Maastricht (Netherlands); Gros, Piet [Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands)

    2015-08-25

    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{sub 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{sub 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.

  17. Monte Carlo simulation of gamma ray tomography for image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Guedes, Karlos A.N.; Moura, Alex; Dantas, Carlos; Melo, Silvio; Lima, Emerson, E-mail: karlosguedes@hotmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Meric, Ilker [University of Bergen (Norway)

    2015-07-01

    The Monte Carlo simulations of known density and shape object was validate with Gamma Ray Tomography in static experiments. An aluminum half-moon piece placed inside a steel pipe was the MC simulation test object that was also measured by means of gamma ray transmission. Wall effect of the steel pipe due to irradiation geometry in a single pair source-detector tomography was evaluated by comparison with theoretical data. MCNPX code requires a defined geometry to each photon trajectory which practically prevents this usage for tomography reconstruction simulation. The solution was found by writing a program in Delphi language to create input files automation code. Simulations of tomography data by automated MNCPX code were carried out and validated by experimental data. Working in this sequence the produced data needed a databank to be stored. Experimental setup used a Cesium-137 isotopic radioactive source (7.4 × 109 Bq), and NaI(Tl) scintillation detector of (51 × 51) × 10−3 m crystal size coupled to a multichannel analyzer. A stainless steel tubes of 0,154 m internal diameter, 0.014 m thickness wall. The results show that the MCNPX simulation code adapted to automated input file is useful for generating a matrix data M(θ,t), of a computerized gamma ray tomography for any known density and regular shape object. Experimental validation used RMSE from gamma ray paths and from attenuation coefficient data. (author)

  18. Real-time generation of kd-trees for ray tracing using DirectX 11

    OpenAIRE

    Säll, Martin; Cronqvist, Fredrik

    2017-01-01

    Context. Ray tracing has always been a simple but effective way to create a photorealistic scene but at a greater cost when expanding the scene. Recent improvements in GPU and CPU hardware have made ray tracing faster, making more complex scenes possible with the same amount of time needed to process the scene. Despite the improvements in hardware ray tracing is still rarely run at a interactive speed. Objectives. The aim of this experiment was to implement a new kdtree generation algorithm us...

  19. Fast solar radiation pressure modelling with ray tracing and multiple reflections

    Science.gov (United States)

    Li, Zhen; Ziebart, Marek; Bhattarai, Santosh; Harrison, David; Grey, Stuart

    2018-05-01

    Physics based SRP (Solar Radiation Pressure) models using ray tracing methods are powerful tools when modelling the forces on complex real world space vehicles. Currently high resolution (1 mm) ray tracing with secondary intersections is done on high performance computers at UCL (University College London). This study introduces the BVH (Bounding Volume Hierarchy) into the ray tracing approach for physics based SRP modelling and makes it possible to run high resolution analysis on personal computers. The ray tracer is both general and efficient enough to cope with the complex shape of satellites and multiple reflections (three or more, with no upper limit). In this study, the traditional ray tracing technique is introduced in the first place and then the BVH is integrated into the ray tracing. Four aspects of the ray tracer were tested for investigating the performance including runtime, accuracy, the effects of multiple reflections and the effects of pixel array resolution.Test results in runtime on GPS IIR and Galileo IOV (In Orbit Validation) satellites show that the BVH can make the force model computation 30-50 times faster. The ray tracer has an absolute accuracy of several nanonewtons by comparing the test results for spheres and planes with the analytical computations. The multiple reflection effects are investigated both in the intersection number and acceleration on GPS IIR, Galileo IOV and Sentinel-1 spacecraft. Considering the number of intersections, the 3rd reflection can capture 99.12 %, 99.14 % , and 91.34 % of the total reflections for GPS IIR, Galileo IOV satellite bus and the Sentinel-1 spacecraft respectively. In terms of the multiple reflection effects on the acceleration, the secondary reflection effect for Galileo IOV satellite and Sentinel-1 can reach 0.2 nm /s2 and 0.4 nm /s2 respectively. The error percentage in the accelerations magnitude results show that the 3rd reflection should be considered in order to make it less than 0.035 % . The

  20. 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

  1. Line shape and ray trace calculations in saturated X-ray lasers: Application to Ni-like silver

    International Nuclear Information System (INIS)

    Benredjem, D.; Guilbaud, O.; Moeller, C.; Klisnick, A.; Ros, D.; Dubau, J.; Calisti, A.; Talin, B.

    2006-01-01

    Longitudinal coherence length in X-ray lasers depends strongly on the shape of the amplified line. We have modelled an experiment performed at the LULI facility of Ecole Polytechnique. The experiment was devoted to the study of the temporal (longitudinal) coherence of the transient Ni-like silver 4d-4p transition X-ray laser at 13.9 nm. Accurate line shape calculations using PPP, a spectral line shape code, confirm that the Voigt profile is a good approximation for this X-ray laser line. This allows us to extensively use the Voigt shape in conditions where the amplifier, i.e. the plasma produced by the interaction of a high intensity laser with a slab target, is neither stationary nor homogeneous. Our calculations involve a ray trace code which is a post-processor to the hydrodynamic simulation EHYBRID. As the effect of saturation is important for the level populations and gains we include the interaction between the amplified beam and the medium using the Maxwell-Bloch formalism. While the FWHM of the spontaneous emission profile is ∼10 mA, the amplified X-ray line exhibits gain narrowing leading to the smaller width ∼3 mA. Comparison with experiment is discussed

  2. New developments in simulating X-ray phase contrast imaging

    International Nuclear Information System (INIS)

    Peterzol, A.; Berthier, J.; Duvauchelle, P.; Babot, D.; Ferrero, C.

    2007-01-01

    A deterministic algorithm simulating phase contrast (PC) x-ray images for complex 3- dimensional (3D) objects is presented. This algorithm has been implemented in a simulation code named VXI (Virtual X-ray Imaging). The physical model chosen to account for PC technique is based on the Fresnel-Kirchhoff diffraction theory. The algorithm consists mainly of two parts. The first one exploits the VXI ray-tracing approach to compute the object transmission function. The second part simulates the PC image due to the wave front distortion introduced by the sample. In the first part, the use of computer-aided drawing (CAD) models enables simulations to be carried out with complex 3D objects. Differently from the VXI original version, which makes use of an object description via triangular facets, the new code requires a more 'sophisticated' object representation based on Non-Uniform Rational B-Splines (NURBS). As a first step we produce a spatial high resolution image by using a point and monochromatic source and an ideal detector. To simulate the polychromatic case, the intensity image is integrated over the considered x-ray energy spectrum. Then, in order to account for the system spatial resolution properties, the high spatial resolution image (mono or polychromatic) is convolved with the total point spread function of the imaging system under consideration. The results supplied by the presented algorithm are examined with the help of some relevant examples. (authors)

  3. Polarization ray tracing in anisotropic optically active media. I. Algorithms

    International Nuclear Information System (INIS)

    McClain, S.C.; Hillman, L.W.; Chipman, R.A.

    1993-01-01

    Procedures for performing polarization ray tracing through birefringent media are presented in a form compatible with the standard methods of geometrical ray tracing. The birefringent materials treated include the following: anisotropic optically active materials such as quartz, non-optically active uniaxial materials such as calcite, and isotropic optically active materials such as mercury sulfide and organic liquids. Refraction and reflection algorithms are presented that compute both ray directions and wave directions. Methods for computing polarization modes, refractive indices, optical path lengths, and Fresnel transmission and reflection coefficients are also specified. A numerical example of these algorithms is given for analyzing the field of view of a quartz rotator. 37 refs., 3 figs

  4. Ray tracing package through a lens system and a spectrometer

    International Nuclear Information System (INIS)

    Zurro, B.; King, P.W.; Lazarus, E.A.

    1980-03-01

    To study the light collection optics of the ISX-B two-dimensional (2-D) Thomson scattering system, we have implemented in the Oak Ridge National Laboratory (ORNL) Fusion Energy Division (FED) PDP-10 two computer programs, LENS and SPECT, that trace rays through a lens system and a spectrometer, respectively. The lens package follows the path of any kind of ray (meridional or skew) through a centered optical system formed by an arbitrary number of spherical surfaces. The spectrometer package performs geometrical ray tracing through a Czerney-Turner spectrometer and can be easily modified for studying any other configuration. Contained herein is a description of the procedures followed and a listing of the computer programs

  5. Three-dimensional ray tracing in spherical and elliptical generalized Luneburg lenses for application in the human eye lens.

    Science.gov (United States)

    Gómez-Correa, J E; Coello, V; Garza-Rivera, A; Puente, N P; Chávez-Cerda, S

    2016-03-10

    Ray tracing in spherical Luneburg lenses has always been represented in 2D. All propagation planes in a 3D spherical Luneburg lens generate the same ray tracing, due to its radial symmetry. A geometry without radial symmetry generates a different ray tracing. For this reason, a new ray tracing method in 3D through spherical and elliptical Luneburg lenses using 2D methods is proposed. The physics of the propagation is shown here, which allows us to make a ray tracing associated with a vortex beam. A 3D ray tracing in a composite modified Luneburg lens that represents the human eye lens is also presented.

  6. GRay: A MASSIVELY PARALLEL GPU-BASED CODE FOR RAY TRACING IN RELATIVISTIC SPACETIMES

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Chi-kwan; Psaltis, Dimitrios; Özel, Feryal [Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States)

    2013-11-01

    We introduce GRay, a massively parallel integrator designed to trace the trajectories of billions of photons in a curved spacetime. This graphics-processing-unit (GPU)-based integrator employs the stream processing paradigm, is implemented in CUDA C/C++, and runs on nVidia graphics cards. The peak performance of GRay using single-precision floating-point arithmetic on a single GPU exceeds 300 GFLOP (or 1 ns per photon per time step). For a realistic problem, where the peak performance cannot be reached, GRay is two orders of magnitude faster than existing central-processing-unit-based ray-tracing codes. This performance enhancement allows more effective searches of large parameter spaces when comparing theoretical predictions of images, spectra, and light curves from the vicinities of compact objects to observations. GRay can also perform on-the-fly ray tracing within general relativistic magnetohydrodynamic algorithms that simulate accretion flows around compact objects. Making use of this algorithm, we calculate the properties of the shadows of Kerr black holes and the photon rings that surround them. We also provide accurate fitting formulae of their dependencies on black hole spin and observer inclination, which can be used to interpret upcoming observations of the black holes at the center of the Milky Way, as well as M87, with the Event Horizon Telescope.

  7. vECTlab-A fully integrated multi-modality Monte Carlo simulation framework for the radiological imaging sciences

    International Nuclear Information System (INIS)

    Peter, Joerg; Semmler, Wolfhard

    2007-01-01

    Alongside and in part motivated by recent advances in molecular diagnostics, the development of dual-modality instruments for patient and dedicated small animal imaging has gained attention by diverse research groups. The desire for such systems is high not only to link molecular or functional information with the anatomical structures, but also for detecting multiple molecular events simultaneously at shorter total acquisition times. While PET and SPECT have been integrated successfully with X-ray CT, the advance of optical imaging approaches (OT) and the integration thereof into existing modalities carry a high application potential, particularly for imaging small animals. A multi-modality Monte Carlo (MC) simulation approach at present has been developed that is able to trace high-energy (keV) as well as optical (eV) photons concurrently within identical phantom representation models. We show that the involved two approaches for ray-tracing keV and eV photons can be integrated into a unique simulation framework which enables both photon classes to be propagated through various geometry models representing both phantoms and scanners. The main advantage of such integrated framework for our specific application is the investigation of novel tomographic multi-modality instrumentation intended for in vivo small animal imaging through time-resolved MC simulation upon identical phantom geometries. Design examples are provided for recently proposed SPECT-OT and PET-OT imaging systems

  8. 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.

  9. 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

  10. 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

  11. Developments in the ray-tracing code Zgoubi for 6-D multiturn tracking in FFAG rings

    International Nuclear Information System (INIS)

    Lemuet, F.; Meot, F.

    2005-01-01

    A geometrical method for 3-D modeling of the magnetic field in scaling and non-scaling FFAG magnets has been installed in the ray-tracing code Zgoubi. The method in particular allows a good simulation of transverse non-linearities, of field fall-offs and possible merging fields in configurations of neighboring magnets, while using realistic models of magnetic fields. That yields an efficient tool for FFAG lattice design and optimizations, and for 6-D tracking studies. It is applied for illustration to the simulation of an acceleration cycle in a 150 MeV radial sector proton FFAG

  12. 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.

  13. 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

  14. McStas 1.1: A tool for building neutron Monte Carlo simulations

    DEFF Research Database (Denmark)

    Lefmann, K.; Nielsen, K.; Tennant, D.A.

    2000-01-01

    McStas is a project to develop general tools for the creation of simulations of neutron scattering experiments. In this paper, we briefly introduce McStas and describe a particular application of the program: the Monte Carlo calculation of the resolution function of a standard triple-axis neutron...

  15. Ray Tracing Study on Top ECCD Launch in KSTAR

    Directory of Open Access Journals (Sweden)

    Bae Young-soon

    2017-01-01

    Full Text Available The current drive efficiency of electron cyclotron (EC wave is typically low compared with other RF and neutral beam heating system in tokamak. It is known that EC current drive by outboard launch suffers from low current drive efficiency due to electron trapping. However, the heating and current drive by EC wave is being regarded as a strong candidate for DEMO reactor due to the simplicity of the launcher, none of its interaction with plasma, and no coupling issue at the plasma edge. Also, off-axis heating and current drive by EC wave plays an important role of steady state operation optimization. To enhance the current drive efficiency in DEMO-relevant operation condition having high density and high temperature, the top launch of EC wave is recently proposed in FNSF design [2]. In FNSF, a top launch makes use of a large toroidal component to the launch direction adjusting the vertical launch angle so that the rays propagate nearly parallel to the resonance layer increasing of Doppler shift with higher n||. The results shows a high dimensional efficiency for a broad ECCD profile peaked off axis. In KSTAR, the possibility of efficient off-axis ECCD using top launch is investigated using the ray tracing code, GENRAY [3] for the operating EC frequencies (105 GHz or 140 GHz, and 170 GHz. The high current drive efficiency is found by adjusting the toroidal magnetic field and the radial pivot position of the final launcher mirror for fundamental O-mode and second harmonic X-mode. A large Doppler shift is not quite sure in the typical plasma profile in KSTAR, but the simulation results show high current drive efficiency. This paper presents ray tracing results for many cases with the wave trajectories and damping of EC by scanning the launching angle for specific launcher pivot positions and toroidal magnetic field, and two equilibriums of the KSTAR.

  16. Modelling of waves propagation on irregular surfaces using ray tracing and GTD approaches: Application to head waves simulation in TOFD inspections for NDT

    Science.gov (United States)

    Ferrand, Adrien; Darmon, Michel; Chatillon, Sylvain; Deschamps, Marc

    2014-04-01

    The Time of Flight Diffraction (TOFD) technique is a classical ultrasonic method used in ultrasonic non-destructive evaluation, which allows a precise positioning and a quantitative size evaluation of cracks in the inspected material. Among the typical phenomena arising in the current TOFD inspection, the so-called "head wave" is the first contribution reaching the receiver. The head wave propagation on a planar interface is well known and identified as a critical refraction taking place on the material surface. On irregular surfaces, it has been shown that the head wave results from the melting of surface and bulk waves mechanisms and that surface irregularities are responsible for numerous diffractions of the incident head wave. To simulate such behaviour, a model has been developed using a ray tracing technique based on time of flight minimization (generalized Fermat's principle). It enables the calculation of the ray path and the corresponding time of flight of all waves propagating in the material, including the head wave. To obtain a complete propagation model for these waves (both trajectory and amplitude), the integration of Geometrical Theory of Diffraction (GTD) models is currently performed by coupling them with the ray-based approach discussed above.

  17. A Monte Carlo Ray Tracing Model to Improve Simulations of Solar-Induced Chlorophyll Fluorescence Radiative Transfer

    Science.gov (United States)

    Halubok, M.; Gu, L.; Yang, Z. L.

    2017-12-01

    A model of light transport in a three-dimensional vegetation canopy is being designed and evaluated. The model employs Monte Carlo ray tracing technique which offers simple yet rigorous approach of quantifying the photon transport in a plant canopy. This method involves simulation of a chain of scattering and absorption events incurred by a photon on its path from the light source. Implementation of weighting mechanism helps avoid `all-or-nothing' type of interaction between a photon packet and a canopy element, i.e. at each interaction a photon packet is split into three parts, namely, reflected, transmitted and absorbed, instead of assuming complete absorption, reflection or transmission. Canopy scenes in the model are represented by a number of polygons with specified set of reflectances and transmittances. The performance of the model is being evaluated through comparison against established plant canopy reflectance models, such as 3D Radiosity-Graphics combined model which calculates bidirectional reflectance distribution function of a 3D canopy scene. This photon transport model is to be coupled to a leaf level solar-induced chlorophyll fluorescence (SIF) model with the aim of further advancing of accuracy of the modeled SIF, which, in its turn, has a potential of improving our predictive capability of terrestrial carbon uptake.

  18. 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)

  19. 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.

  20. 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.

  1. Hybrid simulation of scatter intensity in industrial cone-beam computed tomography

    International Nuclear Information System (INIS)

    Thierry, R.; Miceli, A.; Hofmann, J.; Flisch, A.; Sennhauser, U.

    2009-01-01

    A cone-beam computed tomography (CT) system using a 450 kV X-ray tube has been developed to challenge the three-dimensional imaging of parts of the automotive industry in short acquisition time. Because the probability of detecting scattered photons is high regarding the energy range and the area of detection, a scattering correction becomes mandatory for generating reliable images with enhanced contrast detectability. In this paper, we present a hybrid simulator for the fast and accurate calculation of the scattering intensity distribution. The full acquisition chain, from the generation of a polyenergetic photon beam, its interaction with the scanned object and the energy deposit in the detector is simulated. Object phantoms can be spatially described in form of voxels, mathematical primitives or CAD models. Uncollided radiation is treated with a ray-tracing method and scattered radiation is split into single and multiple scattering. The single scattering is calculated with a deterministic approach accelerated with a forced detection method. The residual noisy signal is subsequently deconvoluted with the iterative Richardson-Lucy method. Finally the multiple scattering is addressed with a coarse Monte Carlo (MC) simulation. The proposed hybrid method has been validated on aluminium phantoms with varying size and object-to-detector distance, and found in good agreement with the MC code Geant4. The acceleration achieved by the hybrid method over the standard MC on a single projection is approximately of three orders of magnitude.

  2. Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Negri, Andrew [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia)]. E-mail: a.negri@aims.gov.au; Burns, Kathryn [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Boyle, Steve [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Brinkman, Diane [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Webster, Nicole [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Biological Sciences, University of Canterbury, Christchurch (New Zealand)

    2006-10-15

    This study examined the concentrations of total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH), and trace metals (Cu, Zn, Cd, Pb, Hg and As) in marine sediments off Scott Base (NZ) and compared them with sediments near the highly polluted McMurdo Station (US) as well as less impacted sites including Turtle Rock and Cape Evans. The Antarctic mollusc, Laternula elliptica and three common sponge species were also analysed for trace metals. The mean THC concentration in sediments from Scott Base was 3 fold higher than the pristine site, Turtle Rock, but 10 fold lower than samples from McMurdo Station. McMurdo Station sediments also contained the highest concentrations of PAHs, PCBs and the trace metals, Cu, Zn, Pb, Cd and Hg. Copper was significantly higher in bivalves from McMurdo Station than other sites. Trace metal concentrations in sponges were generally consistent within sites but no spatial patterns were apparent. - Analyses of Antarctic marine sediments, bivalves and sponges revealed strong PAH, PCB and trace metal gradients in McMurdo Sound.

  3. Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica

    International Nuclear Information System (INIS)

    Negri, Andrew; Burns, Kathryn; Boyle, Steve; Brinkman, Diane; Webster, Nicole

    2006-01-01

    This study examined the concentrations of total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH), and trace metals (Cu, Zn, Cd, Pb, Hg and As) in marine sediments off Scott Base (NZ) and compared them with sediments near the highly polluted McMurdo Station (US) as well as less impacted sites including Turtle Rock and Cape Evans. The Antarctic mollusc, Laternula elliptica and three common sponge species were also analysed for trace metals. The mean THC concentration in sediments from Scott Base was 3 fold higher than the pristine site, Turtle Rock, but 10 fold lower than samples from McMurdo Station. McMurdo Station sediments also contained the highest concentrations of PAHs, PCBs and the trace metals, Cu, Zn, Pb, Cd and Hg. Copper was significantly higher in bivalves from McMurdo Station than other sites. Trace metal concentrations in sponges were generally consistent within sites but no spatial patterns were apparent. - Analyses of Antarctic marine sediments, bivalves and sponges revealed strong PAH, PCB and trace metal gradients in McMurdo Sound

  4. Monte Carlo simulation and gaussian broaden techniques for full energy peak of characteristic X-ray in EDXRF

    International Nuclear Information System (INIS)

    Li Zhe; Liu Min; Shi Rui; Wu Xuemei; Tuo Xianguo

    2012-01-01

    Background: Non-standard analysis (NSA) technique is one of the most important development directions of energy dispersive X-ray fluorescence (EDXRF). Purpose: This NSA technique is mainly based on Monte Carlo (MC) simulation and full energy peak broadening, which were studied preliminarily in this paper. Methods: A kind of MC model was established for Si-PIN based EDXRF setup, and the flux spectra were obtained for iron ore sample. Finally, the flux spectra were broadened by Gaussian broaden parameters calculated by a new method proposed in this paper, and the broadened spectra were compared with measured energy spectra. Results: MC method can be used to simulate EDXRF measurement, and can correct the matrix effects among elements automatically. Peak intensities can be obtained accurately by using the proposed Gaussian broaden technique. Conclusions: This study provided a key technique for EDXRF to achieve advanced NSA technology. (authors)

  5. 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...

  6. 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

  7. Simulation and application of micro X-ray fluorescence based on an ellipsoidal capillary

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jing; Li, Yude; Wang, Xingyi; Zhang, Xiaoyun; Lin, Xiaoyan, E-mail: yangjing_928@126.com

    2017-06-15

    Highlights: • A micro X-ray fluorescence setup based on an ellipsoidal capillary was presented. • The optimal parameters of ellipsoidal capillary were designed. • The 2D mapping image of biological sample was obtained. - Abstract: A micro X-ray fluorescence setup was presented, based on an ellipsoidal capillary and a traditional laboratorial X-ray source. Using Ray-tracing principle, we have simulated the transmission path of X-ray beam in the ellipsoidal capillary and designed the optimal parameters of the ellipsoidal capillary for the micro X-ray fluorescence setup. We demonstrate that ellipsoidal capillary is well suited as condenser for the micro X-ray fluorescence based on traditional laboratorial X-ray source. Furthermore, we obtain the 2D mapping image of the leaf blade sample by using the ellipsoidal capillary we designed.

  8. Analysing neutron scattering data using McStas virtual experiments

    DEFF Research Database (Denmark)

    Udby, L.; Willendrup, Peter Kjær; Bergbäck Knudsen, Erik

    2011-01-01

    With the intention of developing a new data analysis method using virtual experiments we have built a detailed virtual model of the cold triple-axis spectrometer RITA-II at PSI, Switzerland, using the McStas neutron ray-tracing package. The parameters characterising the virtual instrument were...... carefully tuned against real experiments. In the present paper we show that virtual experiments reproduce experimentally observed linewidths within 1–3% for a variety of samples. Furthermore we show that the detailed knowledge of the instrumental resolution found from virtual experiments, including sample...

  9. 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)

  10. Neutron transport study based on assembly modular ray tracing MOC method

    International Nuclear Information System (INIS)

    Tian Chao; Zheng Youqi; Li Yunzhao; Li Shuo; Chai Xiaoming

    2015-01-01

    It is difficulty for the MOC method based on Cell Modular Ray Tracing to deal with the irregular geometry such as the water gap between the PWR lattices. Hence, the neutron transport code NECP-Medlar based on Assembly Modular Ray Tracing is developed. CMFD method is used to accelerate the transport calculation. The numerical results of the 2D C5G7 benchmark and typical PWR lattice prove that NECP-Medlar has an excellent performance in terms of accuracy and efficiency. Besides, NECP-Medlar can describe clearly the flux distribution of the lattice with water gap. (authors)

  11. 2-Dimensional B-Spline Algorithms with Applications to Ray Tracing in Media of Spatially-Varying Refractive Index

    Science.gov (United States)

    2007-08-01

    In the approach, photon trajectories are computed using a solution of the Eikonal equation (ray-tracing methods) rather than linear trajectories. The...coupling the radiative transport solution into heat transfer and damage models. 15. SUBJECT TERMS: B-Splines, Ray-Tracing, Eikonal Equation...multi-layer biological tissue model. In the approach, photon trajectories are computed using a solution of the Eikonal equation (ray-tracing methods

  12. 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.

  13. Modelling of waves propagation on irregular surfaces using ray tracing and GTD approaches: Application to head waves simulation in TOFD inspections for NDT

    International Nuclear Information System (INIS)

    Ferrand, Adrien; Darmon, Michel; Chatillon, Sylvain; Deschamps, Marc

    2014-01-01

    The Time of Flight Diffraction (TOFD) technique is a classical ultrasonic method used in ultrasonic non-destructive evaluation, which allows a precise positioning and a quantitative size evaluation of cracks in the inspected material. Among the typical phenomena arising in the current TOFD inspection, the so-called 'head wave' is the first contribution reaching the receiver. The head wave propagation on a planar interface is well known and identified as a critical refraction taking place on the material surface. On irregular surfaces, it has been shown that the head wave results from the melting of surface and bulk waves mechanisms and that surface irregularities are responsible for numerous diffractions of the incident head wave. To simulate such behaviour, a model has been developed using a ray tracing technique based on time of flight minimization (generalized Fermat's principle). It enables the calculation of the ray path and the corresponding time of flight of all waves propagating in the material, including the head wave. To obtain a complete propagation model for these waves (both trajectory and amplitude), the integration of Geometrical Theory of Diffraction (GTD) models is currently performed by coupling them with the ray-based approach discussed above.

  14. GPM GROUND VALIDATION SATELLITE SIMULATED ORBITS MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Satellite Simulated Orbits MC3E dataset is available in the Orbital database , which takes account for the atmospheric profiles, the...

  15. Simulating Controlled Radical Polymerizations with mcPolymer—A Monte Carlo Approach

    Directory of Open Access Journals (Sweden)

    Georg Drache

    2012-07-01

    Full Text Available Utilizing model calculations may lead to a better understanding of the complex kinetics of the controlled radical polymerization. We developed a universal simulation tool (mcPolymer, which is based on the widely used Monte Carlo simulation technique. This article focuses on the software architecture of the program, including its data management and optimization approaches. We were able to simulate polymer chains as individual objects, allowing us to gain more detailed microstructural information of the polymeric products. For all given examples of controlled radical polymerization (nitroxide mediated radical polymerization (NMRP homo- and copolymerization, atom transfer radical polymerization (ATRP, reversible addition fragmentation chain transfer polymerization (RAFT, we present detailed performance analyses demonstrating the influence of the system size, concentrations of reactants, and the peculiarities of data. Different possibilities were exemplarily illustrated for finding an adequate balance between precision, memory consumption, and computation time of the simulation. Due to its flexible software architecture, the application of mcPolymer is not limited to the controlled radical polymerization, but can be adjusted in a straightforward manner to further polymerization models.

  16. Monte Carlo simulations of neutron-scattering instruments using McStas

    DEFF Research Database (Denmark)

    Nielsen, K.; Lefmann, K.

    2000-01-01

    Monte Carlo simulations have become an essential tool for improving the performance of neutron-scattering instruments, since the level of sophistication in the design of instruments is defeating purely analytical methods. The program McStas, being developed at Rise National Laboratory, includes...

  17. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, H; Zhong, H; Qin, Y; Snyder, K; Chetty, I; Wen, N [Henry Ford Health System, Detroit, MI (United States)

    2016-06-15

    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. 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.

  20. Infant word recognition: Insights from TRACE simulations☆

    Science.gov (United States)

    Mayor, Julien; Plunkett, Kim

    2014-01-01

    The TRACE model of speech perception (McClelland & Elman, 1986) is used to simulate results from the infant word recognition literature, to provide a unified, theoretical framework for interpreting these findings. In a first set of simulations, we demonstrate how TRACE can reconcile apparently conflicting findings suggesting, on the one hand, that consonants play a pre-eminent role in lexical acquisition (Nespor, Peña & Mehler, 2003; Nazzi, 2005), and on the other, that there is a symmetry in infant sensitivity to vowel and consonant mispronunciations of familiar words (Mani & Plunkett, 2007). In a second series of simulations, we use TRACE to simulate infants’ graded sensitivity to mispronunciations of familiar words as reported by White and Morgan (2008). An unexpected outcome is that TRACE fails to demonstrate graded sensitivity for White and Morgan’s stimuli unless the inhibitory parameters in TRACE are substantially reduced. We explore the ramifications of this finding for theories of lexical development. Finally, TRACE mimics the impact of phonological neighbourhoods on early word learning reported by Swingley and Aslin (2007). TRACE offers an alternative explanation of these findings in terms of mispronunciations of lexical items rather than imputing word learning to infants. Together these simulations provide an evaluation of Developmental (Jusczyk, 1993) and Familiarity (Metsala, 1999) accounts of word recognition by infants and young children. The findings point to a role for both theoretical approaches whereby vocabulary structure and content constrain infant word recognition in an experience-dependent fashion, and highlight the continuity in the processes and representations involved in lexical development during the second year of life. PMID:24493907

  1. Ray tracing of auroral Z mode radiation, AKR and auroral hiss

    International Nuclear Information System (INIS)

    Horne, R.B.; Jones, D.; Kimura, I.; Sawada, A.

    1990-01-01

    While observed frequency bandwidths of auroral Z mode radiation cannot be directly accounted for in terms of direct cyclotron maser instability generation, ray tracing in a hot plasma indicates that if the radiation near a plasma frequency lower than the gyrofrequency, the observed bandwidths are explainable in terms of upward propagation away from the earth. An auroral Z-mode generation mechanism is proposed involving mode conversion from O-mode auroral kilometric radiation (AKR) at the plasma frequency, as well as mode conversion from upgoing auroral hiss. Ray tracings in the O mode identify a possible AKR source region along L = 8.55. 11 refs

  2. 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.

  3. 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

  4. Monte Carlo simulation of the imaging properties of scintillator-coated X-ray pixel detectors

    International Nuclear Information System (INIS)

    Hjelm, M.; Norlin, B.; Nilsson, H.-E.; Froejdh, C.; Badel, X.

    2003-01-01

    The spatial resolution of scintillator-coated X-ray pixel detectors is usually limited by the isotropic light spread in the scintillator. One way to overcome this limitation is to use a pixellated scintillating layer on top of the semiconductor pixel detector. Using advanced etching and filling techniques, arrays of CsI columns have been successfully fabricated and characterized. Each CsI waveguide matches one pixel of the semiconductor detector, limiting the spatial spread of light. Another concept considered in this study is to detect the light emitted from the scintillator by diodes formed in the silicon pore walls. There is so far no knowledge regarding the theoretical limits for these two approaches, which makes the evaluation of the fabrication process difficult. In this work we present numerical calculations of the signal-to-noise ratio (SNR) for detector designs based on scintillator-filled pores in silicon. The calculations are based on separate Monte Carlo (MC) simulations of X-ray absorption and light transport in scintillator waveguides. The resulting data are used in global MC simulations of flood exposures of the detector array, from which the SNR values are obtained. Results are presented for two scintillator materials, namely CsI(Tl) and GADOX

  5. 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.

  6. CAD-based Monte Carlo program for integrated simulation of nuclear system SuperMC

    International Nuclear Information System (INIS)

    Wu, Y.; Song, J.; Zheng, H.; Sun, G.; Hao, L.; Long, P.; Hu, L.

    2013-01-01

    SuperMC is a (Computer-Aided-Design) CAD-based Monte Carlo (MC) program for integrated simulation of nuclear systems developed by FDS Team (China), making use of hybrid MC-deterministic method and advanced computer technologies. The design aim, architecture and main methodology of SuperMC are presented in this paper. The taking into account of multi-physics processes and the use of advanced computer technologies such as automatic geometry modeling, intelligent data analysis and visualization, high performance parallel computing and cloud computing, contribute to the efficiency of the code. SuperMC2.1, the latest version of the code for neutron, photon and coupled neutron and photon transport calculation, has been developed and validated by using a series of benchmarking cases such as the fusion reactor ITER model and the fast reactor BN-600 model

  7. Simulation of streamflow in the McTier Creek watershed, South Carolina

    Science.gov (United States)

    Feaster, Toby D.; Golden, Heather E.; Odom, Kenneth R.; Lowery, Mark A.; Conrads, Paul; Bradley, Paul M.

    2010-01-01

    The McTier Creek watershed is located in the Sand Hills ecoregion of South Carolina and is a small catchment within the Edisto River Basin. Two watershed hydrology models were applied to the McTier Creek watershed as part of a larger scientific investigation to expand the understanding of relations among hydrologic, geochemical, and ecological processes that affect fish-tissue mercury concentrations within the Edisto River Basin. The two models are the topography-based hydrological model (TOPMODEL) and the grid-based mercury model (GBMM). TOPMODEL uses the variable-source area concept for simulating streamflow, and GBMM uses a spatially explicit modified curve-number approach for simulating streamflow. The hydrologic output from TOPMODEL can be used explicitly to simulate the transport of mercury in separate applications, whereas the hydrology output from GBMM is used implicitly in the simulation of mercury fate and transport in GBMM. The modeling efforts were a collaboration between the U.S. Geological Survey and the U.S. Environmental Protection Agency, National Exposure Research Laboratory. Calibrations of TOPMODEL and GBMM were done independently while using the same meteorological data and the same period of record of observed data. Two U.S. Geological Survey streamflow-gaging stations were available for comparison of observed daily mean flow with simulated daily mean flow-station 02172300, McTier Creek near Monetta, South Carolina, and station 02172305, McTier Creek near New Holland, South Carolina. The period of record at the Monetta gage covers a broad range of hydrologic conditions, including a drought and a significant wet period. Calibrating the models under these extreme conditions along with the normal flow conditions included in the record enhances the robustness of the two models. Several quantitative assessments of the goodness of fit between model simulations and the observed daily mean flows were done. These included the Nash-Sutcliffe coefficient

  8. Polarization ray tracing in anisotropic optically active media. II. Theory and physics

    International Nuclear Information System (INIS)

    McClain, S.C.; Hillman, L.W.; Chipman, R.A.

    1993-01-01

    Refraction, reflection, and amplitude relations are derived that apply to polarization ray tracing in anisotropic, optically active media such as quartz. The constitutive relations for quartz are discussed. The refractive indices and polarization states associated with the two modes of propagation are derived as a function of wave direction. A procedure for refracting at any uniaxial or optically active interface is derived that computes both the ray direction and the wave direction. A method for computing the optical path length is given, and Fresnel transmission and ref lection equations are derived from boundary conditions on the electromagnetic fields. These ray-tracing formulas apply to uniaxial, optically active media and therefore encompass uniaxial, non-optically active materials and isotropic, optically active materials

  9. Vertex shading of the three-dimensional model based on ray-tracing algorithm

    Science.gov (United States)

    Hu, Xiaoming; Sang, Xinzhu; Xing, Shujun; Yan, Binbin; Wang, Kuiru; Dou, Wenhua; Xiao, Liquan

    2016-10-01

    Ray Tracing Algorithm is one of the research hotspots in Photorealistic Graphics. It is an important light and shadow technology in many industries with the three-dimensional (3D) structure, such as aerospace, game, video and so on. Unlike the traditional method of pixel shading based on ray tracing, a novel ray tracing algorithm is presented to color and render vertices of the 3D model directly. Rendering results are related to the degree of subdivision of the 3D model. A good light and shade effect is achieved by realizing the quad-tree data structure to get adaptive subdivision of a triangle according to the brightness difference of its vertices. The uniform grid algorithm is adopted to improve the rendering efficiency. Besides, the rendering time is independent of the screen resolution. In theory, as long as the subdivision of a model is adequate, cool effects as the same as the way of pixel shading will be obtained. Our practical application can be compromised between the efficiency and the effectiveness.

  10. Partially coherent X-ray wavefront propagation simulations including grazing-incidence focusing optics.

    Science.gov (United States)

    Canestrari, Niccolo; Chubar, Oleg; Reininger, Ruben

    2014-09-01

    X-ray beamlines in modern synchrotron radiation sources make extensive use of grazing-incidence reflective optics, in particular Kirkpatrick-Baez elliptical mirror systems. These systems can focus the incoming X-rays down to nanometer-scale spot sizes while maintaining relatively large acceptance apertures and high flux in the focused radiation spots. In low-emittance storage rings and in free-electron lasers such systems are used with partially or even nearly fully coherent X-ray beams and often target diffraction-limited resolution. Therefore, their accurate simulation and modeling has to be performed within the framework of wave optics. Here the implementation and benchmarking of a wave-optics method for the simulation of grazing-incidence mirrors based on the local stationary-phase approximation or, in other words, the local propagation of the radiation electric field along geometrical rays, is described. The proposed method is CPU-efficient and fully compatible with the numerical methods of Fourier optics. It has been implemented in the Synchrotron Radiation Workshop (SRW) computer code and extensively tested against the geometrical ray-tracing code SHADOW. The test simulations have been performed for cases without and with diffraction at mirror apertures, including cases where the grazing-incidence mirrors can be hardly approximated by ideal lenses. Good agreement between the SRW and SHADOW simulation results is observed in the cases without diffraction. The differences between the simulation results obtained by the two codes in diffraction-dominated cases for illumination with fully or partially coherent radiation are analyzed and interpreted. The application of the new method for the simulation of wavefront propagation through a high-resolution X-ray microspectroscopy beamline at the National Synchrotron Light Source II (Brookhaven National Laboratory, USA) is demonstrated.

  11. Virtual reality-based simulation system for nuclear and radiation safety SuperMC/RVIS

    Energy Technology Data Exchange (ETDEWEB)

    He, T.; Hu, L.; Long, P.; Shang, L.; Zhou, S.; Yang, Q.; Zhao, J.; Song, J.; Yu, S.; Cheng, M.; Hao, L., E-mail: liqin.hu@fds.org.cn [Chinese Academy of Sciences, Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Hefei, Anhu (China)

    2015-07-01

    The suggested work scenarios in radiation environment need to be iterative optimized according to the ALARA principle. Based on Virtual Reality (VR) technology and high-precision whole-body computational voxel phantom, a virtual reality-based simulation system for nuclear and radiation safety named SuperMC/RVIS has been developed for organ dose assessment and ALARA evaluation of work scenarios in radiation environment. The system architecture, ALARA evaluation strategy, advanced visualization methods and virtual reality technology used in SuperMC/RVIS are described. A case is presented to show its dose assessment and interactive simulation capabilities. (author)

  12. Virtual reality-based simulation system for nuclear and radiation safety SuperMC/RVIS

    International Nuclear Information System (INIS)

    He, T.; Hu, L.; Long, P.; Shang, L.; Zhou, S.; Yang, Q.; Zhao, J.; Song, J.; Yu, S.; Cheng, M.; Hao, L.

    2015-01-01

    The suggested work scenarios in radiation environment need to be iterative optimized according to the ALARA principle. Based on Virtual Reality (VR) technology and high-precision whole-body computational voxel phantom, a virtual reality-based simulation system for nuclear and radiation safety named SuperMC/RVIS has been developed for organ dose assessment and ALARA evaluation of work scenarios in radiation environment. The system architecture, ALARA evaluation strategy, advanced visualization methods and virtual reality technology used in SuperMC/RVIS are described. A case is presented to show its dose assessment and interactive simulation capabilities. (author)

  13. 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.

  14. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ying, C. K. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang, Malaysia and School of Medical Sciences, Universiti Sains Malaysia, Kota Bharu (Malaysia); Kamil, W. A. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang, Malaysia and Radiology Department, Hospital USM, Kota Bharu (Malaysia); Shuaib, I. L. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang (Malaysia); Matsufuji, Naruhiro [Research Centre of Charged Particle Therapy, National Institute of Radiological Sciences, NIRS, Chiba (Japan)

    2014-02-12

    Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy-ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations.

  15. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    International Nuclear Information System (INIS)

    Ying, C. K.; Kamil, W. A.; Shuaib, I. L.; Matsufuji, Naruhiro

    2014-01-01

    Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy-ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations

  16. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    International Nuclear Information System (INIS)

    Ying, C.K.; Kamil, W.A.; Shuaib, I.L.; Ying, C.K.; Kamil, W.A.

    2013-01-01

    Full-text: Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations. (author)

  17. Ray-tracing toroidal axisymmetric devices. 1. theoretical analysis

    International Nuclear Information System (INIS)

    Cardinali, A.; Brambilla, M.

    1981-06-01

    Ray tracing technique for lower hybrid waves is used to obtain informations about accessibility, power deposition profiles and eventually electric field distribution. In the first part a critical discussion to establish the meaning and validity of this technique is presented, while in the second part of this work applications to small and to large, fat tokamaks are presented, which support and explain the theoretical arguments

  18. 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.

  19. 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.

  20. RAY-UI: A powerful and extensible user interface for RAY

    Energy Technology Data Exchange (ETDEWEB)

    Baumgärtel, P., E-mail: peter.baumgaertel@helmholtz-berlin.de; Erko, A.; Schäfers, F. [Institute for Nanometre Optics and Technology Helmholtz Zentrum Berlin für Materialien und Energie Albert-Einstein-Str. 15, 12489 Berlin (Germany); Witt, M. [Department Operation Accelerator BESSY II Helmholtz Zentrum Berlin für Materialien und Energie Albert-Einstein-Str. 15, 12489 Berlin (Germany); Baensch, J.; Fabarius, M.; Schirmacher, H. [Fachbereich VI – Informatik und Medien Beuth Hochschule für Technik Berlin, Luxemburger Str. 10, 13353 Berlin (Germany)

    2016-07-27

    The RAY-UI project started as a proof-of-concept for an interactive and graphical user interface (UI) for the well-known ray tracing software RAY [1]. In the meantime, it has evolved into a powerful enhanced version of RAY that will serve as the platform for future development and improvement of associated tools. The software as of today supports nearly all sophisticated simulation features of RAY. Furthermore, it delivers very significant usability and work efficiency improvements. Beamline elements can be quickly added or removed in the interactive sequence view. Parameters of any selected element can be accessed directly and in arbitrary order. With a single click, parameter changes can be tested and new simulation results can be obtained. All analysis results can be explored interactively right after ray tracing by means of powerful integrated image viewing and graphing tools. Unlimited image planes can be positioned anywhere in the beamline, and bundles of image planes can be created for moving the plane along the beam to identify the focus position with live updates of the simulated results. In addition to showing the features and workflow of RAY-UI, we will give an overview of the underlying software architecture as well as examples for use and an outlook for future developments.

  1. 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.

  2. 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.

  3. Development of Extended Ray-tracing method including diffraction, polarization and wave decay effects

    Science.gov (United States)

    Yanagihara, Kota; Kubo, Shin; Dodin, Ilya; Nakamura, Hiroaki; Tsujimura, Toru

    2017-10-01

    Geometrical Optics Ray-tracing is a reasonable numerical analytic approach for describing the Electron Cyclotron resonance Wave (ECW) in slowly varying spatially inhomogeneous plasma. It is well known that the result with this conventional method is adequate in most cases. However, in the case of Helical fusion plasma which has complicated magnetic structure, strong magnetic shear with a large scale length of density can cause a mode coupling of waves outside the last closed flux surface, and complicated absorption structure requires a strong focused wave for ECH. Since conventional Ray Equations to describe ECW do not have any terms to describe the diffraction, polarization and wave decay effects, we can not describe accurately a mode coupling of waves, strong focus waves, behavior of waves in inhomogeneous absorption region and so on. For fundamental solution of these problems, we consider the extension of the Ray-tracing method. Specific process is planned as follows. First, calculate the reference ray by conventional method, and define the local ray-base coordinate system along the reference ray. Then, calculate the evolution of the distributions of amplitude and phase on ray-base coordinate step by step. The progress of our extended method will be presented.

  4. Implementation of diffraction in a ray-tracing model for the prediction of noise in open-plan offices.

    Science.gov (United States)

    Chevret, P; Chatillon, J

    2012-11-01

    Sound prediction in open-plan offices is a real challenge because of the complexity of the layout of such offices, and therefore because of the multitude of acoustic phenomena involved. One such phenomenon, of primary importance, and not the least challenging of them, is the diffraction by screens and low dividers that usually partition the workspace. This paper describes implementing the equations of the Uniform Theory of Diffraction [McNamara et al. (1990). Introduction to the Uniform Theory of Diffraction (Artech House, Boston)] in an existing ray-tracing model initially dedicated to sound prediction in industrial premises. For the purposes of validation, a series of measurements was conducted in a semi-anechoic chamber in the same manner as Wang and Bradley [(2002). Appl. Acoust. 63, 849-866] but including real desktops instead of single screens. A first phase was dedicated to controlling the quality of the installation by making comparisons with McNamara's solution for a single screen on a rigid floor. Then, the validation itself was conducted with measurements on real desktops, first without a ceiling, and then with a rigid ceiling suspended above the double desk. The results of the comparisons between calculations and measurements in this configuration have demonstrated that the model is an effective tool for predicting sound levels in an open-plan office.

  5. A computer code to simulate X-ray imaging techniques

    International Nuclear Information System (INIS)

    Duvauchelle, Philippe; Freud, Nicolas; Kaftandjian, Valerie; Babot, Daniel

    2000-01-01

    A computer code was developed to simulate the operation of radiographic, radioscopic or tomographic devices. The simulation is based on ray-tracing techniques and on the X-ray attenuation law. The use of computer-aided drawing (CAD) models enables simulations to be carried out with complex three-dimensional (3D) objects and the geometry of every component of the imaging chain, from the source to the detector, can be defined. Geometric unsharpness, for example, can be easily taken into account, even in complex configurations. Automatic translations or rotations of the object can be performed to simulate radioscopic or tomographic image acquisition. Simulations can be carried out with monochromatic or polychromatic beam spectra. This feature enables, for example, the beam hardening phenomenon to be dealt with or dual energy imaging techniques to be studied. The simulation principle is completely deterministic and consequently the computed images present no photon noise. Nevertheless, the variance of the signal associated with each pixel of the detector can be determined, which enables contrast-to-noise ratio (CNR) maps to be computed, in order to predict quantitatively the detectability of defects in the inspected object. The CNR is a relevant indicator for optimizing the experimental parameters. This paper provides several examples of simulated images that illustrate some of the rich possibilities offered by our software. Depending on the simulation type, the computation time order of magnitude can vary from 0.1 s (simple radiographic projection) up to several hours (3D tomography) on a PC, with a 400 MHz microprocessor. Our simulation tool proves to be useful in developing new specific applications, in choosing the most suitable components when designing a new testing chain, and in saving time by reducing the number of experimental tests

  6. A computer code to simulate X-ray imaging techniques

    Energy Technology Data Exchange (ETDEWEB)

    Duvauchelle, Philippe E-mail: philippe.duvauchelle@insa-lyon.fr; Freud, Nicolas; Kaftandjian, Valerie; Babot, Daniel

    2000-09-01

    A computer code was developed to simulate the operation of radiographic, radioscopic or tomographic devices. The simulation is based on ray-tracing techniques and on the X-ray attenuation law. The use of computer-aided drawing (CAD) models enables simulations to be carried out with complex three-dimensional (3D) objects and the geometry of every component of the imaging chain, from the source to the detector, can be defined. Geometric unsharpness, for example, can be easily taken into account, even in complex configurations. Automatic translations or rotations of the object can be performed to simulate radioscopic or tomographic image acquisition. Simulations can be carried out with monochromatic or polychromatic beam spectra. This feature enables, for example, the beam hardening phenomenon to be dealt with or dual energy imaging techniques to be studied. The simulation principle is completely deterministic and consequently the computed images present no photon noise. Nevertheless, the variance of the signal associated with each pixel of the detector can be determined, which enables contrast-to-noise ratio (CNR) maps to be computed, in order to predict quantitatively the detectability of defects in the inspected object. The CNR is a relevant indicator for optimizing the experimental parameters. This paper provides several examples of simulated images that illustrate some of the rich possibilities offered by our software. Depending on the simulation type, the computation time order of magnitude can vary from 0.1 s (simple radiographic projection) up to several hours (3D tomography) on a PC, with a 400 MHz microprocessor. Our simulation tool proves to be useful in developing new specific applications, in choosing the most suitable components when designing a new testing chain, and in saving time by reducing the number of experimental tests.

  7. RAY: a ray tracing program in cold magnetized plasma

    International Nuclear Information System (INIS)

    Montes, A.; Souza, L.H.

    1985-01-01

    This report deals with the development of a ray tracing program, that is, the plot of an electromagnetic wave path in a cold magnetized plasma medium. The program was developed based on the validity of the geometrical optics laws to calculate the electromagnetic wave trajectory. This approximation is valid when the wave length is much smaller than the characteristic length of the medium. No hypothesis was made about a particular geometric configuration for the magnetic field, what enables the use of the program in any magnetic confinment scheme. The numerically obtained results were compared with an analytic solution for a particular case (cylindrically symmetric medium, uniform magnetostatic, field along the symmetry axis and ordinary wave) and have shown a satisfactory precision. (Author) [pt

  8. SEDRX: A computer program for the simulation Si(Li) and Ge(Hp) x-ray detectors efficiency

    International Nuclear Information System (INIS)

    Benamar, M.A.; Benouali, A.; Tchantchane, A.; Azbouche, A.; Tobbeche, S. Centre de Developpement des Techniques Nucleaires, Algiers; Labo. des Techniques Nucleaires)

    1992-12-01

    The difficulties encountered in measuring the x-ray detectors efficiency has motivated to develop a computer program to simulate this parameter. this program computes the efficiency of detectors as a function of energy. the computation of this parameter is based on the fitting coefficients of absorption in the case of photoelectric, coherent and incoherent factors. These coefficients are given by Mc Master library or may be determined by the interpolation based on cubic splines

  9. Combination of ray-tracing and the method of moments for electromagnetic radiation analysis using reduced meshes

    Science.gov (United States)

    Delgado, Carlos; Cátedra, Manuel Felipe

    2018-05-01

    This work presents a technique that allows a very noticeable relaxation of the computational requirements for full-wave electromagnetic simulations based on the Method of Moments. A ray-tracing analysis of the geometry is performed in order to extract the critical points with significant contributions. These points are then used to generate a reduced mesh, considering the regions of the geometry that surround each critical point and taking into account the electrical path followed from the source. The electromagnetic analysis of the reduced mesh produces very accurate results, requiring a fraction of the resources that the conventional analysis would utilize.

  10. Ray Tracing Results for Elevation Angle Spread of Departure and its Impact on System Performance

    DEFF Research Database (Denmark)

    Mondal, Bishwarup; Thomas, Timothy; Nguyen, Huan Cong

    2014-01-01

    Elevation spread of departure angles (ESD) is the key parameter characterizing a 3D fast-fading channel model. 3D channel mod-eling is currently being studied in 3GPP to enable the develop-ment of MIMO techniques exploiting both azimuth and elevation dimensions of the channel. In this paper we use...... ray-tracing techniques to estimate the ESD behavior in Manhattan and Copenhagen city environments and compare it with the 3GPP ESD model. We also investigate the ESD spread within a cluster of rays and show that the ESD within a cluster depends significantly on the distance of the mobile from the base......-station. This char-acterization addresses a gap in the existing literature. Simulation results show that the performance of MIMO techniques such as vertical sectorization depends significantly on the ESD of the underlying environment. This observation also underscores the importance of an accurate ESD model....

  11. A fast and efficient adaptive parallel ray tracing based model for thermally coupled surface radiation in casting and heat treatment processes

    International Nuclear Information System (INIS)

    Fainberg, J; Schaefer, W

    2015-01-01

    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. (paper)

  12. Application of synchrotron radiation to x-ray fluorescence analysis of trace elements

    International Nuclear Information System (INIS)

    Gordon, B.M.; Jones, K.W.; Hanson, A.L.

    1986-08-01

    The development of synchrotron radiation x-ray sources has provided the means to greatly extend the capabilities of x-ray fluorescence analysis for determinations of trace element concentrations. A brief description of synchrotron radiation properties provides a background for a discussion of the improved detection limits compared to existing x-ray fluorescence techniques. Calculated detection limits for x-ray microprobes with micrometer spatial resolutions are described and compared with experimental results beginning to appear from a number of laboratories. The current activities and future plans for a dedicated x-ray microprobe beam line at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory are presented

  13. Simulating vegetation response to climate change in the Blue Mountains with MC2 dynamic global vegetation model

    Directory of Open Access Journals (Sweden)

    John B. Kim

    2018-04-01

    Full Text Available Warming temperatures are projected to greatly alter many forests in the Pacific Northwest. MC2 is a dynamic global vegetation model, a climate-aware, process-based, and gridded vegetation model. We calibrated and ran MC2 simulations for the Blue Mountains Ecoregion, Oregon, USA, at 30 arc-second spatial resolution. We calibrated MC2 using the best available spatial datasets from land managers. We ran future simulations using climate projections from four global circulation models (GCM under representative concentration pathway 8.5. Under this scenario, forest productivity is projected to increase as the growing season lengthens, and fire occurrence is projected to increase steeply throughout the century, with burned area peaking early- to mid-century. Subalpine forests are projected to disappear, and the coniferous forests to contract by 32.8%. Large portions of the dry and mesic forests are projected to convert to woodlands, unless precipitation were to increase. Low levels of change are projected for the Umatilla National Forest consistently across the four GCM’s. For the Wallowa-Whitman and the Malheur National Forest, forest conversions are projected to vary more across the four GCM-based simulations, reflecting high levels of uncertainty arising from climate. For simulations based on three of the four GCMs, sharply increased fire activity results in decreases in forest carbon stocks by the mid-century, and the fire activity catalyzes widespread biome shift across the study area. We document the full cycle of a structured approach to calibrating and running MC2 for transparency and to serve as a template for applications of MC2. Keywords: Climate change, Regional change, Simulation, Calibration, Forests, Fire, Dynamic global vegetation model

  14. 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.

  15. Simulation on a limited angle beam gamma ray tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Bum; Jung, Sung Hee; Moon, Jin Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    Limited angle beam tomography was introduced in the medical field more than two decades ago, where it was mainly used for cardiovascular diagnostics. Later, it was also used to trace multiphase flows. In these studies, the detection systems were fixed and a scanning electron beam was rapidly swept across an xray target using deflection coils. Thus very fast scanning was possible in these studies, but their geometry resulted in a heavy and bulky system because of a complex control system and vacuum tube. Because of its heavy hardware, limited angle beam tomography has remained as indoor equipment. If the source section is replaced by a gamma ray source, limited angle beam tomography will have a very light source device. In addition, limited angle beam tomography with a gamma ray source can be designed using an open type portable gantry because it does not need a vacuum guide for an electron beam. There is a lot of need for a portable tomographic system but so far no definitive solution has been created. The inspection of industrial on-line pipes, wood telephone poles, and cultural assets are some application areas. This study introduces limited angle beam gamma ray tomography, its simulation, and image reconstruction results. Image reconstruction was performed on the virtual experimental data from a Monte Carlo simulation. Image reconstruction algorithms that are known to be useful for limited angle data were applied and their results compared

  16. Massively parallel algorithms for trace-driven cache simulations

    Science.gov (United States)

    Nicol, David M.; Greenberg, Albert G.; Lubachevsky, Boris D.

    1991-01-01

    Trace driven cache simulation is central to computer design. A trace is a very long sequence of reference lines from main memory. At the t(exp th) instant, reference x sub t is hashed into a set of cache locations, the contents of which are then compared with x sub t. If at the t sup th instant x sub t is not present in the cache, then it is said to be a miss, and is loaded into the cache set, possibly forcing the replacement of some other memory line, and making x sub t present for the (t+1) sup st instant. The problem of parallel simulation of a subtrace of N references directed to a C line cache set is considered, with the aim of determining which references are misses and related statistics. A simulation method is presented for the Least Recently Used (LRU) policy, which regradless of the set size C runs in time O(log N) using N processors on the exclusive read, exclusive write (EREW) parallel model. A simpler LRU simulation algorithm is given that runs in O(C log N) time using N/log N processors. Timings are presented of the second algorithm's implementation on the MasPar MP-1, a machine with 16384 processors. A broad class of reference based line replacement policies are considered, which includes LRU as well as the Least Frequently Used and Random replacement policies. A simulation method is presented for any such policy that on any trace of length N directed to a C line set runs in the O(C log N) time with high probability using N processors on the EREW model. The algorithms are simple, have very little space overhead, and are well suited for SIMD implementation.

  17. Neutron Transmission through Sapphire Crystals

    DEFF Research Database (Denmark)

    of simulations, in order to reproduce the transmission of cold neutrons through sapphire crystals. Those simulations were part of the effort of validating and improving the newly developed interface between the Monte-Carlo neutron transport code MCNP and the Monte Carlo ray-tracing code McStas....

  18. 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...

  19. Development and validation of real-time simulation of X-ray imaging with respiratory motion.

    Science.gov (United States)

    Vidal, Franck P; Villard, Pierre-Frédéric

    2016-04-01

    We present a framework that combines evolutionary optimisation, soft tissue modelling and ray tracing on GPU to simultaneously compute the respiratory motion and X-ray imaging in real-time. Our aim is to provide validated building blocks with high fidelity to closely match both the human physiology and the physics of X-rays. A CPU-based set of algorithms is presented to model organ behaviours during respiration. Soft tissue deformation is computed with an extension of the Chain Mail method. Rigid elements move according to kinematic laws. A GPU-based surface rendering method is proposed to compute the X-ray image using the Beer-Lambert law. It is provided as an open-source library. A quantitative validation study is provided to objectively assess the accuracy of both components: (i) the respiration against anatomical data, and (ii) the X-ray against the Beer-Lambert law and the results of Monte Carlo simulations. Our implementation can be used in various applications, such as interactive medical virtual environment to train percutaneous transhepatic cholangiography in interventional radiology, 2D/3D registration, computation of digitally reconstructed radiograph, simulation of 4D sinograms to test tomography reconstruction tools. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Bioremediation of trace cobalt from simulated spent decontamination solutions of nuclear power reactors using E. coli expressing NiCoT genes

    International Nuclear Information System (INIS)

    Raghu, G.; Maruthi Mohan, P.; Balaji, V.; Venkateswaran, G.; Rodrigue, A.; Lyon 1 Univ., 69

    2008-01-01

    Removal of radioactive cobalt at trace levels (∼nM) in the presence of large excess (10 6 -fold) of corrosion product ions of complexed Fe, Cr, and Ni in spent chemical decontamination formulations (simulated effluent) of nuclear reactors is currently done by using synthetic organic ion exchangers. A large volume of solid waste is generated due to the nonspecific nature of ion sorption. Our earlier work using various fungi and bacteria, with the aim of nuclear waste volume reduction, realized up to 30% of Co removal with specific capacities calculated up to 1 μg/g in 6-24 h. In the present study using engineered Escherichia coli expressing NiCoT genes from Rhodopseudomonas palustris CGA009 (RP) and Novosphingobium aromaticivorans F-199 (NA), we report a significant increase in the specific capacity for Co removal (12 μg/g) in 1-h exposure to simulated effluent. About 85% of Co removal was achieved in a two-cycle treatment with the cloned bacteria. Expression of NiCoT genes in the E. coli knockout mutant of NiCoT efflux gene (rcnA) was more efficient as compared to expression in wild-type E. coli MC4100, JM109 and BL21 (DE3) hosts. The viability of the E. coli strains in the formulation as well as at different doses of gamma rays exposure and the effect of gamma dose on their cobalt removal capacity are determined. The potential application scheme of the above process of bioremediation of cobalt from nuclear power reactor chemical decontamination effluents is discussed. (orig.)

  1. Simulation and optimization of the SIRIUS IPE soft x-ray beamline

    Science.gov (United States)

    Meyer, Bernd C.; Rocha, Tulio C. R.; Luiz, Sergio A. L.; C. Pinto, Artur; Westfahl, Harry

    2017-08-01

    The soft X-ray beamline IPE is one of the first phase SIRIUS beamlines at the LNLS, Brazil. Divided into two branches, IPE is designed to perform ambient pressure X-ray photo-electron spectroscopy (AP-XPS) and high resolution resonant inelastic X-ray scattering (RIXS) for samples in operando/environmental conditions inside cells and liquid jets. The aim is to maximize the photon flux in the energy range 200-1400 eV generated by an elliptically polarizing undulator source (EPU) and focus it to a 1 μm vertical spot size at the RIXS station and 10 μm at the AP-XPS station. In order to achieve the required resolving power (40.000 at 930 eV) for RIXS both the dispersion properties of the plane grating monochromator (PGM) and the thermal deformation of the optical elements need special attention. The grating parameters were optimized with the REFLEC code to maximize the efficiency at the required resolution. Thermal deformation of the PGM plane mirror limits the possible range of cff parameters depending of the photon energy used. Hence, resolution of the PGM and thermal deformation effects define the boundary conditions of the optical concept and the simulations of the IPE beamline. We compare simulations performed by geometrical ray-tracing (SHADOW) and wave front propagation (SRW) and show that wave front diffraction effects (apertures, optical surface error profiles) has a small effect on the beam spot size and shape.

  2. 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.

  3. Dose calculation of X-ray in medium

    International Nuclear Information System (INIS)

    Liu Yanmei; Xue Dingyu; Xu Xinhe; Chen Zhen; Dong Zaili

    2006-01-01

    The photon transportation in radiotherapy is studied based on Monte Carlo method. The dose calculation based on the MC simulation package DPM has been carried out, and the results have been visualized using MEX technology of Matlab. The dose results of X-ray in homogeneity and inhomogeneity medium have been compared with experimental data and those of other MC simulation package, and these results all agree. The calculation method we proposed has the advantage of high speed and good accuracy, therefore, is applicable in practice. (authors)

  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. Combined visualization for noise mapping of industrial facilities based on ray-tracing and thin plate splines

    Science.gov (United States)

    Ovsiannikov, Mikhail; Ovsiannikov, Sergei

    2017-01-01

    The paper presents the combined approach to noise mapping and visualizing of industrial facilities sound pollution using forward ray tracing method and thin-plate spline interpolation. It is suggested to cauterize industrial area in separate zones with similar sound levels. Equivalent local source is defined for range computation of sanitary zones based on ray tracing algorithm. Computation of sound pressure levels within clustered zones are based on two-dimension spline interpolation of measured data on perimeter and inside the zone.

  6. ERSN-OpenMC, a Java-based GUI for OpenMC Monte Carlo code

    Directory of Open Access Journals (Sweden)

    Jaafar EL Bakkali

    2016-07-01

    Full Text Available OpenMC is a new Monte Carlo transport particle simulation code focused on solving two types of neutronic problems mainly the k-eigenvalue criticality fission source problems and external fixed fission source problems. OpenMC does not have any Graphical User Interface and the creation of one is provided by our java-based application named ERSN-OpenMC. The main feature of this application is to provide to the users an easy-to-use and flexible graphical interface to build better and faster simulations, with less effort and great reliability. Additionally, this graphical tool was developed with several features, as the ability to automate the building process of OpenMC code and related libraries as well as the users are given the freedom to customize their installation of this Monte Carlo code. A full description of the ERSN-OpenMC application is presented in this paper.

  7. 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

  8. A new 3-D ray tracing method based on LTI using successive partitioning of cell interfaces and traveltime gradients

    Science.gov (United States)

    Zhang, Dong; Zhang, Ting-Ting; Zhang, Xiao-Lei; Yang, Yan; Hu, Ying; Qin, Qian-Qing

    2013-05-01

    We present a new method of three-dimensional (3-D) seismic ray tracing, based on an improvement to the linear traveltime interpolation (LTI) ray tracing algorithm. This new technique involves two separate steps. The first involves a forward calculation based on the LTI method and the dynamic successive partitioning scheme, which is applied to calculate traveltimes on cell boundaries and assumes a wavefront that expands from the source to all grid nodes in the computational domain. We locate several dynamic successive partition points on a cell's surface, the traveltimes of which can be calculated by linear interpolation between the vertices of the cell's boundary. The second is a backward step that uses Fermat's principle and the fact that the ray path is always perpendicular to the wavefront and follows the negative traveltime gradient. In this process, the first-arriving ray path can be traced from the receiver to the source along the negative traveltime gradient, which can be calculated by reconstructing the continuous traveltime field with cubic B-spline interpolation. This new 3-D ray tracing method is compared with the LTI method and the shortest path method (SPM) through a number of numerical experiments. These comparisons show obvious improvements to computed traveltimes and ray paths, both in precision and computational efficiency.

  9. A Simbol-X Event Simulator

    International Nuclear Information System (INIS)

    Puccetti, S.; Giommi, P.; Fiore, F.

    2009-01-01

    The ASI Science Data Center (ASDC) has developed an X-ray event simulator to support users (and team members) in simulation of data taken with the two cameras on board the Simbol-X X-Ray Telescope. The Simbol-X simulator is very fast and flexible, compared to ray-tracing simulator. These properties make our simulator advantageous to support the user in planning proposals and comparing real data with the theoretical expectations and for a quick detection of unexpected features. We present here the simulator outline and a few examples of simulated data.

  10. A Simbol-X Event Simulator

    Science.gov (United States)

    Puccetti, S.; Fiore, F.; Giommi, P.

    2009-05-01

    The ASI Science Data Center (ASDC) has developed an X-ray event simulator to support users (and team members) in simulation of data taken with the two cameras on board the Simbol-X X-Ray Telescope. The Simbol-X simulator is very fast and flexible, compared to ray-tracing simulator. These properties make our simulator advantageous to support the user in planning proposals and comparing real data with the theoretical expectations and for a quick detection of unexpected features. We present here the simulator outline and a few examples of simulated data.

  11. BER Performance Simulation of Generalized MC DS-CDMA System with Time-Limited Blackman Chip Waveform

    Directory of Open Access Journals (Sweden)

    I. Develi

    2010-09-01

    Full Text Available Multiple access interference encountered in multicarrier direct sequence-code division multiple access (MC DS-CDMA is the most important difficulty that depends mainly on the correlation properties of the spreading sequences as well as the shape of the chip waveforms employed. In this paper, bit error rate (BER performance of the generalized MC DS-CDMA system that employs time-limited Blackman chip waveform is presented for Nakagami-m fading channels. Simulation results show that the use of Blackman chip waveform can improve the BER performance of the generalized MC DS-CDMA system, as compared to the performances achieved by using timelimited chip waveforms in the literature.

  12. 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....

  13. 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.)

  14. An X-ray outburst from the rapidly accreting young star that illuminates McNeil's nebula.

    Science.gov (United States)

    Kastner, J H; Richmond, M; Grosso, N; Weintraub, D A; Simon, T; Frank, A; Hamaguchi, K; Ozawa, H; Henden, A

    2004-07-22

    Young, low-mass stars are luminous X-ray sources whose powerful X-ray flares may exert a profound influence over the process of planet formation. The origin of the X-ray emission is uncertain. Although many (or perhaps most) recently formed, low-mass stars emit X-rays as a consequence of solar-like coronal activity, it has also been suggested that X-ray emission may be a direct result of mass accretion onto the forming star. Here we report X-ray imaging spectroscopy observations which reveal a factor approximately 50 increase in the X-ray flux from a young star that is at present undergoing a spectacular optical/infrared outburst (this star illuminates McNeil's nebula). The outburst seems to be due to the sudden onset of a phase of rapid accretion. The coincidence of a surge in X-ray brightness with the optical/infrared eruption demonstrates that strongly enhanced high-energy emission from young stars can occur as a consequence of high accretion rates. We suggest that such accretion-enhanced X-ray emission from erupting young stars may be short-lived, because intense star-disk magnetospheric interactions are quenched rapidly by the subsequent flood of new material onto the star.

  15. The quantitative determination of trace elements in giant unicellular plants by particle-induced X-ray emission

    International Nuclear Information System (INIS)

    Navarrete-Dominguez, V.R.; Yoshihara, K.; Tanaka, N.

    1982-01-01

    Particle-induced X-ray emission (PIXE) was applied for the determination of trace elements in biologically interesting materials, giant unicellular plants. It was found that the PIXE method had advantages in multi-element trace analysis of a single cell of the sample plant. (author)

  16. Simulation of the turbine discharge transient with the code Trace

    International Nuclear Information System (INIS)

    Mejia S, D. M.; Filio L, C.

    2014-10-01

    In this paper the results of the simulation of the turbine discharge transient are shown, occurred in Unit 1 of nuclear power plant of Laguna Verde (NPP-L V), carried out with the model of this unit for the best estimate code Trace. The results obtained by the code Trace are compared with those obtained from the Process Information Integral System (PIIS) of the NPP-L V. The reactor pressure, level behavior in the down-comer, steam flow and flow rate through the recirculation circuits are compared. The results of the simulation for the operation power of 2027 MWt, show concordance with the system PIIS. (Author)

  17. (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.

  18. MC 93 - Proceedings of the International Conference on Monte Carlo Simulation in High Energy and Nuclear Physics

    Science.gov (United States)

    Dragovitsch, Peter; Linn, Stephan L.; Burbank, Mimi

    1994-01-01

    The Table of Contents for the book is as follows: * Preface * Heavy Fragment Production for Hadronic Cascade Codes * Monte Carlo Simulations of Space Radiation Environments * Merging Parton Showers with Higher Order QCD Monte Carlos * An Order-αs Two-Photon Background Study for the Intermediate Mass Higgs Boson * GEANT Simulation of Hall C Detector at CEBAF * Monte Carlo Simulations in Radioecology: Chernobyl Experience * UNIMOD2: Monte Carlo Code for Simulation of High Energy Physics Experiments; Some Special Features * Geometrical Efficiency Analysis for the Gamma-Neutron and Gamma-Proton Reactions * GISMO: An Object-Oriented Approach to Particle Transport and Detector Modeling * Role of MPP Granularity in Optimizing Monte Carlo Programming * Status and Future Trends of the GEANT System * The Binary Sectioning Geometry for Monte Carlo Detector Simulation * A Combined HETC-FLUKA Intranuclear Cascade Event Generator * The HARP Nucleon Polarimeter * Simulation and Data Analysis Software for CLAS * TRAP -- An Optical Ray Tracing Program * Solutions of Inverse and Optimization Problems in High Energy and Nuclear Physics Using Inverse Monte Carlo * FLUKA: Hadronic Benchmarks and Applications * Electron-Photon Transport: Always so Good as We Think? Experience with FLUKA * Simulation of Nuclear Effects in High Energy Hadron-Nucleus Collisions * Monte Carlo Simulations of Medium Energy Detectors at COSY Jülich * Complex-Valued Monte Carlo Method and Path Integrals in the Quantum Theory of Localization in Disordered Systems of Scatterers * Radiation Levels at the SSCL Experimental Halls as Obtained Using the CLOR89 Code System * Overview of Matrix Element Methods in Event Generation * Fast Electromagnetic Showers * GEANT Simulation of the RMC Detector at TRIUMF and Neutrino Beams for KAON * Event Display for the CLAS Detector * Monte Carlo Simulation of High Energy Electrons in Toroidal Geometry * GEANT 3.14 vs. EGS4: A Comparison Using the DØ Uranium/Liquid Argon

  19. 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)

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

    International Nuclear Information System (INIS)

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

    2003-01-01

    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

  1. 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.

  2. Comparison of matrix method and ray tracing in the study of complex optical systems

    Science.gov (United States)

    Anterrieu, Eric; Perez, Jose-Philippe

    2000-06-01

    In the context of the classical study of optical systems within the geometrical Gauss approximation, the cardinal elements are efficiently obtained with the aid of the transfer matrix between the input and output planes of the system. In order to take into account the geometrical aberrations, a ray tracing approach, using the Snell- Descartes laws, has been implemented in an interactive software. Both methods are applied for measuring the correction to be done to a human eye suffering from ametropia. This software may be used by optometrists and ophthalmologists for solving the problems encountered when considering this pathology. The ray tracing approach gives a significant improvement and could be very helpful for a better understanding of an eventual surgical act.

  3. Simulation of the Simbol-X telescope: imaging performance of a deformable x-ray telescope

    Science.gov (United States)

    Chauvin, Maxime; Roques, Jean-Pierre

    2009-08-01

    We have developed a simulation tool for a Wolter I telescope subject to deformations. The aim is to understand and predict the behavior of Simbol-X and other future missions (NuSTAR, Astro-H, IXO, ...). Our code, based on Monte-Carlo ray-tracing, computes the full photon trajectories up to the detector plane, along with the deformations. The degradation of the imaging system is corrected using metrology. This tool allows to perform many analyzes in order to optimize the configuration of any of these telescopes.

  4. Photorealistic 3D omni-directional stereo simulator

    Science.gov (United States)

    Reiners, Dirk; Cruz-Neira, Carolina; Neumann, Carsten

    2015-03-01

    While a lot of areas in VR have made significant advances, visual rendering in VR is often not quite keeping up with the state of the art. There are many reasons for this, but one way to alleviate some of the issues is by using ray tracing instead of rasterization for image generation. Contrary to popular belief, ray tracing is a realistic, competitive technology nowadays. This paper looks at the pros and cons of using ray tracing and demonstrates the feasibility of employing it using the example of a helicopter flight simulator image generator.

  5. Introducing GAMER: A Fast and Accurate Method for Ray-tracing Galaxies Using Procedural Noise

    Science.gov (United States)

    Groeneboom, N. E.; Dahle, H.

    2014-03-01

    We developed a novel approach for fast and accurate ray-tracing of galaxies using procedural noise fields. Our method allows for efficient and realistic rendering of synthetic galaxy morphologies, where individual components such as the bulge, disk, stars, and dust can be synthesized in different wavelengths. These components follow empirically motivated overall intensity profiles but contain an additional procedural noise component that gives rise to complex natural patterns that mimic interstellar dust and star-forming regions. These patterns produce more realistic-looking galaxy images than using analytical expressions alone. The method is fully parallelized and creates accurate high- and low- resolution images that can be used, for example, in codes simulating strong and weak gravitational lensing. In addition to having a user-friendly graphical user interface, the C++ software package GAMER is easy to implement into an existing code.

  6. Introducing GAMER: A fast and accurate method for ray-tracing galaxies using procedural noise

    International Nuclear Information System (INIS)

    Groeneboom, N. E.; Dahle, H.

    2014-01-01

    We developed a novel approach for fast and accurate ray-tracing of galaxies using procedural noise fields. Our method allows for efficient and realistic rendering of synthetic galaxy morphologies, where individual components such as the bulge, disk, stars, and dust can be synthesized in different wavelengths. These components follow empirically motivated overall intensity profiles but contain an additional procedural noise component that gives rise to complex natural patterns that mimic interstellar dust and star-forming regions. These patterns produce more realistic-looking galaxy images than using analytical expressions alone. The method is fully parallelized and creates accurate high- and low- resolution images that can be used, for example, in codes simulating strong and weak gravitational lensing. In addition to having a user-friendly graphical user interface, the C++ software package GAMER is easy to implement into an existing code.

  7. Introducing GAMER: A fast and accurate method for ray-tracing galaxies using procedural noise

    Energy Technology Data Exchange (ETDEWEB)

    Groeneboom, N. E.; Dahle, H., E-mail: nicolaag@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway)

    2014-03-10

    We developed a novel approach for fast and accurate ray-tracing of galaxies using procedural noise fields. Our method allows for efficient and realistic rendering of synthetic galaxy morphologies, where individual components such as the bulge, disk, stars, and dust can be synthesized in different wavelengths. These components follow empirically motivated overall intensity profiles but contain an additional procedural noise component that gives rise to complex natural patterns that mimic interstellar dust and star-forming regions. These patterns produce more realistic-looking galaxy images than using analytical expressions alone. The method is fully parallelized and creates accurate high- and low- resolution images that can be used, for example, in codes simulating strong and weak gravitational lensing. In addition to having a user-friendly graphical user interface, the C++ software package GAMER is easy to implement into an existing code.

  8. Report on intercomparison IAEA/W-4 of the determination of trace elements in simulated fresh water

    International Nuclear Information System (INIS)

    Pszonicki, L.; Hanna, A.N.; Suschny, O.

    1985-05-01

    The report presents results of a laboratory intercomparison on the determination of trace elements in simulated fresh water. 20 trace elements were analyzed by 38 laboratories from 21 countries. The results of the reported comparison confirm the agreement of the nominal concentration values of trace elements in the IAEA/W-4 simulated fresh water with the determined values of these elements. They also confirm that concentrated solutions of this type can be stored in quartz ampoules without any noticeable changes due to the adsorption of trace components on the quartz wall of vessels for considerable time. The concentration values of trace elements could be certified and the material IAEA/W-4 simulated fresh water issued as a reference material. 84% of all results were obtained either by atomic absorption or by atomic emission spectroscopy

  9. Monte Carlo simulation of the resolution volume for the SEQUOIA spectrometer

    Directory of Open Access Journals (Sweden)

    Granroth G.E.

    2015-01-01

    Full Text Available Monte Carlo ray tracing simulations, of direct geometry spectrometers, have been particularly useful in instrument design and characterization. However, these tools can also be useful for experiment planning and analysis. To this end, the McStas Monte Carlo ray tracing model of SEQUOIA, the fine resolution fermi chopper spectrometer at the Spallation Neutron Source (SNS of Oak Ridge National Laboratory (ORNL, has been modified to include the time of flight resolution sample and detector components. With these components, the resolution ellipsoid can be calculated for any detector pixel and energy bin of the instrument. The simulation is split in two pieces. First, the incident beamline up to the sample is simulated for 1 × 1011 neutron packets (4 days on 30 cores. This provides a virtual source for the backend that includes the resolution sample and monitor components. Next, a series of detector and energy pixels are computed in parallel. It takes on the order of 30 s to calculate a single resolution ellipsoid on a single core. Python scripts have been written to transform the ellipsoid into the space of an oriented single crystal, and to characterize the ellipsoid in various ways. Though this tool is under development as a planning tool, we have successfully used it to provide the resolution function for convolution with theoretical models. Specifically, theoretical calculations of the spin waves in YFeO3 were compared to measurements taken on SEQUOIA. Though the overall features of the spectra can be explained while neglecting resolution effects, the variation in intensity of the modes is well described once the resolution is included. As this was a single sharp mode, the simulated half intensity value of the resolution ellipsoid was used to provide the resolution width. A description of the simulation, its use, and paths forward for this technique will be discussed.

  10. Analytical approximations to the Hotelling trace for digital x-ray detectors

    Science.gov (United States)

    Clarkson, Eric; Pineda, Angel R.; Barrett, Harrison H.

    2001-06-01

    The Hotelling trace is the signal-to-noise ratio for the ideal linear observer in a detection task. We provide an analytical approximation for this figure of merit when the signal is known exactly and the background is generated by a stationary random process, and the imaging system is an ideal digital x-ray detector. This approximation is based on assuming that the detector is infinite in extent. We test this approximation for finite-size detectors by comparing it to exact calculations using matrix inversion of the data covariance matrix. After verifying the validity of the approximation under a variety of circumstances, we use it to generate plots of the Hotelling trace as a function of pairs of parameters of the system, the signal and the background.

  11. Pseudo forward ray-tracing: A new method for surface validation in cornea topography

    NARCIS (Netherlands)

    Sicam, V.; Snellenburg, J.J.; van der Heijde, R.G.; van Stokkum, I.H.M.

    2007-01-01

    PURPOSE. A pseudo forward ray-tracing (PFRT) algorithm is developed to evaluate surface reconstruction in corneal topography. The method can be applied to topographers where one-to-one correspondence between mire and image points can be established. METHODS. The PFRT algorithm was applied on a

  12. Molecular dynamics simulation for PBR pebble tracking simulation via a random walk approach using Monte Carlo simulation.

    Science.gov (United States)

    Lee, Kyoung O; Holmes, Thomas W; Calderon, Adan F; Gardner, Robin P

    2012-05-01

    Using a Monte Carlo (MC) simulation, random walks were used for pebble tracking in a two-dimensional geometry in the presence of a biased gravity field. We investigated the effect of viscosity damping in the presence of random Gaussian fluctuations. The particle tracks were generated by Molecular Dynamics (MD) simulation for a Pebble Bed Reactor. The MD simulations were conducted in the interaction of noncohesive Hertz-Mindlin theory where the random walk MC simulation has a correlation with the MD simulation. This treatment can easily be extended to include the generation of transient gamma-ray spectra from a single pebble that contains a radioactive tracer. Then the inverse analysis thereof could be made to determine the uncertainty of the realistic measurement of transient positions of that pebble by any given radiation detection system designed for that purpose. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. 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.

  14. Multi-Buffer Simulations for Trace Language Inclusion

    Directory of Open Access Journals (Sweden)

    Milka Hutagalung

    2016-09-01

    Full Text Available We consider simulation games played between Spoiler and Duplicator on two Büchi automata in which the choices made by Spoiler can be buffered by Duplicator in several buffers before she executes them on her structure. We show that the simulation games are useful to approximate the inclusion of trace closures of languages accepted by finite-state automata, which is known to be undecidable. We study the decidability and complexity and show that the game with bounded buffers can be decided in polynomial time, whereas the game with one unbounded and one bounded buffer is highly undecidable. We also show some sufficient conditions on the automata for Duplicator to win the game (with unbounded buffers.

  15. Trace contaminant control simulation computer program, version 8.1

    Science.gov (United States)

    Perry, J. L.

    1994-01-01

    The Trace Contaminant Control Simulation computer program is a tool for assessing the performance of various process technologies for removing trace chemical contamination from a spacecraft cabin atmosphere. Included in the simulation are chemical and physical adsorption by activated charcoal, chemical adsorption by lithium hydroxide, absorption by humidity condensate, and low- and high-temperature catalytic oxidation. Means are provided for simulating regenerable as well as nonregenerable systems. The program provides an overall mass balance of chemical contaminants in a spacecraft cabin given specified generation rates. Removal rates are based on device flow rates specified by the user and calculated removal efficiencies based on cabin concentration and removal technology experimental data. Versions 1.0 through 8.0 are documented in NASA TM-108409. TM-108409 also contains a source file listing for version 8.0. Changes to version 8.0 are documented in this technical memorandum and a source file listing for the modified version, version 8.1, is provided. Detailed descriptions for the computer program subprograms are extracted from TM-108409 and modified as necessary to reflect version 8.1. Version 8.1 supersedes version 8.0. Information on a separate user's guide is available from the author.

  16. 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)

  17. Development and testing of a new ray-tracing approach to GNSS carrier-phase multipath modelling

    Science.gov (United States)

    Lau, Lawrence; Cross, Paul

    2007-11-01

    Multipath is one of the most important error sources in Global Navigation Satellite System (GNSS) carrier-phase-based precise relative positioning. Its theoretical maximum is a quarter of the carrier wavelength (about 4.8 cm for the Global Positioning System (GPS) L1 carrier) and, although it rarely reaches this size, it must clearly be mitigated if millimetre-accuracy positioning is to be achieved. In most static applications, this may be accomplished by averaging over a sufficiently long period of observation, but in kinematic applications, a modelling approach must be used. This paper is concerned with one such approach: the use of ray-tracing to reconstruct the error and therefore remove it. In order to apply such an approach, it is necessary to have a detailed understanding of the signal transmitted from the satellite, the reflection process, the antenna characteristics and the way that the reflected and direct signal are processed within the receiver. This paper reviews all of these and introduces a formal ray-tracing method for multipath estimation based on precise knowledge of the satellite reflector antenna geometry and of the reflector material and antenna characteristics. It is validated experimentally using GPS signals reflected from metal, water and a brick building, and is shown to be able to model most of the main multipath characteristics. The method will have important practical applications for correcting for multipath in well-constrained environments (such as at base stations for local area GPS networks, at International GNSS Service (IGS) reference stations, and on spacecraft), and it can be used to simulate realistic multipath errors for various performance analyses in high-precision positioning.

  18. 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

  19. Development of the McGill simulator for endoscopic sinus surgery: a new high-fidelity virtual reality simulator for endoscopic sinus surgery.

    Science.gov (United States)

    Varshney, Rickul; Frenkiel, Saul; Nguyen, Lily H P; Young, Meredith; Del Maestro, Rolando; Zeitouni, Anthony; Tewfik, Marc A

    2014-01-01

    The technical challenges of endoscopic sinus surgery (ESS) and the high risk of complications support the development of alternative modalities to train residents in these procedures. Virtual reality simulation is becoming a useful tool for training the skills necessary for minimally invasive surgery; however, there are currently no ESS virtual reality simulators available with valid evidence supporting their use in resident education. Our aim was to develop a new rhinology simulator, as well as to define potential performance metrics for trainee assessment. The McGill simulator for endoscopic sinus surgery (MSESS), a new sinus surgery virtual reality simulator with haptic feedback, was developed (a collaboration between the McGill University Department of Otolaryngology-Head and Neck Surgery, the Montreal Neurologic Institute Simulation Lab, and the National Research Council of Canada). A panel of experts in education, performance assessment, rhinology, and skull base surgery convened to identify core technical abilities that would need to be taught by the simulator, as well as performance metrics to be developed and captured. The MSESS allows the user to perform basic sinus surgery skills, such as an ethmoidectomy and sphenoidotomy, through the use of endoscopic tools in a virtual nasal model. The performance metrics were developed by an expert panel and include measurements of safety, quality, and efficiency of the procedure. The MSESS incorporates novel technological advancements to create a realistic platform for trainees. To our knowledge, this is the first simulator to combine novel tools such as the endonasal wash and elaborate anatomic deformity with advanced performance metrics for ESS.

  20. Preparation of tracing source layer in simulation test of nuclide migration

    International Nuclear Information System (INIS)

    Zhao Yingjie; Ni Shiwei; Li Weijuan; Yamamoto, T.; Tanaka, T.; Komiya, T.

    1993-01-01

    In cooperative research between CIRP and JAERI on safety assessment for shallow land disposal of low level radioactive waste, a laboratory simulation test of nuclide migration was carried out, in which the undisturbed loess soil column sampled from CIRP' s field test site was used as testing material, three nuclides, Sr-85, Cs-137 and Co-60 were used as tracers. Special experiment on tracing method was carried out, which included measuring pH value of quartz sand in HCl solution, determining the eligible water content of quartz sand as tracer carrier, measuring distribution uniformity of nuclides in the tracing quartz sand, determining elution rate of nuclides from the tracing quartz sand and detecting activity uniformity of tracing source layer. The experiment results showed that the tracing source layer, in which fine quartz sand was used as tracer carrier, satisfied expected requirement. (1 fig.)

  1. Discrete curved ray-tracing method for radiative transfer in an absorbing-emitting semitransparent slab with variable spatial refractive index

    International Nuclear Information System (INIS)

    Liu, L.H.

    2004-01-01

    A discrete curved ray-tracing method is developed to analyze the radiative transfer in one-dimensional absorbing-emitting semitransparent slab with variable spatial refractive index. The curved ray trajectory is locally treated as straight line and the complicated and time-consuming computation of ray trajectory is cut down. A problem of radiative equilibrium with linear variable spatial refractive index is taken as an example to examine the accuracy of the proposed method. The temperature distributions are determined by the proposed method and compared with the data in references, which are obtained by other different methods. The results show that the discrete curved ray-tracing method has a good accuracy in solving the radiative transfer in one-dimensional semitransparent slab with variable spatial refractive index

  2. 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.

  3. 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.)

  4. 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.

  5. Simulation of the turbine discharge transient with the code Trace; Simulacion del transitorio disparo de turbina con el codigo TRACE

    Energy Technology Data Exchange (ETDEWEB)

    Mejia S, D. M.; Filio L, C., E-mail: dulcemaria.mejia@cnsns.gob.mx [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Jose Ma. Barragan No. 779, Col. Narvarte, 03020 Mexico D. F. (Mexico)

    2014-10-15

    In this paper the results of the simulation of the turbine discharge transient are shown, occurred in Unit 1 of nuclear power plant of Laguna Verde (NPP-L V), carried out with the model of this unit for the best estimate code Trace. The results obtained by the code Trace are compared with those obtained from the Process Information Integral System (PIIS) of the NPP-L V. The reactor pressure, level behavior in the down-comer, steam flow and flow rate through the recirculation circuits are compared. The results of the simulation for the operation power of 2027 MWt, show concordance with the system PIIS. (Author)

  6. Intraocular Telescopic System Design: Optical and Visual Simulation in a Human Eye Model

    OpenAIRE

    Zoulinakis, Georgios; Ferrer-Blasco, Teresa

    2017-01-01

    Purpose. To design an intraocular telescopic system (ITS) for magnifying retinal image and to simulate its optical and visual performance after implantation in a human eye model. Methods. Design and simulation were carried out with a ray-tracing and optical design software. Two different ITS were designed, and their visual performance was simulated using the Liou-Brennan eye model. The difference between the ITS was their lenses’ placement in the eye model and their powers. Ray tracing in bot...

  7. Construction of a catalog of X-ray spectra for mammography simulations; Construção de um catálogo de espectros de raios X para simulações em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Santos, L.C.S.; Vieira, J.W., E-mail: larissa.css@outlook.com [Instituto Federal de Pernambuco (IFPE), Recife, PE (Brazil). Dept. Acadêmico de Ambiente, Saúde e Segurança; Lima, F.R.A., E-mail: falima@cnen.gov.br [Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife-PE (Brazil)

    2017-07-01

    Computational Exposure Models (MCEs) allow the simulation of the interaction of radiation with matter by means of Monte Carlo (MC) techniques. Generally, MCEs are composed of phantom, simulator algorithms of radioactive sources and an MC code to simulate the transport, interaction of the radiation with matter and to evaluate the energy deposited in regions of interest. To compose an MCE for simulations in mammography, the construction of a catalog of X-ray spectra was started, based on the catalog model constructed and using until then in MCEs by the Group of Research in Numerical Dosimetry and by the Group of Research in Computational Dosimetry & Embedded Systems (both referenced in this work as GDN). Potential of 25 kV and 35 kV and used target / filter were applied to the tube: Mo / Mo. The file containing the spectra was read correctly by EGSnrc.

  8. MC/DC and Toggle Coverage Measurement Tool for FBD Program Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eui Sub; Jung, Se Jin; Kim, Jae Yeob; Yoo, Jun Beom [Konkuk University, Seoul (Korea, Republic of)

    2016-05-15

    The functional verification of FBD program can be implemented with various techniques such as testing and simulation. Simulation is preferable to verify FBD program, because it replicates operation of the PLC as well. The PLC is executed repeatedly as long as the controlled system is running based on scan time. Likewise, the simulation technique operates continuously and sequentially. Although engineers try to verify the functionality wholly, it is difficult to find residual errors in the design. Even if 100% functional coverage is accomplished, code coverage have 50%, which might indicate that the scenario is missing some key features of the design. Unfortunately, errors and bugs are often found in the missing points. To assure a high quality of functional verification, code coverage is important as well as functional coverage. We developed a pair tool 'FBDSim' and 'FBDCover' for FBD simulation and coverage measurement. The 'FBDSim' automatically simulates a set of FBD simulation scenarios. While the 'FBDSim' simulates the FBD program, it calculates the MC/DC and Toggle coverage and identifies unstimulated points. After FBD simulation is done, the 'FBDCover' reads the coverage results and shows the coverage with graphical feature and uncovered points with tree feature. The coverages and uncovered points can help engineers to improve the quality of simulation. We slightly dealt with the both coverages, but the coverage is dealt with more concrete and rigorous manner.

  9. McStas and Mantid integration

    DEFF Research Database (Denmark)

    Nielsen, T. R.; Markvardsen, A. J.; Willendrup, Peter Kjær

    2015-01-01

    McStas and Mantid are two well-established software frameworks within the neutron scattering community. McStas has been primarily used for simulating the neutron transport mechanisms in instruments, while Mantid has been primarily used for data reduction. We report here the status of our work don...

  10. Simulation of the KAERI PASCAL Test with MARS-KS and TRACE Codes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Won; Cheong, Aeju; Shin, Andong; Cho, Min Ki [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2016-10-15

    In order to validate the operational performance of the PAFS, KAERI has performed the experimental investigation using the PASCAL (PAFS Condensing heat removal Assessment Loop) facility. In this study, we simulated the KAERI PASCAL SS-540-P1 test with MARS-KS V1.4 and TRACE V5.0 p4 codes to assess the code predictability for the condensation heat transfer inside the passive auxiliary feedwater system. We simulated the KAERI PASCAL SS-540-P1 test with MARS-KS V1.4 and TRACE V5.0 p4 codes to assess the code predictability for the condensation heat transfer inside the passive auxiliary feedwater system. The calculated results of heat flux, inner wall surface temperature of the condensing tube, fluid temperature, and steam mass flow rate are compared with the experimental data. The result shows that the MARS-KS generally under-predict the heat fluxes. The TRACE over-predicts the heat flux at tube inlet region and under-predicts it at tube outlet region. The TRACE prediction shows larger amount of steam condensation by about 3% than the MARS-KS prediction.

  11. 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

  12. 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

    2018-04-01

    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.

  13. Ray-tracing traveltime tomography versus wave-equation traveltime inversion for near-surface seismic land data

    KAUST Repository

    Fu, Lei; Hanafy, Sherif M.

    2017-01-01

    . 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

  14. Correction for interelement effect in X-Ray fluorescence analysis of trace elements in geological materials

    International Nuclear Information System (INIS)

    El-Behay, A.Z.; Attawiya, M.Y.; Khattab, F.M.

    1984-01-01

    In a trial to obtain accurate results from X-ray fluorescence technique for the analysis of trace elements in geological materials, two corrections were used for the obtained data, namely, correction for the observed x-ray intensities for absorption and/or enhancement effects due to the presence of other elements in the system and correction for spectral deconvolution to account for the overlapping lines. Significant improvement in the precision and accuracy was obtained and evaluated

  15. 13.1 micrometers hard X-ray focusing by a new type monocapillary X-ray optic designed for common laboratory X-ray source

    Science.gov (United States)

    Sun, Xuepeng; zhang, Xiaoyun; Zhu, Yu; Wang, Yabing; Shang, Hongzhong; Zhang, Fengshou; Liu, Zhiguo; Sun, Tianxi

    2018-04-01

    A new type of monocapillary X-ray optic, called 'two bounces monocapillary X-ray optics' (TBMXO), is proposed for generating a small focal spot with high power-density gain for micro X-ray analysis, using a common laboratory X-ray source. TBMXO is consists of two parts: an ellipsoidal part and a tapered part. Before experimental testing, the TBMXO was simulated by the ray tracing method in MATLAB. The simulated results predicted that the proposed TBMXO would produce a smaller focal spot with higher power-density gain than the ellipsoidal monocapillary X-ray optic (EMXO). In the experiment, the TBMXO performance was tested by both an optical device and a Cu target X-ray tube with focal spot of 100 μm. The results indicated that the TBMXO had a slope error of 57.6 μrad and a 13.1 μm focal spot and a 1360 gain in power density were obtained.

  16. Mapping of trace elements with photon microprobes: x-ray fluorescence with focussed synchrotron radiation

    International Nuclear Information System (INIS)

    Hanson, A.L.; Jones, K.W.; Gordon, B.M.; Pounds, J.G.; Rivers, M.L.; Schidlovsky, G.

    1985-04-01

    High energy electron synchrotron storage rings provide copious quantities of polarized photons that make possible the mapping of many trace elements with sensitivities at the parts per billion (ppB) level with spatial resolutions in the micrometer range. The brightness of the x-ray ring of the National Synchrotron Light Source (NSLS), presently being commissioned, will be five orders of magnitude larger than that of the bremsstrahlung spectrum of state-of-the-art rotating anode tubes. We will discuss mapping trace elements with a photon microprobe presently being constructed for use at the NSLS. This microprobe will have micrometer spatial resolution

  17. 3-D Ray-tracing and 2-D Fokker-Planck Simulations of Radiofrequency Application to Tokamak Plasmas

    International Nuclear Information System (INIS)

    Cardinali, A.; Paoletti, F.; Bernabei, S.

    1999-01-01

    A state of the art numerical tool has been developed to simulate the propagation and the absorption of coexisting different types of waves in a tokamak geometry. The code includes a numerical solution of the three-dimensional (R, Z, Φ) toroidal wave equation for the electric field of the different waves in the WKBJ approximation. At each step of integration, the two-dimensional (v parallel, v perpendicular) Fokker-Planck equation is solved in the presence of quasilinear diffusion coefficients. The electron Landau damping of the waves is modeled taking into account the interaction of the wave electric fields with the quasilinearly modified distribution function. Consistently, the code calculates the radial profiles of non-inductively generated current densities, the transmitted power traces and the total power damping curves. Synergistic effects among the different type of waves (e.g., lower hybrid and ion Bernstein waves) are studied through the separation of the contributions of the single wave from the effects due to their coexistence

  18. Stochastic approach to municipal solid waste landfill life based on the contaminant transit time modeling using the Monte Carlo (MC) simulation

    International Nuclear Information System (INIS)

    Bieda, Bogusław

    2013-01-01

    The paper is concerned with application and benefits of MC simulation proposed for estimating the life of a modern municipal solid waste (MSW) landfill. The software Crystal Ball® (CB), simulation program that helps analyze the uncertainties associated with Microsoft® Excel models by MC simulation, was proposed to calculate the transit time contaminants in porous media. The transport of contaminants in soil is represented by the one-dimensional (1D) form of the advection–dispersion equation (ADE). The computer program CONTRANS written in MATLAB language is foundation to simulate and estimate the thickness of landfill compacted clay liner. In order to simplify the task of determining the uncertainty of parameters by the MC simulation, the parameters corresponding to the expression Z2 taken from this program were used for the study. The tested parameters are: hydraulic gradient (HG), hydraulic conductivity (HC), porosity (POROS), linear thickness (TH) and diffusion coefficient (EDC). The principal output report provided by CB and presented in the study consists of the frequency chart, percentiles summary and statistics summary. Additional CB options provide a sensitivity analysis with tornado diagrams. The data that was used include available published figures as well as data concerning the Mittal Steel Poland (MSP) S.A. in Kraków, Poland. This paper discusses the results and show that the presented approach is applicable for any MSW landfill compacted clay liner thickness design. -- Highlights: ► Numerical simulation of waste in porous media is proposed. ► Statistic outputs based on correct assumptions about probability distribution are presented. ► The benefits of a MC simulation are examined. ► The uniform probability distribution is studied. ► I report a useful tool applied to determine the life of a modern MSW landfill.

  19. Stochastic approach to municipal solid waste landfill life based on the contaminant transit time modeling using the Monte Carlo (MC) simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bieda, Boguslaw, E-mail: bbieda@zarz.agh.edu.pl

    2013-01-01

    The paper is concerned with application and benefits of MC simulation proposed for estimating the life of a modern municipal solid waste (MSW) landfill. The software Crystal Ball Registered-Sign (CB), simulation program that helps analyze the uncertainties associated with Microsoft Registered-Sign Excel models by MC simulation, was proposed to calculate the transit time contaminants in porous media. The transport of contaminants in soil is represented by the one-dimensional (1D) form of the advection-dispersion equation (ADE). The computer program CONTRANS written in MATLAB language is foundation to simulate and estimate the thickness of landfill compacted clay liner. In order to simplify the task of determining the uncertainty of parameters by the MC simulation, the parameters corresponding to the expression Z2 taken from this program were used for the study. The tested parameters are: hydraulic gradient (HG), hydraulic conductivity (HC), porosity (POROS), linear thickness (TH) and diffusion coefficient (EDC). The principal output report provided by CB and presented in the study consists of the frequency chart, percentiles summary and statistics summary. Additional CB options provide a sensitivity analysis with tornado diagrams. The data that was used include available published figures as well as data concerning the Mittal Steel Poland (MSP) S.A. in Krakow, Poland. This paper discusses the results and show that the presented approach is applicable for any MSW landfill compacted clay liner thickness design. -- Highlights: Black-Right-Pointing-Pointer Numerical simulation of waste in porous media is proposed. Black-Right-Pointing-Pointer Statistic outputs based on correct assumptions about probability distribution are presented. Black-Right-Pointing-Pointer The benefits of a MC simulation are examined. Black-Right-Pointing-Pointer The uniform probability distribution is studied. Black-Right-Pointing-Pointer I report a useful tool applied to determine the life of a

  20. Modeling the reflectance of the lunar regolith by a new method combining Monte Carlo Ray tracing and Hapke's model with application to Chang'E-1 IIM data.

    Science.gov (United States)

    Wong, Un-Hong; Wu, Yunzhao; Wong, Hon-Cheng; Liang, Yanyan; Tang, Zesheng

    2014-01-01

    In this paper, we model the reflectance of the lunar regolith by a new method combining Monte Carlo ray tracing and Hapke's model. The existing modeling methods exploit either a radiative transfer model or a geometric optical model. However, the measured data from an Interference Imaging spectrometer (IIM) on an orbiter were affected not only by the composition of minerals but also by the environmental factors. These factors cannot be well addressed by a single model alone. Our method implemented Monte Carlo ray tracing for simulating the large-scale effects such as the reflection of topography of the lunar soil and Hapke's model for calculating the reflection intensity of the internal scattering effects of particles of the lunar soil. Therefore, both the large-scale and microscale effects are considered in our method, providing a more accurate modeling of the reflectance of the lunar regolith. Simulation results using the Lunar Soil Characterization Consortium (LSCC) data and Chang'E-1 elevation map show that our method is effective and useful. We have also applied our method to Chang'E-1 IIM data for removing the influence of lunar topography to the reflectance of the lunar soil and to generate more realistic visualizations of the lunar surface.

  1. 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

  2. iFit: a new data analysis framework. Applications for data reduction and optimization of neutron scattering instrument simulations with McStas

    DEFF Research Database (Denmark)

    Farhi, E.; Y., Debab,; Willendrup, Peter Kjær

    2014-01-01

    and noisy problems. These optimizers can then be used to fit models onto data objects, and optimize McStas instrument simulations. As an application, we propose a methodology to analyse neutron scattering measurements in a pure Monte Carlo optimization procedure using McStas and iFit. As opposed...

  3. Alloy characterization of a 7th Century BC archeological bronze vase — Overcoming patina constraints using Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Manso, M. [Laboratório de Instrumentação, Engenharia Biomédica e Fisica da Radiação (LIBPhys-UNL), Departamento de Fisica, Faculdade de Ciências e Tecnologias, Universidade Nova de Lisboa, 2829-516 Monte da Caparica (Portugal); Faculdade de Belas-Artes da Universidade de Lisboa, Largo da Academia Nacional de Belas-Artes, 1249-058 Lisboa (Portugal); Schiavon, N. [Hercules Laboratory, University of Évora, Palácio do Vimioso,Largo Marquês de Marialva 8, 7000-809 Évora Portugal (Portugal); Queralt, I. [Laboratory of X-ray Analytical Applications, Institute of Earth Sciences Jaume Almera, CSIC, Solé Sabaris s/n, 08028 Barcelona (Spain); Arruda, A.M. [Centro de Arqueologia da Universidade de Lisboa (UNIARQ), Alameda da Universidade, 1600-214 Lisboa (Portugal); Sampaio, J.M. [BioISI — Biosystems & Integrative Sciences Institute, Faculdade de Ciências da Universidade de Lisboa (Portugal); Brunetti, A., E-mail: brunetti@uniss.it [Department of Political Science and Communication, University of Sassari, Via Piandanna 2, 07100 Sassari (Italy)

    2015-05-01

    In this work we evaluate the composition of a bronze alloy using X-ray fluorescence spectrometry (XRF) and Monte Carlo (MC) simulations. For this purpose, a 7th Century BC archeological vase from the SW Iberian Peninsula, displaying a well formed corrosion patina was analyzed by means of a portable X-ray fluorescence spectrometer. Realistic MC simulations of the experimental setup were performed with the XRMC code package which is based on an intensive use of variance-reduction techniques and uses XRAYLIB a constantly updated X-ray library of atomic data. A single layer model was applied for simulating XRF of polished/pristine bronze whereas a two-or-three-layer model was developed for bronze covered respectively by a corrosion patina alone or coupled with a superficial soil derived crust. These simulations took into account corrosion (cerussite (PbCO{sub 3}), cuprite (Cu{sub 2}O), malachite (Cu{sub 2}CO{sub 3}(OH){sub 2}), litharge (PbO)) and soil derived products (goethite (FeO(OH)) and quartz (SiO{sub 2})) identified by means of X-ray diffraction and Raman micro analytical techniques. Results confirm previous research indicating that the XRF/Monte Carlo protocol is well suited when a two-layered model is considered, whereas in areas where the patina + soil derived products' crust is too thick, X-rays from the alloy substrate are not able to exit the sample. Quantitative results based on MC simulations indicate that the vase is made of a lead–bronze alloy: Mn (0.2%), Fe (1.0%), Cu (81.8%), As (0.5%), Ag (0.6%), Sn (8.0%) and Pb (8.0%). - Highlights: • We study an archeological bronze vase with patina corrosion using XRF spectrometry. • The experimental setup is modeled using Monte Carlo (MC) simulations. • Combining MC simulations with XRF it is possible to derive concentrations. • We demonstrated that this is possible without removing the patina.

  4. 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...

  5. Monte Carlo simulations of plutonium gamma-ray spectra

    International Nuclear Information System (INIS)

    Koenig, Z.M.; Carlson, J.B.; Wang, Tzu-Fang; Ruhter, W.D.

    1993-01-01

    Monte Carlo calculations were investigated as a means of simulating the gamma-ray spectra of Pu. These simulated spectra will be used to develop and evaluate gamma-ray analysis techniques for various nondestructive measurements. Simulated spectra of calculational standards can be used for code intercomparisons, to understand systematic biases and to estimate minimum detection levels of existing and proposed nondestructive analysis instruments. The capability to simulate gamma-ray spectra from HPGe detectors could significantly reduce the costs of preparing large numbers of real reference materials. MCNP was used for the Monte Carlo transport of the photons. Results from the MCNP calculations were folded in with a detector response function for a realistic spectrum. Plutonium spectrum peaks were produced with Lorentzian shapes, for the x-rays, and Gaussian distributions. The MGA code determined the Pu isotopes and specific power of this calculated spectrum and compared it to a similar analysis on a measured spectrum

  6. 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.

  7. 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

  8. 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.

  9. A Wigner-based ray-tracing method for imaging simulations

    NARCIS (Netherlands)

    Mout, B.M.; Wick, M.; Bociort, F.; Urbach, H.P.

    2015-01-01

    The Wigner Distribution Function (WDF) forms an alternative representation of the optical field. It can be a valuable tool for understanding and classifying optical systems. Furthermore, it possesses properties that make it suitable for optical simulations: both the intensity and the angular

  10. Hybrid Model For Reverberant Indoor Radio Channels Using Rays and Graphs

    DEFF Research Database (Denmark)

    Steinböck, Gerhard; Gan, Mingming; Meissner, Paul

    2016-01-01

    efficient calculation of the channel transfer function considering infinitely many components. We use ray-tracing and the theory of room electromagnetics to obtain the parameter settings for the propagation graph. Thus the proposed hybrid model does not require new or additional parameters in comparison...... to ray-tracing. Simulation results show good agreement with measurements with respect to the inclusion of the diffuse tail in both the delay power spectrum and the azimuth delay power spectrum....

  11. GRODY - GAMMA RAY OBSERVATORY DYNAMICS SIMULATOR IN ADA

    Science.gov (United States)

    Stark, M.

    1994-01-01

    Analysts use a dynamics simulator to test the attitude control system algorithms used by a satellite. The simulator must simulate the hardware, dynamics, and environment of the particular spacecraft and provide user services which enable the analyst to conduct experiments. Researchers at Goddard's Flight Dynamics Division developed GRODY alongside GROSS (GSC-13147), a FORTRAN simulator which performs the same functions, in a case study to assess the feasibility and effectiveness of the Ada programming language for flight dynamics software development. They used popular object-oriented design techniques to link the simulator's design with its function. GRODY is designed for analysts familiar with spacecraft attitude analysis. The program supports maneuver planning as well as analytical testing and evaluation of the attitude determination and control system used on board the Gamma Ray Observatory (GRO) satellite. GRODY simulates the GRO on-board computer and Control Processor Electronics. The analyst/user sets up and controls the simulation. GRODY allows the analyst to check and update parameter values and ground commands, obtain simulation status displays, interrupt the simulation, analyze previous runs, and obtain printed output of simulation runs. The video terminal screen display allows visibility of command sequences, full-screen display and modification of parameters using input fields, and verification of all input data. Data input available for modification includes alignment and performance parameters for all attitude hardware, simulation control parameters which determine simulation scheduling and simulator output, initial conditions, and on-board computer commands. GRODY generates eight types of output: simulation results data set, analysis report, parameter report, simulation report, status display, plots, diagnostic output (which helps the user trace any problems that have occurred during a simulation), and a permanent log of all runs and errors. The

  12. Simulation of dose deposition in stereotactic synchrotron radiation therapy: a fast approach combining Monte Carlo and deterministic algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Smekens, F; Freud, N; Letang, J M; Babot, D [CNDRI (Nondestructive Testing using Ionizing Radiations) Laboratory, INSA-Lyon, 69621 Villeurbanne Cedex (France); Adam, J-F; Elleaume, H; Esteve, F [INSERM U-836, Equipe 6 ' Rayonnement Synchrotron et Recherche Medicale' , Institut des Neurosciences de Grenoble (France); Ferrero, C; Bravin, A [European Synchrotron Radiation Facility, Grenoble (France)], E-mail: francois.smekens@insa-lyon.fr

    2009-08-07

    A hybrid approach, combining deterministic and Monte Carlo (MC) calculations, is proposed to compute the distribution of dose deposited during stereotactic synchrotron radiation therapy treatment. The proposed approach divides the computation into two parts: (i) the dose deposited by primary radiation (coming directly from the incident x-ray beam) is calculated in a deterministic way using ray casting techniques and energy-absorption coefficient tables and (ii) the dose deposited by secondary radiation (Rayleigh and Compton scattering, fluorescence) is computed using a hybrid algorithm combining MC and deterministic calculations. In the MC part, a small number of particle histories are simulated. Every time a scattering or fluorescence event takes place, a splitting mechanism is applied, so that multiple secondary photons are generated with a reduced weight. The secondary events are further processed in a deterministic way, using ray casting techniques. The whole simulation, carried out within the framework of the Monte Carlo code Geant4, is shown to converge towards the same results as the full MC simulation. The speed of convergence is found to depend notably on the splitting multiplicity, which can easily be optimized. To assess the performance of the proposed algorithm, we compare it to state-of-the-art MC simulations, accelerated by the track length estimator technique (TLE), considering a clinically realistic test case. It is found that the hybrid approach is significantly faster than the MC/TLE method. The gain in speed in a test case was about 25 for a constant precision. Therefore, this method appears to be suitable for treatment planning applications.

  13. Effect of phantom voxelization in CT simulations

    International Nuclear Information System (INIS)

    Goertzen, Andrew L.; Beekman, Freek J.; Cherry, Simon R.

    2002-01-01

    In computer simulations of x-ray CT systems one can either use continuous geometrical descriptions for phantoms or a voxelized representation. The voxelized approach allows arbitrary phantoms to be defined without being confined to geometrical shapes. The disadvantage of the voxelized approach is that inherent errors are introduced due to the phantom voxelization. To study effects of phantom discretization, analytical CT simulations were run for a fan-beam geometry with phantom voxel sizes ranging from 0.0625 to 2 times the reconstructed pixel size and noise levels corresponding to 10 3 -10 7 photons per detector pixel prior to attenuation. The number of rays traced per detector element was varied from 1 to 16. Differences in the filtered backprojection images caused by changing the phantom matrix sizes and number of rays traced were assessed by calculating the difference between reconstructions based on the finest matrix and coarser matrix simulations. In noise free simulations, all phantom matrix sizes produced a measurable difference in comparison with the finest phantom matrix used. When even a small amount of noise was added to the projection data, the differences due to the phantom discretization were masked by the noise, and in all cases there was almost no improvement by using a phantom matrix that was more than twice as fine as the reconstruction matrix. No substantial improvement was achieved by tracing more than 4 rays per detector pixel

  14. Ray trace visualization of negative refraction of light in two-dimensional air-bridged silicon photonic crystal slabs at 1.55 microm.

    Science.gov (United States)

    Gan, Lin; Liu, Ya-Zhao; Li, Jiang-Yan; Zhang, Ze-Bo; Zhang, Dao-Zhong; Li, Zhi-Yuan

    2009-06-08

    We demonstrate design, fabrication, and ray trace observation of negative refraction of near-infrared light in a two-dimensional square lattice of air holes etched into an air-bridged silicon slab. Special surface morphologies are designed to reduce the impedance mismatch when light refracts from a homogeneous silicon slab into the photonic crystal slab. We clearly observed negative refraction of infrared light for TE-like modes in a broad wavelength range by using scanning near-field optical microscopy technology. The experimental results are in good agreement with finite-difference time-domain simulations. The results indicate the designed photonic crystal structure can serve as polarization beam splitter.

  15. Three-dimensional ray tracing of electrostatic cyclotron harmonic waves and Z mode electromagnetic waves in the magnetosphere

    International Nuclear Information System (INIS)

    Hashimoto, K.; Yamaashi, K.; Kimura, I.; Kyoto Univ., Japan)

    1987-01-01

    Three-dimensional ray tracing is performed for electrostatic electron cyclotron harmonic waves and Z mode electromagnetic waves in the earth's magnetosphere using the hot dispersion relation. Propagation characteristics of cyclotron harmonic waves under the electrostatic approximation are considered, and it is noted that waves starting near the equator can propagate over a long distance without damping. Ray tracing without the electrostatic approximation confirms mode conversion from cyclotron harmonic waves to Z mode electromagnetic waves, and the conditions for the conversion are clarified. It is suggested that further conversion to the L-O mode continuum radiation is possible under strict constraints. The present results are not inconsistent with the conversion mechanism for the generation of escaping continuum radiation in the magnetosphere. 20 references

  16. Improving x-ray fluorescence signal for benchtop polychromatic cone-beam x-ray fluorescence computed tomography by incident x-ray spectrum optimization: a Monte Carlo study.

    Science.gov (United States)

    Manohar, Nivedh; Jones, Bernard L; Cho, Sang Hyun

    2014-10-01

    To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the investigated range of 81-100 ke

  17. Real-time simulator for designing electron dual scattering foil systems.

    Science.gov (United States)

    Carver, Robert L; Hogstrom, Kenneth R; Price, Michael J; LeBlanc, Justin D; Pitcher, Garrett M

    2014-11-08

    The purpose of this work was to develop a user friendly, accurate, real-time com- puter simulator to facilitate the design of dual foil scattering systems for electron beams on radiotherapy accelerators. The simulator allows for a relatively quick, initial design that can be refined and verified with subsequent Monte Carlo (MC) calculations and measurements. The simulator also is a powerful educational tool. The simulator consists of an analytical algorithm for calculating electron fluence and X-ray dose and a graphical user interface (GUI) C++ program. The algorithm predicts electron fluence using Fermi-Eyges multiple Coulomb scattering theory with the reduced Gaussian formalism for scattering powers. The simulator also estimates central-axis and off-axis X-ray dose arising from the dual foil system. Once the geometry of the accelerator is specified, the simulator allows the user to continuously vary primary scattering foil material and thickness, secondary scat- tering foil material and Gaussian shape (thickness and sigma), and beam energy. The off-axis electron relative fluence or total dose profile and central-axis X-ray dose contamination are computed and displayed in real time. The simulator was validated by comparison of off-axis electron relative fluence and X-ray percent dose profiles with those calculated using EGSnrc MC. Over the energy range 7-20 MeV, using present foils on an Elekta radiotherapy accelerator, the simulator was able to reproduce MC profiles to within 2% out to 20 cm from the central axis. The central-axis X-ray percent dose predictions matched measured data to within 0.5%. The calculation time was approximately 100 ms using a single Intel 2.93 GHz processor, which allows for real-time variation of foil geometrical parameters using slider bars. This work demonstrates how the user-friendly GUI and real-time nature of the simulator make it an effective educational tool for gaining a better understanding of the effects that various system

  18. Simulation of a dense plasma focus x-ray source

    International Nuclear Information System (INIS)

    Stark, R.A.

    1994-01-01

    The authors are performing simulations of the magnetohydrodynamics of a Dense Plasma Focus (DPF) x-ray source located at Science Research Laboratory (SRL), Alameda, CA, in order to optimize its performance. The SRL DPF, which was developed as a compact source for x-ray lithography, operates at 20 Hz, giving x-ray power (9--14 Angstroms) of 500 W using neon gas. The simulations are performed with the two dimensional MHD code MACH2, developed by Mission Research Corporation, with a steady state corona model as the equation of state. The results of studies of the sensitivity of x-ray output to charging voltage and current, and to initial gas density will be presented. These studies should indicate ways to optimize x-ray production efficiency. Simulations of various inner electrode configurations will also be presented

  19. A versatile ray-tracing code for studying rf wave propagation in toroidal magnetized plasmas

    International Nuclear Information System (INIS)

    Peysson, Y; Decker, J; Morini, L

    2012-01-01

    A new ray-tracing code named C3PO has been developed to study the propagation of arbitrary electromagnetic radio-frequency (rf) waves in magnetized toroidal plasmas. Its structure is designed for maximum flexibility regarding the choice of coordinate system and dielectric model. The versatility of this code makes it particularly suitable for integrated modeling systems. Using a coordinate system that reflects the nested structure of magnetic flux surfaces in tokamaks, fast and accurate calculations inside the plasma separatrix can be performed using analytical derivatives of a spline-Fourier interpolation of the axisymmetric toroidal MHD equilibrium. Applications to reverse field pinch magnetic configuration are also included. The effects of 3D perturbations of the axisymmetric toroidal MHD equilibrium, due to the discreteness of the magnetic coil system or plasma fluctuations in an original quasi-optical approach, are also studied. Using a Runge–Kutta–Fehlberg method for solving the set of ordinary differential equations, the ray-tracing code is extensively benchmarked against analytical models and other codes for lower hybrid and electron cyclotron waves. (paper)

  20. Optimized polychromatic x-ray imaging with asymmetrically cut bent crystals

    Czech Academy of Sciences Publication Activity Database

    Podorov, S. G.; Renner, Oldřich; Wehrhan, O.; Förster, E.

    2001-01-01

    Roč. 34, - (2001), s. 2363-2368 ISSN 0022-3727 Grant - others:-(DE) B508-99027; CZ-DE Bilateral Corporation in Science(XC) CZE-00-008 Institutional research plan: CEZ:AV0Z1010921 Keywords : x-ray imaging * x-ray diffraction * ray-tracing simulations Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.260, year: 2001

  1. Combined FDTD-Monte Carlo analysis and a novel design for ZnO scintillator rods in polycarbonate membrane for X-ray imaging

    International Nuclear Information System (INIS)

    Mohammadian-Behbahani, Mohammad-Reza; Saramad, Shahyar; Mohammadi, Mohammad

    2017-01-01

    A combination of Finite Difference Time Domain (FDTD) and Monte Carlo (MC) methods is proposed for simulation and analysis of ZnO microscintillators grown in polycarbonate membrane. A planar 10 keV X-ray source irradiating the detector is simulated by MC method, which provides the amount of absorbed X-ray energy in the assembly. The transport of generated UV scintillation light and its propagation in the detector was studied by the FDTD method. Detector responses to different probable scintillation sites and under different energies of X-ray source from 10 to 25 keV are reported. Finally, the tapered geometry for the scintillators is proposed, which shows enhanced spatial resolution in comparison to cylindrical geometry for imaging applications.

  2. Combined FDTD-Monte Carlo analysis and a novel design for ZnO scintillator rods in polycarbonate membrane for X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadian-Behbahani, Mohammad-Reza [Department of Energy Engineering and Physics, Amir-Kabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); Saramad, Shahyar, E-mail: ssaramad@aut.ac.ir [Department of Energy Engineering and Physics, Amir-Kabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); Mohammadi, Mohammad [Department of Electrical Engineering, Amir-Kabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of)

    2017-05-01

    A combination of Finite Difference Time Domain (FDTD) and Monte Carlo (MC) methods is proposed for simulation and analysis of ZnO microscintillators grown in polycarbonate membrane. A planar 10 keV X-ray source irradiating the detector is simulated by MC method, which provides the amount of absorbed X-ray energy in the assembly. The transport of generated UV scintillation light and its propagation in the detector was studied by the FDTD method. Detector responses to different probable scintillation sites and under different energies of X-ray source from 10 to 25 keV are reported. Finally, the tapered geometry for the scintillators is proposed, which shows enhanced spatial resolution in comparison to cylindrical geometry for imaging applications.

  3. 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.

  4. Study on method of characteristics based on cell modular ray tracing

    International Nuclear Information System (INIS)

    Tang Chuntao; Zhang Shaohong

    2009-01-01

    To address the issue of accurately solving neutron transport problem in complex geometry, method of characteristics (MOC) is studied in this paper, and a quite effective and memory saving cell modular ray tracing (CMRT) method is developed and related angle discretization and boundary condition handling issues are discussed. A CMRT based MOC code-PEACH is developed and tested against C5G7 MOX benchmark problem. Numerical results demonstrate that PEACH can give excellent accuracy for both k eff and pin power distribution for neutron transport problem. (authors)

  5. Monte Carlo simulation of x-ray spectra in mammography

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.P. [Department of Optometry and Radiography, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China). E-mail: benngkp at netvigator.com; Kwok, C.S.; Ng, K.P.; Tang, F.H. [Department of Optometry and Radiography, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2000-05-01

    A model for generating x-ray spectra in mammography is presented. This model used the ITS version 3 Monte Carlo code for simulating the radiation transport. Various target/filter combinations such as tungsten/aluminium, molybdenum/molybdenum, molybdenum/rhodium and rhodium/rhodium were used in the simulation. Both bremsstrahlung and characteristic x-ray production were included in the model. The simulated x-ray emission spectra were compared with two sets of spectra, those of Boone et al (1997 Med. Phys. 24 1863-74) and IPEM report 78. The {chi}{sup 2} test was used for the overall goodness of fit of the spectral data. There is good agreement between the simulated x-ray spectra and the comparison spectra as the test yielded a probability value of nearly 1. When the transmitted x-ray spectra for specific target/filter combinations were generated and compared with a measured molybdenum/rhodium spectrum and spectra generated in IPEM report 78, close agreement is also observed. This was demonstrated by the probability value for the {chi}{sup 2} test being almost 1 for all the cases. However, minor differences between the simulated spectra and the 'standard' ones are observed. (author)

  6. Monte Carlo simulation of x-ray spectra in mammography

    International Nuclear Information System (INIS)

    Ng, K.P.

    2000-01-01

    A model for generating x-ray spectra in mammography is presented. This model used the ITS version 3 Monte Carlo code for simulating the radiation transport. Various target/filter combinations such as tungsten/aluminium, molybdenum/molybdenum, molybdenum/rhodium and rhodium/rhodium were used in the simulation. Both bremsstrahlung and characteristic x-ray production were included in the model. The simulated x-ray emission spectra were compared with two sets of spectra, those of Boone et al (1997 Med. Phys. 24 1863-74) and IPEM report 78. The χ 2 test was used for the overall goodness of fit of the spectral data. There is good agreement between the simulated x-ray spectra and the comparison spectra as the test yielded a probability value of nearly 1. When the transmitted x-ray spectra for specific target/filter combinations were generated and compared with a measured molybdenum/rhodium spectrum and spectra generated in IPEM report 78, close agreement is also observed. This was demonstrated by the probability value for the χ 2 test being almost 1 for all the cases. However, minor differences between the simulated spectra and the 'standard' ones are observed. (author)

  7. Numerical Approximations to the Solution of Ray Tracing through the Crystalline Lens

    International Nuclear Information System (INIS)

    Yildirim, A.; Gökdoğan, A.; Merdan, M.; Lakshminarayanan, V.

    2012-01-01

    An approximate analytical solution in the form of a rapidly convergent series for tracing light rays through an inhomogeneous graded index medium is developed, using the multi-step differential transform method based on the classical differential transformation method. Numerical results are compared to those obtained by the fourth-order Runge—Kutta method to illustrate the precision and effectiveness of the proposed method. Results are given in explicit and graphical forms. (fundamental areas of phenomenology(including applications))

  8. Trace metal determinations by total-reflection x-ray fluorescence analysis in the open Atlantic Ocean

    International Nuclear Information System (INIS)

    Schmidt, D.; Gerwinski, W.; Radke, I.

    1993-01-01

    The Intergovernmental Oceanographic Commission (IOC), as a major component of its programme ''Global Investigation of Pollution in the Marine Environment'' (GIPME), maintains a long-standing project on ''Open Ocean Baseline Studies of Trace Contaminants''. Initially, the Atlantic Ocean and trace metals were selected. Four deep-water stations in the Cape Basin, Angola Basin, Cape Verde Abyssal Plain and Seine Abyssal Plain were regularly sampled for at least 36 depths. Additional samples were taken between stations. Samples were distributed to participants and a similar number of additional laboratories. As a central part of our own contribution to the project, we determined the trace heavy metals manganese, nickel, copper, zinc and lead and the lighter selenium by total-reflection X-ray fluorescence analysis. For the TXRF, the pre-enrichment of the trace metals and the separation from the salt matrix were performed by complexation with sodium dibenzyldithiocarbamate and reverse-phase chromatography. Generally, very low levels of trace elements were found in filtered and unfiltered water samples from these remote areas of the open Atlantic Ocean. Typical examples of the distributions of trace metal concentrations on depth profiles from the four deep-water stations as well as intercomparisons between the stations are presented. (author)

  9. HARPA: A versatile three-dimensional Hamiltonian ray-tracing program for acoustic waves in the atmosphere above irregular terrain

    Science.gov (United States)

    Jones, R. M.; Riley, J. P.; Georges, T. M.

    1986-08-01

    The modular FORTRAN 77 computer program traces the three-dimensional paths of acoustic rays through continuous model atmospheres by numerically integrating Hamilton's equations (a differential expression of Fermat's principle). The user specifies an atmospheric model by writing closed-form formulas for its three-dimensional wind and temperature (or sound speed) distribution, and by defining the height of the reflecting terrain vs. geographic latitude and longitude. Some general-purpose models are provided, or users can readily design their own. In addition to computing the geometry of each raypath, HARPA can calculate pulse travel time, phase time, Doppler shift (if the medium varies in time), absorption, and geometrical path length. The program prints a step-by-step account of a ray's progress. The 410-page documentation describes the ray-tracing equations and the structure of the program, and provides complete instructions, illustrated by a sample case.

  10. Effect of a three-month football training program on trace element ...

    African Journals Online (AJOL)

    Yomi

    2012-01-03

    Jan 3, 2012 ... physical exercise and trace element metabolism (Marrella et al., 1993; McDonald ..... induced stress and immune function. Exerc Immunol Rev. ... aerobic exercise upon the trace element levels in blood. Neuro. Endocrinol.

  11. Feasibility Study of Coupling the CASMO-4/TABLES-3/SIMULATE-3 Code System to TRACE/PARCS

    International Nuclear Information System (INIS)

    Demaziere, Christophe; Staalek, Mathias

    2004-12-01

    This report investigates the feasibility of coupling the Studsvik Scandpower CASMO-4/TABLES-3/SIMULATE-3 codes to the US NRC TRACE/PARCS codes. The data required by TRACE/PARCS are actually the ones necessary to run its neutronic module PARCS. Such data are the macroscopic nuclear cross-sections, some microscopic nuclear cross-sections important for the Xenon and Samarium poisoning effects, the Assembly Discontinuity Factors, and the kinetic parameters. All these data can be retrieved from the Studsvik Scandpower codes. The data functionalization is explained in detail for both systems of codes and the possibility of coupling each of these codes to TRACE/PARCS is discussed. Due to confidentiality restrictions in the use of the CASMO-4 files and to an improper format of the TABLES-3 output files, it is demonstrated that TRACE/PARCS can only be coupled to SIMULATE-3. Specifically-dedicated SIMULATE-3 input decks allow easily editing the neutronic data at specific operating statepoints. Although the data functionalization is different between both systems of codes, such a procedure permits reconstructing a set of data directly compatible with PARCS

  12. McSUB V2.0, an upgraded version of the Monte Carlo library McSUB with inclusion of weight factors

    International Nuclear Information System (INIS)

    Hoek, M.

    1991-02-01

    The Monte Carlo library McSUB, which was described in an earlier report, has been upgraded to McSUB V2.0. McSUB V2.0 can be used to simulate the neutron transport in a medium which is a mixture of hydrogen and carbon or a mixture of deuterium and carbon. The implemented neutron energy interval is 0.1 - 20 MeV and the library can be used to simulate elastic and inelastic scattering. The inelastic scattering with carbon takes into account the four lowest excited states of the carbon nucleus. McSUB V2.0 is downward compatible with McSUB expect for the layout of the parameter file which now contains more variables. The major upgrade has been the inclusion of routines using weight factors which has speeded up the old version considerably. McSUB V2.0 also makes a biasing technique possible. It is now possible to e.g. let a neutron scatter with a selected nucleus followed by a biased scattering direction. (au)

  13. Design of a tritium gas cell for beta-ray induced X-ray spectrometry using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hara, Masanori, E-mail: masahara@ctg.u-toyama.ac.jp [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama City, Toyama 930-8555 (Japan); Abe, Shinsuke; Matsuyama, Masao [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama City, Toyama 930-8555 (Japan); Aso, Tsukasa [Electronics and Computer Engineering, National Institute of Technology, Toyama College, 1-2 Ebie-neriya, Imizu City, Toyama 933-0293 (Japan); Tatenuma, Katsuyoshi; Kawakami, Tomohiko; Ito, Takeshi [KAKEN Company Limited, 1044 Horimachi, Mito City, Ibaraki 310-0903 (Japan)

    2017-06-15

    Highlights: • Beta-ray induced X-ray spectrometry (BIXS) is a method for tritium gas analysis. • Gas cell for BIXS was designed by Monte Carlo simulations. • The optimum thickness of the gold layer on a beryllium window was around 150 nm. • This simulation model considered the self-absorption with increasing the cell length. - Abstract: One of the methods used for tritium gas analysis is beta-ray induced X-ray spectrometry (BIXS). Gas cell design is important in this method. The structure of the gas cell for BIXS was optimized by Monte Carlo simulation of beta-ray induced X-ray spectra in various window geometries using the Geant4 tool kit (version 10.01.p02). The simulated spectrum from tritium decay fitted the observed one, and the simulation model was used to obtain the cell parameters for BIXS. The optimum thickness of the gold layer on a beryllium window was around 150 nm. This simulation model also considered the relationship between self-absorption by hydrogen gas and the cell length. Self-absorption increased with increasing cell length and the relationship between the sample pressure and cell length was formulated.

  14. SHOULD ONE USE THE RAY-BY-RAY APPROXIMATION IN CORE-COLLAPSE SUPERNOVA SIMULATIONS?

    International Nuclear Information System (INIS)

    Skinner, M. Aaron; Burrows, Adam; Dolence, Joshua C.

    2016-01-01

    We perform the first self-consistent, time-dependent, multi-group calculations in two dimensions (2D) to address the consequences of using the ray-by-ray+ transport simplification in core-collapse supernova simulations. Such a dimensional reduction is employed by many researchers to facilitate their resource-intensive calculations. Our new code (Fornax) implements multi-D transport, and can, by zeroing out transverse flux terms, emulate the ray-by-ray+ scheme. Using the same microphysics, initial models, resolution, and code, we compare the results of simulating 12, 15, 20, and 25 M ⊙ progenitor models using these two transport methods. Our findings call into question the wisdom of the pervasive use of the ray-by-ray+ approach. Employing it leads to maximum post-bounce/pre-explosion shock radii that are almost universally larger by tens of kilometers than those derived using the more accurate scheme, typically leaving the post-bounce matter less bound and artificially more “explodable.” In fact, for our 25 M ⊙ progenitor, the ray-by-ray+ model explodes, while the corresponding multi-D transport model does not. Therefore, in two dimensions, the combination of ray-by-ray+ with the axial sloshing hydrodynamics that is a feature of 2D supernova dynamics can result in quantitatively, and perhaps qualitatively, incorrect results.

  15. Monte Carlo simulation of the Tomotherapy treatment unit in the static mode using MC HAMMER, a Monte Carlo tool dedicated to Tomotherapy

    International Nuclear Information System (INIS)

    Sterpin, E; Tomsej, M; Cravens, B; Salvat, F; Ruchala, K; Olivera, G H; Vynckier, S

    2007-01-01

    Helical tomotherapy (HT) is designed to deliver highly modulated IMRT treatments. The concept of HT provides new challenges in MC simulation, because simultaneous movement of the gantry, the couch and the multi-leaf collimator (MLC) must be simulated accurately. However, before accounting for gantry, couch movement and multileaf collimator configurations, high accuracy must be achieved while simulating open static fields (1 x 40, 2.5 x 40 and 5 x 40 cm 2 ). This is performed using MC HAMMER, which is a graphical user interface allowing MC simulation using PENELOPE for various configurations of HT. Since the geometry of the different elements and materials involved in the beam generation are precisely known and defined, the only parameters that need to be tuned on are therefore electron source spot size and electron energy. Beyond the build up region, good agreement (2%/1mm) is achieved for all the field sizes between measurements (ion chamber) and simulations with an electron source energy set to 5.5 MeV. The electron source spot size is modelled as a gaussian distribution with full width half maximum equal to 1.4 mm. This value was chosen to match measured and calculated penumbras in the longitudinal direction

  16. Cosmic ray particle dosimetry and trajectory tracing

    International Nuclear Information System (INIS)

    Cruty, M.R.; Benton, E.V.; Turnbill, C.E.; Philpott, D.E.

    1975-01-01

    Five pocket mice (Perognathus longimembris) were flown on Apollo XVII, each with a solid-state (plastic) nuclear track detector implanted beneath its scalp. The subscalp detectors were sensitive to HZE cosmic ray particles with a LET greater than or approximately equal to 0.15 million electron volts per micrometer (MeV/micron). A critical aspect of the dosimetry of the experiment involved tracing individual particle trajectories through each mouse head from particle tracks registered in the individual subscalp detectors, thereby establishing a one-to-one correspondence between a trajectory location in the tissue and the presence or absence of a lesion. The other major aspect was the identification of each registered particle. An average of 16 particles with Z greater than or equal to 6 and 2.2 particles with Z greater than or equal to 20 were found per detector. The track density, 29 tracks/sq cm, when adjusted for detection volume, was in agreement with the photographic emulsion data from an area dosimeter located next to the flight package

  17. Numerical simulation methods for electron and ion optics

    International Nuclear Information System (INIS)

    Munro, Eric

    2011-01-01

    This paper summarizes currently used techniques for simulation and computer-aided design in electron and ion beam optics. Topics covered include: field computation, methods for computing optical properties (including Paraxial Rays and Aberration Integrals, Differential Algebra and Direct Ray Tracing), simulation of Coulomb interactions, space charge effects in electron and ion sources, tolerancing, wave optical simulations and optimization. Simulation examples are presented for multipole aberration correctors, Wien filter monochromators, imaging energy filters, magnetic prisms, general curved axis systems and electron mirrors.

  18. Fast Monte Carlo-simulator with full collimator and detector response modelling for SPECT

    International Nuclear Information System (INIS)

    Sohlberg, A.O.; Kajaste, M.T.

    2012-01-01

    Monte Carlo (MC)-simulations have proved to be a valuable tool in studying single photon emission computed tomography (SPECT)-reconstruction algorithms. Despite their popularity, the use of Monte Carlo-simulations is still often limited by their large computation demand. This is especially true in situations where full collimator and detector modelling with septal penetration, scatter and X-ray fluorescence needs to be included. This paper presents a rapid and simple MC-simulator, which can effectively reduce the computation times. The simulator was built on the convolution-based forced detection principle, which can markedly lower the number of simulated photons. Full collimator and detector response look-up tables are pre-simulated and then later used in the actual MC-simulations to model the system response. The developed simulator was validated by comparing it against 123 I point source measurements made with a clinical gamma camera system and against 99m Tc software phantom simulations made with the SIMIND MC-package. The results showed good agreement between the new simulator, measurements and the SIMIND-package. The new simulator provided near noise-free projection data in approximately 1.5 min per projection with 99m Tc, which was less than one-tenth of SIMIND's time. The developed MC-simulator can markedly decrease the simulation time without sacrificing image quality. (author)

  19. Talbot Carpet Simulation for X-ray grating interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Youngju; Oh, Ohsung; Jeong, Hanseong; Kim, Jeongho; Lee, Seung Wook [Pusan National University, Busan (Korea, Republic of); Kim, Jongyul; Moon, Myungkook [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    In this study, Talbot carpet simulator has been developed to visualize the X-ray grating interference patterns in grating interferometer. We have simulated X-ray interference for a variety of simulations and demonstrated a few examples in this summary. Grating interferometer produces interference of X-ray called Talbot pattern with gratings manufactured in micro scale. Talbot pattern is self-images of phase grating which develops interference as beam splitter that is one of gratings consisted of interferometer. As the other gratings, there are source grating makes coherence and analyze grating is used to analyze interference onto detector. Talbot carpet has been studied as the beam behavior which is distinguished with common X-ray imaging systems. It is helpful to understand grating interferometer and possible to expect beams' oscillation for designing theoretically. We confirm pattern has periodicity produced by interference after pi and pi/2 phase grating and changes in the perpendicular direction to entrance face according to phase objects.

  20. 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.

  1. Integration of OpenMC methods into MAMMOTH and Serpent

    Energy Technology Data Exchange (ETDEWEB)

    Kerby, Leslie [Idaho National Lab. (INL), Idaho Falls, ID (United States); Idaho State Univ., Idaho Falls, ID (United States); DeHart, Mark [Idaho National Lab. (INL), Idaho Falls, ID (United States); Tumulak, Aaron [Idaho National Lab. (INL), Idaho Falls, ID (United States); Univ. of Michigan, Ann Arbor, MI (United States)

    2016-09-01

    OpenMC, a Monte Carlo particle transport simulation code focused on neutron criticality calculations, contains several methods we wish to emulate in MAMMOTH and Serpent. First, research coupling OpenMC and the Multiphysics Object-Oriented Simulation Environment (MOOSE) has shown promising results. Second, the utilization of Functional Expansion Tallies (FETs) allows for a more efficient passing of multiphysics data between OpenMC and MOOSE. Both of these capabilities have been preliminarily implemented into Serpent. Results are discussed and future work recommended.

  2. A NUMERICAL SIMULATION OF COSMIC RAY MODULATION NEAR THE HELIOPAUSE. II. SOME PHYSICAL INSIGHTS

    International Nuclear Information System (INIS)

    Luo, Xi; Feng, Xueshang; Potgieter, Marius S.; Du Toit Strauss, R.; Zhang, Ming; Pogorelov, Nikolai V.

    2016-01-01

    Cosmic ray (CR) transport near the heliopause (HP) is studied using a hybrid transport model, with the parameters constrained by observations from the Voyager 1 spacecraft. We simulate the CR radial flux along different directions in the heliosphere. There is no well-defined thin layer between the solar wind region and the interstellar region along the tail and polar directions of the heliosphere. By analyzing the radial flux curve along the direction of Voyager 2 , together with its trajectory information, the crossing time of the HP by Voyager 2 is predicted to be in 2017.14. We simulate the CR radial flux for different energy values along the direction of Voyager 1 . We find that there is only a modest modulation region of about 10 au wide beyond the HP, so that Voyager 1 observing the Local Interstellar Spectra is justified in numerical modeling. We analyze the heliospheric exit information of pseudo-particles in our stochastic numerical (time-backward) method, conjecturing that they represent the behavior of CR particles, and we find that pseudo-particles that have been traced from the nose region exit in the tail region. This implies that many CR particles diffuse directly from the heliospheric tail region to the nose region near the HP. In addition, when pseudo-particles were traced from the Local Interstellar Medium (LISM), it is found that their exit location (entrance for real particles) from the simulation domain is along the prescribed Interstellar Magnetic Field direction. This indicates that parallel diffusion dominates CR particle transport in the LISM.

  3. 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.

  4. Interior metric and ray-tracing map in the firework black-to-white hole transition

    OpenAIRE

    Rovelli, Carlo; Martin-Dussaud, Pierre

    2018-01-01

    The possibility that a black hole could tunnel into to white hole has recently received attention. Here we present a metric that improves the "firework" metric: it describes the entire process and solves the Einstein's equations everywhere except on a small transition surface that corresponds to the quantum tunneling. We compute the corresponding ray-tracing map from past infinity to future infinity explicitly.

  5. Deficiency in Monte Carlo simulations of coupled neutron-gamma-ray fields

    NARCIS (Netherlands)

    Maleka, Peane P.; Maucec, Marko; de Meijer, Robert J.

    2011-01-01

    The deficiency in Monte Carlo simulations of coupled neutron-gamma-ray field was investigated by benchmarking two simulation codes with experimental data. Simulations showed better correspondence with the experimental data for gamma-ray transport only. In simulations, the neutron interactions with

  6. Micro-Fluidic Dye Ring Laser - Experimental Tuning of the Wavelength and Numerical Simulation of the Cavity Modes

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Balslev, Søren; Mortensen, Niels Asger

    2006-01-01

    We demonstrate wavelength tuning of a micro-fluidic dye ring laser. Wavelength tunability is obtained by controlling the liquid dye concentration. The device performance is modelled by FEM simulations supporting a ray-tracing view.......We demonstrate wavelength tuning of a micro-fluidic dye ring laser. Wavelength tunability is obtained by controlling the liquid dye concentration. The device performance is modelled by FEM simulations supporting a ray-tracing view....

  7. Illuminance: Computerized simulation

    Energy Technology Data Exchange (ETDEWEB)

    Barlow, A

    1991-03-01

    One of the main objectives of a graphics work-station is to create images that are as realistic as possible. This paper reviews and assesses the state-of-the-art in the field of illuminance simulation. The techniques examined are: ray tracing, in which illuminance in a given ambient is calculated in an approximate way by tracing individual rays of light; the 'radiosity' (a term combining surface radiancy and reflectivity) method, based on the calculation of the ambient's thermodynamics and which considers the effects of different surface colours; progressive improvement, in which 'radiosity' is calculated step by step with increasing levels of detail. The Gouraud and Phong methods of representing the effects of shade are also compared.

  8. New developments in the McStas neutron instrument simulation package

    DEFF Research Database (Denmark)

    Willendrup, Peter Kjær; Bergbäck Knudsen, Erik; Klinkby, Esben Bryndt

    2014-01-01

    , virtual experiments, data analysis and user training. McStas was founded as a scienti_c, open-source collaborative code in 1997. This contribution presents the project at its current state and gives an overview of the main new developments in McStas 2.0 (December 2012) and McStas 2.1 (expected fall 2013......), including many new components, component parameter uniformisation, partial loss of backward compatibility, updated source brilliance descriptions, developments toward new tools and user interfaces, web interfaces and a new method for estimating beam losses and background from neutron optics....

  9. Analysis of Simulated and Measured Indoor Channels for mm-Wave Beamforming Applications

    DEFF Research Database (Denmark)

    Karstensen, Anders; Fan, Wei; Zhang, Fengchun

    2018-01-01

    was investigated using both single beam and multiple beams, with two different power allocation schemes applied to multi-beamforming. Channel measurements were performed at 28-30 GHz using a vector network analyzer equipped with a Biconical antenna as the transmit antenna and a rotated horn antenna as the receive...... antenna. 3D ray tracing simulations were carried out in the same replicated propagation environments. Based on measurement and ray tracing simulation data, it is shown that RT-assisted beamforming performs well both for single and multi-beamforming in these two representative indoor propagation...

  10. SHOULD ONE USE THE RAY-BY-RAY APPROXIMATION IN CORE-COLLAPSE SUPERNOVA SIMULATIONS?

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, M. Aaron; Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Dolence, Joshua C., E-mail: burrows@astro.princeton.edu, E-mail: askinner@astro.princeton.edu, E-mail: jdolence@lanl.gov [CCS-2, Los Alamos National Laboratory, P.O. Box 1663 Los Alamos, NM 87545 (United States)

    2016-11-01

    We perform the first self-consistent, time-dependent, multi-group calculations in two dimensions (2D) to address the consequences of using the ray-by-ray+ transport simplification in core-collapse supernova simulations. Such a dimensional reduction is employed by many researchers to facilitate their resource-intensive calculations. Our new code (Fornax) implements multi-D transport, and can, by zeroing out transverse flux terms, emulate the ray-by-ray+ scheme. Using the same microphysics, initial models, resolution, and code, we compare the results of simulating 12, 15, 20, and 25 M {sub ⊙} progenitor models using these two transport methods. Our findings call into question the wisdom of the pervasive use of the ray-by-ray+ approach. Employing it leads to maximum post-bounce/pre-explosion shock radii that are almost universally larger by tens of kilometers than those derived using the more accurate scheme, typically leaving the post-bounce matter less bound and artificially more “explodable.” In fact, for our 25 M {sub ⊙} progenitor, the ray-by-ray+ model explodes, while the corresponding multi-D transport model does not. Therefore, in two dimensions, the combination of ray-by-ray+ with the axial sloshing hydrodynamics that is a feature of 2D supernova dynamics can result in quantitatively, and perhaps qualitatively, incorrect results.

  11. Pressure vessel SBLOCA simulation with trace: application to ISTF (Rosa V) - 151

    International Nuclear Information System (INIS)

    Abella, V.; Gallardo, S.; Verdu, G.

    2010-01-01

    In this work, an overview of the results obtained in the simulation of an Upper Head Small Break Loss-Of-Coolant-Accident (SBLOCA) under the assumption of total failure of High Pressure Injection System (HPIS) in the Large Scale Test Facility (LSTF) is provided. In previous works, an SBLOCA located in the Pressure Vessel (PV) Lower Plenum was simulated with TRACE. In that case, an asymmetrical steam generator secondary-side depressurization was produced as an accident management action at the Steam Generator in loop without pressurizer after the generation of safety injection signal to achieve a determined depressurization rate in the primary system. The new SBLOCA scenario has been simulated and results compared with experimental values, with the purpose of completing the analysis of PV SBLOCA. This study is developed in the frame of the OECD/NEA ROSA Project Test 6-1 (SB-PV-9 in JAEA). Finally, the present paper represents a contribution for the study of safety analysis of vessel SBLOCAs and the assessment of the predictability of thermal-hydraulic codes like TRACE. (authors)

  12. GROSS- GAMMA RAY OBSERVATORY ATTITUDE DYNAMICS SIMULATOR

    Science.gov (United States)

    Garrick, J.

    1994-01-01

    The Gamma Ray Observatory (GRO) spacecraft will constitute a major advance in gamma ray astronomy by offering the first opportunity for comprehensive observations in the range of 0.1 to 30,000 megaelectronvolts (MeV). The Gamma Ray Observatory Attitude Dynamics Simulator, GROSS, is designed to simulate this mission. The GRO Dynamics Simulator consists of three separate programs: the Standalone Profile Program; the Simulator Program, which contains the Simulation Control Input/Output (SCIO) Subsystem, the Truth Model (TM) Subsystem, and the Onboard Computer (OBC) Subsystem; and the Postprocessor Program. The Standalone Profile Program models the environment of the spacecraft and generates a profile data set for use by the simulator. This data set contains items such as individual external torques; GRO spacecraft, Tracking and Data Relay Satellite (TDRS), and solar and lunar ephemerides; and star data. The Standalone Profile Program is run before a simulation. The SCIO subsystem is the executive driver for the simulator. It accepts user input, initializes parameters, controls simulation, and generates output data files and simulation status display. The TM subsystem models the spacecraft dynamics, sensors, and actuators. It accepts ephemerides, star data, and environmental torques from the Standalone Profile Program. With these and actuator commands from the OBC subsystem, the TM subsystem propagates the current state of the spacecraft and generates sensor data for use by the OBC and SCIO subsystems. The OBC subsystem uses sensor data from the TM subsystem, a Kalman filter (for attitude determination), and control laws to compute actuator commands to the TM subsystem. The OBC subsystem also provides output data to the SCIO subsystem for output to the analysts. The Postprocessor Program is run after simulation is completed. It generates printer and CRT plots and tabular reports of the simulated data at the direction of the user. GROSS is written in FORTRAN 77 and

  13. The OpenMC Monte Carlo particle transport code

    International Nuclear Information System (INIS)

    Romano, Paul K.; Forget, Benoit

    2013-01-01

    Highlights: ► An open source Monte Carlo particle transport code, OpenMC, has been developed. ► Solid geometry and continuous-energy physics allow high-fidelity simulations. ► Development has focused on high performance and modern I/O techniques. ► OpenMC is capable of scaling up to hundreds of thousands of processors. ► Results on a variety of benchmark problems agree with MCNP5. -- Abstract: A new Monte Carlo code called OpenMC is currently under development at the Massachusetts Institute of Technology as a tool for simulation on high-performance computing platforms. Given that many legacy codes do not scale well on existing and future parallel computer architectures, OpenMC has been developed from scratch with a focus on high performance scalable algorithms as well as modern software design practices. The present work describes the methods used in the OpenMC code and demonstrates the performance and accuracy of the code on a variety of problems.

  14. Trace element analysis of single synthetic fibres by proton induced X-ray analysis in a helium atmosphere

    International Nuclear Information System (INIS)

    Ahmed, M.; Cookson, J.A.

    1976-10-01

    A technique for measuring the trace element content of synthetic fibres by detecting X-rays produced by 3 MeV proton bombardment has been developed. Largely to reduce the problems of removing heat from the fibres, an arrangement was used in which the beam was brought out of the vacuum into air or helium. Kapton, aluminium, nickel and molybdenum were tested for suitability as exit windows. Of these, aluminium produced significantly the most background in X-ray spectra while helium was found to be significantly better than air as the medium around the targets. With a kapton window, helium in the target chamber, and suitable collimation, trace element concentration down to a few parts per million could be measured when quantities of fibre of only a few times 10 -5 g were available for analysis. (author)

  15. Simulating Terrestrial Gamma-ray Flashes using SWORD (Invited)

    Science.gov (United States)

    Gwon, C.; Grove, J.; Dwyer, J. R.; Mattson, K.; Polaski, D.; Jackson, L.

    2013-12-01

    We report on simulations of the relativistic feedback discharges involved with the production of terrestrial gamma-ray flashes (TGFs). The simulations were conducted using Geant4 using the SoftWare for the Optimization of Radiation Detectors (SWORD) framework. SWORD provides a graphical interface for setting up simulations in select high-energy radiation transport engines. Using Geant4, we determine avalanche length, the energy spectrum of the electrons and gamma-rays as they leave the field region, and the feedback factor describing the degree to which the production of energetic particles is self-sustaining. We validate our simulations against previous work in order to determine the reliability of our results. This work is funded by the Office of Naval Research.

  16. Linear scans of hair strands for trace elements by proton induced x-ray emission

    International Nuclear Information System (INIS)

    Jolly, R.K.; Pehrson, G.R.; Gupta, S.K.; Buckle, D.C.; Aceto, H. Jr.

    1974-01-01

    Hair strands obtained from school children in the 10 to 12 year age group were analyzed for trace element concentration as a function of distance from the root by proton-induced x-ray emission to study the history of exposure of the donors to toxic trace metals. These samples were collected from the vicinity of a copper smelter where high levels of As, Cd, Sb, and Pb have been noted. Scans show a continual build-up of Pb as a function of distance from the root, while As shows a reproducible and distinct maximum approximately 10 cm from the root. The concentration of Zn was found to be constant in all samples (without exception) to within the uncertainties of our measurements

  17. Determination of trace elements in Katana (Japanese sword) by neutron activation analysis with multidimensional γ-ray spectrometry

    International Nuclear Information System (INIS)

    Okada, Y.; Hirai, S.; Ohya, S.; Kimura, Atsushi; Hatsukawa, Yuichi; Toh, Yosuke; Koizumi, Mitsuo; Oshima, Masumi

    2006-01-01

    In this study, we tried to measure trace elements (As and Sb) in Katana (Japanese swords) by multidimensional γ-ray spectrometry method (GEMINI-II) and conventional counting method for neutron activation analysis (NAA). The determined values by GEMINI-II and conventional counting were in good agreement with. Using the multidimensional γ-ray spectrometry (GEMINI-II) to determine As and Sb was improved by 7 times and 10 times compared with the conventional counting method. (author)

  18. [Comparison of ocular modulation transfer function measurements by ray tracing wavefront technology and double-pass system].

    Science.gov (United States)

    Qiao, Liya; Cai, Xiaogu; Wan, Xiuhua; Guan, Zheng; Xiong, Ying; Lin, Zhong; Zhang, Ye; Tan, Jiaxuan; Wang, Ningli

    2015-01-01

    To compare the agreement of the ocular modulation transfer function (MTF) measured by double-pass system and ray tracing wavefront aberrometry, and to analyze the correlations of two MTFs with the visual acuity and contrast sensitivity function results. Comparative study. Subjects with no ocular diseases were consecutively enrolled in an epidemic study field located at the Dongyangzhuang Health Center, Yongnian County, Handan City, Hebei Province, China. After comprehensive ophthalmic examinations, the mean values of subtracted lower order aberration MTF at 5, 10, 15, 20, 25, and 30 cycle/degree(c/d) spatial frequencies were obtained with a double-pass system (optical quality analysis system II, OQAS II system) and a ray tracing wavefront aberrometer (iTrace visual function analyzer, iTrace system) in the 4.0 mm and 6.0 mm pupil after dilation, respectively. Paired-sample t test and Bland-Altman analysis were used to compare the difference and agreement of MTFs obtained with two instruments. Correlation analysis was preformed between two MTF measurement results and subjective visual quality including visual acuity and contrast sensitivity function. Two hundred and fifty-one healthy eyes of 163 subjects were enrolled, aged 30 to 60, mean (44.1 ± 9.7) years, including 139 eyes of 81 males and 112 eyes of 82 females. The mean value of MTF at 5, 10, 15, 20.25, 30 c/d obtained by iTrace in 4.0 mm pupil were 0.730 ± 0.138, 0.431 ± 0.159, 0.262 ± 0.120, 0.169 ± 0.078, 0.118 ± 0.053, 0.094 ± 0.043. The value obtained by OQASII were 0.347 ± 0.123, 0.162 ± 0.086, 0.072 ± 0.049, 0.042 ± 0.033, 0.026 ± 0.022, 0.017 ± 0.022, The result of iTrace were all significant higher than OQAS in both 4mm(t = 38.72, 28.03, 27.32, 27.59, 29.23, 28.96, P < 0.01) and 6.0 mm(t = 4.60, 3.19, 9.34, 13.41, 16.96, 20.24, P < 0.01)pupil diameter. The iTrace-OQAS II MTF difference was smaller in the 6.0 mm pupil. Bland-Altman analysis indicated that the agreement of two instruments was

  19. 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.

  20. Towards clinical application of RayStretch for heterogeneity corrections in LDR permanent 125I prostate brachytherapy.

    Science.gov (United States)

    Hueso-González, Fernando; Ballester, Facundo; Perez-Calatayud, Jose; Siebert, Frank-André; Vijande, Javier

    RayStretch is a simple algorithm proposed for heterogeneity corrections in low-dose-rate brachytherapy. It is built on top of TG-43 consensus data, and it has been validated with Monte Carlo (MC) simulations. In this study, we take a real clinical prostate implant with 71 125 I seeds as reference and we apply RayStretch to analyze its performance in worst-case scenarios. To do so, we design two cases where large calcifications are located in the prostate lobules. RayStretch resilience under various calcification density values is also explored. Comparisons against MC calculations are performed. Dose-volume histogram-related parameters like prostate D 90 , rectum D 2cc , or urethra D 10 obtained with RayStretch agree within a few percent with the detailed MC results for all cases considered. The robustness and compatibility of RayStretch with commercial treatment planning systems indicate its applicability in clinical practice for dosimetric corrections in prostate calcifications. Its use during intraoperative ultrasound planning is foreseen. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  1. Geant4 simulations of soft proton scattering in X-ray optics. A tentative validation using laboratory measurements

    Science.gov (United States)

    Fioretti, Valentina; Mineo, Teresa; Bulgarelli, Andrea; Dondero, Paolo; Ivanchenko, Vladimir; Lei, Fan; Lotti, Simone; Macculi, Claudio; Mantero, Alfonso

    2017-12-01

    Low energy protons (process responsible for the grazing angle scattering processes is mandatory to evaluate the impact of such events on the performance (e.g. observation time, sensitivity) of future X-ray telescopes as the ESA ATHENA mission. The Remizovich model describes particles reflected by solids at glancing angles in terms of the Boltzmann transport equation using the diffuse approximation and the model of continuous slowing down in energy. For the first time this solution, in the approximation of no energy losses, is implemented, verified, and qualitatively validated on top of the Geant4 release 10.2, with the possibility to add a constant energy loss to each interaction. This implementation is verified by comparing the simulated proton distribution to both the theoretical probability distribution and with independent ray-tracing simulations. Both the new scattering physics and the Coulomb scattering already built in the official Geant4 distribution are used to reproduce the latest experimental results on grazing angle proton scattering. At 250 keV multiple scattering delivers large proton angles and it is not consistent with the observation. Among the tested models, the single scattering seems to better reproduce the scattering efficiency at the three energies but energy loss obtained at small scattering angles is significantly lower than the experimental values. In general, the energy losses obtained in the experiment are higher than what obtained by the simulation. The experimental data are not completely representative of the soft proton scattering experienced by current X-ray telescopes because of the lack of measurements at low energies (distribution at the exit of X-ray optics.

  2. Estimation of computed tomography dose index in cone beam computed tomography: MOSFET measurements and Monte Carlo simulations.

    Science.gov (United States)

    Kim, Sangroh; Yoshizumi, Terry; Toncheva, Greta; Yoo, Sua; Yin, Fang-Fang; Frush, Donald

    2010-05-01

    To address the lack of accurate dose estimation method in cone beam computed tomography (CBCT), we performed point dose metal oxide semiconductor field-effect transistor (MOSFET) measurements and Monte Carlo (MC) simulations. A Varian On-Board Imager (OBI) was employed to measure point doses in the polymethyl methacrylate (PMMA) CT phantoms with MOSFETs for standard and low dose modes. A MC model of the OBI x-ray tube was developed using BEAMnrc/EGSnrc MC system and validated by the half value layer, x-ray spectrum and lateral and depth dose profiles. We compared the weighted computed tomography dose index (CTDIw) between MOSFET measurements and MC simulations. The CTDIw was found to be 8.39 cGy for the head scan and 4.58 cGy for the body scan from the MOSFET measurements in standard dose mode, and 1.89 cGy for the head and 1.11 cGy for the body in low dose mode, respectively. The CTDIw from MC compared well to the MOSFET measurements within 5% differences. In conclusion, a MC model for Varian CBCT has been established and this approach may be easily extended from the CBCT geometry to multi-detector CT geometry.

  3. Prediction of beam hardening artefacts in computed tomography using Monte Carlo simulations

    DEFF Research Database (Denmark)

    Thomsen, M.; Bergbäck Knudsen, Erik; Willendrup, Peter Kjær

    2015-01-01

    We show how radiological images of both single and multi material samples can be simulated using the Monte Carlo simulation tool McXtrace and how these images can be used to make a three dimensional reconstruction. Good numerical agreement between the X-ray attenuation coefficient in experimental...

  4. Virtual experiments: the ultimate aim of neutron ray-tracing simulations

    Czech Academy of Sciences Publication Activity Database

    Lefmann, K.; Willendrup, P.K.; Šaroun, Jan

    2008-01-01

    Roč. 16, 3 & 4 (2008), s. 97-111 ISSN 1023-8166 Institutional research plan: CEZ:AV0Z10480505 Keywords : Monte Carlo simulations * neutron scattering * neutron instrumentation Subject RIV: BM - Solid Matter Physics ; Magnetism

  5. Biological X-ray absorption spectroscopy (BioXAS): a valuable tool for the study of trace elements in the life sciences.

    Science.gov (United States)

    Strange, Richard W; Feiters, Martin C

    2008-10-01

    Using X-ray absorption spectroscopy (XAS) the binding modes (type and number of ligands, distances and geometry) and oxidation states of metals and other trace elements in crystalline as well as non-crystalline samples can be revealed. The method may be applied to biological systems as a 'stand-alone' technique, but it is particularly powerful when used alongside other X-ray and spectroscopic techniques and computational approaches. In this review, we highlight how biological XAS is being used in concert with crystallography, spectroscopy and computational chemistry to study metalloproteins in crystals, and report recent applications on relatively rare trace elements utilised by living organisms and metals involved in neurodegenerative diseases.

  6. A Simplified Multipath Component Modeling Approach for High-Speed Train Channel Based on Ray Tracing

    Directory of Open Access Journals (Sweden)

    Jingya Yang

    2017-01-01

    Full Text Available High-speed train (HST communications at millimeter-wave (mmWave band have received a lot of attention due to their numerous high-data-rate applications enabling smart rail mobility. Accurate and effective channel models are always critical to the HST system design, assessment, and optimization. A distinctive feature of the mmWave HST channel is that it is rapidly time-varying. To depict this feature, a geometry-based multipath model is established for the dominant multipath behavior in delay and Doppler domains. Because of insufficient mmWave HST channel measurement with high mobility, the model is developed by a measurement-validated ray tracing (RT simulator. Different from conventional models, the temporal evolution of dominant multipath behavior is characterized by its geometry factor that represents the geometrical relationship of the dominant multipath component (MPC to HST environment. Actually, during each dominant multipath lifetime, its geometry factor is fixed. To statistically model the geometry factor and its lifetime, the dominant MPCs are extracted within each local wide-sense stationary (WSS region and are tracked over different WSS regions to identify its “birth” and “death” regions. Then, complex attenuation of dominant MPC is jointly modeled by its delay and Doppler shift both which are derived from its geometry factor. Finally, the model implementation is verified by comparison between RT simulated and modeled delay and Doppler spreads.

  7. Monte Carlo modeling of a conventional X-ray computed tomography scanner for gel dosimetry purposes.

    Science.gov (United States)

    Hayati, Homa; Mesbahi, Asghar; Nazarpoor, Mahmood

    2016-01-01

    Our purpose in the current study was to model an X-ray CT scanner with the Monte Carlo (MC) method for gel dosimetry. In this study, a conventional CT scanner with one array detector was modeled with use of the MCNPX MC code. The MC calculated photon fluence in detector arrays was used for image reconstruction of a simple water phantom as well as polyacrylamide polymer gel (PAG) used for radiation therapy. Image reconstruction was performed with the filtered back-projection method with a Hann filter and the Spline interpolation method. Using MC results, we obtained the dose-response curve for images of irradiated gel at different absorbed doses. A spatial resolution of about 2 mm was found for our simulated MC model. The MC-based CT images of the PAG gel showed a reliable increase in the CT number with increasing absorbed dose for the studied gel. Also, our results showed that the current MC model of a CT scanner can be used for further studies on the parameters that influence the usability and reliability of results, such as the photon energy spectra and exposure techniques in X-ray CT gel dosimetry.

  8. Simulating Gamma-Ray Emission in Star-forming Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Pfrommer, Christoph [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker, E-mail: cpfrommer@aip.de [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany)

    2017-10-01

    Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way–like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate a bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.

  9. Simulating Gamma-Ray Emission in Star-forming Galaxies

    Science.gov (United States)

    Pfrommer, Christoph; Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker

    2017-10-01

    Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way-like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate a bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.

  10. Simulation of a passive auxiliary feedwater system with TRACE5

    Energy Technology Data Exchange (ETDEWEB)

    Lorduy, María; Gallardo, Sergio; Verdú, Gumersindo, E-mail: maloral@upv.es, E-mail: sergalbe@iqn.upv.es, E-mail: gverdu@iqn.upv.es [Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental (ISIRYM), València (Spain)

    2017-07-01

    The study of the nuclear power plant accidents occurred in recent decades, as well as the probabilistic risk assessment carried out for this type of facility, present human error as one of the main contingency factors. For this reason, the design and development of generation III, III+ and IV reactors, which include inherent and passive safety systems, have been promoted. In this work, a TRACE5 model of ATLAS (Advanced Thermal- Hydraulic Test Loop for Accident Simulation) is used to reproduce an accidental scenario consisting in a prolonged Station BlackOut (SBO). In particular, the A1.2 test of the OECD-ATLAS project is analyzed, whose purpose is to study the primary system cooling by means of the water supply to one of the steam generators from a Passive Auxiliary Feedwater System (PAFS). This safety feature prevents the loss of secondary system inventory by means of the steam condensation and its recirculation. Thus, the conservation of a heat sink allows the natural circulation flow rate until restoring stable conditions. For the reproduction of the test, an ATLAS model has been adapted to the experiment conditions, and a PAFS has been incorporated. >From the simulation test results, the main thermal-hydraulic variables (pressure, flow rates, collapsed water level and temperature) are analyzed in the different circuits, contrasting them with experimental data series. As a conclusion, the work shows the TRACE5 code capability to correctly simulate the behavior of a passive feedwater system. (author)

  11. Steady-state molecular dynamics simulation of vapor to liquid nucleation with Mc Donald's demon

    International Nuclear Information System (INIS)

    Horsch, M.; Miroshnichenko, S.; Vrabec, J.

    2009-01-01

    Grand canonical MD with McDonald's demon is discussed in the present contribution and applied for sampling both nucleation kinetics and steady-state properties of a supersaturated vapor. The idea behind the new approach is to simulate the production of clusters up to a given size for a specified supersaturation. The classical nucleation theory is found to overestimate the free energy of cluster formation and deviate by two orders of magnitude from the nucleation rate below the triple point at high supersaturations.

  12. 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)

  13. A FORMALISM FOR COVARIANT POLARIZED RADIATIVE TRANSPORT BY RAY TRACING

    International Nuclear Information System (INIS)

    Gammie, Charles F.; Leung, Po Kin

    2012-01-01

    We write down a covariant formalism for polarized radiative transfer appropriate for ray tracing through a turbulent plasma. The polarized radiation field is represented by the polarization tensor (coherency matrix) N αβ ≡ (a α k a* β k ), where a k is a Fourier coefficient for the vector potential. Using Maxwell's equations, the Liouville-Vlasov equation, and the WKB approximation, we show that the transport equation in vacuo is k μ ∇ μ N αβ = 0. We show that this is equivalent to Broderick and Blandford's formalism based on invariant Stokes parameters and a rotation coefficient, and suggest a modification that may reduce truncation error in some situations. Finally, we write down several alternative approaches to integrating the transfer equation.

  14. 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.

  15. Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 1.

    Science.gov (United States)

    Thompson, S A; Dummer, P M

    1997-07-01

    The aim of this study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. In all, 40 canals consisting of four different shapes in terms of angle and position of curvature were prepared by a combination of NT Engine and McXim instruments using the technique recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. Overall, the mean preparation time for all canals was 6.01 min, with canal shape having a significant effect (P Engine and McXim instruments prepared canals rapidly, with few deformations, no canal blockages and with minimal change in working length. The three-dimensional form of the canals demonstrated good flow and taper characteristics.

  16. OpenMC In Situ Source Convergence Detection

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Garrett Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of California, Davis, CA (United States); Dutta, Soumya [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); The Ohio State Univ., Columbus, OH (United States); Woodring, Jonathan Lee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-07

    We designed and implemented an in situ version of particle source convergence for the OpenMC particle transport simulator. OpenMC is a Monte Carlo based-particle simulator for neutron criticality calculations. For the transport simulation to be accurate, source particles must converge on a spatial distribution. Typically, convergence is obtained by iterating the simulation by a user-settable, fixed number of steps, and it is assumed that convergence is achieved. We instead implement a method to detect convergence, using the stochastic oscillator for identifying convergence of source particles based on their accumulated Shannon Entropy. Using our in situ convergence detection, we are able to detect and begin tallying results for the full simulation once the proper source distribution has been confirmed. Our method ensures that the simulation is not started too early, by a user setting too optimistic parameters, or too late, by setting too conservative a parameter.

  17. Comparison and Extension of Existing 3D Propagation Models with Real-World Effects Based on Ray-tracing

    DEFF Research Database (Denmark)

    Kifle, Dereje W.; Gimenez, Lucas Chavarria; Wegmann, Bernhard

    2014-01-01

    antenna beam orientation like antenna tilting or when users are distributed in the third dimension (height) in multi-floor scenarios. Ray tracing based generated propagation maps that show the realistic propagation effect are used as 3D real world reference for investigation and model approval....

  18. Virtual experiments: the ultimate aim of neutron ray-tracing simulations

    DEFF Research Database (Denmark)

    Lefmann, Kim; Willendrup, Peter Kjær; Udby, Linda

    2008-01-01

    We define a virtual neutron experiment as a complete simulation of an experiment, from source over sample to detector. The virtual experiment (VE) will ideally interface with the instrument control software for the input and with standard data analysis packages for the virtual data output. Virtual...

  19. A Simulation Tool for Ultrasonic Inspection

    Energy Technology Data Exchange (ETDEWEB)

    Krishnamurthy, Adarsh; Mohan, K. V.; Karthikeyan, Soumya; Krishnamurthy, C. V.; Balasubramaniam, Krishnan [Indian Institute of Technology, Tamil Nadu (India)

    2006-06-15

    A simulation program SIMULTSONIC is under development at CNDE to help determine and/or help optimize ultrasonic probe locations for inspection of complex components. SIMULTSONIC provides a ray-trace based assessment for immersion and contact modes of inspection. The code written in Visual C++ operating in Microsoft Windows environment provides an interactive user interface. In this paper, a description of the various features of SIMULTSONIC is given followed by examples illustrating the capability of SIMULTSONIC to deal with inspection of canonical objects such as pipes. In particular, the use of SIMULTSONIC in the inspection of very thin-walled pipes (with 450 urn wall thickness) is described. Ray trace based assessment was done using SIMULTSONIC to determine the standoff distance and the angle of oblique incidence for an immersion mode focused transducer. A 3-cycle Hanning window pulse was chosen for simulations. Experiments were carried out to validate the simulations. The A-scans and the associated B-Scan images obtained through simulations show good correlation with experimental results, both with the arrival time of the signal as well as with the signal amplitudes

  20. Alpha particle excited x-ray fluorescence analysis for trace elements in cervical spinal cords of amyotrophic lateral sclerosis

    International Nuclear Information System (INIS)

    Mizumoto, Yoshihiko; Iwata, Shiro; Sasajima, Kazuhisa; Yase, Yoshio; Yoshida, Shohei.

    1980-01-01

    The mean contents of trace elements in anterior gray horn section of cervical spinal cords of six amyotrophic lateral sclerosis (ALS) cases were relatively determined against those of six control cases by α-particle excited X-ray fluorescence analysis. The anterior gray horn section of cervical spinal cord samples were excited by 1.6 MeV α-particle beam of 2 mm diameter accelerated with a Van de Graaff accelerator, and characteristic X-ray spectra were measured with a Si(Li) detector. From the peak areas on the X-ray spectra, the relative mean contents of the trace elements in cervical spinal cords of ALS and control cases were determined. As a result, the X-ray peaks of Al, Si, P, S, Cl, K, Ca, Ti, V, Mn, Fe, Cu and Zn were detected. The contents of Al, Si, P, Ca, Ti, V, Mn and Fe in ALS cases were higher than those in control cases. The contents of S, Cl, K, Cu and Zn in ALS and in control cases were equal to each other within standard deviation. The precipitation mechanisms of Al, Si, P, Ca, Ti, V, Mn and Fe into cervical spinal cord of ALS cases are discussed on the basis of the previous studies. (author)

  1. Monte Carlo simulation of discrete γ-ray detectors

    International Nuclear Information System (INIS)

    Bakkali, A.; Tamda, N.; Parmentier, M.; Chavanelle, J.; Pousse, A.; Kastler, B.

    2005-01-01

    Needs in medical diagnosis, especially for early and reliable breast cancer detection, lead us to consider developments in scintillation crystals and position sensitive photomultiplier tubes (PSPMT) in order to develop a high-resolution medium field γ-ray imaging device. However the ideal detector for γ-rays represents a compromise between many conflicting requirements. In order to optimize different parameters involved in the detection process, we have developed a Monte Carlo simulation software. Its aim was to study the light distribution produced by a gamma photon interacting with a pixellated scintillation crystal coupled to a PSPMT array. Several crystal properties were taken into account as well as the intrinsic response of PSPMTs. Images obtained by simulations are compared with experimental results. Agreement between simulation and experimental results validate our simulation model

  2. Multiple x-ray diffraction simulation and applications

    International Nuclear Information System (INIS)

    Costa, C.A.B.S. da.

    1989-09-01

    A computer program (MULTX) was implemented for simulation X-ray multiple diffraction diagrams in Renninger geometries. The program uses the X-ray multiple diffraction theory for imperfect crystals. The iterative calculation of the intensities is based on the Taylor series general term, and the primary beam power expansion is given as function of the beam x penetration in the crystal surface. This development allows to consider the simultaneous interaction of the beams involved in the multiple diffraction phenomenon. The simulated diagrams are calculated point-to-point and the tests for the Si and GaAs presented good reproduction of the experimental diagrams for different primary reflections. (L.C.J.A.)

  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. 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. Measurements of inner-shell characteristic X-ray yields of thick W, Mo and Zr targets by low-energy electron impact and comparison with Monte Carlo simulations

    International Nuclear Information System (INIS)

    Li, X.L.; Zhao, J.L.; Tian, L.X.; An, Z.; Zhu, J.J.; Liu, M.T.

    2014-01-01

    Highlights: •We measured characteristic X-ray yields of thick W, Mo, Zr by 5–29 keV electrons. •Our measured data are in general in good agreement with the MC results with ∼10%. •Error of 10% of characteristic X-ray yields will produce errors of 2–7% for BIXS. -- Abstract: Inner-shell characteristic X-ray yields are one of the important ingredients in the β-ray induced X-ray spectrometry (BIXS) technique which can be used to perform tritium content and depth distribution analyses in plasma facing materials (PLMs) and other tritium-containing materials, such as W, Mo, Zr. In this paper, the measurements of K, L, M-shell X-ray yields Y(E) of pure thick W (Z = 74), Mo (Z = 42) and Zr (Z = 40) element targets produced by electron impact in the energy range of 5–29 keV are presented. The experimental data for Y(E) are compared with the corresponding predictions from Monte Carlo (MC) calculations using the general purpose MC code PENELOPE. In general, a good agreement is obtained between the experiment and the MC calculations for the variation of Y(E) with the impact energy both in shape and in magnitude with ∼10%. The effect of uncertainty of inner-shell characteristic X-ray yields on the BIXS technique is also discussed

  6. A Comparison Of GADRAS Simulated And Measured Gamma Ray Spectra

    International Nuclear Information System (INIS)

    Jeffcoat, R.; Salaymeh, S.

    2010-01-01

    Gamma-ray radiation detection systems are continuously being developed and improved for detecting the presence of radioactive material and for identifying isotopes present. Gamma-ray spectra, from many different isotopes and in different types and thicknesses of attenuation material and matrixes, are needed to evaluate the performance of these devices. Recently, a test and evaluation exercise was performed by the Savannah River National Laboratory that required a large number of gamma-ray spectra. Simulated spectra were used for a major portion of the testing in order to provide a pool of data large enough for the results to be statistically significant. The test data set was comprised of two types of data, measured and simulated. The measured data were acquired with a hand-held Radioisotope Identification Device (RIID) and simulated spectra were created using Gamma Detector Response and Analysis Software (GADRAS, Mitchell and Mattingly, Sandia National Laboratory). GADRAS uses a one-dimensional discrete ordinate calculation to simulate gamma-ray spectra. The measured and simulated spectra have been analyzed and compared. This paper will discuss the results of the comparison and offer explanations for spectral differences.

  7. Simulated BRDF based on measured surface topography of metal

    Science.gov (United States)

    Yang, Haiyue; Haist, Tobias; Gronle, Marc; Osten, Wolfgang

    2017-06-01

    The radiative reflective properties of a calibration standard rough surface were simulated by ray tracing and the Finite-difference time-domain (FDTD) method. The simulation results have been used to compute the reflectance distribution functions (BRDF) of metal surfaces and have been compared with experimental measurements. The experimental and simulated results are in good agreement.

  8. Improving LED CCT uniformity using micropatterned films optimized by combining ray tracing and FDTD methods.

    Science.gov (United States)

    Ding, Xinrui; Li, Jiasheng; Chen, Qiu; Tang, Yong; Li, Zongtao; Yu, Binhai

    2015-02-09

    Although the light-emitting diode (LED) has revolutionized lighting, the non-uniformity of its correlated color temperature (CCT) still remains a major concern. In this context, to improve the light distribution performance of remote phosphor LED lamps, we employ a micropatterned array (MPA) optical film fabricated using a low-cost molding process. The parameters of the MPA, including different installation configurations, positioning, and diameters, are optimized by combining the finite-difference time-domain and ray-tracing methods. Results show that the sample with the upward-facing convex-cone MPA film that has a diameter of half of that of the remote phosphor glass, and is tightly affixed to the inward surface of the remote phosphor glass renders a superior light distribution performance. When compared with the case in which no MPA film is used, the deviation of the CCT distribution decreases from 1033 K to 223 K, and the corresponding output power of the sample is an acceptable level of 85.6%. We perform experiments to verify our simulation results, and the two sets of results exhibit a close agreement. We believe that our approach can be used to optimize MPA films for various lighting applications.

  9. Global Calibration of Multi-Cameras Based on Refractive Projection and Ray Tracing

    Directory of Open Access Journals (Sweden)

    Mingchi Feng

    2017-10-01

    Full Text Available Multi-camera systems are widely applied in the three dimensional (3D computer vision, especially when multiple cameras are distributed on both sides of the measured object. The calibration methods of multi-camera systems are critical to the accuracy of vision measurement and the key is to find an appropriate calibration target. In this paper, a high-precision camera calibration method for multi-camera systems based on transparent glass checkerboards and ray tracing is described, and is used to calibrate multiple cameras distributed on both sides of the glass checkerboard. Firstly, the intrinsic parameters of each camera are obtained by Zhang’s calibration method. Then, multiple cameras capture several images from the front and back of the glass checkerboard with different orientations, and all images contain distinct grid corners. As the cameras on one side are not affected by the refraction of glass checkerboard, extrinsic parameters can be directly calculated. However, the cameras on the other side are influenced by the refraction of glass checkerboard, and the direct use of projection model will produce a calibration error. A multi-camera calibration method using refractive projection model and ray tracing is developed to eliminate this error. Furthermore, both synthetic and real data are employed to validate the proposed approach. The experimental results of refractive calibration show that the error of the 3D reconstruction is smaller than 0.2 mm, the relative errors of both rotation and translation are less than 0.014%, and the mean and standard deviation of reprojection error of the four-camera system are 0.00007 and 0.4543 pixels, respectively. The proposed method is flexible, highly accurate, and simple to carry out.

  10. Cyclotron resonant scattering feature simulations. II. Description of the CRSF simulation process

    Science.gov (United States)

    Schwarm, F.-W.; Ballhausen, R.; Falkner, S.; Schönherr, G.; Pottschmidt, K.; Wolff, M. T.; Becker, P. A.; Fürst, F.; Marcu-Cheatham, D. M.; Hemphill, P. B.; Sokolova-Lapa, E.; Dauser, T.; Klochkov, D.; Ferrigno, C.; Wilms, J.

    2017-05-01

    Context. Cyclotron resonant scattering features (CRSFs) are formed by scattering of X-ray photons off quantized plasma electrons in the strong magnetic field (of the order 1012 G) close to the surface of an accreting X-ray pulsar. Due to the complex scattering cross-sections, the line profiles of CRSFs cannot be described by an analytic expression. Numerical methods, such as Monte Carlo (MC) simulations of the scattering processes, are required in order to predict precise line shapes for a given physical setup, which can be compared to observations to gain information about the underlying physics in these systems. Aims: A versatile simulation code is needed for the generation of synthetic cyclotron lines. Sophisticated geometries should be investigatable by making their simulation possible for the first time. Methods: The simulation utilizes the mean free path tables described in the first paper of this series for the fast interpolation of propagation lengths. The code is parallelized to make the very time-consuming simulations possible on convenient time scales. Furthermore, it can generate responses to monoenergetic photon injections, producing Green's functions, which can be used later to generate spectra for arbitrary continua. Results: We develop a new simulation code to generate synthetic cyclotron lines for complex scenarios, allowing for unprecedented physical interpretation of the observed data. An associated XSPEC model implementation is used to fit synthetic line profiles to NuSTAR data of Cep X-4. The code has been developed with the main goal of overcoming previous geometrical constraints in MC simulations of CRSFs. By applying this code also to more simple, classic geometries used in previous works, we furthermore address issues of code verification and cross-comparison of various models. The XSPEC model and the Green's function tables are available online (see link in footnote, page 1).

  11. A study of x-ray emission from the anode region in a plasma focus device

    International Nuclear Information System (INIS)

    Jia Wang; Tsinchi Yang

    1988-01-01

    The physical process of x-ray emission from the anode region in a plasma focus device due to the interaction of a powerful electron beam with the metal anode and with ionised metallic vapour from the anode is investigated. The influence of the magnetic field of the beam is taken into consideration. A MC-PIC model (Monte Carlo-particle in cell) is proposed for the process, in which an electron-photon collision cascade is simulated by the MC approach and the time-dependent state of metallic vapour is determined by PIC computation. The time-resolved energy spectra and angular distributions of x-ray emission from the extending anode region are calculated. The time-integrated characteristics of the x-ray emission can be compared with the results of experiments as far as they are available. (author)

  12. simEye: computer-based simulation of visual perception under various eye defects using Zernike polynomials

    OpenAIRE

    Fink, Wolfgang; Micol, Daniel

    2006-01-01

    We describe a computer eye model that allows for aspheric surfaces and a three-dimensional computer-based ray-tracing technique to simulate optical properties of the human eye and visual perception under various eye defects. Eye surfaces, such as the cornea, eye lens, and retina, are modeled or approximated by a set of Zernike polynomials that are fitted to input data for the respective surfaces. A ray-tracing procedure propagates light rays using Snell’s law of refraction from an input objec...

  13. The MCNP simulation of the X-ray leakage of X-ray security inspection equipment

    International Nuclear Information System (INIS)

    Wang Kai; Liu Bin; Hu Wenchao; Zhao Wei

    2011-01-01

    Objective: To simulate the radiation leakage of the X-ray security inspection equipment used in the subways stations. Methods: We use the MCNP4C code to simulate the X-ray leakage of the equipment during the working process. Result: the biggest amount of radiation received by the body is 8.26 μSv/a, however, if the Lead screens of the X-ray security equipment is intact, the amount of radiation received by the body is only 0.0727 μSv/a. The final. Conclusions: When the baggage get in /out the X-ray security inspection equipment, the gas in Lead screens was made, and then the amount of radiation received by human body increased; The amount of radiation received by the body is close to but still below 10 μSv/a which is the exemption criteria set by the 'safety of radiation sources of ionizing radiation protection and basic standards'(GB18871-2002). (authors)

  14. Analysis of trace elements in opal using PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, Ruth, E-mail: ruth.hinrichs@ufrgs.br [Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Programa de Pós-graduação em Física, UFRGS, Porto Alegre, RS (Brazil); Bertol, A.P.L. [Programa de Pós-graduação em Física, UFRGS, Porto Alegre, RS (Brazil); Vasconcellos, M.A.Z. [Programa de Pós-graduação em Física, UFRGS, Porto Alegre, RS (Brazil); Instituto de Física, UFRGS, Porto Alegre, RS (Brazil)

    2015-11-15

    Particle induced X-ray emission (PIXE) analysis is particularly important for the analysis of trace elements of precious samples, being one of the few methods to determine elements with ppm concentration that does not affect sample integrity. A PIXE methodology for trace element analysis in opal was developed. To avoid detector count saturation due to the high number of Si-Kα X-rays generated in the sample, several filters were employed to optimize the reduction of the Si-Kα signal, while maintaining acceptable intensities of the other relevant X-ray lines. Two proton beam energies were tested, to establish the signal to noise ratio in different X-ray energies. Spectra were fitted with the software GUPIX, using a matrix composition determined with electron beam excited energy dispersive X-ray spectrometry. Above the energy of the silicon X-ray, several trace elements were quantified.

  15. 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

  16. Gamma-Ray Burst Dynamics and Afterglow Radiation from Adaptive Mesh Refinement, Special Relativistic Hydrodynamic Simulations

    Science.gov (United States)

    De Colle, Fabio; Granot, Jonathan; López-Cámara, Diego; Ramirez-Ruiz, Enrico

    2012-02-01

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with ρvpropr -k , bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the relativistic flow.

  17. GAMMA-RAY BURST DYNAMICS AND AFTERGLOW RADIATION FROM ADAPTIVE MESH REFINEMENT, SPECIAL RELATIVISTIC HYDRODYNAMIC SIMULATIONS

    International Nuclear Information System (INIS)

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; López-Cámara, Diego

    2012-01-01

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with ρ∝r –k , bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the relativistic flow.

  18. GAMMA-RAY BURST DYNAMICS AND AFTERGLOW RADIATION FROM ADAPTIVE MESH REFINEMENT, SPECIAL RELATIVISTIC HYDRODYNAMIC SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    De Colle, Fabio; Ramirez-Ruiz, Enrico [Astronomy and Astrophysics Department, University of California, Santa Cruz, CA 95064 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Lopez-Camara, Diego [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ap. 70-543, 04510 D.F. (Mexico)

    2012-02-20

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with {rho}{proportional_to}r{sup -k}, bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the

  19. X-ray metrology and performance of a 45-cm long x-ray deformable mirror

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, Lisa A., E-mail: poyneer1@llnl.gov; Brejnholt, Nicolai F.; Hill, Randall; Jackson, Jessie; Hagler, Lisle [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Celestre, Richard; Feng, Jun [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2016-05-15

    We describe experiments with a 45-cm long x-ray deformable mirror (XDM) that have been conducted in End Station 2, Beamline 5.3.1 at the Advanced Light Source. A detailed description of the hardware implementation is provided. We explain our one-dimensional Fresnel propagation code that correctly handles grazing incidence and includes a model of the XDM. This code is used to simulate and verify experimental results. Initial long trace profiler metrology of the XDM at 7.5 keV is presented. The ability to measure a large (150-nm amplitude) height change on the XDM is demonstrated. The results agree well with the simulated experiment at an error level of 1 μrad RMS. Direct imaging of the x-ray beam also shows the expected change in intensity profile at the detector.

  20. Simulation Study on Identifiability of UHE Gamma-ray Air Showers

    International Nuclear Information System (INIS)

    Wada, Y.; Inoue, N.; Miyazawa, K.; Vankov, H.P.

    2008-01-01

    The chemical composition of Ultra-High-Energy (UHE) comic rays is one of unsolved mysteries, and its study will give us fruitful information on the origin and acceleration mechanism of UHE cosmic rays. Especially, a detection of UHE gamma-rays by hybrid experiments, such as AUGER and TA, will be a key to solve these questions. The characteristics of UHE gamma-ray showers have been studied by comparing the lateral and longitudinal structures of shower particles calculated with AIRES and our own simulation code, so far. There are apparent differences in a slope of lateral distribution (η) and a depth of shower maximum (Xmax) between gamma-ray and proton induced showers because UHE gamma-ray showers are affected by the LPM effect and the geomagnetic cascading process in an energy region of >10 19.5 eV. Different features between gamma-ray and proton showers are pointed out from the simulation study and an identifiability of gamma-ray showers from proton ones is also discussed by the method of Neural-Network-Analysis

  1. Simulation Study on Identifiability of UHE Gamma-ray Air Showers

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Y.; Inoue, N.; Miyazawa, K. [Graduate School of Science and Engineering, Saitama University, Saitama 338-8570 (Japan); Vankov, H.P. [Institute for Nuclear Research and Nuclear Energy, Bulgaria Academy, Sofia (Bulgaria)

    2008-01-15

    The chemical composition of Ultra-High-Energy (UHE) comic rays is one of unsolved mysteries, and its study will give us fruitful information on the origin and acceleration mechanism of UHE cosmic rays. Especially, a detection of UHE gamma-rays by hybrid experiments, such as AUGER and TA, will be a key to solve these questions. The characteristics of UHE gamma-ray showers have been studied by comparing the lateral and longitudinal structures of shower particles calculated with AIRES and our own simulation code, so far. There are apparent differences in a slope of lateral distribution ({eta}) and a depth of shower maximum (Xmax) between gamma-ray and proton induced showers because UHE gamma-ray showers are affected by the LPM effect and the geomagnetic cascading process in an energy region of >10{sup 19.5}eV. Different features between gamma-ray and proton showers are pointed out from the simulation study and an identifiability of gamma-ray showers from proton ones is also discussed by the method of Neural-Network-Analysis.

  2. Feasibility of using continuous X-ray to simulate cable response under X-ray environment

    International Nuclear Information System (INIS)

    Ma Liang; Zhou Hui; Cheng Yinhui; Wu Wei; Li Jinxi; Zhao Mo; Guo Jinghai

    2014-01-01

    The mechanism and simulating method of cable response induced by X-ray were researched, and the relationship of cable response irradiated by continuous and pulsed X-ray was analyzed. A one-dimension model of strip line irradiation response of X-ray was given, which includes the gap between cable shield and dielectric, and induced conductivity in cable dielectric. The calculation result using the model indicates that the cable responses of continuous and rectangular-pulsed X-ray have the similar current waveform and the same gap voltages. Therefore, continuous X-ray can be used to research some cable responses of pulsed X-ray irradiation under the mechanism described in the one-dimension model. (authors)

  3. Modeling a Miniaturized Scanning Electron Microscope Focusing Column - Lessons Learned in Electron Optics Simulation

    Science.gov (United States)

    Loyd, Jody; Gregory, Don; Gaskin, Jessica

    2016-01-01

    /Fourier series hybrid approach. The presentation will give background remarks about the MSFC mini Lunar SEM concept and electron optics modeling, followed by a description of the alternate field modeling techniques that were tried, along with their incorporation into a ray-trace simulation. Next, the validation of this simulation against commercially available software will be discussed using an example lens as a test case. Then, the efficacy of aberration assessment using direct ray-tracing will be demonstrated, using this same validation case. The discussion will include practical error checks of the field solution. Finally, the ray-trace assessment of the MSFC mini Lunar SEM concept will be shown and discussed. The authors believe this presentation will be of general interest to practitioners of modeling and simulation, as well as those with a general optics background. Because electron optics and photon optics share many basic concepts (e.g., lenses, images, aberrations, etc.), the appeal of this presentation need not be restricted to just those interested in charged particle optics.

  4. Simulation study on unfolding methods for diagnostic X-rays and mixed gamma rays

    International Nuclear Information System (INIS)

    Hashimoto, Makoto; Ohtaka, Masahiko; Ara, Kuniaki; Kanno, Ikuo; Imamura, Ryo; Mikami, Kenta; Nomiya, Seiichiro; Onabe, Hideaki

    2009-01-01

    A photon detector operating in current mode that can sense X-ray energy distribution has been reported. This detector consists of a row of several segment detectors. The energy distribution is derived using an unfolding technique. In this paper, comparisons of the unfolding techniques among error reduction, spectrum surveillance, and neural network methods are discussed through simulation studies on the detection of diagnostic X-rays and gamma rays emitted by a mixture of 137 Cs and 60 Co. For diagnostic X-ray measurement, the spectrum surveillance and neural network methods appeared promising, while the error reduction method yielded poor results. However, in the case of measuring mixtures of gamma rays, the error reduction method was both sufficient and effective. (author)

  5. Hydrologic Process Parameterization of Electrical Resistivity Imaging of Solute Plumes Using POD McMC

    Science.gov (United States)

    Awatey, M. T.; Irving, J.; Oware, E. K.

    2016-12-01

    Markov chain Monte Carlo (McMC) inversion frameworks are becoming increasingly popular in geophysics due to their ability to recover multiple equally plausible geologic features that honor the limited noisy measurements. Standard McMC methods, however, become computationally intractable with increasing dimensionality of the problem, for example, when working with spatially distributed geophysical parameter fields. We present a McMC approach based on a sparse proper orthogonal decomposition (POD) model parameterization that implicitly incorporates the physics of the underlying process. First, we generate training images (TIs) via Monte Carlo simulations of the target process constrained to a conceptual model. We then apply POD to construct basis vectors from the TIs. A small number of basis vectors can represent most of the variability in the TIs, leading to dimensionality reduction. A projection of the starting model into the reduced basis space generates the starting POD coefficients. At each iteration, only coefficients within a specified sampling window are resimulated assuming a Gaussian prior. The sampling window grows at a specified rate as the number of iteration progresses starting from the coefficients corresponding to the highest ranked basis to those of the least informative basis. We found this gradual increment in the sampling window to be more stable compared to resampling all the coefficients right from the first iteration. We demonstrate the performance of the algorithm with both synthetic and lab-scale electrical resistivity imaging of saline tracer experiments, employing the same set of basis vectors for all inversions. We consider two scenarios of unimodal and bimodal plumes. The unimodal plume is consistent with the hypothesis underlying the generation of the TIs whereas bimodality in plume morphology was not theorized. We show that uncertainty quantification using McMC can proceed in the reduced dimensionality space while accounting for the

  6. Multiplexed optical data storage and vectorial ray tracing

    Directory of Open Access Journals (Sweden)

    Foreman M.R.

    2010-06-01

    Full Text Available With the motivation of creating a terabyte-sized optical disk, a novel imaging technique is implemented. This technique merges two existing technologies: confocal microscopy and Mueller matrix imaging. Mueller matrix images from a high numerical space are obtained. The acquisition of these images makes the exploration of polarisation properties in a sample possible. The particular case of optical data storage is used as an example in this presentation. Since we encode information into asymmetric datapits (see Figure 1, the study of the polarisation of the scattered light can then be used to recover the orientation of the pit. It is thus possible to multiplex information by changing the angle of the mark. The storage capacity in the system is hence limited by the number of distinct angles that the optical system can resolve. This presentation thus answers the question; what is the current storage capacity of a polarisation sensitive optical disk? After a brief introduction to polarisation, the decoding method and experimental results are presented so as to provide an answer to this question. With the aim of understanding high NA focusing, an introduction to vectorial ray tracing is then given.

  7. Claude McKay between United States and Soviet Union: African-American Identity and Socialist Utopia

    Directory of Open Access Journals (Sweden)

    Fiorenzo Iuliano

    2016-04-01

    Full Text Available This article analyzes Claude McKay’s essays on politics and society, especially those dealing with the racial question in the 1920s US. It reviews these texts, alongside other works (poems and autobiographical writings that McKay produced on the same topics. The article aims at tracing a trajectory in McKay’s political thought: after criticizing the social and economic structures of capitalist and colonial societies, McKay envisages in post-revolutionary USSR a utopian society for oppressed people worldwide. However, his writings, rather than depicting the actual USSR society he knew in the early 1920s, evokes the multicultural myth of the ‘melting pot’ traditionally used to celebrate the US. McKay, maybe unwillingly, enthusiastically praises the myth of American exceptionalism, referring it to the USSR.

  8. SU-E-T-58: A Novel Monte Carlo Photon Transport Simulation Scheme and Its Application in Cone Beam CT Projection Simulation

    International Nuclear Information System (INIS)

    Xu, Y; Tian, Z; Jiang, S; Jia, X; Zhou, L

    2015-01-01

    Purpose: Monte Carlo (MC) simulation is an important tool to solve radiotherapy and medical imaging problems. Low computational efficiency hinders its wide applications. Conventionally, MC is performed in a particle-by -particle fashion. The lack of control on particle trajectory is a main cause of low efficiency in some applications. Take cone beam CT (CBCT) projection simulation as an example, significant amount of computations were wasted on transporting photons that do not reach the detector. To solve this problem, we propose an innovative MC simulation scheme with a path-by-path sampling method. Methods: Consider a photon path starting at the x-ray source. After going through a set of interactions, it ends at the detector. In the proposed scheme, we sampled an entire photon path each time. Metropolis-Hasting algorithm was employed to accept/reject a sampled path based on a calculated acceptance probability, in order to maintain correct relative probabilities among different paths, which are governed by photon transport physics. We developed a package gMMC on GPU with this new scheme implemented. The performance of gMMC was tested in a sample problem of CBCT projection simulation for a homogeneous object. The results were compared to those obtained using gMCDRR, a GPU-based MC tool with the conventional particle-by-particle simulation scheme. Results: Calculated scattered photon signals in gMMC agreed with those from gMCDRR with a relative difference of 3%. It took 3.1 hr. for gMCDRR to simulate 7.8e11 photons and 246.5 sec for gMMC to simulate 1.4e10 paths. Under this setting, both results attained the same ∼2% statistical uncertainty. Hence, a speed-up factor of ∼45.3 was achieved by this new path-by-path simulation scheme, where all the computations were spent on those photons contributing to the detector signal. Conclusion: We innovatively proposed a novel path-by-path simulation scheme that enabled a significant efficiency enhancement for MC particle

  9. SU-E-T-58: A Novel Monte Carlo Photon Transport Simulation Scheme and Its Application in Cone Beam CT Projection Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y [UT Southwestern Medical Center, Dallas, TX (United States); Southern Medical University, Guangzhou (China); Tian, Z; Jiang, S; Jia, X [UT Southwestern Medical Center, Dallas, TX (United States); Zhou, L [Southern Medical University, Guangzhou (China)

    2015-06-15

    Purpose: Monte Carlo (MC) simulation is an important tool to solve radiotherapy and medical imaging problems. Low computational efficiency hinders its wide applications. Conventionally, MC is performed in a particle-by -particle fashion. The lack of control on particle trajectory is a main cause of low efficiency in some applications. Take cone beam CT (CBCT) projection simulation as an example, significant amount of computations were wasted on transporting photons that do not reach the detector. To solve this problem, we propose an innovative MC simulation scheme with a path-by-path sampling method. Methods: Consider a photon path starting at the x-ray source. After going through a set of interactions, it ends at the detector. In the proposed scheme, we sampled an entire photon path each time. Metropolis-Hasting algorithm was employed to accept/reject a sampled path based on a calculated acceptance probability, in order to maintain correct relative probabilities among different paths, which are governed by photon transport physics. We developed a package gMMC on GPU with this new scheme implemented. The performance of gMMC was tested in a sample problem of CBCT projection simulation for a homogeneous object. The results were compared to those obtained using gMCDRR, a GPU-based MC tool with the conventional particle-by-particle simulation scheme. Results: Calculated scattered photon signals in gMMC agreed with those from gMCDRR with a relative difference of 3%. It took 3.1 hr. for gMCDRR to simulate 7.8e11 photons and 246.5 sec for gMMC to simulate 1.4e10 paths. Under this setting, both results attained the same ∼2% statistical uncertainty. Hence, a speed-up factor of ∼45.3 was achieved by this new path-by-path simulation scheme, where all the computations were spent on those photons contributing to the detector signal. Conclusion: We innovatively proposed a novel path-by-path simulation scheme that enabled a significant efficiency enhancement for MC particle

  10. Non-destructive trace element microanalysis of as-received cometary nucleus samples using synchrotron x ray fluorescence

    International Nuclear Information System (INIS)

    Sutton, S.R.

    1989-01-01

    The Synchrotron X ray Fluorescence (SXRF) microprobe at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, will be an excellent instrument for non-destructive trace element analyses of cometary nucleus samples. Trace element analyses of as-received cometary nucleus material will also be possible with this technique. Bulk analysis of relatively volatile elements will be important in establishing comet formation conditions. However, as demonstrated for meteorites, microanalyses of individual phases in their petrographic context are crucial in defining the histories of particular components in unequilibrated specimens. Perhaps most informative in comparing cometary material with meteorites will be the halogens and trace metals. In-situ, high spatial resolution microanalyses will be essential in establishing host phases for these elements and identifying terrestrial (collection/processing) overprints. The present SXRF microprobe is a simple, yet powerful, instrument in which specimens are excited with filtered, continuum synchrotron radiation from a bending magnet on a 2.5 GeV electron storage ring. A refrigerated cell will be constructed to permit analyses at low temperatures. The cell will consist essentially of an air tight housing with a cold stage. Kapton windows will be used to allow the incident synchrotron beam to enter the cell and fluorescent x rays to exit it. The cell will be either under vacuum or continuous purge by ultrapure helium during analyses. Several other improvements of the NSLS microprobe will be made prior to the cometary nucleus sample return mission that will greatly enhance the sensitivity of the technique

  11. 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.

  12. The ultimate response guideline simulation and analysis by using (TRACE) for Lungmen ABWR nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hao-Tzu [Atomic Energy Council, Inst. of Nuclear Energy Research, Taoyuan City, Taiwan (China); Yang, Shu-Ming; Chen, Shao-Wen; Wang, Jong-Rong; Shih, Chunkuan [National Tsing Hua Univ., Inst. of Nuclear Engineering and Science, HsinChu, Taiwan (China)

    2015-07-15

    In this research, the TRACE/SNAP model of Lungmen ABWR nuclear power plant (NPP) has been established for the simulation and analysis of ultimate response guideline (URG). The main actions of URG are depressurization and low pressure water injection of reactor and containment venting. This research focuses to assess the URG utility of Lungmen NPP under Fukushima-like conditions. This study consists of three steps. The first step is the establishment of Lungmen NPP TRACE/SNAP model. In order to evaluate the system response of TRACE/SNAP model, FSAR data (MSIV closure and loss of feedwater flow transient) were used to compare with the results of TRACE. The second step is the URG simulation and analysis under Fukushima-like conditions by using Lungmen NPP TRACE/SNAP model. In this step, the no URG case was also performed in order to evaluate the URG effectiveness of Lungmen NPP. In order to confirm the mechanical property and integrity of fuel rods, the final step is FRAPTRAN analysis. According to TRACE analysis results, the URG can keep the peak cladding temperature (PCT) below the criteria 1088.7 K under Fukushima-like conditions which indicates that Lungmen NPP can be controlled in a safe situation. Nevertheless, if Lungmen NPP does not perform the URG under Fukushima-like conditions, the water level may drop lower than TAF after 1100 s which means a safety issue about the fuel rods may be generated. The analysis results of FRAPTRAN also indicate the integrity of fuel rods cannot be kept under the above conditions.

  13. Applications of Monte Carlo simulations of gamma-ray spectra

    International Nuclear Information System (INIS)

    Clark, D.D.

    1995-01-01

    A short, convenient computer program based on the Monte Carlo method that was developed to generate simulated gamma-ray spectra has been found to have useful applications in research and teaching. In research, we use it to predict spectra in neutron activation analysis (NAA), particularly in prompt gamma-ray NAA (PGNAA). In teaching, it is used to illustrate the dependence of detector response functions on the nature of gamma-ray interactions, the incident gamma-ray energy, and detector geometry

  14. Ray-tracing techniques to assess the electromagnetic field radiated by radio base stations: Application and experimental validation in an urban environment

    International Nuclear Information System (INIS)

    Adda, S.; Anglesio, L.; D'Amore, G.; Mantovan, M.; Menegolli, M.

    2004-01-01

    This paper aims to validate a ray-tracing model for electromagnetic field calculation, which is used in urban environments to predict irradiation from radio base stations for population exposure evaluation. Validation was carried out through a measurement campaign by choosing measurement points in order to test different propagation environments and analysing broadcast control channels through narrow band measurements. Comparison of the calculated and measured fields indicates that the ray-tracing model used calculates electric field with good accuracy, in spite of the fact that the propagation environment is not described in detail, because of difficulties in modelling the geometrical and electrical characteristics of urban areas. Differences between the calculated and measured results remain below 1.5 dB, with a mean value of 1 dB. (authors)

  15. A simulated regolith medium for multi-wavelength studies

    Science.gov (United States)

    Wilkman, O.; Muinonen, K.; Parviainen, H.; Näränen, J.

    2012-04-01

    Effects arising from the small-scale surface structure are significant in remote studies of regolith surfaces on atmosphereless solar system bodies, such as the Moon, Mercury and the asteroids. The important properties determining these effects are the porosity of the regolith and the roughness of the interface between the bulk material and empty space. We concentrate on the regolith effects in visible light photometry and X-ray spectrometry. The fluorescent X-ray spectrum induced by solar X-rays contains information about the elemental abundances of the surface material, while the photometry can be used to constrain surface properties such as porosity. We have developed a computer model simulating a regolith medium consisting of spherical particles with variable size distribution and properties. The bulk properties of the medium, such as porosity and surface roughness, can be varied. The model can then be used in ray-tracing simulations of the regolith effects in both visible light scattering and X-ray fluorescence. In photometric studies the scattering law of the constituent particles can be chosen to take into account scattering phenomena such as coherent backscattering. In the X-ray simulations, we can choose the elemental abundances of the material and the spectrum of the incident X-ray radiation. The ray-tracing simulations then allow us to determine the characteristics of the emitted radiation in different observational geometries. We present results from various studies which have been based on our regolith model. The model has been used to simulate the regolith effects on X-ray fluorescence spectra under specific situations. These can be compared to laboratory measurements. The visible light simulations have been applied in a study of the shadowing effects in photometry. The model was also used in a study of lunar photometry from SMART-1/AMIE data. Applications in the analysis of X-ray spectrometry from the BepiColombo MIXS/SIXS instruments are planned. An

  16. 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

    Compound refractive lenses (CRL) are widely used to manipulate synchrotron radiation beams. Accurate modelling of X-ray beam propagation through individual lenses and through "transfocators" composed of a large number of CRLs is of high importance, since it allows for comprehensive optimization...

  17. TU-H-BRC-09: Validation of a Novel Therapeutic X-Ray Array Source and Collimation System

    Energy Technology Data Exchange (ETDEWEB)

    Trovati, S; King, GJ; Loo, BW; Maxim, P; Schueler, E; Wang, J; Wang, L [Stanford University School of Medicine, Palo Alto, California (United States); Borchard, P [Tibaray Inc, San Francisco, California (United States); Limborg, CG; McCormick, D; Nicolas, LY; Tantawi, S [Stanford Linear Accelerator, Menlo Park, CA (United States)

    2016-06-15

    Purpose: We have experimentally characterized and simulated the dosimetric properties and spatial fidelity of a novel X-ray array source and collimation system called SPHINX that has the potential to generate complex intensity modulated X-ray beams by varying the electron beam intensity only, and without any moving parts like in multi-leaf collimators. Methods: We investigated the spatial fidelity and the X-ray performances of a SPHINX prototype in tungsten, using a Cyber Knife and the experimental high-energy electron beam line at XTA at SLAC National Laboratory. Dose distributions were recorded with gafchromic films, placed at the distal end of SPHINX and at several depths in a solid water phantom. The geometry of SPHINX and of the experimental set-ups was also modeled in Monte Carlo (MC) simulations with the FLUKA code, used to reproduce the experimental results and, after validation, to predict and optimize the performance and design of the SPHINX. Results: The results indicate significant particle leakage through the channels during a single-channel irradiation for high incident energies, followed by a rapid decrease for energies of clinical interest. When the collimator channels are used as target, the photon production increases, however at expense of the beam size that is also enlarged. The illumination of all channels simultaneously shows a fairly even transmission of the beam. Conclusion: With the measurements we have verified the MC models and the uniformity of beam transmission through SPHINX, and we have evaluated the importance of particle leakage through adjacent channels. These results can be used to optimize SPHINX design through the validated MC simulations. Funding: Weston Havens Foundation, Office of the Dean of Medical School and Office of the Provost (Stanford University). Loo, Maxim, Borchard, Tantawi are co-founders of TibaRay Inc. Loo and Tantawi are TibaRay Inc. board members. Loo and Maxim received grants from Varian Medical Systems and

  18. TU-H-BRC-09: Validation of a Novel Therapeutic X-Ray Array Source and Collimation System

    International Nuclear Information System (INIS)

    Trovati, S; King, GJ; Loo, BW; Maxim, P; Schueler, E; Wang, J; Wang, L; Borchard, P; Limborg, CG; McCormick, D; Nicolas, LY; Tantawi, S

    2016-01-01

    Purpose: We have experimentally characterized and simulated the dosimetric properties and spatial fidelity of a novel X-ray array source and collimation system called SPHINX that has the potential to generate complex intensity modulated X-ray beams by varying the electron beam intensity only, and without any moving parts like in multi-leaf collimators. Methods: We investigated the spatial fidelity and the X-ray performances of a SPHINX prototype in tungsten, using a Cyber Knife and the experimental high-energy electron beam line at XTA at SLAC National Laboratory. Dose distributions were recorded with gafchromic films, placed at the distal end of SPHINX and at several depths in a solid water phantom. The geometry of SPHINX and of the experimental set-ups was also modeled in Monte Carlo (MC) simulations with the FLUKA code, used to reproduce the experimental results and, after validation, to predict and optimize the performance and design of the SPHINX. Results: The results indicate significant particle leakage through the channels during a single-channel irradiation for high incident energies, followed by a rapid decrease for energies of clinical interest. When the collimator channels are used as target, the photon production increases, however at expense of the beam size that is also enlarged. The illumination of all channels simultaneously shows a fairly even transmission of the beam. Conclusion: With the measurements we have verified the MC models and the uniformity of beam transmission through SPHINX, and we have evaluated the importance of particle leakage through adjacent channels. These results can be used to optimize SPHINX design through the validated MC simulations. Funding: Weston Havens Foundation, Office of the Dean of Medical School and Office of the Provost (Stanford University). Loo, Maxim, Borchard, Tantawi are co-founders of TibaRay Inc. Loo and Tantawi are TibaRay Inc. board members. Loo and Maxim received grants from Varian Medical Systems and

  19. Diffractive-refractive optics: (+,-,-,+) X-ray crystal monochromator with harmonics separation.

    Science.gov (United States)

    Hrdý, Jaromír; Mikulík, Petr; Oberta, Peter

    2011-03-01

    A new kind of two channel-cut crystals X-ray monochromator in dispersive (+,-,-,+) position which spatially separates harmonics is proposed. The diffracting surfaces are oriented so that the diffraction is inclined. Owing to refraction the diffracted beam is sagittally deviated. The deviation depends on wavelength and is much higher for the first harmonics than for higher harmonics. This leads to spatial harmonics separation. The idea is supported by ray-tracing simulation.

  20. Trace element measurements with synchrotron radiation

    International Nuclear Information System (INIS)

    Hanson, A.L.; Kraner, H.W.; Jones, K.W.; Gordon, B.M.; Mills, R.E.

    1982-01-01

    Aspects of the application of synchrotron radiation to trace element determinations by x-ray fluorescence have been investigated using beams from the Cornell facility, CHESS. Fluoresced x rays were detected with a Si(Li) detector placed 4 cm from the target at 90 0 to the beam. Thick samples of NBS Standard Reference Materials were used to calibrate trace element sensitivity and estimate minimum detectable limits for this method

  1. Log-stable concentration distributions of trace elements in biomedical samples

    International Nuclear Information System (INIS)

    Kubala-Kukus, A.; Kuternoga, E.; Braziewicz, J.; Pajek, M.

    2004-01-01

    In the present paper, which follows our earlier observation that the asymmetric and long-tailed concentration distributions of trace elements in biomedical samples, measured by the X-ray fluorescence techniques, can be modeled by the log-stable distributions, further specific aspects of this observation are discussed. First, we demonstrate that, typically, for a quite substantial fraction (10-20%) of trace elements studied in different kinds of biomedical samples, the measured concentration distributions are described in fact by the 'symmetric' log-stable distributions, i.e. the asymmetric distributions which are described by the symmetric stable distributions. This observation is, in fact, expected for the random multiplicative process, which models the concentration distributions of trace elements in the biomedical samples. The log-stable nature of concentration distribution of trace elements results in several problems of statistical nature, which have to be addressed in XRF data analysis practice. Consequently, in the present paper, the following problems, namely (i) the estimation of parameters for stable distributions and (ii) the testing of the log-stable nature of the concentration distribution by using the Anderson-Darling (A 2 ) test, especially for symmetric stable distributions, are discussed in detail. In particular, the maximum likelihood estimation and Monte Carlo simulation techniques were used, respectively, for estimation of stable distribution parameters and calculation of the critical values for the Anderson-Darling test. The discussed ideas are exemplified by the results of the study of trace element concentration distributions in selected biomedical samples, which were obtained by using the X-ray fluorescence (XRF, TXRF) methods

  2. Proton induced x-ray emission analysis of trace elements in thick bread samples

    International Nuclear Information System (INIS)

    Mohamed Baker Al-bedri; Ikram Jameel Abdul Ghani; Ibrahim Abdul Rahman Al-aghil

    2009-01-01

    Proton induced X-ray emission (PIXE) technique has been used for identification and quantitative analysis of the elemental concentration in thick bread samples. Bread samples were air-oven dried at 60degC and milled in a clean agate mortar to homogenize the sample and pressed into a pellet. PIXE technique relies on the analysis of the energy spectra of the characteristic X-ray emitted from the thick bread sample and the orchard leaf standard (NIST-SRM-1571) bombarded with 2.0 MeV protons. The concentration of the elements (Cl, K, Ca, Mn, Fe, Cu, and Zn) in the bread samples was determined by comparison with NIST orchard leaf standard. The accuracy of the measurements ranged between ±2% and ±10% for the most elements detected in this method. The aim of this study is to establish the reference concentration of trace elements in the Iraqi bread using PIXE technique. (author)

  3. Integration of Monte-Carlo ray tracing with a stochastic optimisation method: application to the design of solar receiver geometry.

    Science.gov (United States)

    Asselineau, Charles-Alexis; Zapata, Jose; Pye, John

    2015-06-01

    A stochastic optimisation method adapted to illumination and radiative heat transfer problems involving Monte-Carlo ray-tracing is presented. A solar receiver shape optimisation case study illustrates the advantages of the method and its potential: efficient receivers are identified using a moderate computational cost.

  4. 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

  5. Interfering line in trace analysis by X-ray spectrometry: Radiative auger satellites

    International Nuclear Information System (INIS)

    Maeda, Kuniko; Kawai, Jun.

    1994-01-01

    Strong characteristic X-ray lines (e.g. Kα and Kβ) are accompanied by broad low-energy satellites caused by the radiative Auger effect (RAE). In order to prove how the RAE satellites interfere the analysis of minor elements, low-energy side spectra of Ca and Ti Kβ, and Ca-Fe Kα were measured. The obtained RAE intensities are summarized together with published experimental and theoretical data. The integrated intensities of satellites due to K → MM, K → LM and K → LL RAE relative to that of Kα are determined to be of the order of 0.01-0.1%. This warns that the neglecting of the RAE satellites will introduce a serious error in trace analysis. (author)

  6. Distribution of trace levels of therapeutic gallium in bone as mapped by synchrotron X-ray microscopy

    International Nuclear Information System (INIS)

    Bockman, R.S.; Repo, M.A.; Warrell, R.P. Jr.; Pounds, J.G.; Schidlovsky, G.; Gordon, B.M.; Jones, K.W.

    1990-01-01

    Gallium nitrate, a drug that inhibits calcium release from bone, has been proven a safe and effective treatment for the accelerated bone resorption associated with cancer. Though bone is a target organ for gallium, the kinetics, sites, and effects of gallium accumulation in bone are not known. The authors have used synchrotron X-ray microscopy to map the distribution of trace levels of gallium in bone. After short-term in vivo administration of gallium nitrate to rats, trace (nanogram) amounts of gallium preferentially localized to the metabolically active regions in the metaphysis as well as the endosteal and periosteal surfaces of diaphyseal bone, regions where new bone formation and modeling were occurring. The amounts measured were well below the levels known to be cytotoxic. Iron and zinc, trace elements normally found in bone, were decreased in amount after in vivo administration of gallium. These studies represent a first step toward understanding the mechanism(s) of action of gallium in bone by suggesting the possible cellular, structural, and elemental targets of gallium

  7. SU-C-204-06: Monte Carlo Dose Calculation for Kilovoltage X-Ray-Psoralen Activated Cancer Therapy (X-PACT): Preliminary Results

    Energy Technology Data Exchange (ETDEWEB)

    Mein, S [Duke University Medical Physics Graduate Program (United States); Gunasingha, R [Department of Radiation Safety, Duke University Medical Center (United States); Nolan, M [Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University (United States); Oldham, M; Adamson, J [Department of Radiation Oncology, Duke University Medical Center (United States)

    2016-06-15

    Purpose: X-PACT is an experimental cancer therapy where kV x-rays are used to photo-activate anti-cancer therapeutics through phosphor intermediaries (phosphors that absorb x-rays and re-radiate as UV light). Clinical trials in pet dogs are currently underway (NC State College of Veterinary Medicine) and an essential component is the ability to model the kV dose in these dogs. Here we report the commissioning and characterization of a Monte Carlo (MC) treatment planning simulation tool to calculate X-PACT radiation doses in canine trials. Methods: FLUKA multi-particle MC simulation package was used to simulate a standard X-PACT radiation treatment beam of 80kVp with the Varian OBI x-ray source geometry. The beam quality was verified by comparing measured and simulated attenuation of the beam by various thicknesses of aluminum (2–4.6 mm) under narrow beam conditions (HVL). The beam parameters at commissioning were then corroborated using MC, characterized and verified with empirically collected commissioning data, including: percent depth dose curves (PDD), back-scatter factors (BSF), collimator scatter factor(s), and heel effect, etc. All simulations were conducted for N=30M histories at M=100 iterations. Results: HVL and PDD simulation data agreed with an average percent error of 2.42%±0.33 and 6.03%±1.58, respectively. The mean square error (MSE) values for HVL and PDD (0.07% and 0.50%) were low, as expected; however, longer simulations are required to validate convergence to the expected values. Qualitatively, pre- and post-filtration source spectra matched well with 80kVp references generated via SPEKTR software. Further validation of commissioning data simulation is underway in preparation for first-time 3D dose calculations with canine CBCT data. Conclusion: We have prepared a Monte Carlo simulation capable of accurate dose calculation for use with ongoing X-PACT canine clinical trials. Preliminary results show good agreement with measured data and hold

  8. Do Peripheral Refraction and Aberration Profiles Vary with the Type of Myopia? - An Illustration Using a Ray-Tracing Approach

    Directory of Open Access Journals (Sweden)

    Ravi C. Bakaraju

    2009-01-01

    Conclusion: This study has indicated that myopic eyes with primarily an axial component may have a greater risk of progression than their refractive counterparts albeit with the same degree of refractive error. This prediction emerges from the presented theoretical ray tracing model and, therefore, requires clinical confirmation.

  9. A track length estimator method for dose calculations in low-energy X-ray irradiations. Implementation, properties and performance

    Energy Technology Data Exchange (ETDEWEB)

    Baldacci, F.; Delaire, F.; Letang, J.M.; Sarrut, D.; Smekens, F.; Freud, N. [Lyon-1 Univ. - CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Centre Leon Berard (France); Mittone, A.; Coan, P. [LMU Munich (Germany). Dept. of Physics; LMU Munich (Germany). Faculty of Medicine; Bravin, A.; Ferrero, C. [European Synchrotron Radiation Facility, Grenoble (France); Gasilov, S. [LMU Munich (Germany). Dept. of Physics

    2015-05-01

    The track length estimator (TLE) method, an 'on-the-fly' fluence tally in Monte Carlo (MC) simulations, recently implemented in GATE 6.2, is known as a powerful tool to accelerate dose calculations in the domain of low-energy X-ray irradiations using the kerma approximation. Overall efficiency gains of the TLE with respect to analogous MC were reported in the literature for regions of interest in various applications (photon beam radiation therapy, X-ray imaging). The behaviour of the TLE method in terms of statistical properties, dose deposition patterns, and computational efficiency compared to analogous MC simulations was investigated. The statistical properties of the dose deposition were first assessed. Derivations of the variance reduction factor of TLE versus analogous MC were carried out, starting from the expression of the dose estimate variance in the TLE and analogous MC schemes. Two test cases were chosen to benchmark the TLE performance in comparison with analogous MC: (i) a small animal irradiation under stereotactic synchrotron radiation therapy conditions and (ii) the irradiation of a human pelvis during a cone beam computed tomography acquisition. Dose distribution patterns and efficiency gain maps were analysed. The efficiency gain exhibits strong variations within a given irradiation case, depending on the geometrical (voxel size, ballistics) and physical (material and beam properties) parameters on the voxel scale. Typical values lie between 10 and 103, with lower levels in dense regions (bone) outside the irradiated channels (scattered dose only), and higher levels in soft tissues directly exposed to the beams.

  10. Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

    Science.gov (United States)

    Kim, Sangroh; Yoshizumi, Terry T; Toncheva, Greta; Frush, Donald P; Yin, Fang-Fang

    2010-03-01

    The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry.

  11. spMC: an R-package for 3D lithological reconstructions based on spatial Markov chains

    Science.gov (United States)

    Sartore, Luca; Fabbri, Paolo; Gaetan, Carlo

    2016-09-01

    The paper presents the spatial Markov Chains (spMC) R-package and a case study of subsoil simulation/prediction located in a plain site of Northeastern Italy. spMC is a quite complete collection of advanced methods for data inspection, besides spMC implements Markov Chain models to estimate experimental transition probabilities of categorical lithological data. Furthermore, simulation methods based on most known prediction methods (as indicator Kriging and CoKriging) were implemented in spMC package. Moreover, other more advanced methods are available for simulations, e.g. path methods and Bayesian procedures, that exploit the maximum entropy. Since the spMC package was developed for intensive geostatistical computations, part of the code is implemented for parallel computations via the OpenMP constructs. A final analysis of this computational efficiency compares the simulation/prediction algorithms by using different numbers of CPU cores, and considering the example data set of the case study included in the package.

  12. Simulation of 1.5-mm-thick and 15-cm-diameter gated silicon drift X-ray detector operated with a single high-voltage source

    Science.gov (United States)

    Matsuura, Hideharu

    2015-04-01

    High-resolution silicon X-ray detectors with a large active area are required for effectively detecting traces of hazardous elements in food and soil through the measurement of the energies and counts of X-ray fluorescence photons radially emitted from these elements. The thicknesses and areas of commercial silicon drift detectors (SDDs) are up to 0.5 mm and 1.5 cm2, respectively. We describe 1.5-mm-thick gated SDDs (GSDDs) that can detect photons with energies up to 50 keV. We simulated the electric potential distributions in GSDDs with a Si thickness of 1.5 mm and areas from 0.18 to 168 cm2 at a single high reverse bias. The area of a GSDD could be enlarged simply by increasing all the gate widths by the same multiple, and the capacitance of the GSDD remained small and its X-ray count rate remained high.

  13. The McGill simulator for endoscopic sinus surgery (MSESS): a validation study.

    Science.gov (United States)

    Varshney, Rickul; Frenkiel, Saul; Nguyen, Lily H P; Young, Meredith; Del Maestro, Rolando; Zeitouni, Anthony; Saad, Elias; Funnell, W Robert J; Tewfik, Marc A

    2014-10-24

    Endoscopic sinus surgery (ESS) is a technically challenging procedure, associated with a significant risk of complications. Virtual reality simulation has demonstrated benefit in many disciplines as an important educational tool for surgical training. Within the field of rhinology, there is a lack of ESS simulators with appropriate validity evidence supporting their integration into residency education. The objectives of this study are to evaluate the acceptability, perceived realism and benefit of the McGill Simulator for Endoscopic Sinus Surgery (MSESS) among medical students, otolaryngology residents and faculty, and to present evidence supporting its ability to differentiate users based on their level of training through the performance metrics. 10 medical students, 10 junior residents, 10 senior residents and 3 expert sinus surgeons performed anterior ethmoidectomies, posterior ethmoidectomies and wide sphenoidotomies on the MSESS. Performance metrics related to quality (e.g. percentage of tissue removed), efficiency (e.g. time, path length, bimanual dexterity, etc.) and safety (e.g. contact with no-go zones, maximum applied force, etc.) were calculated. All users completed a post-simulation questionnaire related to realism, usefulness and perceived benefits of training on the MSESS. The MSESS was found to be realistic and useful for training surgical skills with scores of 7.97 ± 0.29 and 8.57 ± 0.69, respectively on a 10-point rating scale. Most students and residents (29/30) believed that it should be incorporated into their curriculum. There were significant differences between novice surgeons (10 medical students and 10 junior residents) and senior surgeons (10 senior residents and 3 sinus surgeons) in performance metrics related to quality (p education. This simulator may be a potential resource to help fill the void in endoscopic sinus surgery training.

  14. Monte Carlo semi-empirical model for Si(Li) x-ray detector: Differences between nominal and fitted parameters

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Pino, N.; Padilla-Cabal, F.; Garcia-Alvarez, J. A.; Vazquez, L.; D' Alessandro, K.; Correa-Alfonso, C. M. [Departamento de Fisica Nuclear, Instituto Superior de Tecnologia y Ciencias Aplicadas (InSTEC) Ave. Salvador Allende y Luaces. Quinta de los Molinos. Habana 10600. A.P. 6163, La Habana (Cuba); Godoy, W.; Maidana, N. L.; Vanin, V. R. [Laboratorio do Acelerador Linear, Instituto de Fisica - Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-900, SP (Brazil)

    2013-05-06

    A detailed characterization of a X-ray Si(Li) detector was performed to obtain the energy dependence of efficiency in the photon energy range of 6.4 - 59.5 keV, which was measured and reproduced by Monte Carlo (MC) simulations. Significant discrepancies between MC and experimental values were found when the manufacturer parameters of the detector were used in the simulation. A complete Computerized Tomography (CT) detector scan allowed to find the correct crystal dimensions and position inside the capsule. The computed efficiencies with the resulting detector model differed with the measured values no more than 10% in most of the energy range.

  15. Simulation of reflooding on two parallel heated channel by TRACE

    Energy Technology Data Exchange (ETDEWEB)

    Zakir, Md. Ghulam [Department of Nuclear Engineering, Chalmers University of Technology, Gothenburg (Sweden)

    2016-07-12

    In case of Loss-Of-Coolant accident (LOCA) in a Boiling Water Reactor (BWR), heat generated in the nuclear fuel is not adequately removed because of the decrease of the coolant mass flow rate in the reactor core. This fact leads to an increase of the fuel temperature that can cause damage to the core and leakage of the radioactive fission products. In order to reflood the core and to discontinue the increase of temperature, an Emergency Core Cooling System (ECCS) delivers water under this kind of conditions. This study is an investigation of how the power distribution between two channels can affect the process of reflooding when the emergency water is injected from the top of the channels. The peak cladding temperature (PCT) on LOCA transient for different axial level is determined as well. A thermal-hydraulic system code TRACE has been used. A TRACE model of the two heated channels has been developed, and three hypothetical cases with different power distributions have been studied. Later, a comparison between a simulated and experimental data has been shown as well.

  16. 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)

  17. Development of gamma-ray absorption and scattering simulation platform based on MCNP

    International Nuclear Information System (INIS)

    Lai Wanchang; Chen Henggui; Zhang Zhen; Chen Xiaoqiang

    2010-01-01

    It describes a γ-ray absorption and scattering simulation platform centering on MCNP, and developed corresponding accessories on the basis of the MCNP. Simulation of this simulation platform can be 93 kinds of single-quality materials and 2-3 kinds of multi-element mixture absorption experiment, simulating the absorption thickness of 0-100cm, and the thickness increment in 0.001cm. The media of Scattering Simulation is from the Li to the Am, the angle between the simulation measuring degree and incident ray direction is from-90 to 90, the angle in increments in 1 degree. (authors)

  18. Trace elements in natural azurite pigments found in illuminated manuscript leaves investigated by synchrotron x-ray fluorescence and diffraction mapping

    Science.gov (United States)

    Smieska, Louisa M.; Mullett, Ruth; Ferri, Laurent; Woll, Arthur R.

    2017-07-01

    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.

  19. 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.)

  20. The determination of the C, N, O and trace element content of Triticum aestivum by activation analysis, X-ray excitation and mass spectrometry

    International Nuclear Information System (INIS)

    Leonhardt, J.W.; Dahn, E.; Dietze, H.J.; Freyer, K.; Geisler, M.; Hartmann, G.; Jung, K.; Schelhorn, H.

    1979-01-01

    The results of determinations of the C, N, O and trace element content of grains, sprouts and leaves of Triticum aestivum by means of various methods of activation analysis, X-ray excitation and mass spectrometry are presented. The C and O contents were determined by X-ray excitation; the O, N, P and Si contents were measured by NAA with 14-MeV neutrons, and the trace elements were determined by NAA with thermal neutrons. A mass-spectrometric survey analysis confirmed the results obtained by NAA. The use of neutron-induced nuclear reactions together with autoradiography enabled a representative picture to be formed of the spatial distribution in two dimensions of 14 N in biological specimens. (author)

  1. Non-imaging ray-tracing for sputtering simulation with apodization

    Science.gov (United States)

    Ou, Chung-Jen

    2018-04-01

    Although apodization patterns have been adopted for the analysis of sputtering sources, the analytical solutions for the film thickness equations are yet limited to only simple conditions. Empirical formulations for thin film sputtering lacking the flexibility in dealing with multi-substrate conditions, a suitable cost-effective procedure is required to estimate the film thickness distribution. This study reports a cross-discipline simulation program, which is based on discrete particle Monte-Carlo methods and has been successfully applied to a non-imaging design to solve problems associated with sputtering uniformity. Robustness of the present method is first proved by comparing it with a typical analytical solution. Further, this report also investigates the overall all effects cause by the sizes of the deposited substrate, such that the determination of the distance between the target surface and the apodization index can be complete. This verifies the capability of the proposed method for solving the sputtering film thickness problems. The benefit is that an optical thin film engineer can, using the same optical software, design a specific optical component and consider the possible coating qualities with thickness tolerance, during the design stage.

  2. Interactive Acoustic Simulation in Urban and Complex Environments

    Science.gov (United States)

    2015-03-21

    techniques based on ray tracing [83, 166, 88] or radiosity [159] have been developed for modeling diffuse reflections, but these energy- based formulations...method[7, 22], ray tracing[167, 149], frustum tracing[148], beam tracing[46, 32], sonal mapping[19, 38, 79], path tracing[136], and radiosity [160]. The...ray tracing[167, 149], frustum tracing[148], beam tracing[46, 32], sonal mapping[19, 38, 79], path tracing[136], and radiosity [160]. The ray models

  3. Dibenzylammonium and sodium dibenzyldithiocarbamates as precipitants for preconcentration of trace elements in water for analysis by energy dispersive X-ray fluorescence

    International Nuclear Information System (INIS)

    Moore, R.V.

    1982-01-01

    Precipitation with combined dibenzylammonium dibenzyldithiocarbamate and sodium dibenzyldithiocarbamate at pH 5.0 can be used to separate 22 trace elements from water. Membrane filtration of the precipitate yielded a thin sample, suitable for analysis by energy dispersive X-ray fluorescence spectrometry. Alkalis, alkaline earths, lanthanides, and halides were not precipitated, permitting a clean separation of trace elements from the macro constituents of drinking water and drinking water supplies. Methods are given for preparation of reagents of higher purity than previously described

  4. Computer simulation tools for X-ray analysis scattering and diffraction methods

    CERN Document Server

    Morelhão, Sérgio Luiz

    2016-01-01

    The main goal of this book is to break down the huge barrier of difficulties faced by beginners from many fields (Engineering, Physics, Chemistry, Biology, Medicine, Material Science, etc.) in using X-rays as an analytical tool in their research. Besides fundamental concepts, MatLab routines are provided, showing how to test and implement the concepts. The major difficult in analyzing materials by X-ray techniques is that it strongly depends on simulation software. This book teaches the users on how to construct a library of routines to simulate scattering and diffraction by almost any kind of samples. It provides to a young student the knowledge that would take more than 20 years to acquire by working on X-rays and relying on the available textbooks. In this book, fundamental concepts in applied X-ray physics are demonstrated through available computer simulation tools. Using MatLab, more than eighty routines are developed for solving the proposed exercises, most of which can be directly used in experimental...

  5. Tracing the Origin of Black Hole Accretion Through Numerical Hydrodynamic Simulations

    Science.gov (United States)

    Spicer, Sandy; Somerville, Rachel; Choi, Ena; Brennan, Ryan

    2018-01-01

    It is now widely accepted that supermassive black holes co-evolve with galaxies, and may play an important role in galaxy evolution. However, the origin of the gas that fuels black hole accretion, and the resulting observable radiation, is not well understood or quantified. We use high-resolution "zoom-in" cosmological numerical hydrodynamic simulations including modeling of black hole accretion and feedback to trace the inflow and outflow of gas within galaxies from the early formation period up to present day. We track gas particles that black holes interact with over time to trace the origin of the gas that feeds supermassive black holes. These gas particles can come from satellite galaxies, cosmological accretion, or be a result of stellar evolution. We aim to track the origin of the gas particles that accrete onto the central black hole as a function of halo mass and cosmic time. Answering these questions will help us understand the connection between galaxy and black hole evolution.

  6. Study of new scaling of direct photon production in pp collisions at high energies using MC simulation

    International Nuclear Information System (INIS)

    Tokarev, M.V.; Potrebenikova, E.V.

    1998-01-01

    The new scaling, z scaling, of prompt photon production in pp collisions at high energies is studied. The scaling function H(z) is expressed via the inclusive cross section of photon production Ed 3 σ / dq 3 and the multiplicity density of charged particles, ρ (s), at pseudorapidity η = 0. Monte Carlo (MC) simulation based on the PYTHIA code is used to calculate the cross section and to verify the scaling. The MC technique used to construct the scaling function is described. The H (z) dependence on the scaling variable z, the center-of-mass energy √ s at a produced angle of θ = 90 deg is investigated. The predictions of the Ed 3 σ / dq 3 dependence on transverse momentum q at a colliding energy of √ s = 0.5, 5.0 and 14.0 TeV are made. The obtained results are compared with the experimental data and can be of interest for future experiments at RHIC (BNL). LHC (CERN), HERA (DESY) and Tevatron (Batavia)

  7. Simulation of single grid-based phase-contrast x-ray imaging (g-PCXI)

    Energy Technology Data Exchange (ETDEWEB)

    Lim, H.W.; Lee, H.W. [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Cho, H.S., E-mail: hscho1@yonsei.ac.kr [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Je, U.K.; Park, C.K.; Kim, K.S.; Kim, G.A.; Park, S.Y.; Lee, D.Y.; Park, Y.O.; Woo, T.H. [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Lee, S.H.; Chung, W.H.; Kim, J.W.; Kim, J.G. [R& D Center, JPI Healthcare Co., Ltd., Ansan 425-833 (Korea, Republic of)

    2017-04-01

    Single grid-based phase-contrast x-ray imaging (g-PCXI) technique, which was recently proposed by Wen et al. to retrieve absorption, scattering, and phase-gradient images from the raw image of the examined object, seems a practical method for phase-contrast imaging with great simplicity and minimal requirements on the setup alignment. In this work, we developed a useful simulation platform for g-PCXI and performed a simulation to demonstrate its viability. We also established a table-top setup for g-PCXI which consists of a focused-linear grid (200-lines/in strip density), an x-ray tube (100-μm focal spot size), and a flat-panel detector (48-μm pixel size) and performed a preliminary experiment with some samples to show the performance of the simulation platform. We successfully obtained phase-contrast x-ray images of much enhanced contrast from both the simulation and experiment and the simulated contract seemed similar to the experimental contrast, which shows the performance of the developed simulation platform. We expect that the simulation platform will be useful for designing an optimal g-PCXI system. - Highlights: • It is proposed for the single grid-based phase-contrast x-ray imaging (g-PCXI) technique. • We implemented for a numerical simulation code. • The preliminary experiment with several samples to compare is performed. • It is expected to be useful to design an optimal g-PCXI system.

  8. Simulating Terrestrial Gamma Ray Flashes due to cosmic ray shower electrons and positrons

    Science.gov (United States)

    Connell, Paul

    2017-04-01

    The University of Valencia has developed a software simulator LEPTRACK to simulate the relativistic runaway electron avalanches, RREA, that are presumed to be the cause of Terrestrial Gamma Ray Flashes and their powerful accompanying Ionization/Excitation Flashes. We show here results of LEPTRACK simulations of RREA by the interaction of MeV energy electrons/positrons and photons in cosmic ray showers traversing plausible electric field geometries expected in storm clouds. The input beams of MeV shower products were created using the CORSIKA software package from the Karlsruhe Institute of Technology. We present images, videos and plots showing the different Ionization, Excitation and gamma-ray photon density fields produced, along with their time and spatial profile evolution, which depend critically on where the line of shower particles intercept the electric field geometry. We also show a new effect of incoming positrons in the shower, which make up a significant fraction of shower products, in particular their apparent "orbiting" within a high altitude negative induced shielding charge layer, which has been conjectured to produce a signature microwave emission, as well as a short range 511 keV annihilation line. The interesting question posed is if this conjectured positron emission can be observed and correlated with TGF orbital observations to show if a TGF originates in the macro E-fields of storm clouds or the micro E-fields of lightning leaders where this positron "orbiting" is not likely to occur.

  9. McKinley's Questionable Bequest: Over 100 years of English in Philippine Education

    Science.gov (United States)

    Bernardo, Allan B. I.

    2004-01-01

    The English language has enjoyed a privileged status in Philippine formal education since US President McKinley declared it the medium of instruction of the Philippine public educational system in 1900. But the pre-eminence of English has been vigorously called to question since then. This paper traces the changing status of English in Philippine…

  10. ImaSim, a software tool for basic education of medical x-ray imaging in radiotherapy and radiology

    Science.gov (United States)

    Landry, Guillaume; deBlois, François; Verhaegen, Frank

    2013-11-01

    Introduction: X-ray imaging is an important part of medicine and plays a crucial role in radiotherapy. Education in this field is mostly limited to textbook teaching due to equipment restrictions. A novel simulation tool, ImaSim, for teaching the fundamentals of the x-ray imaging process based on ray-tracing is presented in this work. ImaSim is used interactively via a graphical user interface (GUI). Materials and methods: The software package covers the main x-ray based medical modalities: planar kilo voltage (kV), planar (portal) mega voltage (MV), fan beam computed tomography (CT) and cone beam CT (CBCT) imaging. The user can modify the photon source, object to be imaged and imaging setup with three-dimensional editors. Objects are currently obtained by combining blocks with variable shapes. The imaging of three-dimensional voxelized geometries is currently not implemented, but can be added in a later release. The program follows a ray-tracing approach, ignoring photon scatter in its current implementation. Simulations of a phantom CT scan were generated in ImaSim and were compared to measured data in terms of CT number accuracy. Spatial variations in the photon fluence and mean energy from an x-ray tube caused by the heel effect were estimated from ImaSim and Monte Carlo simulations and compared. Results: In this paper we describe ImaSim and provide two examples of its capabilities. CT numbers were found to agree within 36 Hounsfield Units (HU) for bone, which corresponds to a 2% attenuation coefficient difference. ImaSim reproduced the heel effect reasonably well when compared to Monte Carlo simulations. Discussion: An x-ray imaging simulation tool is made available for teaching and research purposes. ImaSim provides a means to facilitate the teaching of medical x-ray imaging.

  11. SHADOW3: a new version of the synchrotron X-ray optics modelling package

    International Nuclear Information System (INIS)

    Sanchez del Rio, Manuel; Canestrari, Niccolo; Jiang, Fan; Cerrina, Franco

    2011-01-01

    SHADOW3, a new version of the X-ray tracing code SHADOW, is introduced. A new version of the popular X-ray tracing code SHADOW is presented. An important step has been made in restructuring the code following new computer engineering standards, ending with a modular Fortran 2003 structure and an application programming interface (API). The new code has been designed to be compatible with the original file-oriented SHADOW philosophy, but simplifying the compilation, installation and use. In addition, users can now become programmers using the newly designed SHADOW3 API for creating scripts, macros and programs; being able to deal with optical system optimization, image simulation, and also low transmission calculations requiring a large number of rays (>10 6 ). Plans for future development and questions on how to accomplish them are also discussed

  12. Relative distribution of cosmic rays and magnetic fields

    Science.gov (United States)

    Seta, Amit; Shukurov, Anvar; Wood, Toby S.; Bushby, Paul J.; Snodin, Andrew P.

    2018-02-01

    Synchrotron radiation from cosmic rays is a key observational probe of the galactic magnetic field. Interpreting synchrotron emission data requires knowledge of the cosmic ray number density, which is often assumed to be in energy equipartition (or otherwise tightly correlated) with the magnetic field energy. However, there is no compelling observational or theoretical reason to expect such a tight correlation to hold across all scales. We use test particle simulations, tracing the propagation of charged particles (protons) through a random magnetic field, to study the cosmic ray distribution at scales comparable to the correlation scale of the turbulent flow in the interstellar medium (≃100 pc in spiral galaxies). In these simulations, we find that there is no spatial correlation between the cosmic ray number density and the magnetic field energy density. In fact, their distributions are approximately statistically independent. We find that low-energy cosmic rays can become trapped between magnetic mirrors, whose location depends more on the structure of the field lines than on the field strength.

  13. High performance ultrasonic field simulation on complex geometries

    Science.gov (United States)

    Chouh, H.; Rougeron, G.; Chatillon, S.; Iehl, J. C.; Farrugia, J. P.; Ostromoukhov, V.

    2016-02-01

    Ultrasonic field simulation is a key ingredient for the design of new testing methods as well as a crucial step for NDT inspection simulation. As presented in a previous paper [1], CEA-LIST has worked on the acceleration of these simulations focusing on simple geometries (planar interfaces, isotropic materials). In this context, significant accelerations were achieved on multicore processors and GPUs (Graphics Processing Units), bringing the execution time of realistic computations in the 0.1 s range. In this paper, we present recent works that aim at similar performances on a wider range of configurations. We adapted the physical model used by the CIVA platform to design and implement a new algorithm providing a fast ultrasonic field simulation that yields nearly interactive results for complex cases. The improvements over the CIVA pencil-tracing method include adaptive strategies for pencil subdivisions to achieve a good refinement of the sensor geometry while keeping a reasonable number of ray-tracing operations. Also, interpolation of the times of flight was used to avoid time consuming computations in the impulse response reconstruction stage. To achieve the best performance, our algorithm runs on multi-core superscalar CPUs and uses high performance specialized libraries such as Intel Embree for ray-tracing, Intel MKL for signal processing and Intel TBB for parallelization. We validated the simulation results by comparing them to the ones produced by CIVA on identical test configurations including mono-element and multiple-element transducers, homogeneous, meshed 3D CAD specimens, isotropic and anisotropic materials and wave paths that can involve several interactions with interfaces. We show performance results on complete simulations that achieve computation times in the 1s range.

  14. Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 2.

    Science.gov (United States)

    Thompson, S A; Dummer, P M

    1997-07-01

    The aim of this laboratory-based study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. A total of 40 canals with four different shapes in terms of angle and position of curve were prepared with NT Engine and McXim instruments, using the technique recommended by the manufacturer. Part 2 of this report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall postoperative shape. Pre- and postoperative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and postoperative views were superimposed to highlight the amount and position of material removed during preparation. No zips, elbows, perforations or danger zones were created during preparation. Forty-two per cent of canals had ledges on the outer aspect of the curve, the majority of which (16 out of 17) occurred in canals with short acute curves. There were significant differences (P Engine and McXim rotary nickel-titanium instruments created no aberrations other than ledges and produced only minimal transportation. The overall shape of canals was good.

  15. Validation of the intrinsic spatial efficiency method for non cylindrical homogeneous sources using MC simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Ramírez, Pablo, E-mail: rapeitor@ug.uchile.cl; Ruiz, Andrés [Departamento de Física, Facultad de Ciencias, Universidad de Chile (Chile)

    2016-07-07

    The Monte Carlo simulation of the gamma spectroscopy systems is a common practice in these days. The most popular softwares to do this are MCNP and Geant4 codes. The intrinsic spatial efficiency method is a general and absolute method to determine the absolute efficiency of a spectroscopy system for any extended sources, but this was only demonstrated experimentally for cylindrical sources. Due to the difficulty that the preparation of sources with any shape represents, the simplest way to do this is by the simulation of the spectroscopy system and the source. In this work we present the validation of the intrinsic spatial efficiency method for sources with different geometries and for photons with an energy of 661.65 keV. In the simulation the matrix effects (the auto-attenuation effect) are not considered, therefore these results are only preliminaries. The MC simulation is carried out using the FLUKA code and the absolute efficiency of the detector is determined using two methods: the statistical count of Full Energy Peak (FEP) area (traditional method) and the intrinsic spatial efficiency method. The obtained results show total agreement between the absolute efficiencies determined by the traditional method and the intrinsic spatial efficiency method. The relative bias is lesser than 1% in all cases.

  16. TRACING THE LOWEST PROPELLER LINE IN MAGELLANIC HIGH-MASS X-RAY BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, Dimitris M.; Laycock, Silas G. T.; Yang, Jun; Fingerman, Samuel, E-mail: dimitris_christodoulou@uml.edu, E-mail: silas_laycock@uml.edu, E-mail: jun_yang@uml.edu, E-mail: fingerman.samuel@gmail.com [Lowell Center for Space Science and Technology, 600 Suffolk Street, Lowell, MA 01854 (United States)

    2016-09-20

    We have combined the published observations of high-mass X-ray binary (HMXB) pulsars in the Magellanic Clouds with a new processing of the complete archival data sets from the XMM-Newton and Chandra observatories in an attempt to trace the lowest propeller line below which accretion to polar caps is inhibited by the centrifugal force and the pulsations from the most weakly magnetized pulsars cease. Previously published data reveal that some of the faster-spinning pulsars with spin periods of P {sub S} < 12 s, detected at relatively low X-ray luminosities L {sub X} , appear to define such a line in the P {sub S} – L {sub X} diagram, characterized by a magnetic moment of μ = 3 × 10{sup 29} G cm{sup 3}. This value implies the presence of surface magnetic fields of B ≥ 3 × 10{sup 11} G in the compact objects of this class. Only a few quiescent HMXBs are found below the propeller line: LXP4.40 and SXP4.78, for which XMM-Newton and Chandra null detections respectively placed firm upper limits on their X-ray fluxes in deep quiescence; and A0538-66, for which many sub-Eddington detections have never measured any pulsations. On the other hand, the data from the XMM-Newton and Chandra archives show clearly that, during routine observation cycles, several sources have been detected below the propeller line in extremely faint, nonpulsating states that can be understood as the result of weak magnetospheric emission when accretion to the poles is centrifugally stalled or severely diminished. We also pay attention to the anomalous X-ray pulsar CXOU J010043.1-721134 that was reported in HMXB surveys. Its pulsations and locations near and above the propeller line indicate that this pulsar could be accreting from a fossil disk.

  17. Validation of Shielding Analysis Capability of SuperMC with SINBAD

    Directory of Open Access Journals (Sweden)

    Chen Chaobin

    2017-01-01

    Full Text Available Abstract: The shielding analysis capability of SuperMC was validated with the Shielding Integral Benchmark Archive Database (SINBAD. The SINBAD was compiled by RSICC and NEA, it includes numerous benchmark experiments performed with the D-T fusion neutron source facilities of OKTAVIAN, FNS, IPPE, etc. The results from SuperMC simulation were compared with experimental data and MCNP results. Very good agreement with deviation lower than 1% was achieved and it suggests that SuperMC is reliable in shielding calculation.

  18. Sampling Enrichment toward Target Structures Using Hybrid Molecular Dynamics-Monte Carlo Simulations.

    Directory of Open Access Journals (Sweden)

    Kecheng Yang

    Full Text Available Sampling enrichment toward a target state, an analogue of the improvement of sampling efficiency (SE, is critical in both the refinement of protein structures and the generation of near-native structure ensembles for the exploration of structure-function relationships. We developed a hybrid molecular dynamics (MD-Monte Carlo (MC approach to enrich the sampling toward the target structures. In this approach, the higher SE is achieved by perturbing the conventional MD simulations with a MC structure-acceptance judgment, which is based on the coincidence degree of small angle x-ray scattering (SAXS intensity profiles between the simulation structures and the target structure. We found that the hybrid simulations could significantly improve SE by making the top-ranked models much closer to the target structures both in the secondary and tertiary structures. Specifically, for the 20 mono-residue peptides, when the initial structures had the root-mean-squared deviation (RMSD from the target structure smaller than 7 Å, the hybrid MD-MC simulations afforded, on average, 0.83 Å and 1.73 Å in RMSD closer to the target than the parallel MD simulations at 310K and 370K, respectively. Meanwhile, the average SE values are also increased by 13.2% and 15.7%. The enrichment of sampling becomes more significant when the target states are gradually detectable in the MD-MC simulations in comparison with the parallel MD simulations, and provide >200% improvement in SE. We also performed a test of the hybrid MD-MC approach in the real protein system, the results showed that the SE for 3 out of 5 real proteins are improved. Overall, this work presents an efficient way of utilizing solution SAXS to improve protein structure prediction and refinement, as well as the generation of near native structures for function annotation.

  19. gamma-Hadron family description by quasi-scaling model at normal nuclear composition of primary cosmic rays

    CERN Document Server

    Kalmakhelidze, M; Svanidze, M

    2002-01-01

    Primary Cosmic Rays Nuclear Composition was investigated in energy region 10 sup 1 sup 5 -10 sup 1 sup 6 eV. The study is based on comparison of gamma hadron families observed by Pamir and Pamir-Chacaltaya collaborations with those generated by means of quasi-scaling model MC0 at different nuclear compositions. It was shown that all characteristics of the observed families (including their intensity) are in very good agreement with properties of simulated events MC0 at normal composition and are in disagreement at heavy dominant compositions

  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. McNamara vs. the JCS Vietnam's Operation ROLLING THUNDER: A Failure in Civil-Military Relations

    National Research Council Canada - National Science Library

    Rhynedance, George

    2000-01-01

    .... The paper focuses primarily on the period between 1964 and 1968. It traces McNamara's journey from president at Ford Motor Company to Secretary of Defense, as well as how Wheeler came to be the Chairman of the Joint Chiefs of Staff...

  2. 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.

  3. X-ray scattering in X-ray fluorescence spectra with X-ray tube excitation - Modelling, experiment, and Monte-Carlo simulation

    International Nuclear Information System (INIS)

    Hodoroaba, V.-D.; Radtke, M.; Vincze, L.; Rackwitz, V.; Reuter, D.

    2010-01-01

    X-ray scattering may contribute significantly to the spectral background of X-ray fluorescence (XRF) spectra. Based on metrological measurements carried out with a scanning electron microscope (SEM) having attached a well characterised X-ray source (polychromatic X-ray tube) and a calibrated energy dispersive X-ray spectrometer (EDS) the accuracy of a physical model for X-ray scattering is systematically evaluated for representative samples. The knowledge of the X-ray spectrometer efficiency, but also of the spectrometer response functions makes it possible to define a physical spectral background of XRF spectra. Background subtraction relying on purely mathematical procedures is state-of-the-art. The results produced by the analytical model are at least as reliable as those obtained by Monte-Carlo simulations, even without considering the very challenging contribution of multiple scattering. Special attention has been paid to Compton broadening. Relevant applications of the implementation of the analytical model presented in this paper are the prediction of the limits of detection for particular cases or the determination of the transmission of X-ray polycapillary lenses.

  4. Multilayer on-chip stacked Fresnel zone plates: Hard x-ray fabrication and soft x-ray simulations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kenan; Wojcik, Michael J.; Ocola, Leonidas E.; Divan, Ralu; Jacobsen, Chris

    2015-11-01

    Fresnel zone plates are widely used as x-ray nanofocusing optics. To achieve high spatial resolution combined with good focusing efficiency, high aspect ratio nanolithography is required, and one way to achieve that is through multiple e-beam lithography writing steps to achieve on-chip stacking. A two-step writing process producing 50 nm finest zone width at a zone thickness of 1.14 µm for possible hard x-ray applications is shown here. The authors also consider in simulations the case of soft x-ray focusing where the zone thickness might exceed the depth of focus. In this case, the authors compare on-chip stacking with, and without, adjustment of zone positions and show that the offset zones lead to improved focusing efficiency. The simulations were carried out using a multislice propagation method employing Hankel transforms.

  5. Simulation of delayed γ-ray emission following photofission reactions induced by pulsed bremsstrahlung x-rays using MCNPX and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Xianfei, E-mail: wenxianfei@ufl.edu [Nuclear Engineering Program, University of Florida, Gainesville, FL 32611 (United States); School of Nuclear Science and Engineering, Oregon State University, Corvallis, OR 97331 (United States); Yang, Haori, E-mail: haori.yang@oregonstate.edu [School of Nuclear Science and Engineering, Oregon State University, Corvallis, OR 97331 (United States)

    2016-12-21

    There is a great demand to develop non-destructive techniques to identify and quantify Special Nuclear Materials (SNM) in homeland security and nuclear safeguards applications. Passive assay could be extremely challenging in some scenarios. Active interrogation technique based on photofission has been identified as one of the promising approaches. In radiation detection system design based on such technique, it is highly desired to have abilities to accurately and efficiently simulate delayed γ-rays emitted from photofission reactions. In this work, simulation results were compared with measurement outcomes to demonstrate the capabilities and limitations of the code MCNPX 2.7.0 in the simulation of delayed γ-rays from photofission of uranium and plutonium samples. First, high-energy delayed γ-rays (E{sub γ}~2.7–4.5 MeV) from photofission of {sup 238}U were simulated and validated against the energy spectra measured in between linac pulses. Second, low-energy delayed γ-ray spectra (E{sub γ}~0.6–2.7 MeV) measured with a list-mode system after irradiation of {sup 239}Pu were used in the validation.

  6. Designing new guides and instruments using McStas

    CERN Document Server

    Farhi, E; Wildes, A R; Ghosh, R; Lefmann, K

    2002-01-01

    With the increasing complexity of modern neutron-scattering instruments, the need for powerful tools to optimize their geometry and physical performances (flux, resolution, divergence, etc.) has become essential. As the usual analytical methods reach their limit of validity in the description of fine effects, the use of Monte Carlo simulations, which can handle these latter, has become widespread. The McStas program was developed at Riso National Laboratory in order to provide neutron scattering instrument scientists with an efficient and flexible tool for building Monte Carlo simulations of guides, neutron optics and instruments. To date, the McStas package has been extensively used at the Institut Laue-Langevin, Grenoble, France, for various studies including cold and thermal guides with ballistic geometry, diffractometers, triple-axis, backscattering and time-of-flight spectrometers. In this paper, we present some simulation results concerning different guide geometries that may be used in the future at th...

  7. The Advanced Gamma-ray Imaging System (AGIS): Simulation Studies

    Science.gov (United States)

    Fegan, Stephen; Buckley, J. H.; Bugaev, S.; Funk, S.; Konopelko, A.; Maier, G.; Vassiliev, V. V.; Simulation Studies Working Group; AGIS Collaboration

    2008-03-01

    The Advanced Gamma-ray Imaging System (AGIS) is a concept for the next generation instrument in ground-based very high energy gamma-ray astronomy. It has the goal of achieving significant improvement in sensitivity over current experiments. We present the results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance, collecting area, angular resolution, background rejection, and sensitivity are discussed.

  8. Simulation of X-ray irradiation on human hand

    International Nuclear Information System (INIS)

    Amaya, Fabiola; Montoya, Modesto

    2001-01-01

    Using the Monte Carlo code MCNP we simulate a human hand X-rays irradiation with radiodiagnostic energies to find the better range energy to make radiographs with the lowest dose and an optimal contrast. We calculate bone doses by considering a soft tissue - water - and calcium bone hand, which is irradiated with a million of X-rays photons from a punctual source. These photons are directed inside a conic angle on the hand. Afterwards, we simulate elements which normally compose bones (C, H, O, N, Mg, P, Ca, and S). We estimate bone dose considering: a) bone material (water, calcium and bone tissue); b) bone thickness (0.01; 0.1; 0.5; 1.0; 1.5 and 3.0 cm); and c) source-hand distance (30, 50, 70 and 90 cm). We calculate photon transmission percent through soft tissue and bone tissue and the statistics from the number of photons that reach the radiographic film after passing through soft tissue or bone tissue for our geometric configuration. We found that we can obtain a good image contrast by using X-rays with energies in the range of 20 to 40 keV. (author)

  9. MC-DS-CDMA System based on DWT and STBC in ITU Multipath Fading Channels Model

    Directory of Open Access Journals (Sweden)

    Nader Abdullah Khadam

    2018-03-01

    Full Text Available In this paper, the performance of multicarrier direct sequence code division multiple access (MC-DS-CDMA in fixed MC-DS-CDMA and Mobile MC-DS-CDMA applications have been improved by using the compensations of space time block coding and Discrete Fast Fourier transforms (FFT or Discrete Wavelets transform DWT. These MC-DS-CDMA systems had been simulated using MATLAB 2015a. Through simulation of the proposed system, various parameters can be changed and tested. The Bit Error Rate (BERs of these systems are obtained over wide range of signal to noise ratio. All simulation results had been compared with each other using different subcarrier size of FFT or DWT with STBC for 1,2,3 and 4 antennas in transmitter and under different ITU multipath fading channels and different Doppler frequencies (fd. The proposed structures of STBC-MC-DS-CDMA system based on (DWT batter than based on (FFT in varies Doppler frequencies and subcarrier size. Also, proposed system with STBC based on 4 transmitters better than other systems based on 1 or 2 or 3 transmitters in all Doppler frequencies and subcarrier size in all simulation results.

  10. Monte Carlo simulation of the scattered component of neutron capture prompt gamma-ray analyzer responses

    International Nuclear Information System (INIS)

    Jin, Y.; Verghese, K.; Gardner, R.P.

    1986-01-01

    This paper describes a major part of our efforts to simulate the entire spectral response of the neutron capture prompt gamma-ray analyzer for bulk media (or conveyor belt) samples by the Monte Carlo method. This would allow one to use such a model to augment or, in most cases, essentially replace experiments in the calibration and optimum design of these analyzers. In previous work, we simulated the unscattered gamma-ray intensities, but would like to simulate the entire spectral response as we did with the energy-dispersive x-ray fluorescence analyzers. To accomplish this, one must account for the scattered gamma rays as well as the unscattered and one must have available the detector response function to translate the incident gamma-ray spectrum calculated by the Monte Carlo simulation into the detected pulse-height spectrum. We recently completed our work on the germanium detector response function, and the present paper describes our efforts to simulate the entire spectral response by using it with Monte Carlo predicted unscattered and scattered gamma rays

  11. Simulations of multi-contrast x-ray imaging using near-field speckles

    Energy Technology Data Exchange (ETDEWEB)

    Zdora, Marie-Christine [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom and Department of Physics & Astronomy, University College London, London, WC1E 6BT (United Kingdom); Thibault, Pierre [Department of Physics & Astronomy, University College London, London, WC1E 6BT (United Kingdom); Herzen, Julia; Pfeiffer, Franz [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Zanette, Irene [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany)

    2016-01-28

    X-ray dark-field and phase-contrast imaging using near-field speckles is a novel technique that overcomes limitations inherent in conventional absorption x-ray imaging, i.e. poor contrast for features with similar density. Speckle-based imaging yields a wealth of information with a simple setup tolerant to polychromatic and divergent beams, and simple data acquisition and analysis procedures. Here, we present a simulation software used to model the image formation with the speckle-based technique, and we compare simulated results on a phantom sample with experimental synchrotron data. Thorough simulation of a speckle-based imaging experiment will help for better understanding and optimising the technique itself.

  12. Dosimetric comparison between CT and X-ray simulation of radiotherapy for lung cancer

    International Nuclear Information System (INIS)

    Kali Ayguli, Zhang Jinrong; Wang Juwu; Ge Feng; Wang Haifeng; Xu Suling

    2007-01-01

    Objective: To compare radiotherapy plan of conventional X-ray simulation with CT simulation by 3D-TPS for lung cancer. Methods: Thirty-three patients were allotted to receive both conventional X-ray simulation and CT simulation in the same treatment position. 3D-TPS was used to design 4-field conventional plan of X-ray simulation (RT), 4-field two dimensional plan(2D)and three dimensional conformal radiation plan(3DCRT) of CT simulation for all patients. The total dose was 50 Gy. Dose volume histogram(DVH) was applied to evaluate the difference of target coverage, dose distribution and normal tissue protection among the three plans. Results: 3DCRT and 2D based on CT simulation were superior to RT in the target coverage, target conformity index (TCI) and target homogeneity (TH) (P 20 , V 30 and mean lung dose were similar among 3DCRT, 2D and RT plans. Moreover, the maximum doses of spinal cord were significantly different among the three plans. No statistical differences of doses to 30% of the heart and esophagus volume among the three plans were observed. Conclusions: There is significantly better tumour volume coverage in CT simulation when compared with X-ray conventional simulation. Target volume delineation by CT simulation is improved significantly. The dose distribution is improved by using three dimensional treatment planning system. 3DCRT plan is superior to 2D plans in target conformity index and target homogeneity. Doses delivered to organs surrounding the target such as lung and heart were reduced significantly in 3DCRT. (authors)

  13. Experiment vs simulation RT WFNDEC 2014 benchmark: CIVA results

    International Nuclear Information System (INIS)

    Tisseur, D.; Costin, M.; Rattoni, B.; Vienne, C.; Vabre, A.; Cattiaux, G.; Sollier, T.

    2015-01-01

    The French Atomic Energy Commission and Alternative Energies (CEA) has developed for years the CIVA software dedicated to simulation of NDE techniques such as Radiographic Testing (RT). RT modelling is achieved in CIVA using combination of a determinist approach based on ray tracing for transmission beam simulation and a Monte Carlo model for the scattered beam computation. Furthermore, CIVA includes various detectors models, in particular common x-ray films and a photostimulable phosphor plates. This communication presents the results obtained with the configurations proposed in the World Federation of NDEC 2014 RT modelling benchmark with the RT models implemented in the CIVA software

  14. Experiment vs simulation RT WFNDEC 2014 benchmark: CIVA results

    Energy Technology Data Exchange (ETDEWEB)

    Tisseur, D., E-mail: david.tisseur@cea.fr; Costin, M., E-mail: david.tisseur@cea.fr; Rattoni, B., E-mail: david.tisseur@cea.fr; Vienne, C., E-mail: david.tisseur@cea.fr; Vabre, A., E-mail: david.tisseur@cea.fr; Cattiaux, G., E-mail: david.tisseur@cea.fr [CEA LIST, CEA Saclay 91191 Gif sur Yvette Cedex (France); Sollier, T. [Institut de Radioprotection et de Sûreté Nucléaire, B.P.17 92262 Fontenay-Aux-Roses (France)

    2015-03-31

    The French Atomic Energy Commission and Alternative Energies (CEA) has developed for years the CIVA software dedicated to simulation of NDE techniques such as Radiographic Testing (RT). RT modelling is achieved in CIVA using combination of a determinist approach based on ray tracing for transmission beam simulation and a Monte Carlo model for the scattered beam computation. Furthermore, CIVA includes various detectors models, in particular common x-ray films and a photostimulable phosphor plates. This communication presents the results obtained with the configurations proposed in the World Federation of NDEC 2014 RT modelling benchmark with the RT models implemented in the CIVA software.

  15. Hydrodynamic Simulation of the Cosmological X-Ray Background

    Science.gov (United States)

    Croft, Rupert A. C.; Di Matteo, Tiziana; Davé, Romeel; Hernquist, Lars; Katz, Neal; Fardal, Mark A.; Weinberg, David H.

    2001-08-01

    We use a hydrodynamic simulation of an inflationary cold dark matter model with a cosmological constant to predict properties of the extragalactic X-ray background (XRB). We focus on emission from the intergalactic medium (IGM), with particular attention to diffuse emission from warm-hot gas that lies in relatively smooth filamentary structures between galaxies and galaxy clusters. We also include X-rays from point sources associated with galaxies in the simulation, and we make maps of the angular distribution of the emission. Although much of the X-ray luminous gas has a filamentary structure, the filaments are not evident in the simulated maps because of projection effects. In the soft (0.5-2 keV) band, our calculated mean intensity of radiation from intergalactic and cluster gas is 2.3×10-12 ergs-1 cm-2 deg-2, 35% of the total softband emission. This intensity is compatible at the ~1 σ level with estimates of the unresolved soft background intensity from deep ROSAT and Chandra measurements. Only 4% of the hard (2-10 keV) emission is associated with intergalactic gas. Relative to active galactic nuclei flux, the IGM component of the XRB peaks at a lower redshift (median z~0.45) and spans a narrower redshift range, so its clustering makes an important contribution to the angular correlation function of the total emission. The clustering on the scales accessible to our simulation (0.1‧-10') is significant, with an amplitude roughly consistent with an extrapolation of recent ROSAT results to small scales. A cross-correlation analysis of the XRB against nearby galaxies taken from a simulated redshift survey also yields a strong signal from the IGM. Our conclusions about the soft background intensity differ from those of some recent papers that have argued that the expected emission from gas in galaxy, group, and cluster halos would exceed the observed background unless much of the gas is expelled by supernova feedback. We obtain reasonable compatibility with

  16. A comparison of partially specular radiosity and ray tracing for room acoustics modeling

    Science.gov (United States)

    Beamer, C. Walter; Muehleisen, Ralph T.

    2005-04-01

    Partially specular (PS) radiosity is an extended form of the general radiosity method. Acoustic radiosity is a form of bulk transfer of radiant acoustic energy. This bulk transfer is accomplished through a system of energy balance equations that relate the bulk energy transfer of each surface in the system to all other surfaces in the system. Until now acoustic radiosity has been limited to modeling only diffuse surface reflection. The new PS acoustic radiosity method can model all real surface types, diffuse, specular and everything in between. PS acoustic radiosity also models all real source types and distributions, not just point sources. The results of the PS acoustic radiosity method are compared to those of well known ray tracing programs. [Work supported by NSF.

  17. Simultaneous Determination of 30 Trace Elements in Cancerous and Noncancerous Human Tissue Samples with Gamma-ray Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Samsahl, K; Brune, D; Wester, P O

    1963-10-15

    The following trace elements were quantitatively determined by gamma-ray spectrometry in T samples of non-cancerous and 5 samples of cancerous human tissue: P, Ca, Cr, Fe, Co, Cu, Zn, As, Se, Br, Rb, Mo, Ag, Cd, Sb, Cs, La, Au, and Hg. In some of the samples the following elements were qualitatively determined: Ti+Sc, Ga, Sr, In, Ba, Ce, Hf, Os, Pt, and U. Most of the trace elements were found to be present in much higher concentrations in the non-cancerous than in the corresponding cancerous liver samples. In a typical run one sample each of cancerous and non-cancerous tissue was irradiated together with standards of the elements to be determined in a thermal flux of 2.10{sup 13} n/cm{sup 2}/sec. for 24 hours. The radioactive trace elements were separated into 16, and in some cases 18, groups by means of a chemical group separation method. Subsequently, the gamma spectrometric measurements were performed. Two persons can manage the chemical separations and measure the different activities from a run in 1,5 days. A new method of comparing unknown samples with standards was developed.

  18. Rapid Chemometric X-Ray Fluorescence approaches for spectral Diagnostics of Cancer utilizing Tissue Trace Metals and Speciation profiles

    International Nuclear Information System (INIS)

    Okonda, J.J.

    2015-01-01

    Energy dispersive X-ray fluorescence (EDXRF) spectroscopy is an analytical method for identification and quantification of elements in materials by measurement of their spectral energy and intensity. EDXRFS spectroscopic technique involves simultaneous non-invasive acquisition of both fluorescence and scatter spectra from samples for quantitative determination of trace elemental content in complex matrix materials. The objective is develop a chemometric-aided EDXRFS method for rapid diagnosis of cancer and its severity (staging) based on analysis of trace elements (Cu, Zn, Fe, Se and Mn), their speciation and multivariate alterations of the elements in cancerous body tissue samples as cancer biomarkers. The quest for early diagnosis of cancer is based on the fact that early intervention translates to higher survival rate and better quality of life. Chemometric aided EDXRFS cancer diagnostic model has been evaluated as a direct and rapid superior alternative for the traditional quantitative methods used in XRF such as FP method. PCA results of cultured samples indicate that it is possible to characterize cancer at early and late stage of development based on trace elemental profiles

  19. SHADOW3: a new version of the synchrotron X-ray optics modelling package

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez del Rio, Manuel, E-mail: srio@esrf.eu [European Synchrotron Radiation Facility, 6 Jules Horowitz, 38000 Grenoble (France); Canestrari, Niccolo [CNRS, Grenoble (France); European Synchrotron Radiation Facility, 6 Jules Horowitz, 38000 Grenoble (France); Jiang, Fan; Cerrina, Franco [Boston University, 8 St Mary’s Street, Boston, MA 02215 (United States)

    2011-09-01

    SHADOW3, a new version of the X-ray tracing code SHADOW, is introduced. A new version of the popular X-ray tracing code SHADOW is presented. An important step has been made in restructuring the code following new computer engineering standards, ending with a modular Fortran 2003 structure and an application programming interface (API). The new code has been designed to be compatible with the original file-oriented SHADOW philosophy, but simplifying the compilation, installation and use. In addition, users can now become programmers using the newly designed SHADOW3 API for creating scripts, macros and programs; being able to deal with optical system optimization, image simulation, and also low transmission calculations requiring a large number of rays (>10{sup 6}). Plans for future development and questions on how to accomplish them are also discussed.

  20. Voxel-based Monte Carlo simulation of X-ray imaging and spectroscopy experiments

    International Nuclear Information System (INIS)

    Bottigli, U.; Brunetti, A.; Golosio, B.; Oliva, P.; Stumbo, S.; Vincze, L.; Randaccio, P.; Bleuet, P.; Simionovici, A.; Somogyi, A.

    2004-01-01

    A Monte Carlo code for the simulation of X-ray imaging and spectroscopy experiments in heterogeneous samples is presented. The energy spectrum, polarization and profile of the incident beam can be defined so that X-ray tube systems as well as synchrotron sources can be simulated. The sample is modeled as a 3D regular grid. The chemical composition and density is given at each point of the grid. Photoelectric absorption, fluorescent emission, elastic and inelastic scattering are included in the simulation. The core of the simulation is a fast routine for the calculation of the path lengths of the photon trajectory intersections with the grid voxels. The voxel representation is particularly useful for samples that cannot be well described by a small set of polyhedra. This is the case of most naturally occurring samples. In such cases, voxel-based simulations are much less expensive in terms of computational cost than simulations on a polygonal representation. The efficient scheme used for calculating the path lengths in the voxels and the use of variance reduction techniques make the code suitable for the detailed simulation of complex experiments on generic samples in a relatively short time. Examples of applications to X-ray imaging and spectroscopy experiments are discussed

  1. Voxel-based Monte Carlo simulation of X-ray imaging and spectroscopy experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bottigli, U. [Istituto di Matematica e Fisica dell' Universita di Sassari, via Vienna 2, 07100, Sassari (Italy); Sezione INFN di Cagliari (Italy); Brunetti, A. [Istituto di Matematica e Fisica dell' Universita di Sassari, via Vienna 2, 07100, Sassari (Italy); Golosio, B. [Istituto di Matematica e Fisica dell' Universita di Sassari, via Vienna 2, 07100, Sassari (Italy) and Sezione INFN di Cagliari (Italy)]. E-mail: golosio@uniss.it; Oliva, P. [Istituto di Matematica e Fisica dell' Universita di Sassari, via Vienna 2, 07100, Sassari (Italy); Stumbo, S. [Istituto di Matematica e Fisica dell' Universita di Sassari, via Vienna 2, 07100, Sassari (Italy); Vincze, L. [Department of Chemistry, University of Antwerp (Belgium); Randaccio, P. [Dipartimento di Fisica dell' Universita di Cagliari and Sezione INFN di Cagliari (Italy); Bleuet, P. [European Synchrotron Radiation Facility, Grenoble (France); Simionovici, A. [European Synchrotron Radiation Facility, Grenoble (France); Somogyi, A. [European Synchrotron Radiation Facility, Grenoble (France)

    2004-10-08

    A Monte Carlo code for the simulation of X-ray imaging and spectroscopy experiments in heterogeneous samples is presented. The energy spectrum, polarization and profile of the incident beam can be defined so that X-ray tube systems as well as synchrotron sources can be simulated. The sample is modeled as a 3D regular grid. The chemical composition and density is given at each point of the grid. Photoelectric absorption, fluorescent emission, elastic and inelastic scattering are included in the simulation. The core of the simulation is a fast routine for the calculation of the path lengths of the photon trajectory intersections with the grid voxels. The voxel representation is particularly useful for samples that cannot be well described by a small set of polyhedra. This is the case of most naturally occurring samples. In such cases, voxel-based simulations are much less expensive in terms of computational cost than simulations on a polygonal representation. The efficient scheme used for calculating the path lengths in the voxels and the use of variance reduction techniques make the code suitable for the detailed simulation of complex experiments on generic samples in a relatively short time. Examples of applications to X-ray imaging and spectroscopy experiments are discussed.

  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. Cosmic-ray neutron simulations and measurements in Taiwan

    International Nuclear Information System (INIS)

    Chen, Wei-Lin; Jiang, Shiang-Huei; Sheu, Rong-Jiun

    2014-01-01

    This study used simulations of galactic cosmic ray in the atmosphere to investigate the neutron background environment in Taiwan, emphasising its altitude dependence and spectrum variation near interfaces. The calculated results were analysed and compared with two measurements. The first measurement was a mobile neutron survey from sea level up to 3275 m in altitude conducted using a car-mounted high-sensitivity neutron detector. The second was a previous measured result focusing on the changes in neutron spectra near air/ground and air/water interfaces. The attenuation length of cosmic-ray neutrons in the lower atmosphere was estimated to be 163 g cm -2 in Taiwan. Cosmic-ray neutron spectra vary with altitude and especially near interfaces. The determined spectra near the air/ground and air/water interfaces agree well with measurements for neutrons below 10 MeV. However, the high-energy portion of spectra was observed to be much higher than our previous estimation. Because high-energy neutrons contribute substantially to a dose evaluation, revising the annual sea-level effective dose from cosmic-ray neutrons at ground level in Taiwan to 35 μSv, which corresponds to a neutron flux of 5.30 x 10 -3 n cm -2 s -1 , was suggested. The cosmic-ray neutron background in Taiwan was studied using the FLUKA simulations and field measurements. A new measurement was performed using a car-mounted high-efficiency neutron detector, re-coding real-time neutron counting rates from sea level up to 3275 m. The attenuation of cosmic-ray neutrons in the lower atmosphere exhibited an effective attenuation length of 163 g cm -2 . The calculated neutron counting rates over predicted the measurements by ∼32 %, which leaded to a correction factor for the FLUKA-calculated cosmic-ray neutrons in the lower atmosphere in Taiwan. In addition, a previous measurement regarding neutron spectrum variation near the air/ground and air/water interfaces was re-evaluated. The results showed that the

  4. Experience in Collaboration: McDenver at McDonald's.

    Science.gov (United States)

    Combs, Clarice Sue

    2002-01-01

    The McDenver at McDonald's project provided a nontraditional, community-based teaching and learning environment for faculty and students in a health, physical education, and recreation (HPER) department and a school of nursing. Children and parents come to McDonald's, children received developmental screenings, and parents completed conferences…

  5. Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress

    Science.gov (United States)

    Faucher, Giulia; Hoffmann, Linn; Bach, Lennart T.; Bottini, Cinzia; Erba, Elisabetta; Riebesell, Ulf

    2017-07-01

    The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO2, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccoliths of G. oceanica showed a decrease in size only at the highest trace metal concentrations. P. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (P. carterae), intermediate- (E. huxleyi and G. oceanica) and least-tolerant (C. pelagicus) taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.

  6. Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress

    Directory of Open Access Journals (Sweden)

    G. Faucher

    2017-07-01

    Full Text Available The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO2, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccoliths of G. oceanica showed a decrease in size only at the highest trace metal concentrations. P. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (P. carterae, intermediate- (E. huxleyi and G. oceanica and least-tolerant (C. pelagicus taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.

  7. Verification of SuperMC with ITER C-Lite neutronic model

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shu [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui, 230027 (China); Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Yu, Shengpeng [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); He, Peng, E-mail: peng.he@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

    2016-12-15

    Highlights: • Verification of the SuperMC Monte Carlo transport code with ITER C-Lite model. • The modeling of the ITER C-Lite model using the latest SuperMC/MCAM. • All the calculated quantities are consistent with MCNP well. • Efficient variance reduction methods are adopted to accelerate the calculation. - Abstract: In pursit of accurate and high fidelity simulation, the reference model of ITER is becoming more and more detailed and complicated. Due to the complexity in geometry and the thick shielding of the reference model, the accurate modeling and precise simulaion of fusion neutronics are very challenging. Facing these difficulties, SuperMC, the Monte Carlo simulation software system developed by the FDS Team, has optimized its CAD interface for the automatic converting of more complicated models and increased its calculation efficiency with advanced variance reduction methods To demonstrate its capabilites of automatic modeling, neutron/photon coupled simulation and visual analysis for the ITER facility, numerical benchmarks using the ITER C-Lite neutronic model were performed. The nuclear heating in divertor and inboard toroidal field (TF) coils and a global neutron flux map were evaluated. All the calculated nuclear heating is compared with the results of the MCNP code and good consistencies between the two codes is shown. Using the global variance reduction methods in SuperMC, the average speed-up is 292 times for the calculation of inboard TF coils nuclear heating, and 91 times for the calculation of global flux map, compared with the analog run. These tests have shown that SuperMC is suitable for the design and analysis of ITER facility.

  8. Simulation of a main steam line break with steam generator tube rupture using trace

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, S.; Querol, A.; Verdu, G. [Departamento de Ingenieria Quimica Y Nuclear, Universitat Politecnica de Valencia, Camino de Vera s/n, 46022, Valencia (Spain)

    2012-07-01

    A simulation of the OECD/NEA ROSA-2 Project Test 5 was made with the thermal-hydraulic code TRACE5. Test 5 performed in the Large Scale Test Facility (LSTF) reproduced a Main Steam Line Break (MSLB) with a Steam Generator Tube Rupture (SGTR) in a Pressurized Water Reactor (PWR). The result of these simultaneous breaks is a depressurization in the secondary and primary system in loop B because both systems are connected through the SGTR. Good approximation was obtained between TRACE5 results and experimental data. TRACE5 reproduces qualitatively the phenomena that occur in this transient: primary pressure falls after the break, stagnation of the pressure after the opening of the relief valve of the intact steam generator, the pressure falls after the two openings of the PORV and the recovery of the liquid level in the pressurizer after each closure of the PORV. Furthermore, a sensitivity analysis has been performed to know the effect of varying the High Pressure Injection (HPI) flow rate in both loops on the system pressures evolution. (authors)

  9. Dosimetric evaluation of a commercial proton spot scanning Monte-Carlo dose algorithm: comparisons against measurements and simulations

    Science.gov (United States)

    Saini, Jatinder; Maes, Dominic; Egan, Alexander; Bowen, Stephen R.; St. James, Sara; Janson, Martin; Wong, Tony; Bloch, Charles

    2017-10-01

    RaySearch Americas Inc. (NY) has introduced a commercial Monte Carlo dose algorithm (RS-MC) for routine clinical use in proton spot scanning. In this report, we provide a validation of this algorithm against phantom measurements and simulations in the GATE software package. We also compared the performance of the RayStation analytical algorithm (RS-PBA) against the RS-MC algorithm. A beam model (G-MC) for a spot scanning gantry at our proton center was implemented in the GATE software package. The model was validated against measurements in a water phantom and was used for benchmarking the RS-MC. Validation of the RS-MC was performed in a water phantom by measuring depth doses and profiles for three spread-out Bragg peak (SOBP) beams with normal incidence, an SOBP with oblique incidence, and an SOBP with a range shifter and large air gap. The RS-MC was also validated against measurements and simulations in heterogeneous phantoms created by placing lung or bone slabs in a water phantom. Lateral dose profiles near the distal end of the beam were measured with a microDiamond detector and compared to the G-MC simulations, RS-MC and RS-PBA. Finally, the RS-MC and RS-PBA were validated against measured dose distributions in an Alderson-Rando (AR) phantom. Measurements were made using Gafchromic film in the AR phantom and compared to doses using the RS-PBA and RS-MC algorithms. For SOBP depth doses in a water phantom, all three algorithms matched the measurements to within  ±3% at all points and a range within 1 mm. The RS-PBA algorithm showed up to a 10% difference in dose at the entrance for the beam with a range shifter and  >30 cm air gap, while the RS-MC and G-MC were always within 3% of the measurement. For an oblique beam incident at 45°, the RS-PBA algorithm showed up to 6% local dose differences and broadening of distal fall-off by 5 mm. Both the RS-MC and G-MC accurately predicted the depth dose to within  ±3% and distal fall-off to within 2

  10. Dosimetric evaluation of a commercial proton spot scanning Monte-Carlo dose algorithm: comparisons against measurements and simulations.

    Science.gov (United States)

    Saini, Jatinder; Maes, Dominic; Egan, Alexander; Bowen, Stephen R; St James, Sara; Janson, Martin; Wong, Tony; Bloch, Charles

    2017-09-12

    RaySearch Americas Inc. (NY) has introduced a commercial Monte Carlo dose algorithm (RS-MC) for routine clinical use in proton spot scanning. In this report, we provide a validation of this algorithm against phantom measurements and simulations in the GATE software package. We also compared the performance of the RayStation analytical algorithm (RS-PBA) against the RS-MC algorithm. A beam model (G-MC) for a spot scanning gantry at our proton center was implemented in the GATE software package. The model was validated against measurements in a water phantom and was used for benchmarking the RS-MC. Validation of the RS-MC was performed in a water phantom by measuring depth doses and profiles for three spread-out Bragg peak (SOBP) beams with normal incidence, an SOBP with oblique incidence, and an SOBP with a range shifter and large air gap. The RS-MC was also validated against measurements and simulations in heterogeneous phantoms created by placing lung or bone slabs in a water phantom. Lateral dose profiles near the distal end of the beam were measured with a microDiamond detector and compared to the G-MC simulations, RS-MC and RS-PBA. Finally, the RS-MC and RS-PBA were validated against measured dose distributions in an Alderson-Rando (AR) phantom. Measurements were made using Gafchromic film in the AR phantom and compared to doses using the RS-PBA and RS-MC algorithms. For SOBP depth doses in a water phantom, all three algorithms matched the measurements to within  ±3% at all points and a range within 1 mm. The RS-PBA algorithm showed up to a 10% difference in dose at the entrance for the beam with a range shifter and  >30 cm air gap, while the RS-MC and G-MC were always within 3% of the measurement. For an oblique beam incident at 45°, the RS-PBA algorithm showed up to 6% local dose differences and broadening of distal fall-off by 5 mm. Both the RS-MC and G-MC accurately predicted the depth dose to within  ±3% and distal fall-off to within 2

  11. On the development of a comprehensive MC simulation model for the Gamma Knife Perfexion radiosurgery unit

    Science.gov (United States)

    Pappas, E. P.; Moutsatsos, A.; Pantelis, E.; Zoros, E.; Georgiou, E.; Torrens, M.; Karaiskos, P.

    2016-02-01

    This work presents a comprehensive Monte Carlo (MC) simulation model for the Gamma Knife Perfexion (PFX) radiosurgery unit. Model-based dosimetry calculations were benchmarked in terms of relative dose profiles (RDPs) and output factors (OFs), against corresponding EBT2 measurements. To reduce the rather prolonged computational time associated with the comprehensive PFX model MC simulations, two approximations were explored and evaluated on the grounds of dosimetric accuracy. The first consists in directional biasing of the 60Co photon emission while the second refers to the implementation of simplified source geometric models. The effect of the dose scoring volume dimensions in OF calculations accuracy was also explored. RDP calculations for the comprehensive PFX model were found to be in agreement with corresponding EBT2 measurements. Output factors of 0.819  ±  0.004 and 0.8941  ±  0.0013 were calculated for the 4 mm and 8 mm collimator, respectively, which agree, within uncertainties, with corresponding EBT2 measurements and published experimental data. Volume averaging was found to affect OF results by more than 0.3% for scoring volume radii greater than 0.5 mm and 1.4 mm for the 4 mm and 8 mm collimators, respectively. Directional biasing of photon emission resulted in a time efficiency gain factor of up to 210 with respect to the isotropic photon emission. Although no considerable effect on relative dose profiles was detected, directional biasing led to OF overestimations which were more pronounced for the 4 mm collimator and increased with decreasing emission cone half-angle, reaching up to 6% for a 5° angle. Implementation of simplified source models revealed that omitting the sources’ stainless steel capsule significantly affects both OF results and relative dose profiles, while the aluminum-based bushing did not exhibit considerable dosimetric effect. In conclusion, the results of this work suggest that any PFX

  12. Quantitative X-ray fluorescence analysis at the ESRF ID18F microprobe

    International Nuclear Information System (INIS)

    Vekemans, B.; Vincze, L.; Somogyi, A.; Drakopoulos, M.; Kempenaers, L.; Simionovici, A.; Adams, F.

    2003-01-01

    The new ID18F end-station at the European synchrotron radiation facility (ESRF) in Grenoble (France) is dedicated to sensitive and accurate quantitative micro-X-ray fluorescence (XRF) analysis at the ppm level with accuracy better than 10% for elements with atomic numbers above 18. For accurate quantitative analysis, given a high level of instrumental stability, major steps are the extraction and conversion of experimental X-ray line intensities into elemental concentrations. For this purpose a two-step quantification approach was adopted. In the first step, the collected XRF spectra are deconvoluted on the basis of a non-linear least-squares fitting algorithm (AXIL). The extracted characteristic line intensities are then used as input for a detailed Monte Carlo (MC) simulation code dedicated to XRF spectroscopy taking into account specific experimental conditions (excitation/detection) as well as sample characteristics (absorption and enhancement effects, sample topology, heterogeneity etc.). The iterative use of the MC code gives a 'no-compromise' solution for the quantification problem

  13. Quantitative X-ray fluorescence analysis at the ESRF ID18F microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Vekemans, B. E-mail: vekemans@uia.ua.ac.be; Vincze, L.; Somogyi, A.; Drakopoulos, M.; Kempenaers, L.; Simionovici, A.; Adams, F

    2003-01-01

    The new ID18F end-station at the European synchrotron radiation facility (ESRF) in Grenoble (France) is dedicated to sensitive and accurate quantitative micro-X-ray fluorescence (XRF) analysis at the ppm level with accuracy better than 10% for elements with atomic numbers above 18. For accurate quantitative analysis, given a high level of instrumental stability, major steps are the extraction and conversion of experimental X-ray line intensities into elemental concentrations. For this purpose a two-step quantification approach was adopted. In the first step, the collected XRF spectra are deconvoluted on the basis of a non-linear least-squares fitting algorithm (AXIL). The extracted characteristic line intensities are then used as input for a detailed Monte Carlo (MC) simulation code dedicated to XRF spectroscopy taking into account specific experimental conditions (excitation/detection) as well as sample characteristics (absorption and enhancement effects, sample topology, heterogeneity etc.). The iterative use of the MC code gives a 'no-compromise' solution for the quantification problem.

  14. The effect of dose enhancement near metal interfaces on synthetic diamond based X-ray dosimeters

    Science.gov (United States)

    Alamoudi, D.; Lohstroh, A.; Albarakaty, H.

    2017-11-01

    This study investigates the effects of dose enhancement on the photocurrent performance at metallic interfaces in synthetic diamond detectors based X-ray dosimeters as a function of bias voltages. Monte Carlo (MC) simulations with the BEAMnrc code were carried out to simulate the dose enhancement factor (DEF) and compared against the equivalent photocurrent ratio from experimental investigations. The MC simulation results show that the sensitive region for the absorbed dose distribution covers a few micrometers distances from the interface. Experimentally, two single crystals (SC) and one polycrystalline (PC) synthetic diamond samples were fabricated into detectors with carbon based electrodes by boron and carbon ion implantation. Subsequently; the samples were each mounted inside a tissue equivalent encapsulation to minimize unintended fluence perturbation. Dose enhancement was generated by placing copper, lead or gold near the active volume of the detectors using 50 kVp and 100 kVp X-rays relevant for medical dosimetry. The results show enhancement in the detectors' photocurrent performance when different metals are butted up to the diamond bulk as expected. The variation in the photocurrent measurement depends on the type of diamond samples, their electrodes' fabrication and the applied bias voltages indicating that the dose enhancement near the detector may modify their electronic performance.

  15. Particle transport simulation for spaceborne, NaI gamma-ray spectrometers

    International Nuclear Information System (INIS)

    Dyer, C.S.; Truscott, P.R.; Sims, A.J.; Comber, C.; Hammond, N.D.A.

    1988-11-01

    Radioactivity induced in detectors by protons and secondary neutrons limits the sensitivity of spaceborne gamma-ray spectrometers. Three dimensional Monte Carlo transport codes have been employed to simulate particle transport of cosmic rays and inner-belt protons in various representations of the Gamma Ray Observatory Spacecraft and the Oriented Scintillation Spectrometer Experiment. Results are used to accurately quantify the contributions to the radioactive background, assess shielding options and examine the effect of detector and space-craft orientation in anisotropic trapped proton fluxes. (author)

  16. DABAM: an open-source database of X-ray mirrors metrology

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez del Rio, Manuel, E-mail: srio@esrf.eu [ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble (France); Bianchi, Davide [AC2T Research GmbH, Viktro-Kaplan-Strasse 2-C, 2700 Wiener Neustadt (Austria); Cocco, Daniele [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Glass, Mark [ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble (France); Idir, Mourad [NSLS II, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Metz, Jim [InSync Inc., 2511C Broadbent Parkway, Albuquerque, NM 87107 (United States); Raimondi, Lorenzo; Rebuffi, Luca [Elettra-Sincrotrone Trieste SCpA, Basovizza (TS) (Italy); Reininger, Ruben; Shi, Xianbo [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Siewert, Frank [BESSY II, Helmholtz Zentrum Berlin, Institute for Nanometre Optics and Technology, Albert-Einstein-Strasse 15, 12489 Berlin (Germany); Spielmann-Jaeggi, Sibylle [Swiss Light Source at Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Takacs, Peter [Instrumentation Division, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Tomasset, Muriel [Synchrotron Soleil (France); Tonnessen, Tom [InSync Inc., 2511C Broadbent Parkway, Albuquerque, NM 87107 (United States); Vivo, Amparo [ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble (France); Yashchuk, Valeriy [Advanced Light Source, Lawrence Berkeley National Laboratory, MS 15-R0317, 1 Cyclotron Road, Berkeley, CA 94720-8199 (United States)

    2016-04-20

    DABAM, an open-source database of X-ray mirrors metrology to be used with ray-tracing and wave-propagation codes for simulating the effect of the surface errors on the performance of a synchrotron radiation beamline. An open-source database containing metrology data for X-ray mirrors is presented. It makes available metrology data (mirror heights and slopes profiles) that can be used with simulation tools for calculating the effects of optical surface errors in the performances of an optical instrument, such as a synchrotron beamline. A typical case is the degradation of the intensity profile at the focal position in a beamline due to mirror surface errors. This database for metrology (DABAM) aims to provide to the users of simulation tools the data of real mirrors. The data included in the database are described in this paper, with details of how the mirror parameters are stored. An accompanying software is provided to allow simple access and processing of these data, calculate the most usual statistical parameters, and also include the option of creating input files for most used simulation codes. Some optics simulations are presented and discussed to illustrate the real use of the profiles from the database.

  17. Linac particle tracing simulations

    International Nuclear Information System (INIS)

    Lysenko, W.P.

    1979-01-01

    A particle tracing code was developed to study space--charge effects in proton or heavy-ion linear accelerators. The purpose is to study space--charge phenomena as directly as possible without the complications of many accelerator details. Thus, the accelerator is represented simply by harmonic oscillator or impulse restoring forces. Variable parameters as well as mismatched phase--space distributions were studied. This study represents the initial search for those features of the accelerator or of the phase--space distribution that lead to emittance growth

  18. Synergism of the method of characteristics and CAD technology for neutron transport calculation

    International Nuclear Information System (INIS)

    Chen, Z.; Wang, D.; He, T.; Wang, G.; Zheng, H.

    2013-01-01

    The method of characteristics (MOC) is a very popular methodology in neutron transport calculation and numerical simulation in recent decades for its unique advantages. One of the key problems determining whether the MOC can be applied in complicated and highly heterogeneous geometry is how to combine an effective geometry processing method with MOC. Most of the existing MOC codes describe the geometry by lines and arcs with extensive input data, such as circles, ellipses, regular polygons and combination of them. Thus they have difficulty in geometry modeling, background meshing and ray tracing for complicated geometry domains. In this study, a new idea making use of a CAD solid modeler MCAM which is a CAD/Image-based Automatic Modeling Program for Neutronics and Radiation Transport developed by FDS Team in China was introduced for geometry modeling and ray tracing of particle transport to remove these geometrical limitations mentioned above. The diamond-difference scheme was applied to MOC to reduce the spatial discretization error of the flat flux approximation in theory. Based on MCAM and MOC, a new MOC code was developed and integrated into SuperMC system, which is a Super Multi-function Computational system for neutronics and radiation simulation. The numerical testing results demonstrated the feasibility and effectiveness of the new idea for geometry treatment in SuperMC. (authors)

  19. Efficient Time-Domain Ray-Tracing Technique for the Analysis of Ultra-Wideband Indoor Environments including Lossy Materials and Multiple Effects

    Directory of Open Access Journals (Sweden)

    F. Saez de Adana

    2009-01-01

    Full Text Available This paper presents an efficient application of the Time-Domain Uniform Theory of Diffraction (TD-UTD for the analysis of Ultra-Wideband (UWB mobile communications for indoor environments. The classical TD-UTD formulation is modified to include the contribution of lossy materials and multiple-ray interactions with the environment. The electromagnetic analysis is combined with a ray-tracing acceleration technique to treat realistic and complex environments. The validity of this method is tested with measurements performed inside the Polytechnic building of the University of Alcala and shows good performance of the model for the analysis of UWB propagation.

  20. MassiveNuS: cosmological massive neutrino simulations

    Science.gov (United States)

    Liu, Jia; Bird, Simeon; Zorrilla Matilla, José Manuel; Hill, J. Colin; Haiman, Zoltán; Madhavacheril, Mathew S.; Petri, Andrea; Spergel, David N.

    2018-03-01

    The non-zero mass of neutrinos suppresses the growth of cosmic structure on small scales. Since the level of suppression depends on the sum of the masses of the three active neutrino species, the evolution of large-scale structure is a promising tool to constrain the total mass of neutrinos and possibly shed light on the mass hierarchy. In this work, we investigate these effects via a large suite of N-body simulations that include massive neutrinos using an analytic linear-response approximation: the Cosmological Massive Neutrino Simulations (MassiveNuS). The simulations include the effects of radiation on the background expansion, as well as the clustering of neutrinos in response to the nonlinear dark matter evolution. We allow three cosmological parameters to vary: the neutrino mass sum Mν in the range of 0–0.6 eV, the total matter density Ωm, and the primordial power spectrum amplitude As. The rms density fluctuation in spheres of 8 comoving Mpc/h (σ8) is a derived parameter as a result. Our data products include N-body snapshots, halo catalogues, merger trees, ray-traced galaxy lensing convergence maps for four source redshift planes between zs=1–2.5, and ray-traced cosmic microwave background lensing convergence maps. We describe the simulation procedures and code validation in this paper. The data are publicly available at http://columbialensing.org.

  1. SimProp: a simulation code for ultra high energy cosmic ray propagation

    International Nuclear Information System (INIS)

    Aloisio, R.; Grillo, A.F.; Boncioli, D.; Petrera, S.; Salamida, F.

    2012-01-01

    A new Monte Carlo simulation code for the propagation of Ultra High Energy Cosmic Rays is presented. The results of this simulation scheme are tested by comparison with results of another Monte Carlo computation as well as with the results obtained by directly solving the kinetic equation for the propagation of Ultra High Energy Cosmic Rays. A short comparison with the latest flux published by the Pierre Auger collaboration is also presented

  2. Simulation of the radiography formation process from CT patient volume

    International Nuclear Information System (INIS)

    Bifulco, P.; Cesarelli, M.; Verso, E.; Roccasalva Firenze, M.; Sansone, M.; Bracale, M.

    1998-01-01

    The aim of this work is to develop an algorithm to simulate the radiographic image formation process using volumetric anatomical data of the patient, obtained from 3D diagnostic CT images. Many applications, including radiographic driven surgery, virtual reality in medicine and radiologist teaching and training, may take advantage of such technique. The designed algorithm has been developed to simulate a generic radiographic equipment, whatever oriented respect to the patient. The simulated radiography is obtained considering a discrete number of X-ray paths departing from the focus, passing through the patient volume and reaching the radiographic plane. To evaluate a generic pixel of the simulated radiography, the cumulative absorption along the corresponding X-ray is computed. To estimate X-ray absorption in a generic point of the patient volume, 3D interpolation of CT data has been adopted. The proposed technique is quite similar to those employed in Ray Tracing. A computer designed test volume has been used to assess the reliability of the radiography simulation algorithm as a measuring tool. From the errors analysis emerges that the accuracy achieved by the radiographic simulation algorithm is largely confined within the sampling step of the CT volume. (authors)

  3. Simulating the x-ray image contrast to setup techniques with desired flaw detectability

    Science.gov (United States)

    Koshti, Ajay M.

    2015-04-01

    The paper provides simulation data of previous work by the author in developing a model for estimating detectability of crack-like flaws in radiography. The methodology is developed to help in implementation of NASA Special x-ray radiography qualification, but is generically applicable to radiography. The paper describes a method for characterizing the detector resolution. Applicability of ASTM E 2737 resolution requirements to the model are also discussed. The paper describes a model for simulating the detector resolution. A computer calculator application, discussed here, also performs predicted contrast and signal-to-noise ratio calculations. Results of various simulation runs in calculating x-ray flaw size parameter and image contrast for varying input parameters such as crack depth, crack width, part thickness, x-ray angle, part-to-detector distance, part-to-source distance, source sizes, and detector sensitivity and resolution are given as 3D surfaces. These results demonstrate effect of the input parameters on the flaw size parameter and the simulated image contrast of the crack. These simulations demonstrate utility of the flaw size parameter model in setting up x-ray techniques that provide desired flaw detectability in radiography. The method is applicable to film radiography, computed radiography, and digital radiography.

  4. F--Ray: A new algorithm for efficient transport of ionizing radiation

    Science.gov (United States)

    Mao, Yi; Zhang, J.; Wandelt, B. D.; Shapiro, P. R.; Iliev, I. T.

    2014-04-01

    We present a new algorithm for the 3D transport of ionizing radiation, called F2-Ray (Fast Fourier Ray-tracing method). The transfer of ionizing radiation with long mean free path in diffuse intergalactic gas poses a special challenge to standard numerical methods which transport the radiation in position space. Standard methods usually trace each individual ray until it is fully absorbed by the intervening gas. If the mean free path is long, the computational cost and memory load are likely to be prohibitive. We have developed an algorithm that overcomes these limitations and is, therefore, significantly more efficient. The method calculates the transfer of radiation collectively, using the Fast Fourier Transform to convert radiation between position and Fourier spaces, so the computational cost will not increase with the number of ionizing sources. The method also automatically combines parallel rays with the same frequency at the same grid cell, thereby minimizing the memory requirement. The method is explicitly photon-conserving, i.e. the depletion of ionizing photons is guaranteed to equal the photoionizations they caused, and explicitly obeys the periodic boundary condition, i.e. the escape of ionizing photons from one side of a simulation volume is guaranteed to be compensated by emitting the same amount of photons into the volume through the opposite side. Together, these features make it possible to numerically simulate the transfer of ionizing photons more efficiently than previous methods. Since ionizing radiation such as the X-ray is responsible for heating the intergalactic gas when first stars and quasars form at high redshifts, our method can be applied to simulate thermal distribution, in addition to cosmic reionization, in three-dimensional inhomogeneous cosmological density field.

  5. The Advanced Gamma-ray Imaging System (AGIS): Simulation Studies

    OpenAIRE

    Maier, G.; Collaboration, for the AGIS

    2009-01-01

    The Advanced Gamma-ray Imaging System (AGIS) is a next-generation ground-based gamma-ray observatory being planned in the U.S. The anticipated sensitivity of AGIS is about one order of magnitude better than the sensitivity of current observatories, allowing it to measure gammaray emmission from a large number of Galactic and extra-galactic sources. We present here results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance - collect...

  6. Gamma ray observatory dynamics simulator in Ada (GRODY)

    International Nuclear Information System (INIS)

    1990-09-01

    This experiment involved the parallel development of dynamics simulators for the Gamma Ray Observatory in both FORTRAN and Ada for the purpose of evaluating the applicability of Ada to the NASA/Goddard Space Flight Center's flight dynamics environment. The experiment successfully demonstrated that Ada is a viable, valuable technology for use in this environment. In addition to building a simulator, the Ada team evaluated training approaches, developed an Ada methodology appropriate to the flight dynamics environment, and established a baseline for evaluating future Ada projects

  7. Analytical computation of prompt gamma ray emission and detection for proton range verification

    International Nuclear Information System (INIS)

    Sterpin, E; Vynckier, S; Janssens, G; Smeets, J; Stappen, François Vander; Prieels, D; Priegnitz, Marlen; Perali, Irene

    2015-01-01

    A prompt gamma (PG) slit camera prototype recently demonstrated that Bragg Peak position in a clinical proton scanned beam could be measured with 1–2 mm accuracy by comparing an expected PG detection profile to a measured one. The computation of the expected PG detection profile in the context of a clinical framework is challenging but must be solved before clinical implementation. Obviously, Monte Carlo methods (MC) can simulate the expected PG profile but at prohibitively long calculation times. We implemented a much faster method that is based on analytical processing of precomputed MC data that would allow practical evaluation of this range monitoring approach in clinical conditions.Reference PG emission profiles were generated with MC simulations (PENH) in targets consisting of either 12 C, 14 N, 16 O, 31 P or 40 Ca, with 10% of 1 H. In a given geometry, the local PG emission can then be derived by adding the contribution of each element, according to the local energy of the proton obtained by continuous slowing down approximation and the local composition. The actual incident spot size is taken into account using an optical model fitted to measurements and by super sampling the spot with several rays (up to 113). PG transport in the patient/camera geometries and the detector response are modelled by convolving the PG production profile with a transfer function. The latter is interpolated from a database of transfer functions fitted to MC data (PENELOPE) generated for a photon source in a cylindrical phantom with various radiuses and a camera placed at various positions.As a benchmark, the analytical model was compared to MC and experiments in homogeneous and heterogeneous phantoms. Comparisons with MC were also performed in a thoracic CT. For all cases, the analytical model reproduced the prediction of the position of the Bragg peak computed with MC within 1 mm for the camera in nominal configuration. When compared to measurements, the shape of the

  8. One-dimensional simulation of stratification and dissolved oxygen in McCook Reservoir, Illinois

    Science.gov (United States)

    Robertson, Dale M.

    2000-01-01

    As part of the Chicagoland Underflow Plan/Tunnel and Reservoir Plan, the U.S. Army Corps of Engineers, Chicago District, plans to build McCook Reservoir.a flood-control reservoir to store combined stormwater and raw sewage (combined sewage). To prevent the combined sewage in the reservoir from becoming anoxic and producing hydrogen sulfide gas, a coarse-bubble aeration system will be designed and installed on the basis of results from CUP 0-D, a zero-dimensional model, and MAC3D, a three-dimensional model. Two inherent assumptions in the application of MAC3D are that density stratification in the simulated water body is minimal or not present and that surface heat transfers are unimportant and, therefore, may be neglected. To test these assumptions, the previously tested, one-dimensional Dynamic Lake Model (DLM) was used to simulate changes in temperature and dissolved oxygen in the reservoir after a 1-in-100-year event. Results from model simulations indicate that the assumptions made in MAC3D application are valid as long as the aeration system, with an air-flow rate of 1.2 cubic meters per second or more, is operated while the combined sewage is stored in the reservoir. Results also indicate that the high biochemical oxygen demand of the combined sewage will quickly consume the dissolved oxygen stored in the reservoir and the dissolved oxygen transferred through the surface of the reservoir; therefore, oxygen must be supplied by either the rising bubbles of the aeration system (a process not incorporated in DLM) or some other technique to prevent anoxia.

  9. Simulation of cosmic ray interaction at Saturne

    International Nuclear Information System (INIS)

    Michel, R.

    1996-01-01

    Accelerator experiments provide the basis for the development of physical models describing the production of cosmogenic nuclides by cosmic ray particles. Here, experiments are presented by which the irradiation of stony and iron meteoroids in space by galactic cosmic ray protons was successfully simulated; two thick spherical targets made of gabbro and of steel with radii of 25 and 10 cm, respectively, were isotropically irradiated with 1.6 GeV protons at LNS. The artificial meteoroids contained large numbers of individual small targets of up to 27 elements in which the depth-dependent production of radioactive and stable nuclides was analyzed by model calculations based on depth-dependent spectra of primary and secondary particles calculated by the HERMES code system and on experimental and theoretical thin-target cross sections. Due to the results of the two simulation experiments at LNS a consistent modelling of cosmogenic nuclide production rates in stony and iron meteorites was achieved for the first time which allows to interpret the observed abundances of cosmogenic nuclides in stony and iron meteorites with respect to their exposure histories and to describe the history of the cosmic radiation itself. (author)

  10. Advances in X-Ray Simulator Technology

    Science.gov (United States)

    1995-07-01

    d’Etudes de Gramat ; I. Vitkovitsky, Logicon RDA INTRODUCTION DNA’s future x-ray simulators are based upon inductive energy storage, a technology which...switch. SYRINX, a proposed design to be built by the Centre d’Etudes de Gramat (CEG) in France would employ a modular approach, possibly with a...called SYRINX, would be built at the Centred’ Etudes de Gramat (CEG). It would employ a modular.long conduction time current source to drive a PRS

  11. Analysis of ionospheric structure influences on residual ionospheric errors in GNSS radio occultation bending angles based on ray tracing simulations

    Science.gov (United States)

    Liu, Congliang; Kirchengast, Gottfried; Sun, Yueqiang; Zhang, Kefei; Norman, Robert; Schwaerz, Marc; Bai, Weihua; Du, Qifei; Li, Ying

    2018-04-01

    The Global Navigation Satellite System (GNSS) radio occultation (RO) technique is widely used to observe the atmosphere for applications such as numerical weather prediction and global climate monitoring. The ionosphere is a major error source to RO at upper stratospheric altitudes, and a linear dual-frequency bending angle correction is commonly used to remove the first-order ionospheric effect. However, the higher-order residual ionospheric error (RIE) can still be significant, so it needs to be further mitigated for high-accuracy applications, especially from 35 km altitude upward, where the RIE is most relevant compared to the decreasing magnitude of the atmospheric bending angle. In a previous study we quantified RIEs using an ensemble of about 700 quasi-realistic end-to-end simulated RO events, finding typical RIEs at the 0.1 to 0.5 µrad noise level, but were left with 26 exceptional events with anomalous RIEs at the 1 to 10 µrad level that remained unexplained. In this study, we focused on investigating the causes of the high RIE of these exceptional events, employing detailed along-ray-path analyses of atmospheric and ionospheric refractivities, impact parameter changes, and bending angles and RIEs under asymmetric and symmetric ionospheric structures. We found that the main causes of the high RIEs are a combination of physics-based effects - where asymmetric ionospheric conditions play the primary role, more than the ionization level driven by solar activity - and technical ray tracer effects due to occasions of imperfect smoothness in ionospheric refractivity model derivatives. We also found that along-ray impact parameter variations of more than 10 to 20 m are possible due to ionospheric asymmetries and, depending on prevailing horizontal refractivity gradients, are positive or negative relative to the initial impact parameter at the GNSS transmitter. Furthermore, mesospheric RIEs are found generally higher than upper-stratospheric ones, likely due to

  12. Testing FlexRay ECUs with a hardware-in-the-loop simulator; Test von FlexRay-Steuergeraeten am Hardware-in-the-Loop Simulator

    Energy Technology Data Exchange (ETDEWEB)

    Stroop, J.; Koehl, S. [dSPACE GmbH, Paderborn (Germany); Peller, M.; Riedesser, P. [BMW AG, Muenchen (Germany)

    2005-07-01

    To master the data communication of complex and safety relevant systems within future vehicles, the BMW Group prepares the application of FlexRay. The accompanying development process plays an important role for the quality, stability and reliability of those systems. Hardware-in-the-loop simulation and test stands are indispensable constituents and they are an integral part of the validation process. The following contribution describes the technology that is used within the BMW Group in more detail, especially in terms of communication networks with FlexRay. (orig.)

  13. Simulation of X-ray signals

    International Nuclear Information System (INIS)

    Weller, A.

    1980-12-01

    A parameterized form of the local emissivity is used for the simulation of soft X-ray signals obtained on the WENDELSTEIN W VII-A stellarator with a 30 diode array. Numerical calculation of the line integrals for the different viewing angles and for a set of rotation angles covering one full signal period provides simulated periodic signals. In addition radial profiles of the line integrated emmission averaged over some time interval or at specific times, the relative amplitude modulation and the relative phase of the oscillations are calculated. These have to be fitted to the corresponding measured signals and profiles in order to get a reliable picture of the local emissivity. The model can take into account two poloidally asymmetric contributions of the type m = 1,2,3 or 4 (m = poloidal mode number). Each asymmetry can be generated in two ways (modulation of intensity and of geometry parameters). Besides an uniform rotation of the asymmetric terms some specific simple time evolution of the signals can be included (non-uniform rotation, growth of oscillations, sawtooth oscillations). The various input parameters are illustrated and the result of a simulation procedure is presented for a particular discharge in W VII-A. (orig.)

  14. Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers

    International Nuclear Information System (INIS)

    Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto; Mitsuda, Kazuhisa; Hoshino, Akio; Ishisaki, Yoshitaka; Yang Zhen; Takano, Takayuki; Maeda, Ryutaro

    2006-01-01

    To develop x-ray mirrors for micropore optics, smooth silicon (111)sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 μm wide (111) sidewalls was fabricated using a 220 μm thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time,x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements

  15. Micropore x-ray optics using anisotropic wet etching of (110) silicon wafers.

    Science.gov (United States)

    Ezoe, Yuichiro; Koshiishi, Masaki; Mita, Makoto; Mitsuda, Kazuhisa; Hoshino, Akio; Ishisaki, Yoshitaka; Yang, Zhen; Takano, Takayuki; Maeda, Ryutaro

    2006-12-10

    To develop x-ray mirrors for micropore optics, smooth silicon (111) sidewalls obtained after anisotropic wet etching of a silicon (110) wafer were studied. A sample device with 19 microm wide (111) sidewalls was fabricated using a 220 microm thick silicon (110) wafer and potassium hydroxide solution. For what we believe to be the first time, x-ray reflection on the (111) sidewalls was detected in the angular response measurement. Compared to ray-tracing simulations, the surface roughness of the sidewalls was estimated to be 3-5 nm, which is consistent with the atomic force microscope and the surface profiler measurements.

  16. EVALUATING CHAMBERLAIN'S, McGREGOR'S, AND McRAE'S ...

    African Journals Online (AJOL)

    2012-08-08

    Aug 8, 2012 ... spine and base of skull radiographs which however have diagnostic challenges due to the complexity of the ... McGregor's and Mc Rae's using CT bone windows ... metastatic lesion were excluded from the study. RESULTS.

  17. Likelihood Estimation of Gamma Ray Bursts Duration Distribution

    OpenAIRE

    Horvath, Istvan

    2005-01-01

    Two classes of Gamma Ray Bursts have been identified so far, characterized by T90 durations shorter and longer than approximately 2 seconds. It was shown that the BATSE 3B data allow a good fit with three Gaussian distributions in log T90. In the same Volume in ApJ. another paper suggested that the third class of GRBs is may exist. Using the full BATSE catalog here we present the maximum likelihood estimation, which gives us 0.5% probability to having only two subclasses. The MC simulation co...

  18. The HepMC C++ Monte Carlo Event Record for High Energy Physics

    CERN Document Server

    Dobbs, M

    2000-01-01

    HepMC is an Object Oriented event record written in C++ for High Energy Physics Monte Carlo Event Generators. Many extensions from HEPEVT, the Fortran HEP standard, are supported: the number of entries is unlimited, spin density matrices can be stored with each vertex, flow patterns (such as colour) can be stored and traced, random number generator states can be stored, and an arbitrary number of event weights can be included. Particles and vertices are stored separately in a graph structure, reflecting the evolution of a physics event. The added information supports the modularisation of event generators. The event record has been kept as simple as possible with minimal internal/external dependencies. Event information is accessed by means of iterators supplied with HepMC.

  19. 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.

  20. Traces of heavy and superheavy cosmic nuclei in olivins of extraterrestial origin

    International Nuclear Information System (INIS)

    Ignatova, R.; Taneva, T.

    1982-01-01

    The paths of traces of WH nuclei from cosmic rays have been measured in olivines from the meteorites Maryalakhti, Eagle Stein, Liposki khutor with radiation ages 175, 45 and 220 million years respectively. 3 cm 3 olivines of these meteorites have been examined and more than 500 traces of nuclei with Z(>=)90 have been found measured including 3 traces 1.5-1.8 times longer than the traces created by the uranium and thorium nuclei. These traces may be left by nuclei with Z(>=)110. The crystals were chosen from localizations situated at 2-7 cm, 8-9 cm and 10-12 cm from the outside atmospheric surface of the meteorite. The abundancy of the Z(>=)50 nuclei in gigantic cosmic rays, averaged for a period of ( =)110 in galactic cosmic rays. It is 1.4 x 10 -9 from that of the iron group nuclei. (authors)

  1. 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

  2. The Advanced Gamma-ray Imaging System (AGIS)-Simulation Studies

    Science.gov (United States)

    Maier, G.; Buckley, J.; Bugaev, V.; Fegan, S.; Funk, S.; Konopelko, A.; Vassiliev, V. V.

    2008-12-01

    The Advanced Gamma-ray Imaging System (AGIS) is a US-led concept for a next-generation instrument in ground-based very-high-energy gamma-ray astronomy. The most important design requirement for AGIS is a sensitivity of about 10 times greater than current observatories like Veritas, H.E.S.S or MAGIC. We present results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance, collecting area, angular resolution, background rejection, and sensitivity are discussed.

  3. Report on intercomparison air-3/1 of the determination of trace elements in simulated air filters

    International Nuclear Information System (INIS)

    Pszonicki, L.; Veglia, A.; Suschny, O.

    1982-06-01

    The report is a sum up of an intercomparison experiment organized by the Analytical Quality Control Service of the IAEA, for simulated air filters (Air-3/1) spiked with 17 trace elements. The purpose was twofold: to assist participating laboratories in controlling their own performance, and to characterize exactly the prepared batch of air filters in order to be able to use them as reference filters for elemental trace analysis. The results submitted by 29 laboratories from 20 countries are presented and statistically processed. The analytical methods used are also specified. Conclusions concerning the use of filters Air-3/1 as certified reference filters are presented

  4. Monte Carlo simulation of x-ray spectra in diagnostic radiology and mammography using MCNP4C

    Energy Technology Data Exchange (ETDEWEB)

    Ay, M R [Department of Physics and Nuclear Sciences, AmirKabir University of Technology, Tehran (Iran, Islamic Republic of); Shahriari, M [Department of Nuclear Engineering, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Sarkar, S [Department of Medical Physics, Tehran University of Medical Science, Tehran (Iran, Islamic Republic of); Adib, M [TPP Co., GE Medical Systems, Iran Authorized Distributor, Tehran (Iran, Islamic Republic of); Zaidi, H [Division of Nuclear Medicine, Geneva University Hospital, 1211 Geneva (Switzerland)

    2004-11-07

    The general purpose Monte Carlo N-particle radiation transport computer code (MCNP4C) was used for the simulation of x-ray spectra in diagnostic radiology and mammography. The electrons were transported until they slow down and stop in the target. Both bremsstrahlung and characteristic x-ray production were considered in this work. We focus on the simulation of various target/filter combinations to investigate the effect of tube voltage, target material and filter thickness on x-ray spectra in the diagnostic radiology and mammography energy ranges. The simulated x-ray spectra were compared with experimental measurements and spectra calculated by IPEM report number 78. In addition, the anode heel effect and off-axis x-ray spectra were assessed for different anode angles and target materials and the results were compared with EGS4-based Monte Carlo simulations and measured data. Quantitative evaluation of the differences between our Monte Carlo simulated and comparison spectra was performed using student's t-test statistical analysis. Generally, there is a good agreement between the simulated x-ray and comparison spectra, although there are systematic differences between the simulated and reference spectra especially in the K-characteristic x-rays intensity. Nevertheless, no statistically significant differences have been observed between IPEM spectra and the simulated spectra. It has been shown that the difference between MCNP simulated spectra and IPEM spectra in the low energy range is the result of the overestimation of characteristic photons following the normalization procedure. The transmission curves produced by MCNP4C have good agreement with the IPEM report especially for tube voltages of 50 kV and 80 kV. The systematic discrepancy for higher tube voltages is the result of systematic differences between the corresponding spectra.

  5. Monte Carlo simulation of x-ray spectra in diagnostic radiology and mammography using MCNP4C

    Science.gov (United States)

    Ay, M. R.; Shahriari, M.; Sarkar, S.; Adib, M.; Zaidi, H.

    2004-11-01

    The general purpose Monte Carlo N-particle radiation transport computer code (MCNP4C) was used for the simulation of x-ray spectra in diagnostic radiology and mammography. The electrons were transported until they slow down and stop in the target. Both bremsstrahlung and characteristic x-ray production were considered in this work. We focus on the simulation of various target/filter combinations to investigate the effect of tube voltage, target material and filter thickness on x-ray spectra in the diagnostic radiology and mammography energy ranges. The simulated x-ray spectra were compared with experimental measurements and spectra calculated by IPEM report number 78. In addition, the anode heel effect and off-axis x-ray spectra were assessed for different anode angles and target materials and the results were compared with EGS4-based Monte Carlo simulations and measured data. Quantitative evaluation of the differences between our Monte Carlo simulated and comparison spectra was performed using student's t-test statistical analysis. Generally, there is a good agreement between the simulated x-ray and comparison spectra, although there are systematic differences between the simulated and reference spectra especially in the K-characteristic x-rays intensity. Nevertheless, no statistically significant differences have been observed between IPEM spectra and the simulated spectra. It has been shown that the difference between MCNP simulated spectra and IPEM spectra in the low energy range is the result of the overestimation of characteristic photons following the normalization procedure. The transmission curves produced by MCNP4C have good agreement with the IPEM report especially for tube voltages of 50 kV and 80 kV. The systematic discrepancy for higher tube voltages is the result of systematic differences between the corresponding spectra.

  6. The transesophageal echocardiography simulator based on computed tomography images.

    Science.gov (United States)

    Piórkowski, Adam; Kempny, Aleksander

    2013-02-01

    Simulators are a new tool in education in many fields, including medicine, where they greatly improve familiarity with medical procedures, reduce costs, and, importantly, cause no harm to patients. This is so in the case of transesophageal echocardiography (TEE), in which the use of a simulator facilitates spatial orientation and helps in case studies. The aim of the project described in this paper is to simulate an examination by TEE. This research makes use of available computed tomography data to simulate the corresponding echocardiographic view. This paper describes the essential characteristics that distinguish these two modalities and the key principles of the wave phenomena that should be considered in the simulation process, taking into account the conditions specific to the echocardiography. The construction of the CT2TEE (Web-based TEE simulator) is also presented. The considerations include ray-tracing and ray-casting techniques in the context of ultrasound beam and artifact simulation. An important aspect of the interaction with the user is raised.

  7. Development of a polarized neutron beam line at Algerian research reactors using McStas software

    Science.gov (United States)

    Makhloufi, M.; Salah, H.

    2017-02-01

    Unpolarized instrumentation has long been studied and designed using McStas simulation tool. But, only recently new models were developed for McStas to simulate polarized neutron scattering instruments. In the present contribution, we used McStas software to design a polarized neutron beam line, taking advantage of the available spectrometers reflectometer and diffractometer in Algeria. Both thermal and cold neutron was considered. The polarization was made by two types of supermirrors polarizers FeSi and CoCu provided by the HZB institute. For sake of performance and comparison, the polarizers were characterized and their characteristics reproduced. The simulated instruments are reported. Flipper and electromagnets for guide field are developed. Further developments including analyzers and upgrading of the existing spectrometers are underway.

  8. A 3D simulation look-up library for real-time airborne gamma-ray spectroscopy

    Science.gov (United States)

    Kulisek, Jonathan A.; Wittman, Richard S.; Miller, Erin A.; Kernan, Warnick J.; McCall, Jonathon D.; McConn, Ron J.; Schweppe, John E.; Seifert, Carolyn E.; Stave, Sean C.; Stewart, Trevor N.

    2018-01-01

    A three-dimensional look-up library consisting of simulated gamma-ray spectra was developed to leverage, in real-time, the abundance of data provided by a helicopter-mounted gamma-ray detection system consisting of 92 CsI-based radiation sensors and exhibiting a highly angular-dependent response. We have demonstrated how this library can be used to help effectively estimate the terrestrial gamma-ray background, develop simulated flight scenarios, and to localize radiological sources. Source localization accuracy was significantly improved, particularly for weak sources, by estimating the entire gamma-ray spectra while accounting for scattering in the air, and especially off the ground.

  9. SCIENTIFIC PROGRESS OF THE MC-PAD NETWORK

    CERN Document Server

    Aguilar, J; Ambalathankandy, P; Apostolakis, J; Arora, R; Balog, T; Behnke, T; Beltrame, P; Bencivenni, G; Caiazza, S; Dong, J; Heller, M; Heuser, J; Idzik, M; Joram, C; Klanner, R; Koffeman, E; Korpar, S; Kramberger, G; Lohmann, W; Milovanović, M; Miscetti, S; Moll, M; Novgorodova, O; Pacifico, N; Pirvutoiu, C; Radu, R; Rahman, S; Rohe, T; Ropelewski, L; Roukoutakis, F; Schmidt, C; Schön, R; Sibille, J; Tsagri, M; Turala, M; Van Beuzekom, M; Verheyden, R; Villa, M; Zappon, F; Zawiejski, L; Zhang, J

    2013-01-01

    MC-PAD is a multi-site Initial Training Network on particle detectors in physics experiments. It comprises nine academic participants, three industrial partners and two associated academic partners. 17 recruited Early Stage and 5 Experienced Researchers have performed their scientific work in the network. The research and development work of MC-PAD is organized in 12 work packages, which focus on a large variety of aspects of particle detector development, electronics as well as simulation and modelling. The network was established in November 2008 and lasted until October 2012 (48 months). This report describes the R&D activities and highlights the main results achieved during this period.

  10. 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)

  11. A GPU OpenCL based cross-platform Monte Carlo dose calculation engine (goMC)

    Science.gov (United States)

    Tian, Zhen; Shi, Feng; Folkerts, Michael; Qin, Nan; Jiang, Steve B.; Jia, Xun

    2015-09-01

    Monte Carlo (MC) simulation has been recognized as the most accurate dose calculation method for radiotherapy. However, the extremely long computation time impedes its clinical application. Recently, a lot of effort has been made to realize fast MC dose calculation on graphic processing units (GPUs). However, most of the GPU-based MC dose engines have been developed under NVidia’s CUDA environment. This limits the code portability to other platforms, hindering the introduction of GPU-based MC simulations to clinical practice. The objective of this paper is to develop a GPU OpenCL based cross-platform MC dose engine named goMC with coupled photon-electron simulation for external photon and electron radiotherapy in the MeV energy range. Compared to our previously developed GPU-based MC code named gDPM (Jia et al 2012 Phys. Med. Biol. 57 7783-97), goMC has two major differences. First, it was developed under the OpenCL environment for high code portability and hence could be run not only on different GPU cards but also on CPU platforms. Second, we adopted the electron transport model used in EGSnrc MC package and PENELOPE’s random hinge method in our new dose engine, instead of the dose planning method employed in gDPM. Dose distributions were calculated for a 15 MeV electron beam and a 6 MV photon beam in a homogenous water phantom, a water-bone-lung-water slab phantom and a half-slab phantom. Satisfactory agreement between the two MC dose engines goMC and gDPM was observed in all cases. The average dose differences in the regions that received a dose higher than 10% of the maximum dose were 0.48-0.53% for the electron beam cases and 0.15-0.17% for the photon beam cases. In terms of efficiency, goMC was ~4-16% slower than gDPM when running on the same NVidia TITAN card for all the cases we tested, due to both the different electron transport models and the different development environments. The code portability of our new dose engine goMC was validated by

  12. A GPU OpenCL based cross-platform Monte Carlo dose calculation engine (goMC).

    Science.gov (United States)

    Tian, Zhen; Shi, Feng; Folkerts, Michael; Qin, Nan; Jiang, Steve B; Jia, Xun

    2015-10-07

    Monte Carlo (MC) simulation has been recognized as the most accurate dose calculation method for radiotherapy. However, the extremely long computation time impedes its clinical application. Recently, a lot of effort has been made to realize fast MC dose calculation on graphic processing units (GPUs). However, most of the GPU-based MC dose engines have been developed under NVidia's CUDA environment. This limits the code portability to other platforms, hindering the introduction of GPU-based MC simulations to clinical practice. The objective of this paper is to develop a GPU OpenCL based cross-platform MC dose engine named goMC with coupled photon-electron simulation for external photon and electron radiotherapy in the MeV energy range. Compared to our previously developed GPU-based MC code named gDPM (Jia et al 2012 Phys. Med. Biol. 57 7783-97), goMC has two major differences. First, it was developed under the OpenCL environment for high code portability and hence could be run not only on different GPU cards but also on CPU platforms. Second, we adopted the electron transport model used in EGSnrc MC package and PENELOPE's random hinge method in our new dose engine, instead of the dose planning method employed in gDPM. Dose distributions were calculated for a 15 MeV electron beam and a 6 MV photon beam in a homogenous water phantom, a water-bone-lung-water slab phantom and a half-slab phantom. Satisfactory agreement between the two MC dose engines goMC and gDPM was observed in all cases. The average dose differences in the regions that received a dose higher than 10% of the maximum dose were 0.48-0.53% for the electron beam cases and 0.15-0.17% for the photon beam cases. In terms of efficiency, goMC was ~4-16% slower than gDPM when running on the same NVidia TITAN card for all the cases we tested, due to both the different electron transport models and the different development environments. The code portability of our new dose engine goMC was validated by

  13. A GPU OpenCL based cross-platform Monte Carlo dose calculation engine (goMC)

    International Nuclear Information System (INIS)

    Tian, Zhen; Shi, Feng; Folkerts, Michael; Qin, Nan; Jiang, Steve B; Jia, Xun

    2015-01-01

    Monte Carlo (MC) simulation has been recognized as the most accurate dose calculation method for radiotherapy. However, the extremely long computation time impedes its clinical application. Recently, a lot of effort has been made to realize fast MC dose calculation on graphic processing units (GPUs). However, most of the GPU-based MC dose engines have been developed under NVidia’s CUDA environment. This limits the code portability to other platforms, hindering the introduction of GPU-based MC simulations to clinical practice. The objective of this paper is to develop a GPU OpenCL based cross-platform MC dose engine named goMC with coupled photon–electron simulation for external photon and electron radiotherapy in the MeV energy range. Compared to our previously developed GPU-based MC code named gDPM (Jia et al 2012 Phys. Med. Biol. 57 7783–97), goMC has two major differences. First, it was developed under the OpenCL environment for high code portability and hence could be run not only on different GPU cards but also on CPU platforms. Second, we adopted the electron transport model used in EGSnrc MC package and PENELOPE’s random hinge method in our new dose engine, instead of the dose planning method employed in gDPM. Dose distributions were calculated for a 15 MeV electron beam and a 6 MV photon beam in a homogenous water phantom, a water-bone-lung-water slab phantom and a half-slab phantom. Satisfactory agreement between the two MC dose engines goMC and gDPM was observed in all cases. The average dose differences in the regions that received a dose higher than 10% of the maximum dose were 0.48–0.53% for the electron beam cases and 0.15–0.17% for the photon beam cases. In terms of efficiency, goMC was ∼4–16% slower than gDPM when running on the same NVidia TITAN card for all the cases we tested, due to both the different electron transport models and the different development environments. The code portability of our new dose engine goMC was

  14. Simulating X-ray diffraction of textured films

    DEFF Research Database (Denmark)

    Breiby, Dag W.; Bunk, Oliver; Andreasen, Jens Wenzel

    2008-01-01

    Computationally efficient simulations of grazing-incidence X-ray diffraction (GIXD) are discussed, with particular attention given to textured thin polycrystalline films on supporting substrates. A computer program has been developed for simulating scattering from thin films exhibiting varying...... degrees of preferred orientation. One emphasized common case is that of a 'fibre' symmetry axis perpendicular to the sample plane, resulting from crystallites having one well defined crystal facet towards the substrate, but no preferred inplane orientation. Peak splitting caused by additional scattering......, the mathematically simplest possible descriptions are sought whenever feasible. The practical use of the program is demonstrated for a selected thin-film example, perylene, which is of relevance for organic electronics....

  15. Fast simulation of Proton Induced X-Ray Emission Tomography using CUDA

    Energy Technology Data Exchange (ETDEWEB)

    Beasley, D.G., E-mail: dgbeasley@itn.pt; Marques, A.C.; Alves, L.C.; Silva, R.C. da

    2013-07-01

    A new 3D Proton Induced X-Ray Emission Tomography (PIXE-T) and Scanning Transmission Ion Microscopy Tomography (STIM-T) simulation software has been developed in Java and uses NVIDIA™ Common Unified Device Architecture (CUDA) to calculate the X-ray attenuation for large detector areas. A challenge with PIXE-T is to get sufficient counts while retaining a small beam spot size. Therefore a high geometric efficiency is required. However, as the detector solid angle increases the calculations required for accurate reconstruction of the data increase substantially. To overcome this limitation, the CUDA parallel computing platform was used which enables general purpose programming of NVIDIA graphics processing units (GPUs) to perform computations traditionally handled by the central processing unit (CPU). For simulation performance evaluation, the results of a CPU- and a CUDA-based simulation of a phantom are presented. Furthermore, a comparison with the simulation code in the PIXE-Tomography reconstruction software DISRA (A. Sakellariou, D.N. Jamieson, G.J.F. Legge, 2001) is also shown. Compared to a CPU implementation, the CUDA based simulation is approximately 30× faster.

  16. Fast simulation of Proton Induced X-Ray Emission Tomography using CUDA

    International Nuclear Information System (INIS)

    Beasley, D.G.; Marques, A.C.; Alves, L.C.; Silva, R.C. da

    2013-01-01

    A new 3D Proton Induced X-Ray Emission Tomography (PIXE-T) and Scanning Transmission Ion Microscopy Tomography (STIM-T) simulation software has been developed in Java and uses NVIDIA™ Common Unified Device Architecture (CUDA) to calculate the X-ray attenuation for large detector areas. A challenge with PIXE-T is to get sufficient counts while retaining a small beam spot size. Therefore a high geometric efficiency is required. However, as the detector solid angle increases the calculations required for accurate reconstruction of the data increase substantially. To overcome this limitation, the CUDA parallel computing platform was used which enables general purpose programming of NVIDIA graphics processing units (GPUs) to perform computations traditionally handled by the central processing unit (CPU). For simulation performance evaluation, the results of a CPU- and a CUDA-based simulation of a phantom are presented. Furthermore, a comparison with the simulation code in the PIXE-Tomography reconstruction software DISRA (A. Sakellariou, D.N. Jamieson, G.J.F. Legge, 2001) is also shown. Compared to a CPU implementation, the CUDA based simulation is approximately 30× faster

  17. X-ray fluorescence imaging with synchrotron radiation

    International Nuclear Information System (INIS)

    Rivers, M.L.

    1987-01-01

    The micro-distribution of trace elements is of great interest in fields such as geochemistry, biology and material science. The synchrotron x-ray fluorescence microprobe provides a technique to quantitatively measure trace element compositions at individual points and to construct semiquantitative two dimensional maps of trace element compositions. This paper describes an x-ray fluorescence system used at the National Synchrotron Light Source

  18. Condenser discharge system mobile x-ray apparatus MC 125L-30

    International Nuclear Information System (INIS)

    Kohsaka, Mitsuo; Sasaki, Masahiro; Ozawa, Yasushi; Nakanishi, Takeshi; Matsushita, Yoshiyuki

    1978-01-01

    Improvement of x-ray image quality and safety are strongly required of the x-ray system. This applies equally in the case of the mobile type x-ray system. To satisfy the requirements, the new mobile type x-ray system equipped with the improved x-ray tube unit, collimator, mobile unit and x-ray high tension unit has been developed. In this unit mobility and maneuverability are also improved by introducing a new method. (author)

  19. Simulation of the charge ratio of cosmic ray muons in extensive air showers using CORSIKA

    Energy Technology Data Exchange (ETDEWEB)

    Ochilo, Livingstone [University of Siegen (Germany); Kenyatta University, Nairobi (Kenya); Hashim, Nadir; Okumu, John [Kenyatta University, Nairobi (Kenya)

    2013-07-01

    The interaction of primary cosmic rays in the atmosphere produces, among other particles, pions and kaons. They decay to muons, which form an important component of extensive air showers. The ratio of positively to negatively charged muons, called the muon charge ratio, provides important information about the cosmic ray interactions in the atmosphere. In this study, the theoretical hadronic interaction models in the cosmic ray simulation code CORSIKA have been used to study the charge ratio of cosmic ray muons simulated in extensive air showers. An East - West effect on the charge ratio of simulated cosmic ray muons is observed. It is more pronounced for inclined and low-energy muons (momentum less than 100 GeV/c and zenith angle greater than 80 ). Experimental data from ''MINOS Near'' experiment gives similar results.

  20. 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.