DIFFRACTION FROM MODEL CRYSTALS
Although calculating X-ray diffraction patterns from atomic coordinates of a crystal structure is a widely available capability, calculation from non-periodic arrays of atoms has not been widely applied to cellulose. Non-periodic arrays result from modeling studies that, even though started with at...
A Study of Simple Diffraction Models
Agerkvist, Finn
In this paper two simple methods for cabinet edge diffraction are examined. Calculations with both models are compared with more sophisticated theoretical models and with measured data. The parameters involved are studied and their importance for normal loudspeaker box designs is examined....
Diffraction from nonperiodic models of cellulose crystals
Powder and fiber diffraction patterns were calculated for model cellulose crystallites with chains 20 glucose units long. Model sizes ranged from four chains to 169 chains, based on cellulose I' coordinates, and were subjected to various combinations of energy minimization and molecular dynamics (M...
A Study of Simple Diffraction Models
Agerkvist, Finn
1997-01-01
Three different models for calculating edge diffraction are examined. The methods of Vanderkooy, Terai and Biot & Tolstoy are compared with measurements. Although a good agreement is obtained, the measurements also show that none of the methods work completely satisfactorily. The desired properties...
Niu Chun-Hui; Li Zhi-Yuan; Ye Jia-Sheng; Gu Ben-Yuan
2005-01-01
Scalar diffraction theory, although simple and efficient, is too rough for analysing diffractive micro-optical elements.Rigorous vectorial diffraction theory requires extensive numerical efforts, and is not a convenient design tool. In this paper we employ a simple approximate vectorial diffraction model which combines the principle of the scalar diffraction theory with an approximate local field model to analyse the diffraction of optical waves by some typical two-dimensional diffractive micro-optical elements. The TE and TM polarization modes are both considered. We have found that the approximate vectorial diffraction model can agree much better with the rigorous electromagnetic simulation results than the scalar diffraction theory for these micro-optical elements.
Ray-Based Reflectance Model for Diffraction
Cuypers, Tom; Haber, Tom; Bekaert, Philippe; Raskar, Ramesh
2011-01-01
We present a novel method of simulating wave effects in graphics using ray--based renderers with a new function: the Wave BSDF (Bidirectional Scattering Distribution Function). Reflections from neighboring surface patches represented by local BSDFs are mutually independent. However, in many surfaces with wavelength-scale microstructures, interference and diffraction requires a joint analysis of reflected wavefronts from neighboring patches. We demonstrate a simple method to compute the BSDF for the entire microstructure, which can be used independently for each patch. This allows us to use traditional ray--based rendering pipelines to synthesize wave effects of light and sound. We exploit the Wigner Distribution Function (WDF) to create transmissive, reflective, and emissive BSDFs for various diffraction phenomena in a physically accurate way. In contrast to previous methods for computing interference, we circumvent the need to explicitly keep track of the phase of the wave by using BSDFs that include positiv...
Modeling of microelectromechanical systems deformable mirror diffraction grating
Sirbu, Dan; Pluzhnik, Eugene; Belikov, Ruslan
2016-07-01
Model-based wavefront control methods such as electric field conjugation require accurate optical propagation models to create high-contrast regions in the focal plane using deformable mirrors (DMs). Recently, it has been shown that it is possible to exceed the controllable outer-working angle imposed by the Nyquist limit based on the number of actuators by utilizing a diffraction grating. The print-through pattern on MEMS-based DMs formed during the fabrication process creates both an amplitude and a phase diffraction grating that can be used to enable Super-Nyquist wavefront control. Using interferometric measurements of a DM-actuator, we develop a DM-diffraction grating model. We compare the total energy enclosed in the first diffraction order due to the phase, amplitude, and combined phase-amplitude gratings with laboratory measurements.
Microwave Diffraction Techniques from Macroscopic Crystal Models
Murray, William Henry
1974-01-01
Discusses the construction of a diffractometer table and four microwave models which are built of styrofoam balls with implanted metallic reflecting spheres and designed to simulate the structures of carbon (graphite structure), sodium chloride, tin oxide, and palladium oxide. Included are samples of Bragg patterns and computer-analysis results.…
S-UTD-CH model in multiple diffractions
Baris Tabakcioglu, Mehmet
2016-05-01
The propagation of electromagnetic waves in empty space is an extremely simplified case. Thus, the significant question is how an electromagnetic wave propagates in an environment with obstacles such as buildings, trees or hills. Electromagnetic waves are partially reflected and partially diffracted from these obstacles. To predict the relative path loss of electromagnetic waves at the receiving position, many electromagnetic-wave propagation models have been proposed. These propagation models can be classified into models based on numerical integration and those based on ray tracing. Uniform theory of diffraction (UTD) and slope-UTD (S-UTD) models are ray-tracing-based propagation models and are briefly explained in this paper. In addition, detailed information is provided about the improved slope UTD model, which is called the S-UTD with Convex Hull (S-UTD-CH) model. The fundamentals of the S-UTD-CH model are the S-UTD, convex hull and Fresnel zone concept. In particular, the S-UTD-CH model can be applied to multiple diffraction scenarios in the transition region. Moreover, the S-UTD-CH model is considered an optimum model in terms of its accuracy and calculation or computation time. Widespread simulation results are provided to compare the models based on theoretical rays in terms of prediction accuracy and computation time. To compare these models, different operation frequencies and transmitting antenna heights are considered by using a high-performance computing technique.
$^{-} - {}^{12}C$ elastic scattering above the resonance using diffraction model
M R Arafah
2008-01-01
Phenomenological analysis of the $^{-}- ^{12}C$ elastic scattering differential cross-section at 400, 486, 500, 584, 663, 672 and 766 MeV is presented. The analysis is made in the diffraction model framework using the recently proposed parametrization of the phase-shift function. Good description of the experimental data is achieved at all energies. Microscopic interpretation of the parameters of the phase-shift function is provided in terms of Helm's model density parameters.
X-ray wavefront modeling of Bragg diffraction from crystals
Sutter, John P.
2011-09-01
The diffraction of an X-ray wavefront from a slightly distorted crystal can be modeled by the Takagi-Taupin theory, an extension of the well-known dynamical diffraction theory for perfect crystals. Maxwell's equations applied to a perturbed periodic medium yield two coupled differential equations in the incident and diffracted amplitude. These equations are discretized for numerical calculation into the determination of the two amplitudes on the points of an integration mesh, beginning with the incident amplitudes at the crystal's top surface. The result is a set of diffracted amplitudes on the top surface (in the Bragg geometry) or the bottom surface (in the Laue geometry), forming a wavefront that in turn can be propagated through free space using the Fresnel- Huygens equations. The performance of the Diamond Light Source I20 dispersive spectrometer has here been simulated using this method. Methods are shown for transforming displacements calculated by finite element analysis into local lattice distortions, and for efficiently performing 3-D linear interpolations from these onto the Takagi-Taupin integration mesh, allowing this method to be extended to crystals under thermal load or novel mechanical bender designs.
Diffraction pattern and models of liquid antimony trichloride
Johnson, E.; Narten, A.H.; Thiessen, W.E.; Triolo, R.
1978-01-01
Neutron and x-ray diffraction data for liquid SbCl/sub 3/ at 80/sup 0/C are presented and discussed. The liquid consists of discrete molecules with an Sb-Cl distance of 2.35 A and a Cl-Sb-Cl angle of 96/sup 0/. The diffraction data are analyzed to yield structure and correlation functions for intermolecular Sb...Sb, Sb...Cl, and Cl...Cl interactions. These curves yield directly some valuable insight into the nature of the strong orientational correlations present in liquid SbCl/sub 3/. The data are also used to test site-site interaction models for molecular fluids. The relative role of repulsive and attractive forces for the structure of liquid SbCl/sub 3/ is discussed. 6 figures.
Accurate Antenna Models in Ground Penetrating Radar Diffraction Tomography
Meincke, Peter; Kim, Oleksiy S.
2002-01-01
Linear inversion schemes based on the concept of diffraction tomography have proven successful for ground penetrating radar (GPR) imaging. In many GPR surveys, the antennas of the GPR are located close to the air-soil interface and, therefore, it is important to incorporate the presence of this i......Linear inversion schemes based on the concept of diffraction tomography have proven successful for ground penetrating radar (GPR) imaging. In many GPR surveys, the antennas of the GPR are located close to the air-soil interface and, therefore, it is important to incorporate the presence...... of this interface in the inversion scheme (see Hansen, T.B. and Meincke Johansen, P., IEEE Trans. Geoscience and Remote Sensing, vol.38, p.496-506, 2000). Hansen and Meincke Johansen modeled the antennas as ideal (Hertzian) electric dipoles. Since practical GPR antennas are not ideal, it is of interest...... to investigate the validity of this model. We extend that formulation to hold for arbitrary antennas. For simplicity, the 2.5D case is considered, that is, it is assumed that the scattering object in the soil is invariant in one direction, which, for instance, is the case for a pipe. The arbitrary antennas...
Modeling spatially localized photonic nanojets from phase diffraction gratings
Geints, Yu. E., E-mail: ygeints@iao.ru [V.E. Zuev Institute of Atmospheric Optics SB RAS (IAO SB RAS), 1, Academician Zuev Square, Tomsk 634055 (Russian Federation); Tomsk State University, 36, Lenina Avenue, Tomsk 634050 (Russian Federation); Zemlyanov, A. A. [V.E. Zuev Institute of Atmospheric Optics SB RAS (IAO SB RAS), 1, Academician Zuev Square, Tomsk 634055 (Russian Federation)
2016-04-21
We investigated numerically the specific spatially localized intense optical structure, a photonic nanojet (PNJ), formed in the near-field scattering of optical radiation at phase diffraction gratings. The finite-difference time-domain technique was employed to study the PNJ key parameters (length, width, focal distance, and intensity) produced by diffraction gratings with the saw-tooth, rectangle, and hemispheric line profiles. Our analysis showed that each type of diffraction gratings produces a photonic jet with unique characteristics. Based on the numerical calculations, we demonstrate that the PNJ could be manipulated in a wide range through the variation of period, duty cycle, and shape of diffraction grating rulings.
Sound Diffraction Modeling of Rotorcraft Noise Around Terrain
Stephenson, James H.; Sim, Ben W.; Chitta, Subhashini; Steinhoff, John
2017-01-01
A new computational technique, Wave Confinement (WC), is extended here to account for sound diffraction around arbitrary terrain. While diffraction around elementary scattering objects, such as a knife edge, single slit, disc, sphere, etc. has been studied for several decades, realistic environments still pose significant problems. This new technique is first validated against Sommerfeld's classical problem of diffraction due to a knife edge. This is followed by comparisons with diffraction over three-dimensional smooth obstacles, such as a disc and Gaussian hill. Finally, comparisons with flight test acoustics data measured behind a hill are also shown. Comparison between experiment and Wave Confinement prediction demonstrates that a Poisson spot occurred behind the isolated hill, resulting in significantly increased sound intensity near the center of the shadowed region.
Application of S-UTD-CH Model into Multiple Diffraction Scenarios
Mehmet Baris Tabakcioglu
2013-01-01
Full Text Available Propagation prediction models based on ray tracing in coverage estimation for digital broadcasting systems are compared. Geometrical Theory of Diffraction (GTD, Slope Uniform Theory of Diffraction (S-UTD, and Slope UTD with Convex Hull (S-UTD-CH models are compared for computation time and propagation path loss. S-UTD-CH model is optimum model with respect to computation time and relative path loss.
Monitoring model drug microencapsulation in PLGA scaffolds using X-ray powder diffraction
Adeyinka Aina; Manish Gupta; Yamina Boukari; Andrew Morris; Nashiru Billa; Stephen Doughty
2015-01-01
The microencapsulation of three model drugs; metronidazole, paracetamol and sulphapyridine into Poly (dl-Lactide-Co-Glycolide) (PLGA) scaffolds were probed using X-ray Powder Diffraction (XRPD). Changes in the diffraction patterns of the PLGA scaffolds after encapsulation was suggestive of a chemical interaction between the pure drugs and the scaffolds and not a physical intermixture.
Monitoring model drug microencapsulation in PLGA scaffolds using X-ray powder diffraction.
Aina, Adeyinka; Gupta, Manish; Boukari, Yamina; Morris, Andrew; Billa, Nashiru; Doughty, Stephen
2016-03-01
The microencapsulation of three model drugs; metronidazole, paracetamol and sulphapyridine into Poly (dl-Lactide-Co-Glycolide) (PLGA) scaffolds were probed using X-ray Powder Diffraction (XRPD). Changes in the diffraction patterns of the PLGA scaffolds after encapsulation was suggestive of a chemical interaction between the pure drugs and the scaffolds and not a physical intermixture.
Numerical Study of Wave Diffraction Effect Introduced in the SWAN Model
无
2007-01-01
New version of SWAN model includes the wave diffraction effect which is the main improvement compared with the previous versions. Experimental data collected in the wave basin of the University of Delaware were used to test its performance. Wave heights were compared in the four cases (with different wave energies and directional spreading spectra). The results agreed well with the measurements, especially for the broad directional spectra cases. The effect of wave diffraction was analyzed by switching on/off the corresponding term. By introducing the diffraction term, the distributions of wave height and wave direction were smoothed, especially obvious for the narrow spectrum cases. Compared with the calculations without diffraction, the model with diffraction effect gave better results.
New 2D diffraction model and its applications to terahertz parallel-plate waveguide power splitters
Zhang, Fan; Song, Kaijun; Fan, Yong
2017-02-01
A two-dimensional (2D) diffraction model for the calculation of the diffraction field in 2D space and its applications to terahertz parallel-plate waveguide power splitters are proposed in this paper. Compared with the Huygens-Fresnel principle in three-dimensional (3D) space, the proposed model provides an approximate analytical expression to calculate the diffraction field in 2D space. The diffraction filed is regarded as the superposition integral in 2D space. The calculated results obtained from the proposed diffraction model agree well with the ones by software HFSS based on the element method (FEM). Based on the proposed 2D diffraction model, two parallel-plate waveguide power splitters are presented. The splitters consist of a transmitting horn antenna, reflectors, and a receiving antenna array. The reflector is cylindrical parabolic with superimposed surface relief to efficiently couple the transmitted wave into the receiving antenna array. The reflector is applied as computer-generated holograms to match the transformed field to the receiving antenna aperture field. The power splitters were optimized by a modified real-coded genetic algorithm. The computed results of the splitters agreed well with the ones obtained by software HFSS verify the novel design method for power splitter, which shows good applied prospects of the proposed 2D diffraction model.
G.S. Vorobjov
2015-06-01
Full Text Available General procedure for modeling the excitation conditions of Cherenkov and diffraction radiations in periodic metal-dielectric structures is described. It is based on the representation of the electron beam space-charge wave in the form of a dielectric waveguide surface-wave. On the experimental facility of millimeter-wave the basic modes of excitation conditions of spatial harmonics of the Cherenkov and diffraction radiations are simulated. The method is tested by comparing the numerical analysis and experimental results on the layout of the device of the orotron type - generator of diffraction radiation.
A composite numerical model for wave diffraction in a harbor with varying water depth
ZHAO Ming; TENG Bin
2004-01-01
A composite numerical model is presented for computing the wave field in a harbor. The mild slope equation is discretized by a finite element method in the domain concerned. Out of the computational domain, the water depth is assumed to be constant. The boundary element method is applied to the outer boundary for dealing with the infinite boundary condition. Because the model satisfies strictly the infinite boundary condition, more accurate results can be obtained. The model is firstly applied to compute the wave diffraction in a narrow rectangular bay and the wave diffraction from a porous cylinder. The numerical results are compared with the analytical solution, experimental data and other numerical results. Good agreements are obtained. Then the model is applied to computing the wave diffraction in a square harbor with varying water depth. The effects of the water depth in the harbor and the incoming wave direction on the wave height distribution are discussed.
Diffraction enhanced imaging of a rat model of gastric acid aspiration pneumonitis.
Connor, Dean M; Zhong, Zhong; Foda, Hussein D; Wiebe, Sheldon; Parham, Christopher A; Dilmanian, F Avraham; Cole, Elodia B; Pisano, Etta D
2011-12-01
Diffraction-enhanced imaging (DEI) is a type of phase contrast x-ray imaging that has improved image contrast at a lower dose than conventional radiography for many imaging applications, but no studies have been done to determine if DEI might be useful for diagnosing lung injury. The goals of this study were to determine if DEI could differentiate between healthy and injured lungs for a rat model of gastric aspiration and to compare diffraction-enhanced images with chest radiographs. Radiographs and diffraction-enhanced chest images of adult Sprague Dawley rats were obtained before and 4 hours after the aspiration of 0.4 mL/kg of 0.1 mol/L hydrochloric acid. Lung damage was confirmed with histopathology. The radiographs and diffraction-enhanced peak images revealed regions of atelectasis in the injured rat lung. The diffraction-enhanced peak images revealed the full extent of the lung with improved clarity relative to the chest radiographs, especially in the portion of the lower lobe that extended behind the diaphragm on the anteroposterior projection. For a rat model of gastric acid aspiration, DEI is capable of distinguishing between a healthy and an injured lung and more clearly than radiography reveals the full extent of the lung and the lung damage. Copyright Â© 2011 AUR. All rights reserved.
Soneson, Joshua E
2017-04-01
Wide-angle parabolic models are commonly used in geophysics and underwater acoustics but have seen little application in medical ultrasound. Here, a wide-angle model for continuous-wave high-intensity ultrasound beams is derived, which approximates the diffraction process more accurately than the commonly used Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation without increasing implementation complexity or computing time. A method for preventing the high spatial frequencies often present in source boundary conditions from corrupting the solution is presented. Simulations of shallowly focused axisymmetric beams using both the wide-angle and standard parabolic models are compared to assess the accuracy with which they model diffraction effects. The wide-angle model proposed here offers improved focusing accuracy and less error throughout the computational domain than the standard parabolic model, offering a facile method for extending the utility of existing KZK codes.
Modeling laser beam diffraction and propagation by the mode-expansion method.
Snyder, James J
2007-08-01
In the mode-expansion method for modeling propagation of a diffracted beam, the beam at the aperture can be expanded as a weighted set of orthogonal modes. The parameters of the expansion modes are chosen to maximize the weighting coefficient of the lowest-order mode. As the beam propagates, its field distribution can be reconstructed from the set of weighting coefficients and the Gouy phase of the lowest-order mode. We have developed a simple procedure to implement the mode-expansion method for propagation through an arbitrary ABCD matrix, and we have demonstrated that it is accurate in comparison with direct calculations of diffraction integrals and much faster.
Shan, Mingguang; Tan, Jiubin
2007-12-10
A theoretical model is established using Rayleigh-Sommerfeld diffraction theory to describe the diffraction focusing characteristics of low F-number diffractive optical elements with continuous relief fabricated by laser direct writing, and continuous-relief diffractive optical elements with a design wavelength of 441.6nm and a F-number of F/4 are fabricated and measured to verify the validity of the diffraction focusing model. The measurements made indicate that the spot size is 1.75mum and the diffraction efficiency is 70.7% at the design wavelength, which coincide well with the theoretical results: a spot size of 1.66mum and a diffraction efficiency of 71.2%.
Empirically testing vaterite structural models using neutron diffraction and thermal analysis
Chakoumakos, Bryan C.; Pracheil, Brenda M.; Koenigs, Ryan P.; Bruch, Ronald M.; Feygenson, Mikhail
2016-11-01
Otoliths, calcium carbonate (CaCO3) ear bones, are among the most commonly used age and growth structures of fishes. Most fish otoliths are comprised of the most dense CaCO3 polymorph, aragonite. Sturgeon otoliths, in contrast, have been characterized as the rare and structurally enigmatic polymorph, vaterite—a metastable polymorph of CaCO3. Vaterite is an important material ranging from biomedical to personal care applications although its crystal structure is highly debated. We characterized the structure of Lake Sturgeon otoliths using thermal analysis and neutron powder diffraction, which is used non-destructively. We confirmed that while Lake Sturgeon otoliths are primarily composed of vaterite, they also contain the denser CaCO3 polymorph, calcite. For the vaterite fraction, neutron diffraction data provide enhanced discrimination of the carbonate group compared to x-ray diffraction data, owing to the different relative neutron scattering lengths, and thus offer the opportunity to uniquely test the more than one dozen crystal structural models that have been proposed for vaterite. Of those, space group P6522 model, a = 7.1443(4)Å, c = 25.350(4)Å, V = 1121.5(2)Å3 provides the best fit to the neutron powder diffraction data, and allows for a structure refinement using rigid carbonate groups.
Empirically testing vaterite structural models using neutron diffraction and thermal analysis.
Chakoumakos, Bryan C; Pracheil, Brenda M; Koenigs, Ryan P; Bruch, Ronald M; Feygenson, Mikhail
2016-11-18
Otoliths, calcium carbonate (CaCO3) ear bones, are among the most commonly used age and growth structures of fishes. Most fish otoliths are comprised of the most dense CaCO3 polymorph, aragonite. Sturgeon otoliths, in contrast, have been characterized as the rare and structurally enigmatic polymorph, vaterite-a metastable polymorph of CaCO3. Vaterite is an important material ranging from biomedical to personal care applications although its crystal structure is highly debated. We characterized the structure of Lake Sturgeon otoliths using thermal analysis and neutron powder diffraction, which is used non-destructively. We confirmed that while Lake Sturgeon otoliths are primarily composed of vaterite, they also contain the denser CaCO3 polymorph, calcite. For the vaterite fraction, neutron diffraction data provide enhanced discrimination of the carbonate group compared to x-ray diffraction data, owing to the different relative neutron scattering lengths, and thus offer the opportunity to uniquely test the more than one dozen crystal structural models that have been proposed for vaterite. Of those, space group P6522 model, a = 7.1443(4)Å, c = 25.350(4)Å, V = 1121.5(2)Å(3) provides the best fit to the neutron powder diffraction data, and allows for a structure refinement using rigid carbonate groups.
Multipole electron-density modelling of synchrotron powder diffraction data: the case of diamond
Svendsen, H.; Overgaard, J.; Busselez, R.;
2010-01-01
Accurate structure factors are extracted from synchrotron powder diffraction data measured on crystalline diamond based on a novel multipole model division of overlapping reflection intensities. The approach limits the spherical-atom bias in structure factors extracted from overlapping powder data...... parameter. This directly exposes a correlation between electron density and thermal parameters even for a light atom such as carbon, and it also underlines that in organic systems proper deconvolution of thermal motion is important for obtaining correct static electron densities....
Validation of a crystal plasticity model using high energy diffraction microscopy
Beaudoin, A. J.; Obstalecki, M.; Storer, R.; Tayon, W.; Mach, J.; Kenesei, P.; Lienert, U.
2012-03-01
High energy diffraction microscopy is used to measure the crystallographic orientation and evolution of lattice strain in an Al-Li alloy. The relative spatial arrangement of the several pancake-shaped grains in a tensile sample is determined through in situ and ex situ techniques. A model for crystal plasticity with continuity of lattice spin is posed, where grains are represented by layers in a finite element mesh following the arrangement indicated by experiment. Comparison is drawn between experiment and simulation.
High-energy single diffractive dissociation of nucleons and the 3P-model applicability range
Godizov, A.A., E-mail: anton.godizov@gmail.com
2016-11-15
The adequacy of the triple-Pomeron interaction approximation (the 3P-model) for description of the high-energy single diffractive dissociation of nucleons is analyzed via application to the available experimental data on nucleon–nucleon scattering, including the recent results produced by CMS Collaboration which allow to estimate reliably the triple-Pomeron coupling value. It is argued that the total contribution of secondary Reggeon exchanges is not negligible up to the Tevatron energy.
Validation of a Crystal Plasticity Model Using High Energy Diffraction Microscopy
Beaudoin, A. J.; Obstalecki, M.; Storer, R.; Tayon, W.; Mach, J.; Kenesei, P.; Lienert, U.
2012-01-01
High energy diffraction microscopy is used to measure the crystallographic orientation and evolution of lattice strain in an Al Li alloy. The relative spatial arrangement of the several pancake-shaped grains in a tensile sample is determined through in situ and ex situ techniques. A model for crystal plasticity with continuity of lattice spin is posed, where grains are represented by layers in a finite element mesh following the arrangement indicated by experiment. Comparison is drawn between experiment and simulation.
Diffraction and reflection of irregular waves in a harbor employing a spectral model
Nelson Violante-Carvalho
2009-12-01
Full Text Available The SWAN wave model is widely used in coastal waters and the main focus of this work is on its application in a harbor. Its last released version - SWAN 40.51 - includes an approximation to compute diffraction, however, so far there are few published works that discuss this matter. The performance of the model is therefore investigated in a harbor where reflection and diffraction play a relevant role. To assess its estimates, a phase-resolving Boussinesq wave model is employed as well, together with measurements carried out at a small-scale model of the area behind the breakwater. For irregular, short-crested waves with broad directional spreading, the importance of diffraction is relatively small. On the other hand, reflection of the incident waves is significant, increasing the energy inside the harbor. Nevertheless, the SWAN model does not achieve convergence when it is set to compute diffraction and reflection simultaneously. It is concluded that, for situations typically encountered in harbors, with irregular waves near reflective obstacles, the model should be set without the diffraction option.O modelo de ondas SWAN é amplamente empregado em simulações na região costeira e o presente trabalho investiga sua aplicação dentro de um porto. A última versão disponibilizada para a comunidade - SWAN 40.51 - inclui uma aproximação para computar a difração, embora, até o momento, poucos trabalhos abordando este tema foram publicados. O desempenho do modelo é estudado em um porto onde os fenômenos de reflexão e difração são importantes. Para avaliar suas estimativas, um modelo do tipo Boussinesq também é empregado, juntamente com medições realizadas em um modelo em escala reduzida da área atrás do quebramar. Para ondas irregulares, com cristas curtas e espalhamento direcional mais amplo, a importância da difração é relativamente menor. Contudo, o modelo SWAN não alcança convergência quando programado para estimar
Clausen, B.
1997-09-01
The deformation of polycrystals are modelled using three micron mechanic models; the Taylor model, the Sachs model and Hutchinson`s self-consistent (SC) model. The predictions of the rigid plastic Taylor and Sachs models are compared with the predictions of the SC model. As expected, the results of the SC model is about half-way between the upper- and lower-bound models. The influence of the elastic anisotropy is investigated by comparing the SC predictions for aluminium, copper and a hypothetical material (Hybrid) with the elastic anisotropy of copper and the Young`s modulus and hardening behaviour of aluminium. It is concluded that the effect of the elastic anisotropy is limited to the very early stages of plasticity, as the deformation pattern is almost identical for the three materials at higher strains. The predictions of the three models are evaluated by neutron diffraction measurements of elastic lattice strains in grain sub-sets within the polycrystal. The two rigid plastic models do not include any material parameters and therefore the predictions of the SC model is more accurate and more detailed than the predictions of the Taylor and Sachs models. The SC model is used to determine the most suitable reflection for technological applications of neutron diffraction, where focus is on the volume average stress state in engineering components. To be able to successfully to convert the measured elastic lattice strains for a specific reflection into overall volume average stresses, there must be a linear relation between the lattice strain of the reflection and the overall stress. According to the model predictions the 311-reflection is the most suitable reflection as it shows the smallest deviations from linearity and thereby also the smallest build-up of residual strains. The model predictions have pin pointed that the selection of the reflection is crucial for the validity of stresses calculated from the measured elastic lattice strains. (au) 14 tabs., 41
Refinement of a discontinuity-free edge-diffraction model describing focused wave fields.
Sedukhin, Andrey G
2010-03-01
Two equivalent forms of a refined discontinuity-free edge-diffraction model describing the structure of a stationary focused wave field are presented that are valid in the framework of the scalar Debye integral representation for a diffracted rotationally symmetric converging spherical wave of a limited yet not-too-low angular opening. The first form describes the field as the sum of a direct quasi-spherical wave and a plurality of edge quasi-conical waves of different orders, the optimum discontinuity-free angular spectrum functions of all the waves being dependent on the polar angle only. According to the second form, the focused field is fully characterized by only three components--the same quasi-spherical wave and two edge quasi-conical waves of the zero and first order, of which the optimum discontinuity-free angular spectrum functions are dependent on both the polar angle and the polar radius counted from the geometrical focus.
Nonlinear generalized source method for modeling second-harmonic generation in diffraction gratings
Weismann, Martin; Panoiu, Nicolae C
2015-01-01
We introduce a versatile numerical method for modeling light diffraction in periodically patterned photonic structures containing quadratically nonlinear non-centrosymmetric optical materials. Our approach extends the generalized source method to nonlinear optical interactions by incorporating the contribution of nonlinear polarization sources to the diffracted field in the algorithm. We derive the mathematical formalism underlying the numerical method and introduce the Fourier-factorization suitable for nonlinear calculations. The numerical efficiency and runtime characteristics of the method are investigated in a set of benchmark calculations: the results corresponding to the fundamental frequency are compared to those obtained from a reference method and the beneficial effects of the modified Fourier-factorization rule on the accuracy of the nonlinear computations is demonstrated. In order to illustrate the capabilities of our method, we employ it to demonstrate strong enhancement of second-harmonic genera...
Neutron diffraction measurements and modeling of residual strains in metal matrix composites
Saigal, A.; Leisk, G. G.; Hubbard, C. R.; Misture, S. T.; Wang, X. L.
1996-01-01
Neutron diffraction measurements at room temperature are used to characterize the residual strains in tungsten fiber-reinforced copper matrix, tungsten fiber-reinforced Kanthal matrix, and diamond particulate-reinforced copper matrix composites. Results of finite element modeling are compared with the neutron diffraction data. In tungsten/Kanthal composites, the fibers are in compression, the matrix is in tension, and the thermal residual strains are a strong function of the volume fraction of fibers. In copper matrix composites, the matrix is in tension and the stresses are independent of the volume fraction of tungsten fibers or diamond particles and the assumed stress free temperature because of the low yield strength of the matrix phase.
Modelling studies of carbon nanotubes-Comparison of simulations and X-ray diffraction data
Koloczek, J. [A. Chelkowski Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice (Poland); Hawelek, L. [A. Chelkowski Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice (Poland); Burian, A. [A. Chelkowski Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice (Poland)]. E-mail: burian@us.edu.pl; Dore, J.C. [School of Physical Sciences, University of Kent, Canterbury CT2 7NR (United Kingdom); Honkimaeki, V. [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble (France); Kyotani, T. [Institute of Multidisciplinary Research and Advanced Materials, Tohoku University, Katahira, Sendai 980-8577 (Japan)
2005-09-29
Computer simulations of the powder diffraction profiles for multi-wall carbon nanotubes were performed using the Debye equation including a generalized Debye-Waller factor. The X-ray diffraction data were recorded using high-energy synchrotron radiation and an image plate as a detector for the carbon nanotubes produced by a template chemical vapour deposition (CVD) process. The computed and experimental structure factors were converted to real-space via the Fourier transform. The results of computation, obtained in the form of the structure factor and the pair correlation function, are compared with the X-ray experimental data in both reciprocal and real-space. The nanotube model consisting of five layers with the length of 12 A has proved to account very well for the experimental data.
Bodermann, Bernd; Ehret, Gerd
2005-08-01
High resolution optical microscopy is still an important instrument for dimensional characterisation of micro- und nanostructures. For precise measurements of dimensional quantities a highly accurate modelling of the optical imaging on the basis of rigorous diffraction calculation is essential, which accounts for both the polarisation effects and the 2D or 3D geometry of the structures. Some applications like for example the measurements of linewidths on photomasks demands for measurement uncertainties of few nm or less. For these requirements the numerical and the model induced uncertainty, respectively, may be limiting factors even for sophisticated modelling software. At PTB we use two different rigorous grating diffraction models for modelling of the intensity distribution in the image plane, the rigorous coupled wave analysis (RCWA) method and the finite elements (FEM) method. In order to evaluate the performance of both methods we performed comparative calculations on the basis of a test suite of binary chrome on glass gratings with different line widths reaching from 100nm to 10μm, and with different line/space ratios between 0.01 and 100. We present results of this comparison for TE, TM and unpolarised Koehler illumination of the grating. Residual deviations between both methods and the resulting measurement uncertainty and related to the corresponding time consumptions are considered.
Highly-optimized TWSM software package for seismic diffraction modeling adapted for GPU-cluster
Zyatkov, Nikolay; Ayzenberg, Alena; Aizenberg, Arkady
2015-04-01
Oil producing companies concern to increase resolution capability of seismic data for complex oil-and-gas bearing deposits connected with salt domes, basalt traps, reefs, lenses, etc. Known methods of seismic wave theory define shape of hydrocarbon accumulation with nonsufficient resolution, since they do not account for multiple diffractions explicitly. We elaborate alternative seismic wave theory in terms of operators of propagation in layers and reflection-transmission at curved interfaces. Approximation of this theory is realized in the seismic frequency range as the Tip-Wave Superposition Method (TWSM). TWSM based on the operator theory allows to evaluate of wavefield in bounded domains/layers with geometrical shadow zones (in nature it can be: salt domes, basalt traps, reefs, lenses, etc.) accounting for so-called cascade diffraction. Cascade diffraction includes edge waves from sharp edges, creeping waves near concave parts of interfaces, waves of the whispering galleries near convex parts of interfaces, etc. The basic algorithm of TWSM package is based on multiplication of large-size matrices (make hundreds of terabytes in size). We use advanced information technologies for effective realization of numerical procedures of the TWSM. In particular, we actively use NVIDIA CUDA technology and GPU accelerators allowing to significantly improve the performance of the TWSM software package, that is important in using it for direct and inverse problems. The accuracy, stability and efficiency of the algorithm are justified by numerical examples with curved interfaces. TWSM package and its separate components can be used in different modeling tasks such as planning of acquisition systems, physical interpretation of laboratory modeling, modeling of individual waves of different types and in some inverse tasks such as imaging in case of laterally inhomogeneous overburden, AVO inversion.
Wang, Tiansi; Zhang, Chong; Aleksov, Aleksandar; Salama, Islam; Kar, Aravinda
2017-04-01
Phased array ultrasonic transducers enable modulating the focal position of the acoustic waves, and this capability is utilized in many applications, such as medical imaging and non-destructive testing. This type of transducers also provides a mechanism to generate tilted wavefronts in acousto-optic deflectors to deflect laser beams for high precision advanced laser material processing. In this paper, a theoretical model is presented for the diffraction of ultrasonic waves emitted by several phased array transducers into an acousto-optic medium such as TeO2 crystal. A simple analytic expression is obtained for the distribution of the ultrasonic displacement field in the crystal. The model prediction is found to be in good agreement with the results of a numerical model that is based on a non-paraxial multi-Gaussian beam (NMGB) model.
Modeling the Radar Return of Powerlines Using an Incremental Length Diffraction Coefficient Approach
Macdonald, Douglas
A method for modeling the signal from cables and powerlines in Synthetic Aperture Radar (SAR) imagery is presented. Powerline detection using radar is an active area of research. Accurately identifing the location of powerlines in a scene can be used to aid pilots of low flying aircraft in collision avoidance, or map the electrical infrastructure of an area. The focus of this research was on the forward modeling problem of generating the powerline SAR signal from first principles. Previous work on simulating SAR imagery involved methods that ranged from efficient but insufficiently accurate, depending on the application, to more exact but computationally complex. A brief survey of the numerous ways to model the scattering of electromagnetic radiation is provided. A popular tool that uses the geometric optics approximation for modeling imagery for remote sensing applications across a wide range of modalities is the Digitial Imaging and Remote Sensing Image Generation (DIRSIG) tool. This research shows the way in which DIRSIG generates the SAR phase history is unique compared to other methods used. In particular, DIRSIG uses the geometric optics approximation for the scattering of electromagnetic radiation and builds the phase history in the time domain on a pulse-by-pulse basis. This enables an efficient generation of the phase history of complex scenes. The drawback to this method is the inability to account for diffraction. Since the characteristic diameter of many communication cables and powerlines is on the order of the wavelength of the incident radiation, diffraction is the dominant mechanism by which the radiation gets scattered for these targets. Comparison of DIRSIG imagery to field data shows good scene-wide qualitative agreement as well as Rayleigh distributed noise in the amplitude data, as expected for coherent imaging with speckle. A closer inspection of the Radar Cross Sections of canonical targets such as trihedrals and dihedrals, however, shows
Validating a Model for Welding Induced Residual Stress Using High-Energy X-ray Diffraction
Mach, J. C.; Budrow, C. J.; Pagan, D. C.; Ruff, J. P. C.; Park, J.-S.; Okasinski, J.; Beaudoin, A. J.; Miller, M. P.
2017-03-01
Integrated computational materials engineering (ICME) provides a pathway to advance performance in structures through the use of physically-based models to better understand how manufacturing processes influence product performance. As one particular challenge, consider that residual stresses induced in fabrication are pervasive and directly impact the life of structures. For ICME to be an effective strategy, it is essential that predictive capability be developed in conjunction with critical experiments. In the present work, simulation results from a multi-physics model for gas metal arc welding are evaluated through x-ray diffraction using synchrotron radiation. A test component was designed with intent to develop significant gradients in residual stress, be representative of real-world engineering application, yet remain tractable for finely spaced strain measurements with positioning equipment available at synchrotron facilities. The experimental validation lends confidence to model predictions, facilitating the explicit consideration of residual stress distribution in prediction of fatigue life.
Validating a Model for Welding Induced Residual Stress Using High-Energy X-ray Diffraction
Mach, J. C.; Budrow, C. J.; Pagan, D. C.; Ruff, J. P. C.; Park, J.-S.; Okasinski, J.; Beaudoin, A. J.; Miller, M. P.
2017-05-01
Integrated computational materials engineering (ICME) provides a pathway to advance performance in structures through the use of physically-based models to better understand how manufacturing processes influence product performance. As one particular challenge, consider that residual stresses induced in fabrication are pervasive and directly impact the life of structures. For ICME to be an effective strategy, it is essential that predictive capability be developed in conjunction with critical experiments. In the present work, simulation results from a multi-physics model for gas metal arc welding are evaluated through x-ray diffraction using synchrotron radiation. A test component was designed with intent to develop significant gradients in residual stress, be representative of real-world engineering application, yet remain tractable for finely spaced strain measurements with positioning equipment available at synchrotron facilities. The experimental validation lends confidence to model predictions, facilitating the explicit consideration of residual stress distribution in prediction of fatigue life.
Chappell, Helen F.; Thom, William; Bowron, Daniel T.; Faria, Nuno; Hasnip, Philip J.; Powell, Jonathan J.
2017-08-01
Ferrihydrite, with a ``two-line'' x-ray diffraction pattern (2L-Fh), is the most amorphous of the iron oxides and is ubiquitous in both terrestrial and aquatic environments. It also plays a central role in the regulation and metabolism of iron in bacteria, algae, higher plants, and animals, including humans. In this study, we present a single-phase model for ferrihydrite that unifies existing analytical data while adhering to fundamental chemical principles. The primary particle is small (20-50 Å) and has a dynamic and variably hydrated surface, which negates long-range order; collectively, these features have hampered complete characterization and frustrated our understanding of the mineral's reactivity and chemical/biochemical function. Near and intermediate range neutron diffraction (NIMROD) and first-principles density functional theory (DFT) were employed in this study to generate and interpret high-resolution data of naturally hydrated, synthetic 2L-Fh at standard temperature. The structural optimization overcomes transgressions of coordination chemistry inherent within previously proposed structures, to produce a robust and unambiguous single-phase model.
Diffraction-based overlay measurement on dedicated mark using rigorous modeling method
Lu, Hailiang; Wang, Fan; Zhang, Qingyun; Chen, Yonghui; Zhou, Chang
2012-03-01
Diffraction Based Overlay (DBO) is widely evaluated by numerous authors, results show DBO can provide better performance than Imaging Based Overlay (IBO). However, DBO has its own problems. As well known, Modeling based DBO (mDBO) faces challenges of low measurement sensitivity and crosstalk between various structure parameters, which may result in poor accuracy and precision. Meanwhile, main obstacle encountered by empirical DBO (eDBO) is that a few pads must be employed to gain sufficient information on overlay-induced diffraction signature variations, which consumes more wafer space and costs more measuring time. Also, eDBO may suffer from mark profile asymmetry caused by processes. In this paper, we propose an alternative DBO technology that employs a dedicated overlay mark and takes a rigorous modeling approach. This technology needs only two or three pads for each direction, which is economic and time saving. While overlay measurement error induced by mark profile asymmetry being reduced, this technology is expected to be as accurate and precise as scatterometry technologies.
Hard diffraction at HERA in the dipole model of BFKL dynamics
Munier, S; Royon, C; Royon, Ch.
1998-01-01
Using the QCD dipole picture of the hard BFKL pomeron, we derive the general expressions of the elastic and inelastic components of the proton diffractive structure functions. We obtain a good 7 parameter fit (including a secondary reggeon contribution) to data taken at HERA by the H1 and ZEUS collaborations. The main characteristic features of the model in reproducing the data are discussed, namely the effective pomeron intercept, the scaling violations and the beta dependence. A difference obtained in the separate H1 and ZEUS fits leads us to analyse directly the differences between both measurements. Predictions on R, the ratio of longitudinal to transverse photon cross sections are performed and lead to very large values at high beta and large virtuality Q which may lead to a discrimination between models.
Korsunsky, Alexander M; Hofmann, Felix; Song, Xu; Eve, Sophie; Collins, Steve P
2010-09-01
Materials characterization at the nano-scale is motivated by the desire to resolve the structural aspects and deformation behavior at length scales relevant to those mechanisms that define the novel and unusual properties of nano-structured materials. A range of novel techniques has recently become accessible with the help of synchrotron X-ray beams that can be focused down to spot sizes of less than a few microns on the sample. The unique combination of tunability (energy selection), parallelism and brightness of synchrotron X-ray beams allows their use for high resolution diffraction (determination of crystal structure and transformations, analysis of dislocation sub-structures, orientation and texture analysis, strain mapping); small angle X-ray scattering (analysis of nano-scale voids and defects; orientation analysis) and imaging (radiography and tomography). After a brief review of the state-of-the-art capabilities for monochromatic and white beam synchrotron diffraction, we consider the usefulness of these techniques for the task of bridging the gap between experiment and modeling. Namely, we discuss how the experiments can be configured to provide information relevant to the validation and improvement of modeling approaches, and also how the results of various simulations can be post-processed to improve the possibility of (more or less) direct comparison with experiments. Using the example of some recent experiments carried out on beamline 116 at Diamond Light Source near Oxford, we discuss how such experimental results can be interpreted in view and in conjunction with numerical deformation models, particularly those incorporating dislocation effects, e.g., finite-element based pseudo-continuum strain gradient formulations, and discrete dislocation simulations. Post-processing of FE and discrete dislocation simulations is described, illustrating the kind of information that can be extracted from comparisons between modeling and experimental data.
I Ahmad; M R Arafah
2006-03-01
Elastic scattering of 800 MeV/c pions by 12C has been studied in the diffraction model with a view to determine pion optical potential by the method of inversion. Finding an earlier diffraction model analysis to be deficient in some respects, we propose a Glauber model based parametrization for the elastic -matrix and show that it provides an exceedingly good fit to the pion-carbon data. The proposed elastic -matrix gives a closed expression for the pion-12C optical potential by the method of inversion in the high energy approximation.
Pantoja-Cortés, Juan; Sánchez-Bajo, Florentino; Ortiz, Angel L
2012-05-30
Nanograin sizes and crystal lattice microstrains in nanocrystalline materials are typically evaluated from the broadening of their x-ray diffraction (XRD) peaks under the assumption of symmetrical diffraction profiles. Since this assumption is not entirely satisfactory, we formulate a line-broadening analysis model of a single peak that considers explicitly the XRD peak asymmetry. The model is a generalization of the variance method in which the shape of the XRD peaks is idealized through asymmetrical split pseudo-Voigt functions. The model is validated on two nanocrystalline powders.
Martin, A D; Khoze, V A; Krauss, F; Ryskin, M G; Zapp, K
2012-01-01
`Soft' high-energy interactions are clearly important in pp collisions. Indeed, these events are dominant by many orders of magnitude, and about 40% are of diffractive origin; that is, due to elastic scattering or proton dissociation. Moreover, soft interactions unavoidably give an underlying component to the rare `hard' events, from which we hope to extract new physics. Here, we discuss how to quantify this contamination. First we present a brief introduction to diffraction. We emphasize the different treatment required for proton dissociation into low- and high-mass systems; the former requiring a multichannel eikonal approach, and the latter the computation of triple-Pomeron diagrams with multi-Pomeron corrections. Then we give an overview of the Pomeron, and explain how the QCD (BFKL-type) Pomeron is the natural object to continue from the `hard' to the `soft' domain. In this way we can obtain a partonic description of soft interactions. We introduce the so-called KMR model, based on this partonic approac...
A boundary element model for diffraction of water waves on varying water depth
Poulin, Sanne
1997-12-31
In this thesis a boundary element model for calculating diffraction of water waves on varying water depth is presented. The varying water depth is approximated with a perturbed constant depth in the mild-slope wave equation. By doing this, the domain integral which is a result of the varying depth is no longer a function of the unknown wave potential but only a function of position and the constant depth wave potential. The number of unknowns is the resulting system of equations is thus reduced significantly. The integration procedures in the model are tested very thoroughly and it is found that a combination of analytical integration in the singular region and standard numerical integration outside works very well. The gradient of the wave potential is evaluated successfully using a hypersingular integral equation. Deviations from the analytical solution are only found on the boundary or very close to, but these deviations have no significant influence on the accuracy of the solution. The domain integral is evaluated using the dual reciprocity method. The results are compared with a direct integration of the integral, and the accuracy is quite satisfactory. The problem with irregular frequencies is taken care of by the CBIEM (or CHIEF-method) together with a singular value decomposition technique. This method is simple to implement and works very well. The model is verified using Homma`s island as a test case. The test cases are limited to shallow water since the analytical solution is only valid in this region. Several depth ratios are examined, and it is found that the accuracy of the model increases with increasing wave period and decreasing depth ratio. Short waves, e.g. wind generated waves, can allow depth variations up to approximately 2 before the error exceeds 10%, while long waves can allow larger depth ratios. It is concluded that the perturbation idea is highly usable. A study of (partially) absorbing boundary conditions is also conducted. (EG)
Itoh, Keiji
2017-02-01
Pulsed neutron diffraction and synchrotron X-ray diffraction measurements were performed on Se100-xTex bulk glasses with x=10, 20, 30 and 40. The coordination numbers obtained from the diffraction results demonstrate that Se and Te atoms are twofold coordinated and the glass structure is formed by the chain network. The three-dimensional structure model for Se60Te40 glass obtained by using reverse Monte Carlo modelling shows that the alternating arrangements of Se and Te atoms compose the major part of the chain clusters but several other fragments such as Sen chains and Te-Te dimers are also present in large numbers. The chain clusters have geometrically disordered forms and the interchain atomic order is different from those in the crystal structures of trigonal Se and trigonal Te.
Model-based correction of diffraction effects of the virtual source element.
Wennerström, Erik; Stepinski, Tadeusz
2007-08-01
A method for ultrasonic synthetic aperture imaging using finite-sized transducers is introduced that is based on a virtual source (VS) concept. In this setup, a focused transducer creates a VS element at its focal point that facilitates the use of synthetic aperture focusing technique (SAFT). It is shown that the performance of the VS method may be unsatisfactory due to the distortion introduced by the diffraction effects of the aperture used for creating the VS element. A solution to this problem is proposed that consists of replacing the classical SAFT by the extended synthetic aperature focusing technique (ESAFT) algorithm presented in our earlier works. In ESAFT, the full geometry of the VS is modeled, instead of applying the simplified point source approximation used when VS is combined with classical SAFT. The proposed method yields a substantial improvement in spatial resolution compared to that obtained using SAFT. Performance of the proposed algorithm is first demonstrated on simulated data, then verified on real data acquired with an array system.
Connor, D.M.; Miller, L.; Benveniste, H.; Dilmanian, A.; Kritzer, M.; Zhong, Z.
2009-03-19
Our understanding of early development in Alzheimer's disease (AD) is clouded by the scale at which the disease progresses; amyloid beta (A{beta}) plaques, a hallmark feature of AD, are small ({approx} 50 {micro}m) and low contrast in diagnostic clinical imaging techniques. Diffraction enhanced imaging (DEI), a phase contrast x-ray imaging technique, has greater soft tissue contrast than conventional radiography and generates higher resolution images than magnetic resonance microimaging. Thus, in this proof of principle study, DEI in micro-CT mode was performed on the brains of AD-model mice to determine if DEI can visualize A{beta} plaques. Results revealed small nodules in the cortex and hippocampus of the brain. Histology confirmed that the features seen in the DEI images of the brain were A{beta} plaques. Several anatomical structures, including hippocampal subregions and white matter tracks, were also observed. Thus, DEI has strong promise in early diagnosis of AD, as well as general studies of the mouse brain.
Katerinopoulou, Anna; Balic Zunic, Tonci; Lundegaard, Lars Fahl
2012-01-01
Anisotropic broadening correction in X-ray powder diffraction by an ellipsoidal formula is applied on samples with nanosized crystals. Two cases of minerals with largely anisotropic crystallite shapes are presented. The properly applied formalism not only improves the fitting of the theoretical a...... and observed diffraction diagrams but also gives direct information about realistic crystallite shapes and sizes. The approach is demonstrated using the Rietveld refinement program TOPAS and it is easily adaptable to other similar software....
Simulation of X-ray diffraction-line broadening due to dislocations in a model composite material
Bor, T.C.; Cleveringa, H.H.M.; Delhez, R.; Giessen, van der E.
2001-01-01
X-ray diffraction-line profiles of two-dimensional, plastically deformed model composite materials are calculated and analysed in detail. The composite consists of elastic reinforcements in a crystalline solid and is subjected to macroscopic shear. Slip occurs in the matrix only due to the collectiv
Disposition of Ceramide in Model Lipid Membranes Determined by Neutron Diffraction
Groen, D.; Gooris, G.S.; Barlow, D.J.; Lawrence, M.J.; van Mechelen, J.B.; Demé, B.; Bouwstra, J.A.
2011-01-01
The lipid matrix present in the uppermost layer of the skin, the stratum corneum, plays a crucial role in the skin barrier function. The lipids are organized into two lamellar phases. To gain more insight into the molecular organization of one of these lamellar phases, we performed neutron diffraction studies. In the diffraction pattern, five diffraction orders were observed attributed to a lamellar phase with a repeat distance of 5.4 nm. Using contrast variation, the scattering length density profile could be calculated showing a typical bilayer arrangement. To obtain information on the arrangement of ceramides in the unit cell, a mixture that included a partly deuterated ceramide was also examined. The scattering length density profile of the 5.4-nm phase containing this deuterated ceramide demonstrated a symmetric arrangement of the ceramides with interdigitating acyl chains in the center of the unit cell. PMID:21402030
Disposition of ceramide in model lipid membranes determined by neutron diffraction.
Groen, D; Gooris, G S; Barlow, D J; Lawrence, M J; van Mechelen, J B; Demé, B; Bouwstra, J A
2011-03-16
The lipid matrix present in the uppermost layer of the skin, the stratum corneum, plays a crucial role in the skin barrier function. The lipids are organized into two lamellar phases. To gain more insight into the molecular organization of one of these lamellar phases, we performed neutron diffraction studies. In the diffraction pattern, five diffraction orders were observed attributed to a lamellar phase with a repeat distance of 5.4 nm. Using contrast variation, the scattering length density profile could be calculated showing a typical bilayer arrangement. To obtain information on the arrangement of ceramides in the unit cell, a mixture that included a partly deuterated ceramide was also examined. The scattering length density profile of the 5.4-nm phase containing this deuterated ceramide demonstrated a symmetric arrangement of the ceramides with interdigitating acyl chains in the center of the unit cell.
The ATLAS collaboration
2016-01-01
We present a new tune of the Pythia8 event generator, titled ``A3'' and suitable for inclusive QCD modelling, including minimum bias physics and pile-up overlay. The tuning uses the early Run~2 charged particle distribution and inelastic cross section results from ATLAS in addition to the Run~1 data used to construct previous minimum-bias tunes. For the first time, the tuning included a consideration of diffraction modelling parameters and a diffractive model other than the Pythia8 default is used in the final configuration. That resulted in a better descriptions of the measured inelastic cross-sections, and similar or better level of agreement compared to the currently used A2 tune for other distributions considered.
Modelling the X-ray powder diffraction of nitrogen-expanded austenite using the Debye formula
Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny
2008-01-01
Stress-free and homogeneous samples of nitrogen-expanded austenite, a defect-rich f.c.c. structure with a high interstitial nitrogen occupancy (between 0.36 and 0.61), have been studied using X-ray powder diffraction and Debye simulations. The simulations confirm the presence of deformation stack...
Improved characterization of small particles in laser diffraction by better optical modeling
Butselaar, V.C.L.; Schouten, L.A.; Verheijen, P.J.T.
2004-01-01
Laser Diffraction is widely used for the characterization of particle size distributions of powders. For a lot of materials however, the quantification of small particles (< 2 μm) in relation to the rest of the distribution can be ambiguous. The deconvolution of the scattering pattern is done either
Song, Xu; Hofmann, Felix; Korsunsky, Alexander M.
2010-10-01
A physically-based, rate and length-scale dependent strain gradient crystal plasticity framework was employed to simulate the polycrystalline plastic deformation at the microscopic level in a large-grained, commercially pure Ni sample. The latter was characterised in terms of the grain morphology and orientation (in the bulk) by micro-beam Laue diffraction experiments carried out on beamline B16 at Diamond Light Source. The corresponding finite element model was developed using a grain-based mesh with the specific grain orientation assignment appropriate for the sample considered. Sample stretching to 2% plastic strain was simulated, and a post-processor was developed to extract the information about the local lattice misorientation (curvature), enabling forward-prediction of the Laue diffraction patterns. The 'streaking' phenomenon of the Laue spots (anisotropic broadening of two-dimensional (2D) diffraction peaks observed on the 2D detector) was correctly captured by the simulation, as constructed by direct superposition of reflections from different integration points within the diffraction gauge volume. Good agreement was found between the images collected from experiments and simulation patterns at various positions in the sample.
X-ray microstructural analysis of nanocrystalline TiZrN thin films by diffraction pattern modeling
Escobar, D. [Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 Vía al Magdalena, Manizales (Colombia); PCM Computacional Applications, Universidad Nacional de Colombia Sede Manizales, Km. 9 Vía al Magdalena, Manizales (Colombia); Ospina, R. [Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 Vía al Magdalena, Manizales (Colombia); Gómez, A.G. [Pontificia Universidad Javeriana Seccional Cali, Facultad de Ingeniería, Departamento de Ciencias de la Ingeniería y la Producción (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 Vía al Magdalena, Manizales (Colombia); PCM Computacional Applications, Universidad Nacional de Colombia Sede Manizales, Km. 9 Vía al Magdalena, Manizales (Colombia); Arango, P.J. [Laboratorio de Física del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 Vía al Magdalena, Manizales (Colombia)
2014-02-15
A detailed microstructural characterization of nanocrystalline TiZrN thin films grown at different substrate temperatures (T{sub S}) was carried out by X-ray diffraction (XRD). Total diffraction pattern modeling based on more meaningful microstructural parameters, such as crystallite size distribution and dislocation density, was performed to describe the microstructure of the thin films more precisely. This diffraction modeling has been implemented and used mostly to characterize powders, but the technique can be very useful to study hard thin films by taking certain considerations into account. Nanocrystalline films were grown by using the cathodic pulsed vacuum arc technique on stainless steel 316L substrates, varying the temperature from room temperature to 200 °C. Further surface morphology analysis was performed to study the dependence of grain size on substrate temperature using atomic force microscopy (AFM). The crystallite and surface grain sizes obtained and the high density of dislocations observed indicate that the films underwent nanostructured growth. Variations in these microstructural parameters as a function of T{sub S} during deposition revealed a competition between adatom mobility and desorption processes, resulting in a specific microstructure. These films also showed slight anisotropy in their microstructure, and this was incorporated into the diffraction pattern modeling. The resulting model allowed for the films' microstructure during synthesis to be better understood according to the experimental results obtained. - Highlights: • Mobility and desorption competition generates a critical temperature. • A microstructure anisotropy related to the local strain was observed in thin films. • Adatom mobility and desorption influence grain size and microstrain.
Tamari, V F
2003-01-01
De-diffraction (DD), a new procedure to totally cancel diffraction effects from wave-fields is presented, whereby the full field from an aperture is utilized and a truncated geometrical field is obtained, allowing infinitely sharp focusing and non-diverging beams. This is done by reversing a diffracted wave-fields' direction. The method is derived from the wave equation and demonstrated in the case of Kirchhoff's integral. An elementary bow-wavelet is described and the DD process is related to quantum and relativity theories.
Rasmussen, Christine O
2015-01-01
We present an overview of the options for diffraction implemented in the general--purpose event generator Pythia 8. We review the existing model for low-- and high--mass soft diffraction and present a new model for hard diffraction in pp and ppbar collisions. Both models uses the Pomeron approach pioneered by Ingelman and Schlein, factorising the single diffractive cross section into a Pomeron flux and a Pomeron PDF. The model for hard diffraction is implemented as a part of the multiparton interactions framework, thereby introducing a dynamical rapidity gap survival probability that explicitly breaks factorisation.
Rasmussen, Christine O
2015-01-01
We present an overview of the options for diffraction implemented in the general-purpose event generator Pythia 8. We review the existing model for soft diffraction and present a new model for hard diffraction. Both models use the Pomeron approach pioneered by Ingelman and Schlein, factorising the diffractive cross section into a Pomeron flux and a Pomeron PDF, with several choices for both implemented in Pythia 8. The model of hard diffraction is implemented as a part of the multiparton interactions (MPI) framework, thus introducing a dynamical gap survival probability that explicitly breaks factorisation.
Overgaard Rasmussen, Christine
2016-07-01
We present an overview of the options for diffraction implemented in the general-purpose event generator Pythia 8 [1]. We review the existing model for soft diffraction and present a new model for hard diffraction. Both models use the Pomeron approach pioneered by Ingelman and Schlein, factorising the diffractive cross section into a Pomeron flux and a Pomeron PDF, with several choices for both implemented in Pythia 8. The model of hard diffraction is implemented as a part of the multiparton interactions (MPI) framework, thus introducing a dynamical gap survival probability that explicitly breaks factorisation.
Victoria Gómez-Murcia
2016-06-01
Full Text Available Here we present some of our data about the interaction of idebenone and idebenol with dipalmitoyl-phosphatidylcholine (DPPC. In particular, we include data of small angle X-ray diffraction (SAXD and wide angle X-ray diffraction experiments, obtention of electronic profiles of the membranes, 2H-NMR and 31P-NMR, as part of the research article: “Both idebenone and idebenol are localized near the lipid-water interface of the membrane and increase its fluidity” (Gomez-Murcia et al., 2016 [1]. These data were obtained from model membranes that included different proportions of idebenone and idebenol, at temperatures both above and below of the gel to fluid phase. The X-ray experiments were carried out by using a modified Kratky compact camera (MBraun-Graz-Optical Systems, Graz Austria, incorporating two coupled linear position sensitive detectors. The NMR data were collected from a a Bruker Avance 600 instrument.
Extending the reach of powder diffraction modelling by user defined macros
Scardi, Paolo
2010-01-01
The main focus of this special topic volume is the development and possibilities of the MACRO language within TOPAS, with a specific session dedicated to WPPM. The collection is presented here in the form of a ""macro tutorial"" for the benefit of the entire powder diffraction community. More than a collection of standard scientific papers, the contributions to this special issue provide methods, tutorials and practical suggestions and solutions for the proper use of TOPAS and WPPM in a number of applications; ranging from the most common to the most refined and specific cases.Readers will fin
Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)
1996-12-31
X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.
Cobourne, G.; Mountjoy, G.; Rodriguez Blanco, Juan Diego
2014-01-01
from CO3 molecules and 0.6 oxygen atoms from H2O molecules. The average CaO bond length is 2.40 Å. The distribution of Ca in the model is homogeneous with a uniformly distributed Ca-rich network and no evidence of the Ca-poor channels as previously reported for a reverse Monte Carlo model of ACC......Amorphous calcium carbonate (ACC) plays a key role in biomineralisation processes in sea organisms. Neutron and X-ray diffraction have been performed for a sample of magnesium-stabilised ACC, which was prepared with a Mg:Ca ratio of 0.05:1 and 0.25 H2O molecules per molecule of CO3. The empirical...... potential structure refinement method has been used to make a model of magnesium-stabilised ACC and the results revealed a fair agreement with the experimental diffraction data. The model has well-defined CO3 and H2O molecules. The average coordination number of Ca is 7.4 and is composed of 6.8 oxygen atoms...
Sæther, Mathias; Ersland, Geir
2016-01-01
Acoustic material parameters of gas hydrate bearing porous rocks are important for evaluation of methods to exploit the vast methane gas resources present in the earth's subsurface, potentially combined with CO2 injection. A solid buffer method for measuring changes of the compressional wave velocity in porous rocks with changing methane hydrate contents under high-pressure hydrate-forming conditions, is tested and evaluated with respect to effects influencing on the measurement accuracy. The limited space available in the pressure chamber represents a challenge for the measurement method. Several effects affect the measured compressional wave velocity, such as interference from sidewall reflections, diffraction effects, the amount of torque (force) used to achieve acoustic coupling, and water draining of the watersaturated rock specimen. Test measurements using the solid buffer method in the pressure chamber at atmospheric conditions are compared to independent measurements using a water-bath immersion measu...
Taupin, V.; Pesci, R. [Laboratoire d' Etude des Microstructures et de Mecanique des Materiaux, LEM3, CNRS, University of Lorraine/Arts et Metiers ParisTech, Metz Cedex 57045 (France); Berbenni, S., E-mail: stephane.berbenni@univ-lorraine.fr [Laboratoire d' Etude des Microstructures et de Mecanique des Materiaux, LEM3, CNRS, University of Lorraine/Arts et Metiers ParisTech, Metz Cedex 57045 (France); Berveiller, S.; Ouahab, R. [Laboratoire d' Etude des Microstructures et de Mecanique des Materiaux, LEM3, CNRS, University of Lorraine/Arts et Metiers ParisTech, Metz Cedex 57045 (France); Bouaziz, O. [Arcelor Research, Arcelor Mittal, Maizieres-les-Metz 57210 (France)
2013-01-20
In situ tensile tests were performed at room temperature on a ferrite-cementite steel specifically designed for this study. The evolution of the average stress in ferrite during loading was analyzed by X-ray diffraction. Lattice strain measurements were performed with synchrotron ring diffraction in both ferrite and cementite. These in situ tests were complemented by macroscopic tensile and reversible tensile-compression tests to study the Bauschinger effect. In order to reproduce stresses in ferrite and cementite particles, a recently developed micromechanical Internal Length Mean Field (ILMF) model based on a generalized self-consistent scheme is applied. In this designed ferrite-cementite steel, the third 'phase' of the model represents finite intermediate 'layers' in ferrite due to large geometrically necessary dislocation (GND) densities around cementite particles. The assumed constant thickness of the layers is calibrated thanks to the obtained experimental data. The ILMF model is validated by realistic estimates of the Bauschinger stress and the large difference between mean stresses in ferrite and in cementite phases. This difference cannot be reproduced by classic two-phase homogenization schemes without intermediate GND layers.
Clérouin, Jean; Desbiens, Nicolas; Dubois, Vincent; Arnault, Philippe
2016-12-01
We show that the Bayesian inference of recently measured x-ray diffraction spectra from laser-shocked aluminum [L. B. Fletcher et al., Nat. Photon. 9, 274 (2015), 10.1038/nphoton.2015.41] with the one-component-plasma (OCP) model performs remarkably well at estimating the ionic density and temperature. This statistical approach requires many evaluations of the OCP static structure factor, which were done using a recently derived analytic fit. The atomic form factor is approximated by an exponential function in the diffraction window of the first peak. The electronic temperature is then estimated from a comparison of this approximated form factor with the electronic structure of an average atom model. Out-of-equilibrium states, with electrons hotter than ions, are diagnosed for the spectra obtained early after the pump, whereas at a late time delay the plasma is at thermal equilibrium. Apart from the present findings, this OCP-based modeling of warm dense matter has an important role to play in the interpretation of x-ray Thomson scattering measurements currently performed at large laser facilities.
Beti Andonovic
2015-11-01
Full Text Available A model consisting of an equation that includes graphene thickness distribution is used to calculate theoretical 002 X-ray diffraction (XRD peak intensities. An analysis was performed upon graphene samples produced by two different electrochemical procedures: electrolysis in aqueous electrolyte and electrolysis in molten salts, both using a nonstationary current regime. Herein, the model is enhanced by a partitioning of the corresponding 2θ interval, resulting in significantly improved accuracy of the results. The model curves obtained exhibit excellent fitting to the XRD intensities curves of the studied graphene samples. The employed equation parameters make it possible to calculate the j-layer graphene region coverage of the graphene samples, and hence the number of graphene layers. The results of the thorough analysis are in agreement with the calculated number of graphene layers from Raman spectra C-peak position values and indicate that the graphene samples studied are few-layered.
Ariosa, D.; Cancellieri, C.; Lin, P. H.; Pavuna, D.
2007-05-01
We propose a simple model for the nucleation of random intercalates during the growth of high-temperature superconductor (HTSC) films by pulsed laser deposition (PLD). The model predicts a very particular spatial distribution of defects: a Markovian-like sequence of displacements along the growth direction ( c axis), as well as a two-component in-plane correlation function, characteristic of self-organized intercalates. A model for x-ray diffraction (XRD) on such structures is also developed and accounts for both c -axis and in-plane anomalies observed in XRD experiments. The method presented in this work constitutes a useful characterization tool in the optimization of deposition parameters for the growth of HTSC films.
Foglia, Fabrizia; Lawrence, M. Jayne; Demeė, Bruno; Fragneto, Giovanna; Barlow, David
2012-10-01
Over the last 50 years or so, amphotericin has been widely employed in treating life-threatening systemic fungal infections. Its usefulness in the clinic, however, has always been circumscribed by its dose-limiting side-effects, and it is also now compromised by an increasing incidence of pathogen resistance. Combating these problems through development of new anti-fungal agents requires detailed knowledge of the drug's molecular mechanism, but unfortunately this is far from clear. Neutron diffraction studies of the drug's incorporation within lipid-sterol membranes have here been performed to shed light on this problem. The drug is shown to disturb the structures of both fungal and mammalian membranes, and co-localises with the membrane sterols in a manner consistent with trans-membrane pore formation. The differences seen in the membrane lipid ordering and in the distributions of the drug-ergosterol and drug-cholesterol complexes within the membranes are consistent with the drug's selectivity for fungal vs. human cells.
Alcaraz, Olga; Trullàs, Joaquim; Tahara, Shuta; Kawakita, Yukinobu; Takeda, Shin'ichi
2016-09-01
The results of the structural properties of molten copper chloride are reported from high-energy X-ray diffraction measurements, reverse Monte Carlo modeling method, and molecular dynamics simulations using a polarizable ion model. The simulated X-ray structure factor reproduces all trends observed experimentally, in particular the shoulder at around 1 Å-1 related to intermediate range ordering, as well as the partial copper-copper correlations from the reverse Monte Carlo modeling, which cannot be reproduced by using a simple rigid ion model. It is shown that the shoulder comes from intermediate range copper-copper correlations caused by the polarized chlorides.
Lane, M. [Emory & Henry College, VA (United States); Chaiken, A.; Michel, R.P. [Lawrence Livermore National Lab., CA (United States)
1994-12-01
We have characterized thin-film multilayers grown by ion-beam sputtering using magnetization curves and modeling of low-angle x-ray diffraction data. In our films, we use ferromagnetic layer = Co, Fe, and NiFe and spacer layer = Si, Ge, FeSi{sub 2}, and CoSi{sub 2}. We have studied the effects of (1) deposition conditions; (2) thickness of layers; (3) different layer materials; and (4) annealing. We find higher magnetization in films grown at 1000V rather than 500V and in films with spacer layers of 50{angstrom} rather than 100{angstrom}. We find higher coercivity in films with cobalt grown on germanium rather than silicon, metal grown on gold underlayers rather than on glass substrates, and when using thinner spacer layers. Finally, modeling reveals that films grown with disilicide layers are more thermally stable than films grown with silicon spacer layers.
Clausen, Bjørn
of calculated and measured lattice strains are made for three diﬀerent materials; alu-minium, copper and austenitic stainless steel. The predictions of the self-consistent model is more accurate and detailed than the predictions of the Taylor and Sachs models, though some discrepancies are noted for some...
Kessner, Doreen; Kiselev, Mikhail; Dante, Silvia; Hauss, Thomas; Lersch, Peter; Wartewig, Siegfried; Neubert, Reinhard H H
2008-07-01
The lipid matrix in stratum corneum (SC) plays a key role in the barrier function of the mammalian skin. The major lipids are ceramides (CER), cholesterol (CHOL) and free fatty acids (FFA). Especially the unique-structured omega-acylceramide CER[EOS] is regarded to be essential for skin barrier properties by inducing the formation of a long-periodicity phase of 130 angstroms (LPP). In the present study, the arrangement of CER[EOS], either mixed with CER[AP] and CHOL or with CER[AP], CHOL and palmitic acid (PA), inside a SC lipid model membrane has been studied for the first time by neutron diffraction. For a mixed CER[EOS]/CER[AP]/CHOL membrane in a partly dehydrated state, the internal membrane nanostructure, i.e. the neutron scattering length density profile in the direction normal to the surface, was obtained by Fourier synthesis from the experimental diffraction patterns. The membrane repeat distance is equal to that of the formerly used SC lipid model system composed of CER[AP]/CHOL/PA/ChS. By comparing both the neutron scattering length density profiles, a possible arrangement of synthetic long-chain CER[EOS] molecules inside a SC lipid model matrix is suggested. The analysis of the internal membrane nanostructure implies that one CER[EOS] molecule penetrates from one membrane layer into an adjacent layer. A 130 angstroms periodicity phase could not be observed under experimental conditions, either in CER/CHOL mixtures or in CER/CHOL/FFA mixture. CER[EOS] can be arranged inside a phase with a repeat unit of 45.2 angstroms which is predominately formed by short-chain CER[AP] with distinct polarity.
Random vs realistic amorphous carbon models for high resolution microscopy and electron diffraction
Ricolleau, C., E-mail: Christian.Ricolleau@univ-paris-diderot.fr; Alloyeau, D. [Laboratoire Matériaux et Phénomènes Quantiques, CNRS-UMR 7162, Université Paris Diderot-Paris 7, Case 7021, 75205 Paris Cedex 13 (France); Le Bouar, Y.; Amara, H.; Landon-Cardinal, O. [Laboratoire d' Etude des Microstructures, UMR CNRS/Onera, 29, avenue de la Division Leclerc, 92322 Châtillon (France)
2013-12-07
Amorphous carbon and amorphous materials in general are of particular importance for high resolution electron microscopy, either for bulk materials, generally covered with an amorphous layer when prepared by ion milling techniques, or for nanoscale objects deposited on amorphous substrates. In order to quantify the information of the high resolution images at the atomic scale, a structural modeling of the sample is necessary prior to the calculation of the electron wave function propagation. It is thus essential to be able to reproduce the carbon structure as close as possible to the real one. The approach we propose here is to simulate a realistic carbon from an energetic model based on the tight-binding approximation in order to reproduce the important structural properties of amorphous carbon. At first, we compare this carbon with the carbon obtained by randomly generating the carbon atom positions. In both cases, we discuss the limit thickness of the phase object approximation. In a second step, we show the influence of both carbons models on (i) the contrast of Cu, Ag, and Au single atoms deposited on carbon and (ii) the determination of the long-range order parameter in CoPt bimetallic nanoalloys.
Low-Mass Diffraction at the LHC
Jenkovszky, Laszlo; Lämsä, Jerry; Orava, Risto
2011-01-01
The expected resonance structure for the low-mass single diffractive states from a Regge-dual model elaborated paper by the present authors in a previous is predicted. Estimates for the observable low-mass single diffraction dissociation (SDD) cross sections and efficiencies for single diffractive events simulated by PYTHIA 6.2 as a function of the diffractive mass are given.
Turner, Todd J.; Shade, Paul A.; Bernier, Joel V.; Li, Shiu Fai; Schuren, Jay C.; Kenesei, Peter; Suter, Robert M.; Almer, Jonathan
2017-02-01
High-Energy Diffraction Microscopy (HEDM) is a 3-d X-ray characterization method that is uniquely suited to measuring the evolving micro-mechanical state and microstructure of polycrystalline materials during in situ processing. The near-field and far-field configurations provide complementary information; orientation maps computed from the near-field measurements provide grain morphologies, while the high angular resolution of the far-field measurements provides intergranular strain tensors. The ability to measure these data during deformation in situ makes HEDM an ideal tool for validating micro-mechanical deformation models that make their predictions at the scale of individual grains. Crystal Plasticity Finite Element Models (CPFEM) are one such class of micro-mechanical models. While there have been extensive studies validating homogenized CPFEM response at a macroscopic level, a lack of detailed data measured at the level of the microstructure has hindered more stringent model validation efforts. We utilize an HEDM dataset from an alpha-titanium alloy (Ti-7Al), collected at the Advanced Photon Source, Argonne National Laboratory, under in situ tensile deformation. The initial microstructure of the central slab of the gage section, measured via near-field HEDM, is used to inform a CPFEM model. The predicted intergranular stresses for 39 internal grains are then directly compared to data from 4 far-field measurements taken between 4 and 80 pct of the macroscopic yield strength. The evolution of the elastic strain state from the CPFEM model and far-field HEDM measurements up to incipient yield are shown to be in good agreement, while residual stress at the individual grain level is found to influence the intergranular stress state even upon loading. Implications for application of such an integrated computational/experimental approach to phenomena such as fatigue are discussed.
Zhou, Hanying; Krist, John; Nemati, Bijan
2016-08-01
Current coronagraph instrument design (CGI), as a part of a proposed NASA WFIRST (Wide-Field InfraRed Survey Telescope) mission, allocates two subband filters per full science band in order to contain system complexity and cost. We present our detailed investigation results on the adequacy of such limited number of finite subband filters in achieving full band dark hole contrast with shaped pupil coronagraph. The study is based on diffraction propagation modeling with realistic WFIRST optics, where each subband's complex field estimation is obtained, using Electric Field Conjugation (EFC) wavefront sensing / control algorithm, from pairwise pupil plane deformable mirror (DM) probing and image plane intensity averaging of the resulting fields of multiple (subband) wavelengths. Multiple subband choices and probing and control strategies are explored, including standard subband probing; mixed wavelength and/or weighted Jacobian matrix; subband probing with intensity subtraction; and extended subband probing with intensity subtraction. Overall, the investigation shows that the achievable contrast with limited number of finite subband EFC probing is about 2 2.5x worse than the designed post-EFC contrast for current SPC design. The result suggests that for future shaped pupil design, slightly larger over intended full bandwidth should be considered if it will be used with limited subbands for probing.
Fabian, M.; Svab, E.; Krezhov, K.
2016-09-01
Rare-earth molybdate glasses have been prepared by rapid quench technique, the network structure was investigated by neutron and high-energy X-ray diffraction. For data evaluation the reverse Monte Carlo simulation technique was applied to obtain a possible 3dimensional network configuration, which is consistent with the experimental data. From the modelling the partial atomic correlation functions giJ(r) and the coordination number distributions CNij have been revealed. Formation of MoO4 (55%) and MoO6 (25%) units was established for the binary 90MoO3-10Nd2O3 glass. The B-O first neighbour distribution show a relatively broad first neighbour distance at 1.40A, the average coordination numbers show the presents of trigonal BO3 and tetrahedral BO4 groups. For 50MoO3-25Nd2O3-25B2O3 sample mixed MoO4-BO4 and MoO4-BO3 linkages form pronounced intermediate-range order.
2014-10-01
Predicting grain growth in nanocrystalline materials requires modeling approaches that incorporate grain boundary thermodynamics and kinetics. In...growth in nanocrystalline materials and this extended model can be applied to understanding how grain size evolves with temperature in other nanocrystalline systems....this work, a thermokinetic model for grain growth was applied to experimental X-ray diffraction measurements from nanocrystalline Fe Zr in an effort 1
Terentyev, V. S.; Simonov, V. A.
2016-02-01
Numerical modelling demonstrates the possibility of fabricating an all-fibre multibeam two-mirror reflection interferometer based on a metal-dielectric diffraction structure in its front mirror. The calculations were performed using eigenmodes of a double-clad single-mode fibre. The calculation results indicate that, using a metallic layer in the structure of the front mirror of such an interferometer and a diffraction effect, one can reduce the Ohmic loss by a factor of several tens in comparison with a continuous thin metallic film.
Terentyev, V S; Simonov, V A [Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)
2016-02-28
Numerical modelling demonstrates the possibility of fabricating an all-fibre multibeam two-mirror reflection interferometer based on a metal–dielectric diffraction structure in its front mirror. The calculations were performed using eigenmodes of a double-clad single-mode fibre. The calculation results indicate that, using a metallic layer in the structure of the front mirror of such an interferometer and a diffraction effect, one can reduce the Ohmic loss by a factor of several tens in comparison with a continuous thin metallic film. (laser crystals and braggg ratings)
Diffractive optics and nanophotonics resolution below the diffraction limit
Minin, Igor
2016-01-01
In this book the authors present several examples of techniques used to overcome the Abby diffraction limit using flat and 3D diffractive optical elements, photonic crystal lenses, photonic jets, and surface plasmon diffractive optics. The structures discussed can be used in the microwave and THz range and also as scaled models for optical frequencies. Such nano-optical microlenses can be integrated, for example, into existing semiconductor heterostructure platforms for next-generation optoelectronic applications. Chapter 1 considers flat diffractive lenses and innovative 3D radiating structures including a conical millimeter-wave Fresnel zone plate (FZP) lens proposed for subwavelength focusing. In chapter 2 the subwavelength focusing properties of diffractive photonic crystal lenses are considered and it is shown that at least three different types of photonic crystal lens are possible. With the aim of achieving subwavelength focusing, in chapter 3 an alternative mechanism to produce photonic jets at Tera...
Khoze, V.A.; Ryskin, M.G. [University of Durham, Institute for Particle Physics Phenomenology, Durham (United Kingdom); NRC Kurchatov Institute, Gatchina, Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation); Martin, A.D. [University of Durham, Institute for Particle Physics Phenomenology, Durham (United Kingdom)
2013-07-15
We show that the diffractive pp (and p anti p) data (on {sigma}{sub tot}, d{sigma}{sub el}/dt, proton dissociation into low-mass systems, {sigma}{sup D}{sub low} {sub M}, and high-mass dissociation, d{sigma}/d({Delta}{eta})) in a wide energy range from CERN-ISR to LHC energies, may be described in a two-channel eikonal model with only one 'effective' pomeron. By allowing the pomeron coupling to the diffractive eigenstates to depend on the collider energy (as is expected theoretically) we are able to explain the low value of {sigma}{sup D}{sub low} {sub M} measured at the LHC. We calculate the survival probability, S{sup 2}, of a rapidity gap to survive 'soft rescattering'. We emphasise that the values found for S{sup 2} are particularly sensitive to the detailed structure of the diffractive eigenstates. (orig.)
Diffractive Bremsstrahlung in Hadronic Collisions
Roman Pasechnik
2015-01-01
Full Text Available Production of heavy photons (Drell-Yan, gauge bosons, Higgs bosons, and heavy flavors, which is treated within the QCD parton model as a result of hard parton-parton collision, can be considered a bremsstrahlung process in the target rest frame. In this review, we discuss the basic features of the diffractive channels of these processes in the framework of color dipole approach. The main observation is a dramatic breakdown of diffractive QCD factorisation due to the interplay between soft and hard interactions, which dominates these processes. This observation is crucial for phenomenological studies of diffractive reactions in high energy hadronic collisions.
Diffractive Production of the Higgs Boson
Peschanski, R
2003-01-01
Diffractive production of the Higgs boson at hadron colliders is discussed in the light of the observed rate of hard diffractive dijet events at the Tevatron. The Higgs predictions of models successful for dijets are compared. LHC seems promising for a diffractive light Higgs boson and its mass determination. Hard diffractive dijets, diphotons and dileptons at the Tevatron (Run II) will be necessary to remove the remaining large uncertainties on cross-sections and signals.
Smith, C. B.
1982-01-01
The Fymat analytic inversion method for retrieving a particle-area distribution function from anomalous diffraction multispectral extinction data and total area is generalized to the case of a variable complex refractive index m(lambda) near unity depending on spectral wavelength lambda. Inversion tests are presented for a water-haze aerosol model. An upper-phase shift limit of 5 pi/2 retrieved an accurate peak area distribution profile. Analytical corrections using both the total number and area improved the inversion.
Pothoczki, Szilvia, E-mail: pothoczki.szilvia@wigner.mta.hu; Temleitner, László; Pusztai, László [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Konkoly-Thege M. út 29-33, 1121 Budapest (Hungary)
2014-02-07
Synchrotron X-ray diffraction measurements have been conducted on liquid phosphorus trichloride, tribromide, and triiodide. Molecular Dynamics simulations for these molecular liquids were performed with a dual purpose: (1) to establish whether existing intermolecular potential functions can provide a picture that is consistent with diffraction data and (2) to generate reliable starting configurations for subsequent Reverse Monte Carlo modelling. Structural models (i.e., sets of coordinates of thousands of atoms) that were fully consistent with experimental diffraction information, within errors, have been prepared by means of the Reverse Monte Carlo method. Comparison with reference systems, generated by hard sphere-like Monte Carlo simulations, was also carried out to demonstrate the extent to which simple space filling effects determine the structure of the liquids (and thus, also estimating the information content of measured data). Total scattering structure factors, partial radial distribution functions and orientational correlations as a function of distances between the molecular centres have been calculated from the models. In general, more or less antiparallel arrangements of the primary molecular axes that are found to be the most favourable orientation of two neighbouring molecules. In liquid PBr{sub 3} electrostatic interactions seem to play a more important role in determining intermolecular correlations than in the other two liquids; molecular arrangements in both PCl{sub 3} and PI{sub 3} are largely driven by steric effects.
Dridi, Kim; Bjarklev, Anders Overgaard
1999-01-01
An electromagnetic vector-field modle for design of optical components based on the finite-difference-time-domain method and radiation integrals in presented. Its ability to predict the optical electromagnetic dynamics in structures with complex material distribution is demonstrated. Theoretical...... and numerical investigations of finite-length surface-relief structures embedded in polymer dielectric waveguiding materials are presented. The importance of several geometric parameter dependencies is indicated as far-field power distributions are rearranged between diffraction orders. The influences...
Diffraction coherence in optics
Françon, M; Green, L L
2013-01-01
Diffraction: Coherence in Optics presents a detailed account of the course on Fraunhofer diffraction phenomena, studied at the Faculty of Science in Paris. The publication first elaborates on Huygens' principle and diffraction phenomena for a monochromatic point source and diffraction by an aperture of simple form. Discussions focus on diffraction at infinity and at a finite distance, simplified expressions for the field, calculation of the path difference, diffraction by a rectangular aperture, narrow slit, and circular aperture, and distribution of luminous flux in the airy spot. The book th
Smith, D. K.; Smith, K. L.
1980-01-01
Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)
Smith, D. K.; Smith, K. L.
1980-01-01
Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)
Can Kinematic Diffraction Distinguish Order from Disorder?
Baake, Michael
2008-01-01
Diffraction methods are at the heart of structure determination of solids. While Bragg-like scattering (pure point diffraction) is a characteristic feature of crystals and quasicrystals, it is not straightforward to interpret continuous diffraction intensities, which are generally linked to the presence of disorder. However, based on simple model systems, we demonstrate that it may be impossible to draw conclusions on the degree of order in the system from its diffraction image. In particular, we construct a family of one-dimensional binary systems which cover the entire entropy range but still share the same purely diffuse diffraction spectrum.
Diffractive production of mesons
Schicker, R
2014-01-01
The interest in the study of diffractive meson production is discussed. The description of diffraction within Regge phenomenology is presented, and the QCD-based understanding of diffractive processes is given. Central production is reviewed, and the corresponding main results from the COMPASS experiment and from the experiments at the ISR, RHIC, TEVATRON and LHC collider are summarised.
Robustness via Diffractal Architectures
Moocarme, Matthew
2015-01-01
When plane waves diffract through fractal-patterned apertures, the resulting far-field profiles or diffractals also exhibit iterated, self-similar features. Here we show that this specific architecture enables robust signal processing and spatial multiplexing: arbitrary parts of a diffractal contain sufficient information to recreate the entire original sparse signal.
Diffractive production of mesons
Schicker Rainer
2014-01-01
Full Text Available The interest in the study of diffractive meson production is discussed. The description of diffraction within Regge phenomenology is presented, and the QCD-based understanding of diffractive processes is given. Central production is reviewed, and the corresponding main results from the COMPASS experiment and from the experiments at the ISR, RHIC, TEVATRON and LHC collider are summarised.
Hickstein, Daniel D.; Cole, Jacqueline M.; Turner, Michael J.; Jayatilaka, Dylan
2013-08-01
The rational design of next-generation optical materials requires an understanding of the connection between molecular structure and the solid-state optical properties of a material. A fundamental challenge is to utilize the accurate structural information provided by X-ray diffraction to explain the properties of a crystal. For years, the multipole refinement has been the workhorse technique for transforming high-resolution X-ray diffraction datasets into the detailed electron density distribution of crystalline material. However, the electron density alone is not sufficient for a reliable calculation of the nonlinear optical properties of a material. Recently, the X-ray constrained wavefunction refinement has emerged as a viable alternative to the multipole refinement, offering several potential advantages, including the calculation of a wide range of physical properties and seeding the refinement process with a physically reasonable starting point. In this study, we apply both the multipole refinement and the X-ray constrained wavefunction technique to four molecules with promising nonlinear optical properties and diverse structural motifs. In general, both techniques obtain comparable figures of merit and generate largely similar electron densities, demonstrating the wide applicability of the X-ray constrained wavefunction method. However, there are some systematic differences between the electron densities generated by each technique. Importantly, we find that the electron density generated using the X-ray constrained wavefunction method is dependent on the exact location of the nuclei. The X-ray constrained wavefunction refinement makes smaller changes to the wavefunction when coordinates from the Hartree-Fock-based Hirshfeld atom refinement are employed rather than coordinates from the multipole refinement, suggesting that coordinates from the Hirshfeld atom refinement allow the X-ray constrained wavefunction method to produce more accurate wavefunctions. We
Hard diffraction with dynamic gap survival
Rasmussen, Christine O.; Sjöstrand, Torbjörn
2016-02-01
We present a new framework for the modelling of hard diffraction in pp and poverline{p} collisions. It starts from the the approach pioneered by Ingelman and Schlein, wherein the single diffractive cross section is factorized into a Pomeron flux and a Pomeron PDF. To this it adds a dynamically calculated rapidity gap survival factor, derived from the modelling of multiparton interactions. This factor is not relevant for diffraction in ep collisions, giving non-universality between HERA and Tevatron diffractive event rates. The model has been implemented in P ythia 8 and provides a complete description of the hadronic state associated with any hard single diffractive process. Comparisons with poverline{p} and pp data reveal improvement in the description of single diffractive events.
Hard Diffraction with Dynamic Gap Survival
Rasmussen, Christine O
2015-01-01
We present a new framework for the modelling of hard diffraction in pp and ppbar collisions. It starts from the the approach pioneered by Ingelman and Schlein, wherein the single diffractive cross section is factorized into a Pomeron flux and a Pomeron PDF. To this it adds a dynamically calculated rapidity gap survival factor, derived from the modelling of multiparton interactions. This factor is not relevant for diffraction in ep collisions, giving non-universality between HERA and Tevatron diffractive event rates. The model has been implemented in Pythia 8 and provides a complete description of the hadronic state associated with any hard single diffractive process. Comparisons with ppbar and pp data reveal improvement in the description of single diffractive events.
Zhao, Xinyun; Chen, Xi; Yang, Guang-Fu; Zhan, Chang-Guo
2010-05-27
6-Oxy purine derivatives have been considered as potential therapeutic agents in various drug discovery efforts reported in the literature. However, the structural assignment of this important class of compounds has been controversial concerning the specific position of a hydrogen atom in the structure. To theoretically determine the most favorable type of tautomeric form of 6-oxy purine derivatives, we have carried out first-principles electronic structure calculations on the possible tautomeric forms (A, B, and C) and their relative stability of four representative 6-oxy purine derivatives (compounds 1-4). The computational results in both the gas phase and aqueous solution clearly reveal that the most favorable type of tautomeric form of these compounds is A, in which a hydrogen atom bonds with the N1 atom on the purine ring. To examine the computational results, one of the 6-oxy purine derivatives (i.e., compound 4) has been synthesized and its structure has been characterized by X-ray diffraction and spectroscopic analysis. All of the obtained computational and experimental data are consistent with the conclusion that the 6-oxy purine derivative exists in tautomer A. The conclusive structural assignment reported here is expected to be valuable for future computational studies on 6-oxy purine derivative binding with proteins and for computational drug design involving this type of compounds.
Wang, Xiaozhen; Lu, Tianjian; Yu, Xin; Jin, Jian-Ming; Goddard, Lynford L
2017-07-04
We studied the nanoscale thermal expansion of a suspended resistor both theoretically and experimentally and obtained consistent results. In the theoretical analysis, we used a three-dimensional coupled electrical-thermal-mechanical simulation and obtained the temperature and displacement field of the suspended resistor under a direct current (DC) input voltage. In the experiment, we recorded a sequence of images of the axial thermal expansion of the central bridge region of the suspended resistor at a rate of 1.8 frames/s by using epi-illumination diffraction phase microscopy (epi-DPM). This method accurately measured nanometer level relative height changes of the resistor in a temporally and spatially resolved manner. Upon application of a 2 V step in voltage, the resistor exhibited a steady-state increase in resistance of 1.14 Ω and in relative height of 3.5 nm, which agreed reasonably well with the predicted values of 1.08 Ω and 4.4 nm, respectively.
Dittrich, Birger; Wandtke, Claudia M; Meents, Alke; Pröpper, Kevin; Mondal, Kartik Chandra; Samuel, Prinson P; Amin Sk, Nurul; Singh, Amit Pratap; Roesky, Herbert W; Sidhu, Navdeep
2015-02-02
Single-crystal X-ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid-state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical-atom least-squares refinement of conventional diffraction data of organometallic compounds is proposed. The iterative procedure is conceptually similar to Hirshfeld-atom refinement (Acta Crystallogr. Sect. A- 2008, 64, 383-393; IUCrJ. 2014, 1,61-79), but it relies on tabulated invariom scattering factors (Acta Crystallogr. Sect. B- 2013, 69, 91-104) and the Hansen/Coppens multipole model; disordered structures can be handled as well. Five linear-coordinate 3d metal complexes, for which the wrong element is found if standard independent-atom model scattering factors are relied upon, are studied, and it is shown that only aspherical-atom scattering factors allow a reliable assignment. The influence of anomalous dispersion in identifying the correct element is investigated and discussed.
Fiber diffraction without fibers.
Poon, H-C; Schwander, P; Uddin, M; Saldin, D K
2013-06-28
Postprocessing of diffraction patterns of completely randomly oriented helical particles, as measured, for example, in so-called "diffract-and-destroy" experiments with an x-ray free electron laser can yield "fiber diffraction" patterns expected of fibrous bundles of the particles. This will allow "single-axis alignment" to be performed computationally, thus obviating the need to do this by experimental means such as forming fibers and laser or flow alignment. The structure of such particles may then be found by either iterative phasing methods or standard methods of fiber diffraction.
Mittemeijer, E J
2013-01-01
The role of diffraction methods for the solid-state sciences has been pivotal to determining the (micro)structure of a material. Particularly, the expanding activities in materials science have led to the development of new methods for analysis by diffraction. This book offers an authoritative overview of the new developments in the field of analysis of matter by (in particular X-ray, electron and neutron) diffraction. It is composed of chapters written by leading experts on 'modern diffraction methods'. The focus in the various chapters of this book is on the current forefront of research on
Robustness of Cantor diffractals.
Verma, Rupesh; Sharma, Manoj Kumar; Banerjee, Varsha; Senthilkumaran, Paramasivam
2013-04-08
Diffractals are electromagnetic waves diffracted by a fractal aperture. In an earlier paper, we reported an important property of Cantor diffractals, that of redundancy [R. Verma et. al., Opt. Express 20, 8250 (2012)]. In this paper, we report another important property, that of robustness. The question we address is: How much disorder in the Cantor grating can be accommodated by diffractals to continue to yield faithfully its fractal dimension and generator? This answer is of consequence in a number of physical problems involving fractal architecture.
Radial Reflection Diffraction Tomography
Lehman, S K; Norton, S J
2003-10-10
We develop a wave-based tomographic imaging algorithm based upon a single rotating radially outward oriented transducer. At successive angular locations at a fixed radius, the transducer launches a primary field and collects the backscattered field in a ''pitch/catch'' operation. The hardware configuration, operating mode, and data collection method is identical to that of most medical intravascular ultrasound (IVUS) systems. IVUS systems form images of the medium surrounding the probe based upon ultrasonic B-scans, using a straight-ray model of sound propagation. Our goal is to develop a wave-based imaging algorithm using diffraction tomography techniques. Given the hardware configuration and the imaging method, we refer to this system as ''radial reflection diffraction tomography.'' We consider two hardware configurations: a multimonostatic mode using a single transducer as described above, and a multistatic mode consisting of a single transmitter and an aperture formed by multiple receivers. In this latter case, the entire source/receiver aperture rotates about the fixed radius. Practically, such a probe is mounted at the end of a catheter or snaking tube that can be inserted into a part or medium with the goal of forming images of the plane perpendicular to the axis of rotation. We derive an analytic expression for the multimonostatic inverse but ultimately use the new Hilbert space inverse wave (HSIW) algorithm to construct images using both operating modes. Applications include improved IVUS imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts with existing access holes.
Wang, Jimin; Askerka, Mikhail; Brudvig, Gary W; Batista, Victor S
2017-02-10
Understanding structure-function relations in photosystem II (PSII) is important for the development of biomimetic photocatalytic systems. X-ray crystallography, computational modeling, and spectroscopy have played central roles in elucidating the structure and function of PSII. Recent breakthroughs in femtosecond X-ray crystallography offer the possibility of collecting diffraction data from the X-ray free electron laser (XFEL) before radiation damage of the sample, thereby overcoming the main challenge of conventional X-ray diffraction methods. However, the interpretation of XFEL data from PSII intermediates is challenging because of the issues regarding data-processing, uncertainty on the precise positions of light oxygen atoms next to heavy metal centers, and different kinetics of the S-state transition in microcrystals compared to solution. Here, we summarize recent advances and outstanding challenges in PSII structure-function determination with emphasis on the implementation of quantum mechanics/molecular mechanics techniques combined with isomorphous difference Fourier maps, direct methods, and high-resolution spectroscopy.
Surprises in aperiodic diffraction
Baake, Michael
2009-01-01
Mathematical diffraction theory is concerned with the diffraction image of a given structure and the corresponding inverse problem of structure determination. In recent years, the understanding of systems with continuous and mixed spectra has improved considerably. Moreover, the phenomenon of homometry shows various unexpected new facets. Here, we report on some of the recent results in an exemplary and informal fashion.
Diffractive lenses recorded in absorbent photopolymers.
Fernández, R; Gallego, S; Márquez, A; Francés, J; Navarro-Fuster, V; Pascual, I
2016-01-25
Photopolymers can be appealing materials for diffractive optical elements fabrication. In this paper, we present the recording of diffractive lenses in PVA/AA (Polyvinyl alcohol acrylamide) based photopolymers using a liquid crystal device as a master. In addition, we study the viability of using a diffusion model to simulate the lens formation in the material and to study the influence of the different parameters that govern the diffractive formation in photopolymers. Once we control the influence of each parameter, we can fit an optimum recording schedule to record each different diffractive optical element with the optimum focalization power.
Calculation of Loudspeaker Cabinet Diffraction and Correction
LE Yi; SHEN Yong; XIA Jie
2011-01-01
A method of calculating the cabinet edge diffractions for loudspeaker driver when mounted in an enclosure is proposed,based on the extended Biot-Tolstoy-Medwin model.Up to the third order,cabinet diffractions are discussed in detail and the diffractive effects on the radiated sound field of the loudspeaker system are quantitatively described,with a correction function built to compensate for the diffractive interference.The method is applied to a practical loudspeaker enclosure that has rectangular facets.The diffractive effects of the cabinet on the forward sound radiation are investigated and predictions of the calculations show quite good agreements with experimental measurements.Most loudspeaker systems employ box-like cabinets.The response of a loudspeaker mounted in a box is much rougher than that of the same driver mounted on a large baffle.Although resonances in the box are partly responsible for the lack of smoothness,a major contribution is the diffraction of the cabinet edges,which aggravates the final response performance.Consequently,an analysis of the cabinet diffraction problem is required.%A method of calculating the cabinet edge diffractions for loudspeaker driver when mounted in an enclosure is proposed, based on the extended Biot-Tolstoy-Medwin model. Up to the third order, cabinet diffractions are discussed in detail and the diffractive effects on the radiated sound field of the loudspeaker system are quantitatively described, with a correction function built to compensate for the diffractive interference. The method is applied to a practical loudspeaker enclosure that has rectangular facets. The diffractive effects of the cabinet on the forward sound radiation are investigated and predictions of the calculations show quite good agreements with experimental measurements.
Exclusive Diffraction at HERA and Beyond
Fazio, S
2010-01-01
The exclusive diffractive production of vector mesons and real photons in ep collisions has been studied at HERA in a wide kinematic range. Here the most recent experimental results are presented together with a Regge-type model and projects for new diffractive studies at LHC.
Alves, Gilvan A. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Lab. de Cosmologia e Fisica Experimental de Altas Energias
2000-07-01
Full text follows: We review recent Hard Diffraction results from the D{phi} experiment at Fermilab, for the following processes: hard color singlet exchange, hard single diffraction, and hard double pomeron exchange. Measurements of rates, {eta}, E{sub T} and {radical}S dependencies are presented and comparisons made with predictions of several models. (author)
M. Sabri Kocakülah
2012-06-01
Full Text Available In this study, effect of designed constructivist teaching approach about diffraction of light in a single-slit on students’ conceptual change was investigated with a pretest-posttest control group design. An achievement test, a conceptual understanding test and semi-structured interviews were used as data collection instruments. It was observed that control group students were unable to clarify the reason of calculating path difference and made mistakes in explaining how the path difference was found after teaching. Some students were found to preserve the idea that light bends at the ends of the slit and those bended light rays interfere while some others developed hybrid responses by composing wave and particle models of light. It was revealed that experimental group students reached higher levels of conceptual understandings than control group students considering their responses of explaining successfully the notions of path difference, order of bright and dark fringes on a screen and the change in fringe width.
Hernandez-Figueroa, Hugo E; Recami, Erasmo
2013-01-01
This continuation and extension of the successful book ""Localized Waves"" by the same editors brings together leading researchers in non-diffractive waves to cover the most important results in their field and as such is the first to present the current state.The well-balanced presentation of theory and experiments guides readers through the background of different types of non-diffractive waves, their generation, propagation, and possible applications. The authors include a historical account of the development of the field, and cover different types of non-diffractive waves, including Airy
Coherent diffractive {rho} production
Hyett, N.M.; Tovey, S.N. [Melbourne Univ., Parkville, VIC (Australia). School of Physics
1995-12-31
Coherent diffractive {rho} production by neutrinos occurs at low four-momentum transfer and high energy transfer. These interactions are generally understood to occur via the coupling of the weak charged current to the vector meson, which scatters diffractively from the target nucleus. Since coherent events are those in which the nucleus interacts as a whole, ie without breakup, and with small recoil energy, these events have a very sharp |t|-distribution. This presentation deals mostly with the Monte Carlo simulation of the coherent diffractive production of the {rho} production and in particular with the reconstruction algorithm (description and efficiency) and the |t| distribution. 4 refs., 1 fig.
Confinement, Turbulence and Diffraction Catastrophes
Blaizot, J.-P.; Nowak, M. A.
2009-08-01
Many features of the large N transition that occurs in the spectral density of Wilson loops as a function of loop area (observed recently in numerical simulations of Yang-Mills theory by Narayanan and Neuberger) can be captured by a simple Burgers equation used to model turbulence. Spectral shock waves that precede this asymptotic limit exhibit universal scaling with N, with indices that can be related to Berry indices for diffraction catastrophes.
Achilles, C. N.; Bish, D. L.; Rampe, E. B.; Morris, R. V.
2015-01-01
Soils on Mars have been analyzed by the Mars Exploration Rovers (MER) and most recently by the Mars Science Laboratory (MSL) rover. Chemical analyses from a majority of soil samples suggest that there is a relatively uniform global soil composition across much of the planet. A soil site, Rocknest, was sampled by the MSL science payload including the CheMin X-ray diffractometer and the Alpha Particle X-ray Spectrometer (APXS). Che- Min X-ray diffraction (XRD) data revealed crystalline phases and a broad, elevated background, indicating the presence of amorphous or poorly ordered materials (Fig 1). Based on the chemical composition of the bulk soil measured by APXS and the composition of crystalline phases derived from unit-cell parameters determined with CheMin data, the percentages of crystalline and amorphous phases were calculated at 51% and 49%, respectively. Attempts to model the amorphous contribution to CheMin XRD patterns were made using amorphous standards and full-pattern fitting methods and show that the broad, elevated background region can be fitted by basaltic glass, allophane, and palagonite. However, the modeling shows only that these phases have scattering patterns similar to that for the soil, not that they represent unique solutions. Here, we use pair distribution function (PDF) analysis to determine the short-range order of amorphous analogs in martian soils and better constrain the amorphous material detected by CheMin.
The logarithmic slope in diffractive DIS
Gay-Ducati, M B; Machado, M V T
2002-01-01
The logarithmic slope of diffractive structure function is a potential observable to separate the hard and soft contributions in diffraction, allowing to disentangle the QCD dynamics at small-x region. In this paper we extend our previous analyzes and calculate the diffractive logarithmic slope for three current approaches in the literature: (i) the Bartels-Wusthoff model, based on perturbative QCD, (ii) the CKMT model, based on Regge theory and (iii) the Golec-Biernat-Wusthoff model which assumes that the saturation phenomena is present in the HERA kinematic region. We analyze the transition region of small to large momentum transfer and verify that future experimental results on the diffractive logarithmic slope could discriminate between these approaches.
Golden, G A; Rubin, R T; Mason, R P
1998-01-19
The classical, genomic mechanisms of steroid hormone action cannot account for their rapid cellular effects. Membrane-bound steroid receptors have been partially characterized, but many rapid steroid effects occur in the absence of steroid-protein binding. Although it has been proposed that these effects could be due to steroid-induced biophysical alterations of the cell membrane, only indirect supporting evidence for this hypothesis has been forthcoming. In the present study, the ability of cortisol and estradiol (E2), natural steroids of different lipophilicity, to induce alterations in a model membrane (lecithin) bilayer was examined directly by small-angle X-ray diffraction under physiologic-like conditions. Within minutes, both steroids partitioned to distinct sites in the membrane. With increasing membrane cholesterol content, cortisol was displaced toward the polar headgroup region of the phospholipid bilayer, whereas E2 was displaced in the opposite direction, toward the nonpolar hydrocarbon core. Membrane-based partition coefficients (Kp[mem]) for both steroids (>100:1) were highest at those cholesterol concentrations that displaced the steroids toward the headgroup region (high cholesterol for cortisol; low for E2). Both steroids, when located in the headgroup region, increased overall bilayer width by 3-4 A, a change that could modulate the structure and function of integral membrane proteins independent from steroid effects on the genome.
Couling, A. J.; Goupee, A. J.; Robertson, A. N.; Jonkman, J. M.
2013-06-01
To better access the abundant offshore wind resource, efforts across the world are being undertaken to develop and improve floating offshore wind turbine technologies. A critical aspect of creating reliable, mature floating wind turbine technology is the development, verification, and validation of efficient computer-aided-engineering (CAE) tools that can be relied upon in the design process. The National Renewable Energy Laboratory (NREL) has created a comprehensive, coupled analysis CAE tool for floating wind turbines, FAST, which has been verified and utilized in numerous floating wind turbine studies. Several efforts are currently underway that leverage the extensive 1/50th-scale DeepCwind wind/wave basin model test dataset, obtained at the Maritime Research Institute Netherlands (MARIN) in 2011, to validate the floating platform functionality of FAST to complement its already validated aerodynamic and structural simulation capabilities. In this paper, further work is undertaken to continue this validation. In particular, the ability of FAST to replicate global response behaviors associated with dynamic wind forces, second-order difference-frequency wave-diffraction forces and their interaction with one another are investigated.
Choi, K. S.; Liu, W. N.; Sun, X.; Khaleel, M. A.; Ren, Y.; Wang, Y. D.
2008-12-01
Compared to other advanced high-strength steels, transformation-induced plasticity (TRIP) steels exhibit better ductility at a given strength level and can be used to produce complicated automotive parts. This enhanced formability comes from the transformation of retained austenite to martensite during plastic deformation. In this study, as a first step in predicting optimum processing parameters in TRIP steel productions, a micromechanical finite element model is developed based on the actual microstructure of a TRIP 800 steel. The method uses a microstructure-based representative volume element (RVE) to capture the complex deformation behavior of TRIP steels. The mechanical properties of the constituent phases of the TRIP 800 steel and the fitting parameters describing the martensite transformation kinetics are determined using the synchrotron-based in-situ high-energy X-ray diffraction (HEXRD) experiments performed under a uniaxial tensile deformation. The experimental results suggest that the HEXRD technique provides a powerful tool for characterizing the phase transformation behavior and the microstress developed due to the phase-to-phase interaction of TRIP steels during deformation. The computational results suggest that the response of the RVE well represents the overall macroscopic behavior of the TRIP 800 steel under deformation. The methodology described in this study may be extended for studying the effects of the various processing parameters on the macroscopic behaviors of TRIP steels.
Wezka, Kamil; Salmon, Philip S.; Zeidler, Anita; Whittaker, Dean A. J.; Drewitt, James W. E.; Klotz, Stefan; Fischer, Henry E.; Marrocchelli, Dario
2012-12-01
The structure of the network forming glass GeO2 is investigated by making the first application of the method of in situ neutron diffraction with isotope substitution at pressures increasing from ambient to 8 GPa. Of the various models, the experimental results are in quantitative agreement only with molecular dynamics simulations made using interaction potentials that include dipole-polarization effects. When the reduced density ρ/ρ0 ≳ 1.16, where ρ0 is the value at ambient pressure, network collapse proceeds via an interplay between the predominance of distorted square pyramidal GeO5 units versus octahedral GeO6 units as they replace tetrahedral GeO4 units. This replacement necessitates the formation of threefold coordinated oxygen atoms and leads to an increase with density in the number of small rings, where a preference is shown for sixfold rings when ρ/ρ0 = 1 and fourfold rings when ρ/ρ0 = 1.64.
Calculating cellulose diffraction patterns
Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...
Ball, Philip
2016-09-01
A new implementation of X-ray diffraction using free-electron lasers can take snapshots of biological molecules that are inaccessible via X-ray crystallography. As Philip Ball reports, the technique can even be used to create stop-motion films of dynamic molecular processes
Stretchable diffraction gratings for spectrometry.
Simonov, Aleksey N; Grabarnik, Semen; Vdovin, Gleb
2007-07-23
We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly changed by mechanical stretching. When used in a monochromator with two slits, the stretchable grating permits scanning the spectral components over the output slit, converting the monochromator into a scanning spectrometer. The spectral resolution of such a spectrometer was found to be limited mainly by the wave-front aberrations due to the grating deformation. A model relating the deformation-induced aberrations in different diffraction orders is presented. In the experiments, a 12-mm long viscoelastic grating with a spatial frequency of 600 line pairs/mm provided a full-width at half-maximum resolution of up to ~1.2 nm in the 580-680 nm spectral range when slowly stretched by a micrometer screw and ~3 nm when repeatedly stretched by a voice coil at 15 Hz. Comparison of aberrations in transmitted and diffracted beams measured by a Shack- Hartmann wave-front sensor showed that astigmatisms caused by stretch-dependent wedge deformation are the main factors limiting the resolution of the viscoelastic-grating-based spectrometer.
Genetic Synthesis of the Diffraction Profile
Stanislav Jurecka
2004-01-01
Full Text Available In this paper we describe theoretical synthesis of the x-ray diffraction line profile as a superposition of the spectral components Ka1 and Ka2 optimized to the experimental data by the genetic algorithm and nonlinear optimization methods 'Nelder-Mead downhill simplex' and Levenberg-Marquardt method. Such combination of global and local optimization methods results in a mathematical model of the diffraction profile, providing reliable determininig of diffraction line characteristics for the material structure properties study. Experimetal results of the optimization preocedures are given too.
Diffraction and diffusion in room acoustics
Rindel, Jens Holger; Rasmussen, Birgit
1996-01-01
Diffraction and diffusion are two phenomena that are both related to the wave nature of sound. Diffraction due to the finite size of reflecting surfaces and the design of single reflectors and reflector arrays are discussed. Diffusion is the result of scattering of sound reflected from surfaces...... that are not plane but curved or irregular. The importance of diffusion has been demonstrated in concert halls. Methods for the design of diffusing surfaces and the development of new types of diffusers are reviewed. Finally, the importance of diffraction and diffusion in room acoustic computer models is discussed....
On the interpretation of time-resolved anisotropic diffraction patterns
Lorenz, Ulf; Møller, Klaus Braagaard; Henriksen, Niels Engholm
2010-01-01
In this paper, we review existing systematic treatments for the interpretation of anisotropic diffraction patterns from partially aligned symmetric top molecules. Such patterns arise in the context of time-resolved diffraction experiments. We calculate diffraction patterns for ground-state NaI ex......I excited with an ultraviolet laser. The results are interpreted with the help of a qualitative analytic model, and general recommendations on the analysis and interpretation of anisotropic diffraction patterns are given....
A Spectrometer Based on Diffractive Lens
WANG Daoyi; YAN Yingbai; JIN Guofan; WU Minxian
2001-01-01
A novel spectrometer is designed based on diffractive lens. It is essentially a flat field spectrometer. All the focal points are along the optical axis. Besides, all the asymmetrical aberrations vanish in our mounting. Thus low aberration can be obtained. In this article a diffractive lens is modeled as a special grating and analyzed by using a grating-based method. And a stigmatic point is introduced to reduce the aberrations.
SINGLE CRYSTAL NEUTRON DIFFRACTION.
KOETZLE,T.F.
2001-03-13
Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.
Polychromatic diffraction contrast tomography
King, A., E-mail: king@synchrotron-soleil.fr [Synchrotron SOLEIL, Gif-sur-Yvette 91192 (France); Reischig, P. [Xnovo Technology ApS, 4600 Køge (Denmark); Department of Materials Science and Engineering, Delft University of Technology, Delft 2628 CD (Netherlands); Adrien, J. [MATEIS, INSA de Lyon, Villeurbanne 69621 (France); Peetermans, S. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Ludwig, W. [MATEIS, INSA de Lyon, Villeurbanne 69621 (France); European Synchrotron Radiation Facility, Grenoble 38043 (France)
2014-11-15
This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented.
Eichner, Adina; Sonnenberger, Stefan; Dobner, Bodo; Hauß, Thomas; Schroeter, Annett; Neubert, Reinhard H H
2016-11-01
The outermost layer of the mammalian skin, the stratum corneum (SC), is a very thin structure and realizes simultaneously the main barrier properties. The penetration barrier for xenobiotica is mostly represented by a complex lipid matrix. There is great interest in the subject of getting information about the arrangement of the lipids, which are mainly ceramides (CER), free fatty acids (FFA) and cholesterol (CHOL). SC lipid model membranes containing synthetically derived lipids in a non-physiological ratio were investigated. To compare the study to a former experiment, a methyl-branched ceramide [EOS] species in presence of the ultra-long chain CER[AP], CHOL and behenic acid (23/10/33/33, wt%) was applied. The membrane structure was studied using the very versatile technique of neutron diffraction. We were able to identify a long-periodicity phase (LPP) with a size of 114Å or 118Å with CER[EOS]-br in a ratio of >60wt% of the ceramides. Furthermore, we figured out two additional coexisting short-periodicity phases (SPP) with repeat distances of 48Å and 45Å, respectively. Partial deuterations of CER[EOS]-br and CER[AP] enabled the localization of the molecules within the multiphase system. CER[EOS]-d3 was present in the LPP, but absent in both SPP. CER[AP]-d3 was determined in both short phases but not localized within the LPP. Besides, we revealed influences of humidity and time with respect to the long-periodicity phase. Copyright © 2016 Elsevier B.V. All rights reserved.
Miyasaka, Keiichi; Hano, Hiroko; Kubota, Yoshiki; Lin, Yangzheng; Ryoo, Ryong; Takata, Masaki; Kitagawa, Susumu; Neimark, Alexander V; Terasaki, Osamu
2012-08-13
We present a modeling scheme to analyze cagelike silica mesoporous crystals based on in situ X-ray diffraction (XRD) data collected during gas adsorption-desorption (physisorption) processes. Nitrogen physisorption on a silica mesoporous crystal of SBA-16 was directly monitored by using synchrotron in situ powder XRD measurements conducted at SPring-8. SBA-16 is a well-ordered mesoporous silica in which three-dimensional interconnected cagelike primary mesopores are located at the body-centered cubic lattice points. In addition, the surrounding silica matrix contains random microporous and mesoporous intrawall porosities that are significantly influential to the diffusion properties, and thus important to be quantified for this media. The in situ XRD data exhibits seven Bragg reflections throughout the measurements, and the present method allows one to obtain the maximal and stand-alone information about the pore structure (for example, the mesopore size, the matrix density, the intrawall porosity, and pore surface roughness) together with the nitrogen film evolution in the primary mesopores and the intrawall pore-filling in the silica matrix. We furthermore observe a macroscopic amount of nitrogen adsorbed assuming the density of the fluid, and confirm that the XRD "isotherm" recalculated from the analysis result is consistent with the conventional nitrogen isotherm on a semi-quantitative level; however, these results suggest that the intrawall pores would have a greater contribution to the adsorption than considered based on the conventional isotherm analyses. The present method is readily extendable to any ordered mesopores wrapped by the wall matrix containing a certain intrawall porosity.
Bhaway, Sarang M; Qiang, Zhe; Xia, Yanfeng; Xia, Xuhui; Lee, Byeongdu; Yager, Kevin G; Zhang, Lihua; Kisslinger, Kim; Chen, Yu-Ming; Liu, Kewei; Zhu, Yu; Vogt, Bryan D
2017-02-28
Emergent lithium-ion (Li(+)) batteries commonly rely on nanostructuring of the active electrode materials to decrease the Li(+) ion diffusion path length and to accommodate the strains associated with the insertion and de-insertion of Li(+), but in many cases these nanostructures evolve during electrochemical charging-discharging. This change in the nanostructure can adversely impact performance, and challenges remain regarding how to control these changes from the perspective of morphological design. In order to address these questions, operando grazing-incidence small-angle X-ray scattering and X-ray diffraction (GISAXS/GIXD) were used to assess the structural evolution of a family of model ordered mesoporous NiCo2O4 anode films during battery operation. The pore dimensions were systematically varied and appear to impact the stability of the ordered nanostructure during the cycling. For the anodes with small mesopores (≈9 nm), the ordered nanostructure collapses during the first two charge-discharge cycles, as determined from GISAXS. This collapse is accompanied by irreversible Li-ion insertion within the oxide framework, determined from GIXD and irreversible capacity loss. Conversely, anodes with larger ordered mesopores (17-28 nm) mostly maintained their nanostructure through the first two cycles with reversible Li-ion insertion. During the second cycle, there was a small additional deformation of the mesostructure. This preservation of the ordered structure lead to significant improvement in capacity retention during these first two cycles; however, a gradual loss in the ordered nanostructure from continuing deformation of the ordered structure during additional charge-discharge cycles leads to capacity decay in battery performance. These multiscale operando measurements provide insight into how changes at the atomic scale (lithium insertion and de-insertion) are translated to the nanostructure during battery operation. Moreover, small changes in the
Raulot, Victorien; Gérard, Philippe; Serio, Bruno; Flury, Manuel; Kress, Bernard; Meyrueis, Patrick
2010-08-16
A new rigorous vector-based design and analysis approach of diffractive lenses is presented. It combines the use of two methods: the Finite-Difference Time-Domain for the study in the near field, and the Radiation Spectrum Method for the propagation in the far field. This approach is proposed to design and optimize effective medium cylindrical diffractive lenses for high efficiency structured light illumination systems. These lenses are realised with binary subwavelength features that cannot be designed using the standard scalar theory. Furthermore, because of their finite and high frequencies characteristics, such devices prevent the use of coupled wave theory. The proposed approach is presented to determine the angular tolerance in the cases of binary subwavelength cylindrical lenses by calculating the diffraction efficiency as a function of the incidence angle.
Mao, Shan; Cui, Qingfeng; Piao, Mingxu; Zhao, Lidong
2016-05-01
A mathematical model of diffraction efficiency and polychromatic integral diffraction efficiency affected by environment temperature change and incident angle for three-layer diffractive optics with different dispersion materials is put forward, and its effects are analyzed. Taking optical materials N-FK5 and N-SF1 as the substrates of multilayer diffractive optics, the effect on diffraction efficiency and polychromatic integral diffraction efficiency with intermediate materials POLYCARB is analyzed with environment temperature change as well as incident angle. Therefore, three-layer diffractive optics can be applied in more wide environmental temperature ranges and larger incident angles for refractive-diffractive hybrid optical systems, which can obtain better image quality. Analysis results can be used to guide the hybrid imaging optical system design for optical engineers.
Diffractive Dijet Photoproduction
Klasen, M
2005-01-01
We have calculated diffractive dijet production in deep-inelastic scattering (DIS) at low-Q^2 and next-to-leading order (NLO) of perturbative QCD, including contributions from direct and resolved photons. We study how the cross section depends on the factorization scheme and scale M_\\gamma at the virtual photon vertex for the occurance of factorization breaking. The strong M_\\gamma-dependence, which is present when only the resolved cross section is suppressed, is tamed by intodrucing the suppression also in the initial-state NLO correction of the direct part.
Higher Order Diffraction Characteristics of Fiber Bragg Grating
Sunita P. Ugale
2013-02-01
Full Text Available The effect of grating saturation on higher order diffraction characteristic of FBG is investigated by using Coupled mode theory. Grating saturation effects were considered in the index distribution model showing the significant influence on the coupling process and hence on the reflectivity characteristics of FBG. Maximum reflectivity curves for first and higher order diffraction of FBG are plotted for different values of saturation coefficient. The effect of change in length and change in refractive index are studied. The behavior of grating for higher order of diffraction is totally different than first order of diffraction. In saturated gratings, the higher order diffraction can be utilized for multiparameter sensing
Inclusive Hard Diffraction at HERA
Proskuryakov, Alexander
2010-01-01
Recent data from the H1 and ZEUS experiments on hard inclusive diffraction are discussed. Results of QCD analyses of the diffractive deep-inelastic scattering processes are reported. Predictions based on the extracted parton densities are compared to diffractive dijet measurements.
Field Guide to Diffractive Optics
Soskind, Yakov
2011-01-01
This SPIE Field Guide provides the operational principles and established terminology of diffractive optics as well as a comprehensive overview of the main types of diffractive optics components. An emphasis is placed on the qualitative explanation of the diffraction phenomenon by the use of field distributions and graphs, providing the basis for understanding the fundamental relations and important trends.
de Sousa Neto, Diogenes; Gooris, Gert; Bouwstra, Joke
2011-03-01
The lipid organization in the outermost layer of the skin, the stratum corneum, is important for the skin barrier function. The stratum corneum lipids are composed of ceramides (CER), free fatty acids (FFA) and cholesterol (CHOL). In the present study Fourier transform infrared (FTIR) and small-angle X-ray scattering (SAXS) techniques were utilized to evaluate the effect of three C18 fatty acid esterified ω-acylceramides (CER EOS) on the lipid organization of stratum corneum model membranes. FTIR spectra (scissoring and rocking bands) showed as a function of temperature significant line-shape changes for both components assigned to the orthorhombic phase. Second-derivative analyzes revealed a significant decrease in the interchain coupling strength (Δν values) for the samples formed by CER EOS with the linoleate (CER EOS-L) and oleate (CER EOS-O) moiety around 28.5°C. However, only a gradual decrease in the Δν values was noticed for the mixture formed with CER EOS with the stearate moiety (CER EOS-S) over the whole temperature range. In the absence of CER EOS the decrease started already at 25.5°C, demonstrating that CER EOS stabilized the orthorhombic lattice. This stabilization was most pronounced for the CER EOS-S. Spectral fittings allowed to evaluate the orientation changes of the skeletal plane within the orthorhombic unit cell (θ values) for a given temperature range. From the best-fit parameters (peak area values), a decrease in the orthorhombic phase contribution to the scissoring band was also monitored as a function of the temperature. SAXS studies showed the coexistence of two lamellar phases with a periodicity of ∼5.5 nm (short periodicity phase, SPP) and ∼12 nm (LPP) in the presence of the CER EOS-L and CER EOS-O. However, no diffraction peaks associated to the LPP were detected for CER EOS-S. While CER EOS-S most efficiently stabilized the orthorhombic phase, CER EOS-L and CER EOS-O promoted the presence of the LPP. Therefore, the
Sitepu, H; Dreele, R B V
2002-01-01
We present a feasibility study to extract quantitative texture and precise crystal structure information of polycrystalline monoclinic NiTi shape-memory alloys from a simultaneous refinement of 52 time-of-flight neutron-diffraction patterns taken in 13 orientations in the diffractometer. The multiple-data-set capabilities and the generalized spherical harmonic texture model of the GSAS program system were employed. (orig.)
Birefringent coherent diffraction imaging
Karpov, Dmitry; dos Santos Rolo, Tomy; Rich, Hannah; Kryuchkov, Yuriy; Kiefer, Boris; Fohtung, E.
2016-10-01
Directional dependence of the index of refraction contains a wealth of information about anisotropic optical properties in semiconducting and insulating materials. Here we present a novel high-resolution lens-less technique that uses birefringence as a contrast mechanism to map the index of refraction and dielectric permittivity in optically anisotropic materials. We applied this approach successfully to a liquid crystal polymer film using polarized light from helium neon laser. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of emergent brilliant X-ray sources. Applications of this novel imaging technique are in disruptive technologies, including novel electronic devices, in which both charge and spin carry information as in multiferroic materials and photonic materials such as light modulators and optical storage.
Study of Diffraction with the ATLAS detector at the LHC
Rafal, Staszewski; Royon, Christophe
The thesis is devoted to the study of diffractive physics with the ATLAS detector at the LHC. After a short introduction to diffractive physics including soft and hard diffraction, we discuss diffractive exclusive production at the LHC whichis particularly interesting for Higgs and jet production. The QCD mechanism described by the Khoze Martin Ryskin and the CHIDe models are elucidated in detail. The uncertainties on these models are still large and a new possible exclusive jetmeasurement at the LHC will allow to reduce the uncertainty on diffarctive Higgs boson production to a factor 2 to 3. An additional measurement of exclusive pion production pp ! p_+_−p allows to constrain further exclusive model relying on theuse of the ALFA stations, which are used in the ATLAS Experiment for detection of protons scattered in elastic and diffractive interactions. In the last part of the thesis, the AFP detectors, aiming at measuring the protons scattered in diffractive interactions, are presented. They allow to exte...
Okido, Shinobu; Hayashi, Makoto [Hitachi Ltd., Tokyo (Japan); Morii, Yukio; Minakawa, Nobuaki; Tsuchiya, Yoshinori
1997-06-01
In a residual stress measurement by x-ray diffraction method and a neutron diffraction method, strictly speaking, the strain measurement of various diffracted surface was conducted and it is necessary to use its elastic modulus to convert from the strain to the stress. Then, in order to establish the residual stress measuring technique using neutron diffraction, it is an aim at first to make clear a diffraction surface dependency of elastic modulus for the stress conversion in various alloys. As a result of investigations the diffraction surface dependency of elastic module on SUS304 and STS410 steels by using RESA (Neutron diffractometer for residual stress analysis) installed at JRR-3M in Tokai Establishment of JAERI, following results are obtained. The elastic modulus of each diffraction surface considering till plastic region could be confirmed to be in a region of {+-}20% of that calculated by Kroner`s model and to be useful for that used on conversion to the stress. And, error of this elastic modulus was thought to cause the transition and defect formed at inner portion of the materials due to a plastic deformation. (G.K.)
GENERALIZED FRESNEL DIFFRACTION INTEGRAL AND ITS APPLICATIONS
YANG JUN; FAN DIAN-YUAN; WANG SHI-JI; GU YUAN
2000-01-01
Within the generalized definition of ABCDGH matrices, the conventional ABCDGH diffraction integral is ex-tended for a misaligned complex paraxial system with a curved optical axis. On this basis the transformation lawfor Gaussian-Schell model beams through an ABCDGH systems is derived, the propagation behavior of the mutualcoherence function through ABCDGH systems in the presence of random media is investigated as well.
Diffraction and diffusion in room acoustics
Rindel, Jens Holger; Rasmussen, Birgit
1996-01-01
that are not plane but curved or irregular. The importance of diffusion has been demonstrated in concert halls. Methods for the design of diffusing surfaces and the development of new types of diffusers are reviewed. Finally, the importance of diffraction and diffusion in room acoustic computer models is discussed....
Diffraction manipulation by four-wave mixing
Katzir, Itay; Firstenberg, Ofer
2014-01-01
We suggest a scheme to manipulate paraxial diffraction by utilizing the dependency of a four-wave mixing process on the relative angle between the light fields. A microscopic model for four-wave mixing in a Lambda-type level structure is introduced and compared to recent experimental data. We show that images with feature size as low as 10 micrometers can propagate with very little or even negative diffraction. The inherent gain prevents loss and allows for operating at high optical depths. Our scheme does not rely on atomic motion and is thus applicable to both gaseous and solid media.
Factorization breaking in diffractive dijet photoproduction
Klasen, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik]|[Centre National de la Recherche Scientifique, 38 - Grenoble (France). Univ. Joseph Fourier, Lab. de Physique Subatomique et de Cosmologie; Kramer, G. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2004-08-01
We have calculated the diffractive dijet cross section in low-Q{sup 2} ep scattering in the HERA regime. The results of the calculation in LO and NLO are compared to recent experimental data of the H1 collaboration. We find that in LO the calculated cross sections are in reasonable agreement with the experimental results. In NLO, however, some of the cross sections disagree, showing that factorization breaking occurs in that order. By suppressing the resolved contribution by a factor of approximately three, good agreement with all the data is found. The size of the factorization breaking effects in diffractive dijet photoproduction agrees well with absorptive model predictions. (orig.)
Factorization breaking in diffractive dijet photoproduction
Klasen, M. [Universite Joseph Fourier, CNRS-IN2P3, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Universitaet Hamburg, II. Institut fuer Theoretische Physik, Hamburg (Germany); Kramer, G. [Universitaet Hamburg, II. Institut fuer Theoretische Physik, Hamburg (Germany)
2004-12-01
We have calculated the diffractive dijet cross section in low-Q{sup 2} ep scattering in the HERA regime. The results of the calculation in LO and NLO are compared to recent experimental data of the H1 Collaboration. We find that in LO the calculated cross sections are in reasonable agreement with the experimental results. In NLO, however, some of the cross sections disagree, showing that factorization breaking occurs in that order. By suppressing the resolved contribution by a factor of approximately three, good agreement with all the data is found. The size of the factorization breaking effects in diffractive dijet photoproduction agrees well with absorptive model predictions. (orig.)
Study of optical Laue diffraction
Chakravarthy, Giridhar, E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com; Allam, Srinivasa Rao, E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com; Satyanarayana, S. V. M., E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com; Sharan, Alok, E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com [Department of Physics, Pondicherry University, Puducherry-605014 (India)
2014-10-15
We present the study of the optical diffraction pattern of one and two-dimensional gratings with defects, designed using desktop pc and printed on OHP sheet using laser printer. Gratings so prepared, using novel low cost technique provides good visual aid in teaching. Diffraction pattern of the monochromatic light (632.8nm) from the grating so designed is similar to that of x-ray diffraction pattern of crystal lattice with point defects in one and two-dimensions. Here both optical and x-ray diffractions are Fraunhofer. The information about the crystalline lattice structure and the defect size can be known.
Phenomenology of hard diffraction at high energies
Machado, Magno V T
2016-01-01
We present some of the topics covered in two lectures under the same title that was given at the "Summer School on High Energy Physics at the LHC: New trends in HEP" in Natal, Brazil. In this contribution we give a brief review on the application of perturbative QCD to the hard diffractive processes. Such reactions involving a hard scale can be understood in terms of quarks and gluons degrees of freedom and have become an useful tool for investigating the low-$x$ structure of the proton and the behavior of QCD in the high-density regime. We start using the information from the $ep$ collisions at HERA concerned to the inclusive diffraction to introduce the concept of diffractive parton distributions. Their interpretation in the resolved pomeron model is addressed and we discuss the limits of diffractive hard-scattering factorization for hadron-hadron collisions. Some examples of phenomenology for the diffractive production of $W/Z$, heavy $Q\\bar{Q}$ and quarkonium in hadron-hadron reactions are presented. We a...
Higher order diffractions from a circular disk
Marsland, Diane P.; Balanis, Constantine A.; Brumley, Stephen A.
1987-12-01
The backscattering from a circular disk is analyzed using the geometrical theory of diffraction. First-, second-, and third-order diffractions are included in the hard polarization analysis, while first-, second-, and third-order slope diffractions are included for soft polarization. Improvements in the prediction of the monostatic radar cross section over previous works are noted. For hard polarization, an excellent agreement is exhibited between experimental and theoretical results, while a very good agreement is noted for soft polarization. To further improve the soft polarization results for wide angles, a model for the creeping wave or circulating current on the edge of the disk is obtained and used to find an additional component of the backscattered field. The addition of this component significantly improves the results for wide angles, leading to excellent agreement for soft polarization also. An axial-caustic correction method using equivalent currents is also included in the analysis.
Diffraction manipulation by four-wave mixing.
Katzir, Itay; Ron, Amiram; Firstenberg, Ofer
2015-03-09
We suggest a scheme to manipulate paraxial diffraction by utilizing the dependency of a four-wave mixing process on the relative angle between the light fields. A microscopic model for four-wave mixing in a Λ-type level structure is introduced and compared to recent experimental data. We show that images with feature size as low as 10 μm can propagate with very little or even negative diffraction. The mechanism is completely different from that conserving the shape of spatial solitons in nonlinear media, as here diffraction is suppressed for arbitrary spatial profiles. At the same time, the gain inherent to the nonlinear process prevents loss and allows for operating at high optical depths. Our scheme does not rely on atomic motion and is thus applicable to both gaseous and solid media.
Diffractive hadronic production of D mesons
MacKay, William Wallace [Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Physcis
1980-01-01
This thesis reports on data taken in experiment E369 using the Chicago Cyclotron Spectrometer at Fermilab. A search for charmed D mesons was made using a beam of 217 GeV π^{-} incident on a liquid hydrogen target. The trigger required a recoil proton and a prompt muon. A total of 50 ± 12 charged D events were seen in the K^{±}π^{∓}π^{∓} channels and were split between the two channels in about equal amounts. Cuts were made which selected diffractive events, but when these cuts were removed the signal remained the same although the background was greatly increased. The Feynman x and angular distributions were consistent with diffractive production. A diffractive model yields a cross section of (6 -10) + 4 µb.
Liu, Zhongxian; Liang, Jianwen; Wu, Chengqing
2016-06-01
Two dimensional diffraction of Rayleigh waves by a fluid-saturated poroelastic alluvial valley of arbitrary shape in a poroelastic half-space is investigated using the method of fundamental solutions (MFS). To satisfy the free surface boundary conditions exactly, Green's functions of compressional (PI and PII) and shear (SV) wave sources buried in a fluid-saturated poroelastic half-space are adopted. Next, the procedure for solving the scattering wave field is presented. It is verified that the MFS is of excellent accuracy and numerical stability. Numerical results illustrate that the dynamic response strongly depends on such factors as the incident frequency, the porosity of alluvium, the boundary drainage condition, and the valley shape. There is a significant difference between the diffraction of Rayleigh waves for the saturated soil case and for the corresponding dry soil case. The wave focusing effect both on the displacement and pore pressure can be observed inside the alluvial valley and the amplification effect seems most obvious in the case of higher porosity and lower frequency. Additionally, special attention should also be paid to the concentration of pore pressure, which is closely related to the site liquefaction in earthquakes.
Introduction of acoustical diffraction in the radiative transfer method
Reboul, Emeline; Le Bot, Alain; Perret-Liaudet, Joël
2004-07-01
This Note presents an original approach to include diffraction in the radiative transfer method when applied to acoustics. This approach leads to a better spatial description of the acoustical energy. An energetic diffraction coefficient and some diffraction sources are introduced to model the diffraction phenomena. The amplitudes of these sources are determined by solving a linear sytem of equations resulting from the power balance between all acoustical sources. The approach is applied on bidimensional examples and gives good results except at geometrical boundaries. To cite this article: E. Reboul et al., C. R. Mecanique 332 (2004).
Vectorial diffraction of extreme ultraviolet light and ultrashort light pulses
Nugrowati, A.M.
2008-01-01
In this thesis, we present applications in optics involving the diffraction theory of light for two advanced technologies. We have used a rigorous vectorial diffraction method to model: (i) the imaging of mask structures in extreme ultraviolet lithography, and (ii) ultrashort pulse propagation thro
Grazing incidence diffraction : A review
Gilles, B. [LTPCM, ENSEEG. St. Martin d`Heres. (France)
1996-09-01
Different Grazing Incidence Diffraction (GID) methods for the analysis of thin films and multilayer structures are reviewed in three sections: the reflectivity is developed in the first one, which includes the non-specular diffuse scattering. The second one is devoted to the extremely asymmetric Bragg diffraction and the third one to the in-plane Bragg diffraction. Analytical formulations of the scattered intensities are developed for each geometry, in the framework of the kinetical analysis as well as the dynamical theory. Experimental examples are given to illustrate the quantitative possibility of the GID techniques.
The diffractive achromat full spectrum computational imaging with diffractive optics
Peng, Yifan
2016-07-11
Diffractive optical elements (DOEs) have recently drawn great attention in computational imaging because they can drastically reduce the size and weight of imaging devices compared to their refractive counterparts. However, the inherent strong dispersion is a tremendous obstacle that limits the use of DOEs in full spectrum imaging, causing unacceptable loss of color fidelity in the images. In particular, metamerism introduces a data dependency in the image blur, which has been neglected in computational imaging methods so far. We introduce both a diffractive achromat based on computational optimization, as well as a corresponding algorithm for correction of residual aberrations. Using this approach, we demonstrate high fidelity color diffractive-only imaging over the full visible spectrum. In the optical design, the height profile of a diffractive lens is optimized to balance the focusing contributions of different wavelengths for a specific focal length. The spectral point spread functions (PSFs) become nearly identical to each other, creating approximately spectrally invariant blur kernels. This property guarantees good color preservation in the captured image and facilitates the correction of residual aberrations in our fast two-step deconvolution without additional color priors. We demonstrate our design of diffractive achromat on a 0.5mm ultrathin substrate by photolithography techniques. Experimental results show that our achromatic diffractive lens produces high color fidelity and better image quality in the full visible spectrum. © 2016 ACM.
Results of Soft-Diffraction at LHCb
Meissner, Marco
2013-01-01
The LHCb detector with its unique pseudorapidity coverage allows to perform soft-QCD measurements in the kinematic forward region where QCD models have large uncertainties. Selected analyses related to soft-Diffraction will be summarised in these proceedings. Energy flow and charged particle multiplicity have been measured separately in different event classes. They give input for modelling the underlying event in $pp$ collisions. Prompt hadron ratios are important for hadronisation models, while the $p/p$ ratio is a good observable to test models of baryon number transport.
Transurethral Ultrasound Diffraction Tomography
2006-03-01
scattering inverse source theory, J. Math. Phys., pp. 1647-1650, 1981. [8] A.J. Devaney, and G.C. Sherman: Nonuniqueness in inverse source and...models, Ph.D. Thesis, Dept. of Electrical Engineering , University of Utah, Salt Lake City, 1989. [27] X.M. Xu and Q.H. Liu: Fast Spectral-Domain Method
Ross, Marc H.
This monograph was written for the Conference on the New Instructional Materials in Physics, held at the University of Washington in summer, 1965. The measurement of very small distances and sizes, and the concept of models are discussed in the introduction. The optics of slits is dealt with in chapter 2. Chapter 3 presents the optics of holes.…
Advances in powder diffraction analysis
Louer, D. [Lab. de Chimie du Solide et Inorganique Moleculaire, Rennes (France). Groupe de Cristallochimie
1998-11-01
Powder diffraction offers a wide spectrum of applications to solid-state scientists. The method traditionally used for phase analysis and the study of structural imperfections has benefited, in the last twenty years, from great advances in the instrumentation and computer-based approaches for pattern indexing and modelling. The factors at the origin of the metamorphosis of the method are presented. The major modern applications reported include quantitative analysis and the extraction of three-dimensional structural and microstructural properties. The use of pattern-fitting techniques for the characterization of the microstructure is discussed through applications to nanocrystalline materials. Remarkable results achieved in the solution of crystal structures are presented, as well as the impact in solid-state chemistry of powder crystallography, particularly for elucidating the crystal chemistry of families of compounds for which only powders are available. New strategies for solving the phase problem have been introduced and new classes of solids are being studied, such as drugs, coordination and organic compounds. (orig.) 100 refs.
Atoms in parallel fields: Analysis with diffractive periodic orbits
Owen, S. M.; Monteiro, T. S.; Dando, P. A.
2000-11-01
We show that fluctuations in the density of states of nonhydrogenic atoms in parallel fields are strongly influenced by diffractive periodic orbits. Unlike typical systems with a diffractive point scatterer, the atomic core of small atoms like lithium and helium is best understood as a combined geometric and diffractive scatterer. Each Gutzwiller (geometric) periodic orbit is paired with a diffractive orbit of the same action. We investigate, particularly, amplitudes for contributions from repetitions, and multiple scattering orbits. We find that periodic orbit repetitions are described by ``hybrid'' orbits, combining both diffractive and geometric core scatters, and that by including all possible permutations we can obtain excellent agreement between the semiclassical model and accurate fully quantal calculations. For high repetitions, we find even one-scatter diffractive contributions become of the same order as those of the geometric periodic orbit for repetition numbers n~ħ-1/2. Although the contribution of individual diffractive orbits is suppressed by O(ħ1/2) relative to the geometric periodic orbits, the proliferation of diffractive orbits with increasing period means that the diffractive effect for the atom can persist in the ħ-->0 limit.
Multiple annular linear diffractive axicons.
Bialic, Emilie; de la Tocnaye, Jean-Louis de Bougrenet
2011-04-01
We propose a chromatic analysis of multiple annular linear diffractive axicons. Large aperture axicons are optical devices providing achromatic nondiffracting beams, with an extended depth of focus, when illuminated by a white light source, due to chromatic foci superimposition. Annular apertures introduce chromatic foci separation, and because chromatic aberrations result in focal segment axial shifts, polychromatic imaging properties are partially lost. We investigate here various design parameters that can be used to achieve color splitting, filtering, and combining using these properties. In order to improve the low-power efficiency of a single annular axicon, we suggest a spatial multiplexing of concentric annular axicons with different sizes and periods we call multiple annular aperture diffractive axicons (MALDAs). These are chosen to maintain focal depths while enabling color imaging with sufficient diffraction efficiency. Illustrations are given for binary phase diffractive axicons, considering technical aspects such as grating design wavelength and phase dependence due to the grating thickness.
Unified approach to hard diffraction
Peschanski, R
2001-01-01
Using a combination of S-Matrix and perturbative QCD properties in the small x_{Bj} regime, we propose a formulation of hard diffraction unifying the partonic (Ingelman-Schlein) Pomeron, Soft Colour Interaction and QCD dipole descriptions.
Blake, David F. (Inventor); Bryson, Charles (Inventor); Freund, Friedmann (Inventor)
1996-01-01
An x-ray diffraction apparatus for use in analyzing the x-ray diffraction pattern of a sample is introduced. The apparatus includes a beam source for generating a collimated x-ray beam having one or more discrete x-ray energies, a holder for holding the sample to be analyzed in the path of the beam, and a charge-coupled device having an array of pixels for detecting, in one or more selected photon energy ranges, x-ray diffraction photons produced by irradiating such a sample with said beam. The CCD is coupled to an output unit which receives input information relating to the energies of photons striking each pixel in the CCD, and constructs the diffraction pattern of photons within a selected energy range striking the CCD.
Bugaev, A. L.; Guda, A. A.; Yefanov, O. M.; Lorenz, U.; Soldatov, A. V.; Vartanyants, I. A.
2016-05-01
The development of the next generation synchrotron radiation sources - free electron lasers - is approaching to become an effective tool for the time-resolved experiments aimed to solve actual problems in various fields such as chemistry’ biology’ medicine’ etc. In order to demonstrate’ how these experiments may be performed for the real systems to obtain information at the atomic and macromolecular levels’ we have performed a molecular dynamics computer simulation combined with quantum chemistry calculations for the human phosphoglycerate kinase enzyme with Mg containing substrate. The simulated structures were used to calculate coherent X-ray diffraction patterns’ reflecting the conformational state of the enzyme, and Mg K-edge X-ray absorption spectra, which depend on the local structure of the substrate. These two techniques give complementary information making such an approach highly effective for time-resolved investigation of various biological complexes, such as metalloproteins or enzymes with metal-containing substrate, to obtain information about both metal-containing active site or substrate and the atomic structure of each conformation.
New CDF results on diffraction
Mesropian, Christina; /Rockefeller U.
2006-12-01
We report new diffraction results obtained by the CDF collaboration in proton-antiproton collisions at the Fermilab Tevatron collider at {radical}s=1.96 TeV. The first experimental evidence of exclusive dijet and diphoton production is presented. The exclusive results are discussed in context of the exclusive Higgs production at LHC. We also present the measurement of the Q{sup 2} and t dependence of the diffractive structure function.
Diffraction method of vocal chord oscillation sensing
Kuzmin, Sergey Y.; Tuchin, Valery V.
1996-04-01
A method of small-amplitude biovibrations detection is presented in the paper. The method uses a dependence of properties of speckle-structures formed by focused coherent light field diffraction from rough surfaces on the statistics and movement parameters of the surface. With the help of computer modeling the different components of skin surface vibration were analyzed and their influence on speckles dynamics was studied. Human vocal chord oscillations spectrum was monitored using the developed technique.
董平; 王虹; 李建; 孙光爱; 廖哲; 杨江荣
2015-01-01
利用稳态堆上的中子衍射应力谱仪开展了铍环激光焊接后的残余应力测试.先进行铍材中子衍射应力测试的参数及其优化研究 ,在固定堆功率、衍射晶面和规范体积的条件下 ,选取测试时间分别为600 s和6 000 s进行铍环上同一点的中子衍射峰的重复性测试 ,结果表明 ,后者测试铍材应变的统计误差仅为前者的1/3 ,其标准偏差约为1. 10 × 10-5 .取后者测试时间作为优化参数 ,对铍环焊缝附近轴向应变和环向应变方向的中子衍射峰进行测试 ,获得两个方向的残余应变分布 ,进一步计算出焊接残余应力分布.对铍环激光焊接过程的温度场和应力场进行三维有限元数值模拟 ,将有限元计算得到的铍环焊缝附近中间壁厚处的残余应力和应变与中子衍射测试结果进行对比 ,结果表明二者分布规律较为一致 .%The residual stresses in a laser welded beryllium ring were measured using neutron diffraction stress instrument on a stable reactor .Firstly ,the parameters of neu-tron diffraction stress measurement for beryllium were studied and optimized .Keeping the reactor power ,diffraction plane and gauge volume fixed ,the neutron diffraction curves at a point in the beryllium ring were measured repeatedly by using the measure time of 600 s and 6 000 s ,then the statistical errors for the strains of beryllium were deduced ,w hich for the later is only 1/3 of the former ,and the standard error is about 1.10 × 10-5 .The neutron diffraction curves along axial strain and hoop strain near the weld line of the beryllium ring were measured using the optimized time 6 000 s .Both of the residual strains in the beryllium ring were obtained ,and the residual stresses were also calculated . The temperature and stress fields in the beryllium ring during laser welding process were simulated by using a 3D finite element model . The computed residual stress and strain at the middle of thick wall in
J. Reséndiz-Muñoz
2017-01-01
Full Text Available A novel procedure based on the use of the Boltzmann equation to model the x parameter, the film deposition rate, and the optical band gap of BaxSr1−xTiO3 thin films is proposed. The BaxSr1−xTiO3 films were prepared by RF cosputtering from BaTiO3 and SrTiO3 targets changing the power applied to each magnetron to obtain different Ba/Sr contents. The method to calculate x consisted of fitting the angular shift of (110, (111, and (211 diffraction peaks observed as the density of substitutional Ba2+ increases in the solid solution when the applied RF power increases, followed by a scale transformation from applied power to x parameter using the Boltzmann equation. The Ba/Sr ratio was obtained from X-ray energy dispersive spectroscopy; the comparison with the X-ray diffraction derived composition shows a remarkable coincidence while the discrepancies offer a valuable diagnosis on the sputtering flux and phase composition. The proposed method allows a quick setup of the RF cosputtering system to control film composition providing a versatile tool to optimization of the process.
Catti, Michele, E-mail: michele.catti@mater.unimib.it [Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, I-20125 Milano (Italy); Pinus, Ilya [Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, I-20125 Milano (Italy); Knight, Kevin [ISIS Facility, CCLRC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)
2015-09-15
TiNb{sub 2}O{sub 7}, a good candidate as anode in lithium batteries, was treated with n-butyllithium to synthesize Li{sub x}TiNb{sub 2}O{sub 7} phases similar to those formed during electrochemical reactions. The Li{sub 2.67}TiNb{sub 2}O{sub 7} and Li{sub 3.33}TiNb{sub 2}O{sub 7} compounds, monoclinic C2/m, were studied by time-of-flight powder neutron diffraction. Their crystal structures, containing 3×3 blocks of (Ti,Nb)O{sub 6} octahedra, were Rietveld refined including Li positions. The Li atoms are distributed in similar amounts over sites with (Li–O) Coordination Numbers 5 and 4, although CN=5 should be preferred for having lower energy. Quantum-mechanical calculations were also performed, determining the average charge–discharge voltages to be 1.415 and 1.571 V for Li{sub 3.33}TiNb{sub 2}O{sub 7} and Li{sub 2.67}TiNb{sub 2}O{sub 7}, respectively, in good agreement with experimental results. An analysis of the theoretical charge distribution shows that, on lithiation, the chemical reduction of Ti and Nb atoms concentrates in the more condensed peripheral octahedra of the 3×3 block. This corresponds to electrons moving into a partly spin-polarized small band which gives rise to semi-metallic conductivity. - Graphical abstract: Structure of monoclinic Li{sub 3.33}TiNb{sub 2}O{sub 7}, and corresponding electron density of states. - Highlights: • Lithium was chemically inserted into the battery anode material TiNb{sub 2}O{sub 7}. • Li atoms are distributed over four- and fivefold oxygen coordinated sites. • On lithiation Nb and Ti atoms are reduced according to a peculiar structural pattern. • Theoretically predicted charge–discharge voltages fit experiments very well.
Enhancing electron diffraction through precession
Pavia, Giuseppe; Benner, Gerd; Niebel, Harald [Carl Zeiss NTS, Oberkochen (Germany); Patout, Loic [ONERA, Paris (France)
2011-07-01
Nanostructures are often investigated in Transmission Electron Microscopy (TEM), and electron diffraction (ED) can be used to solve nanocrystals. Electrons interact very strongly with matter, and the diffracted intensities are highly dynamical. Precession Electron Diffraction (PED) is a recent technique delivering more kinematical diffraction patterns. We have used an in column energy filtered TEM equipped with precession electron diffraction hardware, which allows working up to 3 precession angle, and energy filtering of the precession patterns. High Order Laue Zones, useful for space group symmetry determination and to enhance fine structure details, appear more clearly. We have compared a microdiffraction pattern and a precession microdiffraction pattern performed along the orientation [010] of a sample TiSi{sub 2} with a space group Fddd. For cubic systems, this orientation allows to distinguish the Bravais lattice and the presence of glide mirrors. We show that with precession, we conserve the distinction of the gap and the difference of periodicity between the ZOLZ and the FOLZ is improved.
2005-03-31
Model 4005) TEC has found that residual stress measurements can be made through thin layers of paint on steel surfaces (but not lead-based paints ...indicator lamp Operation and Maintenance Manual 5-11 TEC MAX System (Model 4005) 4005-OM-01 Revision 0, March 31, 2005 XRay Tube Status @ 0 20 40 60
Enhanced analysis of biomaterials by synchrotron diffraction
Rogers, K. [Cranfield Postgraduate Medical School, Cranfield University, Shrivenham, Swindon, Wiltshire, SN6 8LA (United Kingdom)]. E-mail: k.d.rogers@cranfield.ac.uk; Etok, S. [Cranfield Postgraduate Medical School, Cranfield University, Shrivenham, Swindon, Wiltshire, SN6 8LA (United Kingdom); Broadhurst, A. [Cranfield Postgraduate Medical School, Cranfield University, Shrivenham, Swindon, Wiltshire, SN6 8LA (United Kingdom); Scott, R. [Biomet-Europe, Dorcan Way, Swindon, Wiltshire, SN3 5HY (United Kingdom)
2005-08-11
There is an increasing body of evidence that prosthetic implants based upon titanium alloys attain improved performance when coated with calcium hydroxyapatite (HAP). Such coatings appear to promote osteointegration and bone in-growth. Plasma spraying is the most frequently employed route to coating fabrication. Detailed chemical and structural characterisation of these coatings is essential for (i) coating technology development (ii) ensuring consistent material quality and (iii) assessing coating performance. The work presented here employed combined conventional powder diffraction and glancing angle synchrotron diffraction to examine the in vitro performance of apatite coatings formed by plasma spraying. Coatings were exposed to simulated body fluid and foetal calf serum, and changes to the coating chemistry and structure determined. A new analysis method, synchrotron depth profiling tomography, has been applied to obtain structural features through the coating depth. The dissolution and re-precipitation behaviour of the coatings was found to be significantly different for each media. For the first time, it has been possible to identify and quantify the formation of a nanocrystalline, carbonated HAP phase. It has been possible to simultaneously model all coating phases apparent within the X-ray diffraction data and thus quantify changes to film composition. DPT has also revealed subtle changes in coating features with depth and these may have a significant impact on coating dissolution. The findings are discussed in the context of kinematic models for the coating behaviour and implications for the performance of such coatings in vivo.
Diffractive and Exclusive Measurements at CMS
Ruspa, Marta
2014-01-01
Recent measurements are discussed of inclusive and exclusive diffractive processes in pp colli- sions at √ s = 7 TeV at the LHC using the CMS detector. Results are presented of the single- and double-diffractive cross section and of the inclusive differential cross section for events with a forward rapidity gap. A study of exclusive W + W − production by two-photon exchange, where, in different kinematic regions, both con fi rmation and deviations from the Standard Model predic- tions are searched, is reported. Finally, a joint measurement with the CMS and TOTEM detectors of the pseudorapidity distribution of charged particles produced in pp collisions at √ s = 8 TeV is presented. This is the fi rst joint study between the two experiments.
Periodically distributed objects with quasicrystalline diffraction pattern
Wolny, Janusz, E-mail: wolny@fis.agh.edu.pl; Strzalka, Radoslaw [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Kuczera, Pawel [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow (Poland); Laboratory of Crystallography, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)
2015-03-30
It is possible to construct fully periodically distributed objects with a diffraction pattern identical to the one obtained for quasicrystals. These objects are probability distributions of distances obtained in the statistical approach to aperiodic structures distributed periodically. The diffraction patterns have been derived by using a two-mode Fourier transform—a very powerful method not used in classical crystallography. It is shown that if scaling is present in the structure, this two-mode Fourier transform can be reduced to a regular Fourier transform with appropriately rescaled scattering vectors and added phases. Detailed case studies for model sets 1D Fibonacci chain and 2D Penrose tiling are discussed. Finally, it is shown that crystalline, quasicrystalline, and approximant structures can be treated in the same way.
X-ray diffraction with novel geometry
Prokopiou, Danae [Department of Engineering and Applied Science Cranfield University, Shrivenham Campus, Swindon (United Kingdom); Rogers, Keith, E-mail: k.d.rogers@cranfield.ac.uk [Department of Engineering and Applied Science Cranfield University, Shrivenham Campus, Swindon (United Kingdom); Evans, Paul; Godber, Simon [Imaging Science Group, School of Science and Technology, Nottingham Trent University Clifton Campus, Nottingham (United Kingdom); Shackel, James [Department of Engineering and Applied Science Cranfield University, Shrivenham Campus, Swindon (United Kingdom); Dicken, Anthony [Imaging Science Group, School of Science and Technology, Nottingham Trent University Clifton Campus, Nottingham (United Kingdom)
2014-01-21
An innovative geometry for high efficiency harvesting of diffracted X-rays is explored. Further to previous work where planar samples were fixed normal to the primary axis, this work extends focal construct geometry (FCG), to samples randomly oriented with respect to the incident beam. The effect of independent sample rotation around two axes upon the scattering distributions was investigated in analytical, simulation and empirical manners. It was found that, although the profile of Bragg maxima were modified when the sample was rotated, high intensity diffraction data was still acquired. Modelling produced a good match to the empirical data and it was shown that the distortions caused by sample rotation were not severe and predictable even when sample rotations were large. The implications for this are discussed.
Diffraction past, present and future
Predazzi, Enrico
1998-01-01
Hadronic diffraction has become a hot and fashionable subject in recent years due to the great interest triggered by the HERA and Tevatron data. These data have helped to put the field in a different perspective paving the road to a hopefully more complete understanding than hitherto achieved. The forthcoming data in the next few years from even higher energies (LHC) promise to sustain this interest for a long time. It is, therefore, necessary to provide the younger generations with as complete as possible discussion of the main developments that have marked the growth of high energy diffractive physics in the past and to assess the present state of the art. For this reason, this part will be by far the largest. The analysis of the relationship between conventional diffractive physics and the low-x physics from deep inelastic scattering will allow us also to review the instruments which could help to understand the developments we can expect from the future.
Diffractive dijet production at HERA
Bruni, A; Krämer, G; Schatzel, S
2005-01-01
We present recent experimental data from the H1 and ZEUS Collaborations at HERA for diffractive dijet production in deep-inelastic scattering (DIS) and photoproduction and compare them with next-to-leading order (NLO) QCD predictions using diffractive parton densities. While good agreement is found for DIS, the dijet photoproduction data are overestimated by the NLO theory, showing that factorization breaking occurs at this order. While this is expected theoretically for resolved photoproduction, the fact that the data are better described by a global suppression of direct and resolved contribution by about a factor of two comes as a surprise. We therefore discuss in some detail the factorization scheme and scale dependence between direct and resolved contributions and propose a new factorization scheme for diffractive dijet photoproduction.
Acoustooptic Diffraction in Borate Crystals
Martynyuk-Lototska, I; Krupych, O; Adamiv, V; Smirnov, Ye; Vlokh, R
2004-01-01
The efficiency of acoustooptic (AO) diffraction in a-BaB2O4 and Li2B4O7 crystals is studied experimentally. The crystals are shown to be quite good AO materials. The efficiency of AO diffraction in a-BaB2O4 reaches h=30% at the electric signal power of P=0.7W for the transverse acoustic wave and 15% at the power of P=0.56W for the longitudinal wave. The same parameter for Li2B4O7 reaches h=21% at P=0,81W for the longitudinal acoustic wave.
High-pressure neutron diffraction
Xu, Hongwu [Los Alamos National Laboratory
2011-01-10
This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.
Hard diffraction and rapidity gaps
Albrow, M.G.
1994-08-01
I describe the evolution of experiments at hadron colliders on (a) high mass diffraction (b) double pomeron exchange, from the ISR through the Sp{bar p}S to the Tevatron. I emphasize an experimental approach to the question: ``What is the pomeron?``
Diffractive charged meson pair production
Lehmann-Dronke, B; Schäfer, S; Stein, E; Schäfer, A
1999-01-01
We investigate the possibility to measure the nonforward gluon distribution function by means of diffractively produced charged pion and kaon pairs in polarized lepton nucleon scattering. The resulting cross sections are sizable and are dominated by the gluonic contribution. We find large spin asymmetries, both for pion pairs and for kaon pairs.
3D -Ray Diffraction Microscopy
Poulsen, Henning Friis; Schmidt, Søren; Juul Jensen, Dorte
2014-01-01
Three-dimensional X-ray diffraction (3DXRD) microscopy is a fast and non-destructive structural characterization technique aimed at the study of individual crystalline elements (grains or subgrains) within mm-sized polycrystalline specimens. It is based on two principles: the use of highly penetr...
Stretchable diffraction gratings for spectrometry
Simonov, A.N.; Grabarnik, S.; Vdovine, G.V
2007-01-01
We have investigated the possibility of using transparent stretchable diffraction gratings for spectrometric applications. The gratings were fabricated by replication of a triangular-groove master into a transparent viscoelastic. The sample length, and hence the spatial period, can be reversibly cha
Unifying approach to hard diffraction
Navelet, H
2001-01-01
We find a formulation of hard diffraction unifying the partonic (Ingelman-Schlein) Pomeron, Soft Colour Interaction and QCD dipole descriptions. A theoretical interpretation in terms of S-Matrix and perturbative QCD properties in the small x_{Bj} regime is proposed.
Progress in Diffraction Enhanced Imaging
无
2004-01-01
@@ In cooperation with the Topography Station of Beijing Synchrotron Radiation under CAS Institute of High Energy Physics, a research group from the CAS Shanghai Institute of Optics and Fine Mechanics (SIOM) has made encouraging progress in the diffraction enhanced imaging technology through phase-contrast microscope by hard X-rays.
A QCD analysis of ZEUS diffractive data
Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)
2009-11-15
ZEUS inclusive diffractive cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to constrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data. (orig.)
Anisotropic parameter inversion in VTI media using diffraction data
Waheed, Umair bin
2013-09-22
Diffracted waves contain useful information regarding the subsurface geometry and velocity. They are particularly valuable for anisotropic media as they inherently possess a wide range of dips necessary to resolve angular dependence of velocity. Using this property of diffraction data to our vantage, we develop an algorithm to invert for effective η model, assuming no prior knowledge of it. The obtained effective η model is then converted to interval η model using Dix-type inversion formula. The effectiveness of this approach is tested on the VTI Marmousi model, which yields good structural match even for a highly complex media such as the Marmousi model.
Zhang, Tiantian; Jiang, Jun; Britton, Ben; Shollock, Barbara; Dunne, Fionn
2016-05-01
A crystal plasticity finite-element model, which explicitly and directly represents the complex microstructures of a non-metallic agglomerate inclusion within polycrystal nickel alloy, has been developed to study the mechanistic basis of fatigue crack nucleation. The methodology is to use the crystal plasticity model in conjunction with direct measurement at the microscale using high (angular) resolution-electron backscatter diffraction (HR-EBSD) and high (spatial) resolution-digital image correlation (HR-DIC) strain measurement techniques. Experimentally, this sample has been subjected to heat treatment leading to the establishment of residual (elastic) strains local to the agglomerate and subsequently loaded under conditions of low cyclic fatigue. The full thermal and mechanical loading history was reproduced within the model. HR-EBSD and HR-DIC elastic and total strain measurements demonstrate qualitative and quantitative agreement with crystal plasticity results. Crack nucleation by interfacial decohesion at the nickel matrix/agglomerate inclusion boundaries is observed experimentally, and systematic modelling studies enable the mechanistic basis of the nucleation to be established. A number of fatigue crack nucleation indicators are also assessed against the experimental results. Decohesion was found to be driven by interface tensile normal stress alone, and the interfacial strength was determined to be in the range of 1270-1480 MPa.
Sanchez-Bajo, F. [Universidad de Extremadura, Departamento de Fisica Aplicada, Badajoz (Spain); Ortiz, A.L. [Universidad de Extremadura, Departamento de Ingenieria Mecanica, Energetica y de los Materiales, Badajoz (Spain); Cumbrera, F.L. [Universidad de Extremadura, Departamento de Fisica, Badajoz (Spain)
2009-01-15
An analytical model for the determination of crystallite size and crystal lattice microstrain distributions in nanocrystalline (nc) materials by X-ray diffractometry (XRD) is presented. It entails generalizing the variance method to establish analytically the connection between the variance coefficients of the physically broadened XRD peaks and the characteristic parameters of explicit distributions of crystallite sizes and crystal lattice microstrains, which results in a more detailed characterization of the nc-materials. The proposed model is generic in nature and has the potential to be used under the assumption of different mathematical functions for the two distributions, which suggests that it may have an important role to play in the characterization of nc-materials. Nevertheless, the specialization to the case of nc-materials with log-normal crystallite size distribution and three typical types of lattice microstrains is used as an illustration and to formulate explicit analytical expressions of interest. Finally, the usefulness of the proposed model is demonstrated on standard XRD profiles. (orig.)
Probing the diffractive production of gauge bosons at forward rapidities
Basso, E; Rangel, M S
2016-01-01
The gauge boson production at forward rapidities in single diffractive events at the LHC is investigated considering $pp$ collisions at $\\sqrt{s} =$ 8 and 13 TeV. The impact of gap survival effects is analysed using two different models for the soft rescattering contributions. We demonstrate that using the Forward Shower Counter Project at LHCb -- HERSCHEL, together with the Vertex Locator -- VELO, it is possible to discriminate diffractive production of the gauge bosons $W$ and $Z$ from the non-diffractive processes and studies of the Pomeron structure and diffraction phenomenology are feasible. Moreover, we show that the analysis of this process can be useful to constrain the modelling of the gap survival effects.
Probing diffractive production of gauge bosons at forward rapidities
Basso, Eduardo; Rangel, Murilo S. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, Caixa Postal 68528, Rio de Janeiro, RJ (Brazil); Goncalves, Victor P. [Universidade Federal de Pelotas, Instituto de Fisica e Matematica, Pelotas, RS (Brazil)
2016-12-15
Gauge boson production at forward rapidities in single diffractive events at the LHC is investigated considering pp collisions at √(s) = 8 and 13 TeV. The impact of gap survival effects is analysed using two different models for the soft rescattering contributions. We demonstrate that using the forward shower counter Project at LHCb-HERSCHEL, together with the Vertex Locator-VELO, it is possible to discriminate diffractive production of the gauge bosons W and Z from the non-diffractive processes and studies of the Pomeron structure and diffraction phenomenology are feasible. Moreover, we show that the analysis of this process can be useful to constrain the modelling of the gap survival effects. (orig.)
Diffractive and Exclusive Processes at CMS
Kuznetsova, Ekaterina
2014-01-01
We present an overview of the CMS results on diffractive and exclusive production.Measurements of inclusive single and double diffractive production are discussedas well as measurements of the diffractive production at a hard scale. Measurementsof charged particle multiplicities for single diffractive enhanced data sample and studies of central diffractive jet production were perfrmed in a collaboration with the TOTEM experiment. CMS results on cross section measurements for exclusive dilepton and WW production are also presented.
Blakeley, M. P. [European Molecular Biology Laboratory (EMBL), France; Ruiz, Fredrico [Institut de Genetique et de Biologie Moleculaire et Cellulaire, CNRS, ULP, INSER; Cachau, Raul [SAIC-Frederick, Inc., National Cancer Institute at Frederick, Frederick, MD; Hazemann, I. [Institut Laue-Langevin (ILL); Meilleur, Flora [Institut Laue-Langevin (ILL); Mitschler, A. [IGBMC; Ginell, Stephan [Argonne National Laboratory (ANL); Afonine, Pavel [Lawrence Berkeley National Laboratory (LBNL); Ventura, Oscar [Computational Chemical Physics Group, DETEMA, Facultad de Quimica, UdelaR, C.C.1; Cousido-Siah, Alexandra [Institut de Genetique et de Biologie Moleculaire et Cellulaire, CNRS, ULP, INSER; Haertlein, M. [Institut Laue-Langevin (ILL); Joachimiak, Andrzej [Argonne National Laboratory (ANL); Myles, Dean A A [ORNL; Podjarny, A. [IGBMC
2008-01-01
We present results of combined studies of the enzyme human aldose reductase (h-AR, 36 kDa) using single-crystal x-ray data (0.66 Angstroms, 100K; 0.80 Angstroms, 15K; 1.75 Angstroms, 293K), neutron Laue data (2.2 Angstroms, 293K), and quantum mechanical modeling. These complementary techniques unveil the internal organization and mobility of the hydrogen bond network that defines the properties of the catalytic engine, explaining how this promiscuous enzyme overcomes the simultaneous requirements of efficiency and promiscuity offering a general mechanistic view for this class of enzymes.
Gegner, Juergen [SKF GmbH, Dept. of Material Physics, Schweinfurt (Germany)
2009-07-01
After heat treatment, finish machining of the hardened steel represents the last manufacturing step of machine elements. The practically most important operation of grinding is applied to achieve edge zone compressive residual stresses, best surface quality and dimensional accuracy. Metal removal involves high plastic deformation work. Glide and intersection processes raise the density and produce lower energy substructures of dislocations. The temperature and time behavior of post-machining thermal treatment is analyzed on ground and honed martensitic SAE 52100 rolling bearing steel. Microstructure stabilization is reflected in a large XRD line width decrease on the surface. The kinetics is modeled by rate-controlling carbide dissolution as the carbon source for Cottrell-type segregation at dislocations. This static strain aging is verified by the formation of a slight white etching surface layer. The metal physics model is extended to also consider superimposed thermal dislocation recovery. Both effects are separable. In rolling contact fatigue tests under mixed friction running conditions, air reheating of the samples below the tempering temperature, which avoids hardness loss, leads to a significant lifetime increase. Thermal post-treatment after cold working results in similar changes of the XRD line width in the larger mechanically affected edge zone.
Computing Composition/Depth Profiles From X-Ray Diffraction
Wiedemann, K. E.; Unnam, J.
1986-01-01
Diffraction-intensity bands deconvolved relatively quickly. TIBAC constructs composition/depth profiles from X-ray diffraction-intensity bands. Intensity band extremely sensitive to shape of composition/depth profile. TIBAC incorporates straightforward transformation of intensity band that retains accuracy of earlier simulation models, but is several orders of magnitude faster in total computational time. TIBAC written in FORTRAN 77 for batch execution.
Adaptive perfectly matched layer for Wood's anomalies in diffraction gratings
Vial, Benjamin; Nicolet, André; Commandré, Mireille; Tisserand, Stéphane
2015-01-01
We propose an Adaptive Perfectly Matched Layer (APML) to be used in diffraction grating modeling. With a properly tailored co-ordinate stretching depending both on the incident field and on grating parameters, the APML may efficiently absorb diffracted orders near grazing angles (the so-called Wood's anomalies). The new design is implemented in a finite element method (FEM) scheme and applied on a numerical example of a dielectric slit grating. Its performances are compared with classical PML with constant stretching coefficient.
Phase-diffractive coating for daylight control on smart window
Perennes, Frederic; Twardowski, Patrice J.; Gesbert, D.; Meyrueis, Patrick
1992-11-01
Daylight can be processed by a smart window in a transmission, reflective, refractive, and diffractive mode. In the future an optimization will be realized by a mixing of these approaches depending on the applied cases. Non-imaging diffractive optics has its roots in the work done in holographic diffractive coating for head up displays (HUD) and helmet mounted displays. For having globally good results on smart window with diffractive coating, a very high diffraction efficiency must be reached close to 100% without having a too important lowering of the control of other parameters of the light processed by a smart window (direction and frequency control essentially). We propose a method for designing, realizing, and using diffractive coating for a smart window that is based on a new organic material and diffractive model that were already validated in HUD. Potential low cost is possible for mass production on a large surface with an adapted investment. We describe the present technology and its limits and the ones that can be reached in the future. In this work, we present a holographic way to modify the slant of sun rays through a window, and to filter infrared radiations by using dichromated gelatin material. In this way it would be able to ensure a more uniform lighting and a more pleasant temperature inside buildings or vehicles, without using dye or photochromics glasses.
Anomalous diffraction in hyperbolic materials
Alberucci, Alessandro; Boardman, Allan D; Assanto, Gaetano
2016-01-01
We demonstrate that light is subject to anomalous (i.e., negative) diffraction when propagating in the presence of hyperbolic dispersion. We show that light propagation in hyperbolic media resembles the dynamics of a quantum particle of negative mass moving in a two-dimensional potential. The negative effective mass implies time reversal if the medium is homogeneous. Such property paves the way to diffraction compensation, spatial analogue of dispersion compensating fibers in the temporal domain. At variance with materials exhibiting standard elliptic dispersion, in inhomogeneous hyperbolic materials light waves are pulled towards regions with a lower refractive index. In the presence of a Kerr-like optical response, bright (dark) solitons are supported by a negative (positive) nonlinearity.
Phase Aberrations in Diffraction Microscopy
Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M
2005-09-29
In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.
Anomalous diffraction in hyperbolic materials
Alberucci, Alessandro; Jisha, Chandroth P.; Boardman, Allan D.; Assanto, Gaetano
2016-09-01
We demonstrate that light is subject to anomalous (i.e., negative) diffraction when propagating in the presence of hyperbolic dispersion. We show that light propagation in hyperbolic media resembles the dynamics of a quantum particle of negative mass moving in a two-dimensional potential. The negative effective mass implies time reversal if the medium is homogeneous. Such property paves the way to diffraction compensation, i.e., spatial analog of dispersion compensating fibers in the temporal domain. At variance with materials exhibiting standard elliptic dispersion, in inhomogeneous hyperbolic materials light waves are pulled towards regions with a lower refractive index. In the presence of a Kerr-like optical response, bright (dark) solitons are supported by a negative (positive) nonlinearity.
Diffraction operators in paraxial approach
Lasso, William; Navas, Marianela; Añez, Liz; Urdaneta, Romer; Díaz, Leonardo; Torres, César O.
2014-07-01
Nowadays, research in the field of science education points to the creation of alternative ways of teaching contents encouraging the development of more elaborate reasoning, where a high degree of abstraction and generalization of scientific knowledge prevails. On that subject, this research shows a didactic alternative proposal for the construction of Fresnel and Fraunhoffer diffraction concepts applying the Fourier transform technique in the study of electromagnetic waves propagation in free space. Curvature transparency and Fourier sphere operators in paraxial approximation are used in order to make the usual laborious mathematical approach easier. The main result shows that the composition of optic metaxial operators results in the discovery of a simpler way out of the standard electromagnetic wave propagation in free space between a transmitter and a receptor separated from a given distance. This allows to state that the didactic proposal shown encourages the construction of Fresnel and Fraunhoffer diffraction concepts in a more effective and easier way than the traditional teaching.
Polarimetry by classical ghost diffraction
Kellock, Henri; Friberg, Ari T; Shirai, Tomohiro
2014-01-01
We present a technique for studying the polarimetric properties of a birefringent object by means of classical ghost diffraction. The standard ghost diffraction setup is modified to include polarizers for controlling the state of polarization of the beam in various places. The object is characterized by a Jones matrix and the absolute values of the Fourier transforms of its individual elements are measured. From these measurements the original complex-valued functions can be retrieved through iterative methods resulting in the full Jones matrix of the object. We present two different placements of the polarizers and show that one of them leads to better polarimetric quality, while the other placement offers the possibility to perform polarimetry without controlling the source's state of polarization. The concept of an effective source is introduced to simplify the calculations. Ghost polarimetry enables the assessment of polarization properties as a function of position within the object through simple intens...
Eugster, Jurg
In this thesis, two analyses using proton-proton (pp) collision data at a center of mass energy of $\\sqrt{s}$ = 7 TeV, recorded with the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), are presented: The first analysis, using an integrated luminosity of 36 pb$^{=1}$ of low pile-up data recorded in 2010, uses the forward energy flow and the central charged particle multiplicity in events with leptonically decaying W and Z bosons to study the effects of the underlying event model. None of the studied Monte Carlo simulations describes the observed distributions from data sufficiently. Weak boson events with no significant energy deposits in one of the forward calorimeters are observed. This corresponds to a large pseudorapidity gap (LRG) of at least 1.9 units. The fraction of W(Z) events having a LRG is found to be 1.46 $\\pm$ 0.09(stat.) $\\pm$ 0.38(syst.)% (1.57 $\\pm$ 0.25(stat.) $\\pm$ 0.42(syst.)%). The majority of the charged leptons from these W/Z decays are found in the hemisphere ...
Sparse diffraction imaging method using an adaptive reweighting homotopy algorithm
Yu, Caixia; Zhao, Jingtao; Wang, Yanfei; Qiu, Zhen
2017-02-01
Seismic diffractions carry valuable information from subsurface small-scale geologic discontinuities, such as faults, cavities and other features associated with hydrocarbon reservoirs. However, seismic imaging methods mainly use reflection theory for constructing imaging models, which means a smooth constraint on imaging conditions. In fact, diffractors occupy a small account of distributions in an imaging model and possess discontinuous characteristics. In mathematics, this kind of phenomena can be described by the sparse optimization theory. Therefore, we propose a diffraction imaging method based on a sparsity-constraint model for studying diffractors. A reweighted L 2-norm and L 1-norm minimization model is investigated, where the L 2 term requests a least-square error between modeled diffractions and observed diffractions and the L 1 term imposes sparsity on the solution. In order to efficiently solve this model, we use an adaptive reweighting homotopy algorithm that updates the solutions by tracking a path along inexpensive homotopy steps. Numerical examples and field data application demonstrate the feasibility of the proposed method and show its significance for detecting small-scale discontinuities in a seismic section. The proposed method has an advantage in improving the focusing ability of diffractions and reducing the migration artifacts.
Comparative study of different Schlieren diffracting elements
Raj Kumar; Sushil K Kaura; D P Chhachhia; D Mohan; A K Aggarwal
2008-01-01
This paper presents an analysis of diffraction effects taking place at different Schlieren diffracting elements. Two types of diffraction effects are prominent in the Schlieren schemes. One is diffraction of direct light (source image) at the Schlieren element, which limits the sensitivity and resolution of Schlieren systems. The second type is the diffraction of light deflected from the test object at the Schlieren-diffracting element. This second type of diffraction degrades the quality of Schlieren results. Experimental results showing the effect of diffraction of light deflected from the test object at a phase knife-edge, corner of a square phase aperture and an optical fiber tip as Schlieren diffracting elements have been presented and discussed.
Inversion of diffraction data for amorphous materials
Pandey, Anup; Biswas, Parthapratim; Drabold, D. A.
2016-09-01
The general and practical inversion of diffraction data-producing a computer model correctly representing the material explored-is an important unsolved problem for disordered materials. Such modeling should proceed by using our full knowledge base, both from experiment and theory. In this paper, we describe a robust method to jointly exploit the power of ab initio atomistic simulation along with the information carried by diffraction data. The method is applied to two very different systems: amorphous silicon and two compositions of a solid electrolyte memory material silver-doped GeSe3. The technique is easy to implement, is faster and yields results much improved over conventional simulation methods for the materials explored. By direct calculation, we show that the method works for both poor and excellent glass forming materials. It offers a means to add a priori information in first-principles modeling of materials, and represents a significant step toward the computational design of non-crystalline materials using accurate interatomic interactions and experimental information.
Revealing small-scale diffracting discontinuities by an optimization inversion algorithm
Yu, Caixia; Zhao, Jingtao; Wang, Yanfei
2017-02-01
Small-scale diffracting geologic discontinuities play a significant role in studying carbonate reservoirs. The seismic responses of them are coded in diffracted/scattered waves. However, compared with reflections, the energy of these valuable diffractions is generally one or even two orders of magnitude weaker. This means that the information of diffractions is strongly masked by reflections in the seismic images. Detecting the small-scale cavities and tiny faults from the deep carbonate reservoirs, mainly over 6 km, poses an even bigger challenge to seismic diffractions, as the signals of seismic surveyed data are weak and have a low signal-to-noise ratio (SNR). After analyzing the mechanism of the Kirchhoff migration method, the residual of prestack diffractions located in the neighborhood of the first Fresnel aperture is found to remain in the image space. Therefore, a strategy for extracting diffractions in the image space is proposed and a regularized L 2-norm model with a smooth constraint to the local slopes is suggested for predicting reflections. According to the focusing conditions of residual diffractions in the image space, two approaches are provided for extracting diffractions. Diffraction extraction can be directly accomplished by subtracting the predicted reflections from seismic imaging data if the residual diffractions are focused. Otherwise, a diffraction velocity analysis will be performed for refocusing residual diffractions. Two synthetic examples and one field application demonstrate the feasibility and efficiency of the two proposed methods in detecting the small-scale geologic scatterers, tiny faults and cavities.
Triple Bragg diffraction in paratellurite crystal
Kotov, V. M.; Averin, S. V.; Voronko, A. I.; Kotov, E. V.; Tikhomirov, S. A.
2017-07-01
Triple Bragg diffraction in a paratellurite crystal has been considered for the case when the plane of diffraction is oblique to the optical axis of the crystal. It has been shown that effective photoelastic constants for isotropic and anisotropic diffraction depend on the inclination of the plane of diffraction insignificantly. Triple Bragg diffraction of 0.63-μm coherent radiation in paratellurite at a 47.3-MHz slow acoustic wave has been experimentally demonstrated. For an optical power of 0.69 W delivered to a piezoconverter, the relative intensities of diffraction orders equal 0.4, 0.4, 0.1, and 0.1, respectively.
Diffraction structural biology – a new horizon
Yamane, Takashi [Nagoya Industrial Science Research Institute, 1-13 Yotsuya-dori, Chikusa-ku, Nagoya 464-0819 (Japan); Helliwell, John R. [University of Manchester, Manchester M13 9PL (United Kingdom); Johnson, John E. [Scripps Research Institute, San Diego, CA (United States); Yasuoka, Noritake, E-mail: nori-yasuoka@nifty.com [AIST Kansai Center, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Sakabe, Noriyoshi [Photon Factory, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
2013-11-01
An introductory overview to the special issue papers on diffraction structural biology in this issue of the journal. An introductory overview to the special issue papers on diffraction structural biology in this issue of the journal.
50 years of fiber diffraction.
Holmes, Kenneth C
2010-05-01
In 1955 Ken Holmes started working on tobacco mosaic virus (TMV) as a research student with Rosalind Franklin at Birkbeck College, London. Afterward he spent 18months as a post doc with Don Caspar and Carolyn Cohen at the Children's Hospital, Boston where he continued the work on TMV and also showed that the core of the thick filament of byssus retractor muscle from mussels is made of two-stranded alpha-helical coiled-coils. Returning to England he joined Aaron Klug's group at the newly founded Laboratory of Molecular Biology in Cambridge. Besides continuing the TMV studies, which were aimed at calculating the three-dimensional density map of the virus, he collaborated with Pringle's group in Oxford to show that two conformation of the myosin cross-bridge could be identified in insect flight muscle. In 1968 he opened the biophysics department at the Max Planck Institute for Medical Research in Heidelberg, Germany. With Gerd Rosenbaum he initiated the use of synchrotron radiation as a source for X-ray diffraction. In his lab the TMV structure was pushed to 4A resolution and showed how the RNA binds to the protein. With his co-workers he solved the structure of g-actin as a crystalline complex and then solved the structure of the f-actin filament by orientating the g-actin structure so as to give the f-actin fiber diffraction pattern. He was also able to solve the structure of the complex of actin with tropomyosin from fiber diffraction.
The Diffraction Response Interpolation Method
Jespersen, Søren Kragh; Wilhjelm, Jens Erik; Pedersen, Peder C.
1998-01-01
medium, is presented. The DRIM is based on the velocity potential impulseresponse method, adapted to pulse-echo applications by the use of acoustical reciprocity. Specifically, the DRIM operates bydividing the reflector surface into planar elements, finding the diffraction response at the corners...... of the elements, calculating theresponse integrated over the surface element by time-domain convolutions with analytically determined filters, and summing theresponses from the individual surface elements. As the method is based on linearity, effects such as shadowing, higher-orderdiffraction, nonlinear...
Undergraduate Experiment with Fractal Diffraction Gratings
Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.
2011-01-01
We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…
The account of polarizable singularities of diffractional field in VHF range
Abarykov, V. N.; Batoroev, A. S.
2008-02-01
On the basis of confrontation of account results of diffractional attenuation on absorptive and impedance sample models of a convex obstacle the model of the count of a complementary field reduction of vertical polarisation on diffraction radio paths with woody tops mountain obstacle is offered. This model well explains the experimental results.
Panicaud, B., E-mail: benoit.panicaud@utt.fr [Universite de Technologie de Troyes (UTT), CNRS UMR 6279, 12 rue Marie Curie, 10010 Troyes (France); Grosseau-Poussard, J.L. [LEMMA, Pole Sciences et Technologie, Universite de La Rochelle, Av. M. Crepeau, 17042 La Rochelle Cedex (France)
2010-12-01
In this present work, local stress development in the iron oxide layers growing on phosphated {alpha}-Fe at 400 deg. C in ambient air is investigated by Raman spectroscopy. Coupled with X-ray diffraction it enables to obtain directly local stresses' maps in the oxide layers. Use of Raman spectroscopy allows obtaining better accuracy on mechanical behaviour at local scale. This characterisation technique is very useful to study systems developing mechanical heterogeneities on surface, especially in case of buckling phenomenon. Investigations on particular local blisters have been done to measure some characteristic lengths at local scale. From local measurements, we are able to evaluate general effect of buckling from simplified scale transition. So, a macroscopic approach has been performed to calculate global stress evolution of the oxide layer, based on continuous damage mechanics. Consequently, it leads to good comparison between modelling and experimental values (global stresses versus oxidation time) in {alpha}-Fe{sub 2}O{sub 3} oxide.
Diffractive molecular-orbital tomography
Zhai, Chunyang; Zhu, Xiaosong; Lan, Pengfei; Wang, Feng; He, Lixin; Shi, Wenjing; Li, Yang; Li, Min; Zhang, Qingbin; Lu, Peixiang
2017-03-01
High-order-harmonic generation in the interaction of femtosecond lasers with atoms and molecules opens the path to molecular-orbital tomography and to probe the electronic dynamics with attosecond-Ångström resolutions. Molecular-orbital tomography requires both the amplitude and phase of the high-order harmonics. Yet the measurement of phases requires sophisticated techniques and represents formidable challenges at present. Here we report a scheme, called diffractive molecular-orbital tomography, to retrieve the molecular orbital solely from the amplitude of high-order harmonics without measuring any phase information. We have applied this method to image the molecular orbitals of N2, CO2, and C2H2 . The retrieved orbital is further improved by taking account the correction of Coulomb potential. The diffractive molecular-orbital tomography scheme, removing the roadblock of phase measurement, significantly simplifies the molecular-orbital tomography procedure and paves an efficient and robust way to the imaging of more complex molecules.
ATLAS results on diffraction and exclusive production
Tasevsky, Marek; The ATLAS collaboration
2016-01-01
The ATLAS collaboration has carried out a study of diffractive dijet production at 7 TeV pp collisions at the LHC, i.e. events with a hadronic system containing at least two jets in addition to a large region of pseudorapidity devoid of hadronic activity. The data distributions are compared with Monte Carlo models and the rapidity gap survival probability has been estimated in the kinematic region with high diffractive contribution. In the absence of forward proton tagging, exclusive processes can be distinguished in the central part of the ATLAS detector exploiting the large rapidity gap in the central region and the absence of charged particles reconstructed in the inner tracking detector. This strategy has been exploited to study the exclusive production of dilepton pairs in the data taken at centreofmass energies of 7 and 8 TeV. The 7 TeV study concentrates on a precision measurement of the dielectron and dimuon process, while the 8 TeV measurement explores the exclusive production of WW pairs in the elec...
Quantum vortices and trajectories in particle diffraction
Delis, N; Contopoulos, G
2011-01-01
We investigate the phenomenon of the diffraction of charged particles by thin material targets using the method of the de Broglie-Bohm quantum trajectories. The particle wave function can be modeled as a sum of two terms $\\psi=\\psi_{ingoing}+\\psi_{outgoing}$. A thin separator exists between the domains of prevalence of the ingoing and outgoing wavefunction terms. The structure of the quantum-mechanical currents in the neighborhood of the separator implies the formation of an array of \\emph{quantum vortices}. The flow structure around each vortex displays a characteristic pattern called `nodal point - X point complex'. The X point gives rise to stable and unstable manifolds. We find the scaling laws characterizing a nodal point-X point complex by a local perturbation theory around the nodal point. We then analyze the dynamical role of vortices in the emergence of the diffraction pattern. In particular, we demonstrate the abrupt deflections, along the direction of the unstable manifold, of the quantum trajector...
Advances in structure research by diffraction methods
Brill, R
1970-01-01
Advances in Structure Research by Diffraction Methods reviews advances in the use of diffraction methods in structure research. Topics covered include the dynamical theory of X-ray diffraction, with emphasis on Ewald waves in theory and experiment; dynamical theory of electron diffraction; small angle scattering; and molecular packing. This book is comprised of four chapters and begins with an overview of the dynamical theory of X-ray diffraction, especially in terms of how it explains all the absorption and propagation properties of X-rays at the Bragg setting in a perfect crystal. The next
Advances in structure research by diffraction methods
Hoppe, W
1974-01-01
Advances in Structure Research by Diffraction Methods: Volume 5 presents discussions on application of diffraction methods in structure research. The book provides the aspects of structure research using various diffraction methods. The text contains 2 chapters. Chapter 1 reviews the general theory and experimental methods used in the study of all types of amorphous solid, by both X-ray and neutron diffraction, and the detailed bibliography of work on inorganic glasses. The second chapter discusses electron diffraction, one of the major methods of determining the structures of molecules in the
Diffractive and non-diffractive wounded nucleons and final states in pA collisions
Bierlich, Christian; Lönnblad, Leif
2016-01-01
We review the state-of-the-art of Glauber-inspired models for estimating the distribution of the number of participating nucleons in pA and AA collisions. We argue that there is room for improvement in these models when it comes to the treatment of diffractive excitation processes, and present a new simple Glauber-like model where these processes are better taken into account. We also suggest a new way of using the number of participating, or wounded, nucleons to extrapolate event characteristics from pp collisions, and hence get an estimate of basic hadronic final-state properties in pA collisions, which may be used to extract possible nuclear effects. The new method is inspired by the Fritiof model, but based on the full, semi-hard multiparton interaction model of Pythia 8.
Diffractive and non-diffractive wounded nucleons and final states in pA collisions
Bierlich, Christian; Gustafson, Gösta; Lönnblad, Leif [Department of Astronomy and Theoretical Physics,Sölvegatan 14A, S-223 62 Lund (Sweden)
2016-10-25
We review the state-of-the-art of Glauber-inspired models for estimating the distribution of the number of participating nucleons in pA and AA collisions. We argue that there is room for improvement in these model when it comes to the treatment of diffractive excitation processes, and present a new simple Glauber-like model where these processes are better taken into account. We also suggest a new way of using the number of participating, or wounded, nucleons to extrapolate event characteristics from pp collisions, and hence get an estimate of basic hadronic final-state properties in pA collisions, which may be used to extract possible nuclear effects. The new method is inspired by the Fritiof model, but based on the full, semi-hard multiparton interaction model of PYTHIA8.
Diffraction tomography with Fourier ptychography
Horstmeyer, Roarke
2015-01-01
This article presents a method to perform diffraction tomography in a standard microscope that includes an LED array for illumination. After acquiring a sequence of intensity-only images of a thick sample, a ptychography-based reconstruction algorithm solves for its unknown complex index of refraction across three dimensions. The experimental microscope demonstrates a spatial resolution of 0.39 $\\mu$m and an axial resolution of 3.7 $\\mu$m at the Nyquist-Shannon sampling limit (0.54 $\\mu$m and 5.0 $\\mu$m at the Sparrow limit, respectively), across a total imaging volume of 2.2 mm $\\times$ 2.2 mm $\\times$ 110 $\\mu$m. Unlike competing methods, the 3D tomograms presented in this article are continuous, quantitative, and formed without the need for interferometry or any moving parts. Wide field-of-view reconstructions of thick biological specimens demonstrate potential applications in pathology and developmental biology.
Skinner, Gerald K.
2010-01-01
Diffractive X-ray telescopes, using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution many orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro-arc-seconds or even better, that would allow, for example, imaging of the distorted spacetime in the immediate vicinity of the super-massive black holes in the center of active galaxies. What then is precluding their immediate adoption? Extremely long focal lengths, very limited bandwidth, and difficulty stabilizing the image are the main problems. The history, and status of the development of such lenses is reviewed here and the prospects for managing the challenges that they present are discussed.
Skinner, Gerald K
2010-01-01
Diffractive X-ray telescopes using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution several orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro-arc-seconds or even better, that would allow, for example, imaging of the distorted space- time in the immediate vicinity of the super-massive black holes in the center of active galaxies What then is precluding their immediate adoption? Extremely long focal lengths, very limited bandwidth, and difficulty stabilizing the image are the main problems. The history, and status of the development of such lenses is reviewed here and the prospects for managing the challenges that they present are discussed.
Classification using diffraction patterns for single-particle analysis
Hu, Hongli; Zhang, Kaiming [Department of Biophysics, the Health Science Centre, Peking University, Beijing 100191 (China); Meng, Xing, E-mail: xmeng101@gmail.com [Wadsworth Centre, New York State Department of Health, Albany, New York 12201 (United States)
2016-05-15
An alternative method has been assessed; diffraction patterns derived from the single particle data set were used to perform the first round of classification in creating the initial averages for proteins data with symmetrical morphology. The test protein set was a collection of Caenorhabditis elegans small heat shock protein 17 obtained by Cryo EM, which has a tetrahedral (12-fold) symmetry. It is demonstrated that the initial classification on diffraction patterns is workable as well as the real-space classification that is based on the phase contrast. The test results show that the information from diffraction patterns has the enough details to make the initial model faithful. The potential advantage using the alternative method is twofold, the ability to handle the sets with poor signal/noise or/and that break the symmetry properties. - Highlights: • New classification method. • Create the accurate initial model. • Better in handling noisy data.
Phase effects due to beam misalignment on diffraction gratings
Lodhia, Deepali; Brueckner, Frank; Carbone, Ludovico; Fulda, Paul; Kokeyama, Keiko; Freise, Andreas
2013-01-01
All-reflective interferometer configurations have been proposed for the next generation of gravitational wave detectors, with diffractive elements replacing transmissive optics. However, an additional phase noise creates more stringent conditions for alignment stability. A framework for alignment stability with the use of diffractive elements was required using a Gaussian model. We successfully create such a framework involving modal decomposition to replicate small displacements of the beam (or grating) and show that the modal model does not contain the phase changes seen in an otherwise geometric planewave approach. The modal decomposition description is justified by verifying experimentally that the phase of a diffracted Gaussian beam is independent of the beam shape, achieved by comparing the phase change between a zero-order and first-order mode beam. To interpret our findings we employ a rigorous time-domain simulation to demonstrate that the phase changes resulting from a modal decomposition are correc...
2010 Diffraction Methods in Structural Biology
Dr. Ana Gonzalez
2011-03-10
Advances in basic methodologies have played a major role in the dramatic progress in macromolecular crystallography over the past decade, both in terms of overall productivity and in the increasing complexity of the systems being successfully tackled. The 2010 Gordon Research Conference on Diffraction Methods in Structural Biology will, as in the past, focus on the most recent developments in methodology, covering all aspects of the process from crystallization to model building and refinement, complemented by examples of structural highlights and complementary methods. Extensive discussion will be encouraged and it is hoped that all attendees will participate by giving oral or poster presentations, the latter using the excellent poster display area available at Bates College. The relatively small size and informal atmosphere of the meeting provides an excellent opportunity for all participants, especially younger scientists, to meet and exchange ideas with leading methods developers.
Diffraction Correlation to Reconstruct Highly Strained Particles
Brown, Douglas; Harder, Ross; Clark, Jesse; Kim, J. W.; Kiefer, Boris; Fullerton, Eric; Shpyrko, Oleg; Fohtung, Edwin
2015-03-01
Through the use of coherent x-ray diffraction a three-dimensional diffraction pattern of a highly strained nano-crystal can be recorded in reciprocal space by a detector. Only the intensities are recorded, resulting in a loss of the complex phase. The recorded diffraction pattern therefore requires computational processing to reconstruct the density and complex distribution of the diffracted nano-crystal. For highly strained crystals, standard methods using HIO and ER algorithms are no longer sufficient to reconstruct the diffraction pattern. Our solution is to correlate the symmetry in reciprocal space to generate an a priori shape constraint to guide the computational reconstruction of the diffraction pattern. This approach has improved the ability to accurately reconstruct highly strained nano-crystals.
Design of structurally colored surfaces based on scalar diffraction theory
Johansen, Villads Egede; Andkjær, Jacob Anders; Sigmund, Ole
2014-01-01
reflective surface, paint-free text and coloration, UV-resistant coloring, etc. In this initial study, the main focus is on finding a systematic way to obtain these results. For now the simulation and optimization is based on a simple scalar diffraction theory model. From the results, several design issues...
Computer Simulation and X-ray Diffraction of Nanocrystals
无
2001-01-01
X-ray diffraction of structure in nanocrystalline α-Fe and Cu was studied by atomistic simulation. Atomic position equilibrium was reached by using molecular dynamics method to simulate nanocrystalline structure with Finnis potentials to model interatomic interactions. lt was found that the boundary component exhibits short-range order, and the distortion in crystalline component increases with the decrease of grain size.
High-energy electron diffraction and microscopy
Peng, L M; Whelan, M J
2011-01-01
This book provides a comprehensive introduction to high energy electron diffraction and elastic and inelastic scattering of high energy electrons, with particular emphasis on applications to modern electron microscopy. Starting from a survey of fundamental phenomena, the authors introduce the most important concepts underlying modern understanding of high energy electron diffraction. Dynamical diffraction in transmission (THEED) and reflection (RHEED) geometries is treated using ageneral matrix theory, where computer programs and worked examples are provided to illustrate the concepts and to f
CMS results on soft and hard diffraction
Obertino, Margherita Maria
2016-01-01
The measurement of the soft diffractive cross sections in single- and double-diffractive final states is presented at 7 TeV. Furthermore, also the production of jet-gap-get final states is discussed and the results are interpreted in terms of a hard color singlet exchange. Finally, general features of particle production in single-diffractive enhanced events are shown at 13 TeV.
Spectral Anomalies in the Fraunhofer Diffraction Pattern
PU Ji-Xiong; CAI Chao; HU Xian-Dai; LIU Xiao-Yun
2005-01-01
@@ We study the spectral characteristics theoretically and experimentally in the Fraunhofer diffraction pattern formed by the diffraction of a spatially coherent, polychromatic light through a slit. It is found that the spectrum in some diffraction directions close to the singular direction is redshifted, compared to the spectrum of the incident polychromatic light, and blueshifted in other directions, and splits into two lines at the singular direction. We show that the experimental results are consistent with the theoretical expectations.
Theory of edge diffraction in electromagnetics
Ufimtsev, Pyotr
2009-01-01
This book is an essential resource for researchers involved in designing antennas and RCS calculations. It is also useful for students studying high frequency diffraction techniques. It contains basic original ideas of the Physical Theory of Diffraction (PTD), examples of its practical application, and its validation by the mathematical theory of diffraction. The derived analytic expressions are convenient for numerical calculations and clearly illustrate the physical structure of the scattered field.
Christiana Zenonos; Dewi W. Lewis; Gopinathan Sankar
2015-01-01
Phase pure AlPO4 with the AlPO4-18 (AEI) structure was synthesised using N,N-diisopropylethyla-mine as a template. Using a combination of X-ray powder diffraction and computational methods, the location and orientation of the N,N-diisopropylethylamine molecules inside the cages of the AEI structure were determined. Thermogravimetric analysis confirmed that the number of template molecules per unit cell was consistent with the diffraction study. We unequivocally show that only one template molecule is present in each cage of the crystalline AEI material. Our work demon-strates that a combined approach enables accurate structure resolution of such complex materials.
Ultrafast Molecular Imaging by Laser Induced Electron Diffraction
Peters, Michel; Cornaggia, Christian; Saugout, Sébastien; Charron, Eric; Keller, Arne; Atabek, Osman
2010-01-01
We address the feasibility of imaging geometric and orbital structure of a polyatomic molecule on an attosecond time-scale using the Laser Induced Electron Diffraction, LIED, technique [T. Zuo \\textit{et al.}, Chem. Phys. Lett. \\textbf{259}, 313 (1996)]. We present numerical results obtained for the CO$_2$ molecule using a single active electron model. The molecular geometry (bond-lengths) is determined within 3% of accuracy from a diffraction pattern which also reflects the nodal properties of the initial molecular orbital. Robustness of the structure determination is discussed with respect to vibrational and rotational motions with a complete interpretation of the laser-induced mechanisms.
Coherence Time Resolvable Diffraction and New Tunnelling Electronics
易林
2002-01-01
With the help of the perturbation method and the Feynman path integral technique, we analytically demonstrate that, when the electronic spectrum of a mesoscopic box is measured through two connecting leads, there exists a class of new diffraction phenomena in the coherence time domain, based on the new coherent tunnelling model.It is shown that the new diffraction effect determines the minimal resolvable coherence time to the Heisenberg limit. In particular, Fraunhofer optical phenomena, such as missing order and grating effects, can be reproduced in the meso-systems. The predicted periodic oscillations as a function of voltage are in excellent agreement with experimental observations.
Gaussian beam diffraction in weakly anisotropic inhomogeneous media
Kravtsov, Yu.A., E-mail: kravtsov@am.szczecin.p [Institute of Physics, Maritime University of Szczecin, Szczecin 70-500 (Poland); Space Research Institute, Russian Academy of Science, Moscow 117 997 (Russian Federation); Berczynski, P., E-mail: pawel.berczynski@ps.p [Institute of Physics, West Pomeranian University of Technology, Szczecin 70-310 (Poland); Bieg, B., E-mail: b.bieg@am.szczecin.p [Institute of Physics, Maritime University of Szczecin, Szczecin 70-500 (Poland)
2009-08-10
Combination of quasi-isotropic approximation (QIA) of geometric optics with paraxial complex geometric optics (PCGO) is suggested, which allows describing both diffraction and polarization evolution of Gaussian electromagnetic beams in weakly anisotropic inhomogeneous media. Combination QIA/PCGO reduces Maxwell equations to the system of the ordinary differential equations of the first order and radically simplifies solution of various problems, related to microwave plasma diagnostics, including plasma polarimetry, interferometry and refractometry in thermonuclear reactors. Efficiency of the method is demonstrated by the example of electromagnetic beam diffraction in a linear layer of magnetized plasma with parameters, modeling tokamak plasma in the project ITER.
Quantum-information approach to dynamical diffraction theory
Nsofini, J.; Ghofrani, K.; Sarenac, D.; Cory, D. G.; Pushin, D. A.
2016-12-01
We present a simplified model for dynamical diffraction of particles through a periodic thick perfect crystal based on repeated application of a coherent beam-splitting unitary at coarse-grained lattice sites. By demanding translational invariance and a computationally tractable number of sites in the coarse graining, we show how this approach reproduces many results typical of dynamical diffraction theory and experiments. This approach has the benefit of being applicable in the thick, thin, and intermediate crystal regimes. The method is applied to a three-blade neutron interferometer to predict the output beam profiles, interference patterns, and contrast variation.
Sub-wavelength diffractive optics
Warren, M.E.; Wendt, J.R.; Vawter, G.A.
1998-03-01
This report represents the completion of a three-year Laboratory-Directed Research and Development (LDRD) program to investigate sub-wavelength surface relief structures fabricated by direct-write e-beam technology as unique and very high-efficiency optical elements. A semiconductor layer with sub-wavelength sized etched openings or features can be considered as a layer with an effective index of refraction determined by the fraction of the surface filled with semiconductor relative to the fraction filled with air or other material. Such as a layer can be used to implement planar gradient-index lenses on a surface. Additionally, the nanometer-scale surface structures have diffractive properties that allow the direct manipulation of polarization and altering of the reflective properties of surfaces. With this technology a single direct-write mask and etch can be used to integrate a wide variety of optical functions into a device surface with high efficiencies; allowing for example, direct integration of polarizing optics into the surface with high efficiencies; allowing for example, direct integration of polarizing optics into the surfaces of devices, forming anti-reflection surfaces or fabricating high-efficiency, high-numerical aperture lenses, including integration inside vertical semiconductor laser cavities.
Optical diffraction for measurements of nano-mechanical bending
Hermans, Rodolfo I.; Dueck, Benjamin; Ndieyira, Joseph Wafula; McKendry, Rachel A.; Aeppli, Gabriel
2016-06-01
We explore and exploit diffraction effects that have been previously neglected when modelling optical measurement techniques for the bending of micro-mechanical transducers such as cantilevers for atomic force microscopy. The illumination of a cantilever edge causes an asymmetric diffraction pattern at the photo-detector affecting the calibration of the measured signal in the popular optical beam deflection technique (OBDT). The conditions that avoid such detection artefacts conflict with the use of smaller cantilevers. Embracing diffraction patterns as data yields a potent detection technique that decouples tilt and curvature and simultaneously relaxes the requirements on the illumination alignment and detector position through a measurable which is invariant to translation and rotation. We show analytical results, numerical simulations and physiologically relevant experimental data demonstrating the utility of the diffraction patterns. We offer experimental design guidelines and quantify possible sources of systematic error in OBDT. We demonstrate a new nanometre resolution detection method that can replace OBDT, where diffraction effects from finite sized or patterned cantilevers are exploited. Such effects are readily generalized to cantilever arrays, and allow transmission detection of mechanical curvature, enabling instrumentation with simpler geometry. We highlight the comparative advantages over OBDT by detecting molecular activity of antibiotic Vancomycin.
Classification using diffraction patterns for single-particle analysis.
Hu, Hongli; Zhang, Kaiming; Meng, Xing
2016-05-01
An alternative method has been assessed; diffraction patterns derived from the single particle data set were used to perform the first round of classification in creating the initial averages for proteins data with symmetrical morphology. The test protein set was a collection of Caenorhabditis elegans small heat shock protein 17 obtained by Cryo EM, which has a tetrahedral (12-fold) symmetry. It is demonstrated that the initial classification on diffraction patterns is workable as well as the real-space classification that is based on the phase contrast. The test results show that the information from diffraction patterns has the enough details to make the initial model faithful. The potential advantage using the alternative method is twofold, the ability to handle the sets with poor signal/noise or/and that break the symmetry properties.
Coherent X-ray diffraction studies of mesoscopic materials
Shabalin, Anatoly
2015-12-15
This thesis is devoted to three separate projects, which can be considered as independent. First, the dynamical scattering effects in the Coherent X-ray Diffractive Imaging (CXDI) method are discussed. Based on the simulation results, a straightforward method for correction for the refraction and absorption artifacts in the Bragg CXDI reconstruction is suggested. The second part summarizes the results of an Coherent X-ray Diffractive Imaging experiment with a single colloidal crystal grain. A remarkable result is that positions of individual particles in the crystal lattice have been resolved in three dimensions. The third project is devoted to X-ray diffraction experimental studies of structural evolution of colloidal crystalline films upon incremental heating. Based on the results of the analysis a model of structural evolution of a colloidal crystal upon heating on nanoscopic and mesoscopic length scales is suggested.
Optical diffraction for measurements of nano-mechanical bending
Hermans, Rodolfo I; Ndieyira, Joseph Wafula; McKendry, Rachel A; Aeppli, Gabriel
2015-01-01
Micromechanical transducers such as cantilevers for AFM often rely on optical readout methods that require illumination of a specific region of the microstructure. Here we explore and exploit the diffraction effects that have been previously neglected when modeling cantilever bending measurement techniques. The illumination of a cantilever end causes an asymmetric diffraction pattern at the photodetector that significantly affects the calibration of the signal in the popular optical beam deflection technique (OBDT). Conditions for optimized linear signals that avoid detection artifacts conflict with small numerical aperture illumination and narrow cantilevers which are softer and therefore more sensitive. Embracing diffraction patterns as a physical measurable allows a richer detection technique that decouples measurements of tilt and curvature and simultaneously relaxes the requirements on the alignment of illumination and detector. We show analytical results, numerical simulations and physiologically releva...
Diffraction and polarization effects in Earth radiation budget measurements.
Mahan, J R; Barki, A R; Priestley, K J
2016-12-01
Thermal radiation emitted and reflected from the Earth and viewed from near-Earth orbit may be characterized by its spectral distribution, its degree of coherence, and its state of polarization. The current generation of broadband Earth radiation budget instruments has been designed to minimize the effect of diffraction and polarization on science products. We used Monte Carlo ray-trace (MCRT) models that treat individual rays as quasi-monochromatic, polarized entities to explore the possibility of improving the performance of such instruments by including measures of diffraction and polarization during calibration and operation. We have demonstrated that diffraction and polarization sensitivity associated with typical Earth radiation budget instrument design features has a negligible effect on measurements.
Sprauel, J.M.; Castex, L. [ENSAM, 13 - Aix-en-Provence (France)
1996-04-01
The different factors having an influence on the X-ray or neutron diffraction peak spread, are reviewed. It is shown that the diffraction profile shape involves not only the instrumental broadening, the diffraction coherent domain size and the distribution of the atomic displacements inside these elementary volumes, but also the distribution of compositions and mean deformations of diffracting volume crystallites. Modelizations of these phenomenons are proposed, which allow for a finer definition of the microscopic mechanical state of the material. 24 refs.
Diffractive Higgs boson production at the Fermilab Tevatron and the CERN Large Hadron Collider.
Enberg, R; Ingelman, G; Kissavos, A; Tîmneanu, N
2002-08-19
Improved possibilities to find the Higgs boson in diffractive events, having less hadronic activity, depend on whether the cross section is large enough. Based on the soft color interaction models that successfully describe diffractive hard scattering at DESY HERA and the Fermilab Tevatron, we find that only a few diffractive Higgs events may be produced at the Tevatron, but we predict a substantial rate at the CERN Large Hadron Collider.
Salek, David
2011-05-15
A measurement of the longitudinal diffractive structure function F{sub L}{sup D} using the H1 detector at HERA is presented. The structure function is extracted from first measurements of the diffractive cross section ep{yields}eXY at centre of mass energies {radical}(s) of 225 and 252 GeV at high values of inelasticity y, together with a new measurement at {radical}(s) of 319 GeV, using data taken in 2006 and 2007. Previous H1 data at {radical}(s) of 301 GeV complete the kinematic coverage needed to extract F{sub L}{sup D} in the range of photon virtualities 2.5diffractive parton densities extracted in NLO QCD fits to previous diffractive DIS data and to a model which additionally includes a higher twist contribution derived from a colour dipole approach. The photoabsorption ratio for diffraction RD is extracted for Q{sup 2}>7 GeV{sup 2} and compared to the analogous quantity for inclusive DIS. (orig.)
X-Ray Diffraction Analysis Program
Wiedemann, K. E.; Unnam, J.; Naidu, S. V. N.; Houska, C. R.
1986-01-01
SOPAD separates overlapping peaks and analyzes derivatives of X-ray diffraction data. SOPAD helps analyst get most information out of available diffraction data. SOPAD uses Marquardt-type nonlinear regression routine to refine initial estimates of individual peak positions, intensities, shapes, and half-widths.
Low mass diffractive systems at LHC
Schicker, R
2008-01-01
A rapidity gap trigger for the ALICE detector at the Large Hadron Collider LHC is presented and a few selected physics observables are discussed. First, some properties of double pomeron events are outlined. Second, signatures of the odderon in diffractive J/Psi production is discussed. Third, possible evidence of gluon saturation in the cross section of diffractive heavy quark photoproduction is investigated.
ATLAS results on diffraction and forward physics
Tasevsky, M; The ATLAS collaboration
2014-01-01
Report on activity in the field of diffraction and forward physics in the ATLAS experiment is given. Results from four analyses are discussed, namely based on diffractively enhanced events by vetoing one side of detector, on soft events with rapidity gaps, on events with jet vetoes and on total cross section measurement by the ALFA subdetector.
Diffractive Optics of Anisotropic Polarization Gratings
Xu, M.
2009-01-01
Diffraction gratings are being used to manipulate light in many different applications, such as in flat panel display systems, modern lighting systems, and optical recording. Diffraction gratings can be made polarization selective due to form birefringence. An alternative approach to polarization
White-Light Diffraction with a CD
Ivanov, Dragia Trifonov; Nikolaev, Stefan
2010-01-01
Various wave optics experiments can be carried out using an ordinary compact disc. The CD is suitable for use as a diffraction grating. For instance, a standard CD (700 MB) has 625 lines/mm. In this article, the authors describe two white-light diffraction demonstrations for a large audience, realizable using a CD (as reflection or transmission…
Generalized upper bound for inelastic diffraction
Troshin, S. M.; Tyurin, N. E.
2017-01-01
For inelastic diffraction, we obtain an upper bound valid for the whole range of the elastic scattering amplitude variation allowed by unitarity. We discuss the energy dependence of the inelastic diffractive cross-section on the base of this bound and recent Large Hadron Collider (LHC) data.
A generalized upper bound for inelastic diffraction
Troshin, S M
2016-01-01
For the inelastic diffraction, we obtain an upper bound valid in the whole range of the elastic scattering amplitude variation allowed by unitarity. We discuss the energy dependence of the inelastic diffractive cross-section on the base of this bound and recent LHC data.
Accurate Charge Densities from Powder Diffraction
Bindzus, Niels; Wahlberg, Nanna; Becker, Jacob;
Synchrotron powder X-ray diffraction has in recent years advanced to a level, where it has become realistic to probe extremely subtle electronic features. Compared to single-crystal diffraction, it may be superior for simple, high-symmetry crystals owing to negligible extinction effects and minimal...... of conventional and novel extraction methods....
QCD subgroup on diffractive and forward physics
Albrow, M.G.; Baker, W.; Bhatti, A. [and others
1996-10-01
The goal is to understand the pomeron, and hence the behavior of total cross sections, elastic scattering and diffractive excitation, in terms of the underlying theory, QCD. A description of the basic ideas and phenomenology is followed by a discussion of hadron-hadron and electron-proton experiments. An appendix lists recommended diffractive-physics terms and definitions. 44 refs., 6 figs.
Uniting Electron Crystallography and Powder Diffraction
Shankland, Kenneth; Meshi, Louisa; Avilov, Anatoly; David, William
2012-01-01
The polycrystalline and nanocrystalline states play an increasingly important role in exploiting the properties of materials, encompassing applications as diverse as pharmaceuticals, catalysts, solar cells and energy storage. A knowledge of the three-dimensional atomic and molecular structure of materials is essential for understanding and controlling their properties, yet traditional single-crystal X-ray diffraction methods lose their power when only polycrystalline and nanocrystalline samples are available. It is here that powder diffraction and single-crystal electron diffraction techniques take over, substantially extending the range of applicability of the crystallographic principles of structure determination. This volume, a collection of teaching contributions presented at the Crystallographic Course in Erice in 2011, clearly describes the fundamentals and the state-of-the-art of powder diffraction and electron diffraction methods in materials characterisation, encompassing a diverse range of discipl...
"Good-Walker" + QCD dipoles = Hard Diffraction
Peschanski, R
1998-01-01
The Good-Walker mechanism for diffraction is shown to provide a link between total and diffractive structure functions and to be relevant for QCD calculations at small x_{Bj}. For Deep-Inelastic scattering on a small-size target (cf. an onium) the r\\^ ole of Good-Walker ``diffractive eigenstates'' is played by the QCD dipoles appearing in the $1/N_C$ limit of QCD. Hard diffraction is thus related to the QCD tripe-dipole vertex which has been recently identified (and calculated) as being a conformal invariant correlator and/or a closed-string amplitude. An extension to hard diffraction at HERA via $k_T-$factorisation of the proton vertices leads to interesting phenomenology.
Elastic diffractive scattering of nucleons at ultra-high energies
Godizov, A.A., E-mail: anton.godizov@gmail.com
2014-07-30
A simple Regge-eikonal model with the eikonal represented as a single-reggeon-exchange term is applied to description of the nucleon–nucleon elastic diffractive scattering at ultra-high energies. The range of validity of the proposed approximation is discussed. The model predictions for the proton–proton cross-sections at the collision energy 14 TeV are given.
11. international conference on elastic and diffractive scattering: towards high energy frontiers
NONE
2005-07-01
This conference is held every 2 years. Every time these conferences on elastic and diffractive scattering adapt their content to the most recent experimental and theoretical results concerning not only quantum chromodynamics (QCD) but also other fields of particle physics where diffractive physics is present. This year, besides classical themes such as: -) forward scattering, -) total cross-sections, -) real parts, and -) pomeron and odderon, the participants have addressed many other subjects such as: -) LHC physics, -) non-perturbative approaches to high-energy scattering, -) the dipole model, -) small-x evolution, -) hard diffraction in QCD, -) nuclear shadowing, -) diffractive Higgs studies, -) spin effects, -) 4-quarks and 5-quarks, or -) B-physics.
Femtosecond laser induced surface structuring on silicon by diffraction-assisted micropatterning
Wang, Shutong; Feng, Guoying
2015-02-01
Femtosecond laser micropatterning of silicon with nanometric surface modulation is demonstrated by irradiating through a diffracting pinhole. The irradiation results obtained at fluences above the melting threshold are characterized by optical and scanning electron microscopy and reveal a good agreement with Fresnel diffraction theory. LIPSS have been generated in the micropatterning surface. We found Ripples spacing were found of 550-680 nm. Based on the Sipe and Drude model, the theoretical period of LIPSS is closer to experimental measurements. Due to the diffraction, the LIPPS having a different period appear in a diffraction micropatterning.
Diffractive production of heavy mesons at the LHC within $k_t$ - factorization approach
Luszczak, Marta
2016-01-01
We discuss diffractive production of heavy mesons at the LHC. The differential cross sections for single- and central-diffractive mechanisms for $c\\bar c$ pair production are calculated in the framework of the Ingelman-Schlein model corrected for absorption effects. Here, leading-order gluon-gluon fusion and quark-antiquark anihilation partonic subprocesses are taken into consideration. Both pomeron flux factors as well as parton distributions in the pomeron are taken from the H1 Collaboration analysis of diffractive structure function and diffractive dijets at HERA. The extra corrections from subleading reggeon exchanges are also taken into consideration. In addition to standard collinear approach, for the first time the differential cross sections for the diffractive $c\\bar c$ pair production are calculated in the framework of the $k_t$-factorization approach, i.e. effectively including higher-order corrections. The unintegrated (transverse momentum dependent) diffractive parton distributions in proton are ...
Diffraction analysis of beams for barcode scanning
Eastman, Jay M.; Quinn, Anna M.
1991-02-01
Laser based bar code scanners utilize large f/# beams to attain a large depth of focus. The intensity cross-section of the laser beam is generally not uniform but is frequently approximated by a Gaussian intensity profile. In the case of laser diodes the beam cross-section is a two dimensional distribution. It is well known that the focusing properties of large f/# Gaussian beams differ from the predictions of ray tracing techniques. Consequently analytic modeling of laser based bar code scanning systems requires techniques based on diffraction rather than on ray tracing in order to obtain agreement between theory and practice. The line spread function of the focused laser beam is generally the parameter of interest due to the one-dimensional nature of the bar code symbol. Some bar code scanners utilize an anamorphic optical system to produce a beam that that maintains an elliptical cross-section over an extended depth of focus. This elliptical beam shape is used to average over voids and other printing defects that occur in real world symbols. Since the scanner must operate over the maximum possible depth of field the beam emergent from the scanner must be analyzed in both its near field and far field regions in order to properly model the performance of the scanner.
Engineering related neutron diffraction measurements probing strains, texture and microstructure
Clausen, Bjorn [Los Alamos National Laboratory; Brown, Donald W [Los Alamos National Laboratory; Tome, Carlos N [Los Alamos National Laboratory; Balogh, Levente [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory
2010-01-01
Neutron diffraction has been used for engineering applications for nearly three decades. The basis of the technique is powder diffraction following Bragg's Law. From the measured diffraction patterns information about internal, or residual, strain can be deduced from the peak positions, texture information can be extracted from the peak intensities, and finally the peak widths can provide information about the microstructure, e.g. dislocation densities and grain sizes. The strains are measured directly from changes in lattice parameters, however, in many cases it is non-trivial to determine macroscopic values of stress or strain from the measured data. The effects of intergranular strains must be considered, and combining the neutron diffraction measurements with polycrystal deformation modeling has proven invaluable in determining the overall stress and strain values of interest in designing and dimensioning engineering components. Furthelmore, the combined use of measurements and modeling has provided a tool for elucidating basic material properties, such as critical resolved shear stresses for the active deformation modes and their evolution as a function of applied deformation.
Neutron Diffraction Studies of the Modulated Magnetic Structures of CeSb and Nd Metal
Lebech, Bente
1981-01-01
The magnetic phase diagram of CeSb, which has been determined by neutron diffraction and other experimental techniques, is briefly reviewed and related to some of the theoretical models that have been developed to account for it. The results of neutron diffraction studies of Nd metal are also...
Diffractive optics and micro-optics: introduction to the feature issue.
Magnusson, R; Gale, M T
2001-11-10
This issue of Applied Optics features 16 papers on the fabrication, design, and applications of diffractive optics and micro-optics. A companion issue of the Journal of the Optical Society of America A, guest edited by J. N. Mait and H. P. Herzig, presents papers that emphasize the modeling and design of diffractive and micro-optical components.
Diffraction contrast imaging using virtual apertures
Gammer, Christoph, E-mail: cgammer@lbl.gov [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Department of Materials Science and Engineering, University of California, Berkeley (United States); Physics of Nanostructured Materials, Faculty of Physics, University of Vienna (Austria); Burak Ozdol, V. [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Liebscher, Christian H.; Minor, Andrew M. [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Department of Materials Science and Engineering, University of California, Berkeley (United States)
2015-08-15
Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field.
Two-dimensional x-ray diffraction
He, Bob B
2009-01-01
Written by one of the pioneers of 2D X-Ray Diffraction, this useful guide covers the fundamentals, experimental methods and applications of two-dimensional x-ray diffraction, including geometry convention, x-ray source and optics, two-dimensional detectors, diffraction data interpretation, and configurations for various applications, such as phase identification, texture, stress, microstructure analysis, crystallinity, thin film analysis and combinatorial screening. Experimental examples in materials research, pharmaceuticals, and forensics are also given. This presents a key resource to resea
New diffractive results from the Tevatron
Gallinaro, Michele; /Rockefeller U.
2005-05-01
Experimental results in diffractive processes are summarized and a few notable characteristics described in terms of Quantum Chromodynamics. Exclusive dijet production is used to establish a benchmark for future experiments in the quest for diffractive Higgs production at the Large Hadron Collider. Using new data from the Tevatron and dedicated diffractive triggers, no excess over a smooth falling distribution for exclusive dijet events could be found. Stringent upper limits on the exclusive dijet production cross section are presented. The quark/gluon composition of dijet final states is used to provide additional hints on exclusive dijet production.
Diffractive triangulation of radiative point sources
Vespucci, Stefano; Maneuski, Dzmitry; O'Shea, Val; Winkelmann, Aimo
2016-01-01
We describe a general method to determine the location of a point source of waves relative to a two-dimensional active pixel detector. Based on the inherent structural sensitivity of crystalline sensor materials, characteristic detector diffraction patterns can be used to triangulate the location of a wave emitter. As a practical application of the wide-ranging principle, a digital hybrid pixel detector is used to localize a source of electrons for Kikuchi diffraction pattern measurements in the scanning electron microscope. This provides a method to calibrate Kikuchi diffraction patterns for accurate measurements of microstructural crystal orientations, strains, and phase distributions.
Inclusive measurement of diffractive deep-inelastic scattering at HERA
Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (RU)] (and others)
2012-03-15
The diffractive process ep {yields} eXY, where Y denotes a proton or its low mass excitation with M{sub Y}<1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space region of the photon virtuality 3{<=} Q{sup 2} {<=}1600 GeV{sup 2}, the square of the four-momentum transfer at the proton vertex vertical stroke t vertical stroke <1.0 GeV{sup 2} and the longitudinal momentum fraction of the incident proton carried by the colourless exchange x{sub P}<0.05. Triple differential cross sections are measured as a function of x{sub P}, Q{sup 2} and {beta}=x/x{sub P} where x is the Bjorken scaling variable. These measurements are made after selecting diffractive events by demanding a large empty rapidity interval separating the final state hadronic systems X and Y. High statistics measurements covering the data taking periods 1999-2000 and 2004-2007 are combined with previously published results in order to provide a single set of diffractive cross sections from the H1 experiment using the large rapidity gap selection method. The combined data represent a factor between three and thirty increase in statistics with respect to the previously published results. The measurements are compared with predictions from NLO QCD calculations based on diffractive parton densities and from a dipole model. The proton vertex factorisation hypothesis is tested. (orig.)
Study of diffractive processes at the ATLAS Experiment
Kus, Vlastimil
A data sample of $pp$ collisions corresponding to an integrated luminosity of 6.75 $\\mathrm{nb}^{-1}$ was collected at $\\sqrt{s} = 7$ TeV using the ATLAS detector at the Large Hadron Collider. Collision events with at least two jets with $p_{\\mathrm{T}}>20$ GeV are used to measure the differential cross section of the diffractive dijet production as a function of the rapidity gap size $\\Delta\\eta^{\\mathrm{F}}$, the largest forward region extending from $|\\eta| = 4.8$ devoid of particle activity above threshold momentum cuts, and an estimator of the fractional momentum loss of the scattered proton assuming the single diffractive dissociation ($pp \\rightarrow pX$), $\\tilde\\xi^{\\pm}$. Comparisons with various Monte Carlo models reveal that though the region of small $\\tilde\\xi^{\\pm}$ and large rapidity gaps is dominated by diffraction, a contribution form non-diffractive events cannot be neglected. The rapidity gap survival probability is estimated based on data to Monte Carlo comparisons in the $-3.2 2$ require...
Inclusive measurement of diffractive deep-inelastic scattering at HERA
Aaron, F.D.; Alexa, C.; Rotaru, M.; Stoicea, G.; Andreev, V.; Belousov, A.; Eliseev, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Shtarkov, L.N.; Soloviev, Y.; Vazdik, Y.; Backovic, S.; Dubak, A.; Lastovicka-Medin, G.; Picuric, I.; Raicevic, N.; Baghdasaryan, A.; Baghdasaryan, S.; Zohrabyan, H.; Barrelet, E.; Bartel, W.; Belov, P.; Brandt, G.; Brinkmann, M.; Britzger, D.; Campbell, A.J.; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Gouzevitch, M.; Grebenyuk, A.; Habib, S.; Haidt, D.; Kleinwort, C.; Kraemer, M.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Nowak, K.; Olsson, J.E.; Pahl, P.; Panagoulias, I.; Papadopoulou, T.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Radescu, V.; Schmitt, S.; Sefkow, F.; Shushkevich, S.; South, D.; Steder, M.; Wuensch, E.; Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B.; Bizot, J.C.; Brisson, V.; Delcourt, B.; Jacquet, M.; Pascaud, C.; Tran, T.H.; Zhang, Z.; Zomer, F.; Boudry, V.; Moreau, F.; Specka, A.; Bozovic-Jelisavcic, I.; Pandurovic, M.; Bracinik, J.; Kenyon, I.R.; Newman, P.R.; Thompson, P.D.; Bruncko, D.; Cerny, V.; Ferencei, J.; Bunyatyan, A.; Bylinkin, A.; Bystritskaya, L.; Fedotov, A.; Lubimov, V.; Ozerov, D.; Rostovtsev, A.; Zhokin, A.; Cantun Avila, K.B.; Contreras, J.G.; Ruiz Tabasco, J.E.; Ceccopieri, F.; Delvax, J.; Wolf, E.A. de; Favart, L.; Hreus, T.; Janssen, X.; Roosen, R.; Staykova, Z.; Mechelen, P. van; Cerny, K.; Pokorny, B.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Zlebcik, R.; Chekelian, V.; Dossanov, A.; Grindhammer, G.; Kiesling, C.; Coughlan, J.A.; Morris, J.V.; Sankey, D.P.C.; Cvach, J.; Hladky, J.; Reimer, P.; Zalesak, J.; Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kluge, T.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D.; Daum, K.; Meyer, H.; Diaconu, C.; Hoffmann, D.; Sauvan, E.; Vallee, C.; Dobre, M.; Kogler, R.; Dodonov, V.; Povh, B.; Egli, S.; Hildebrandt, M.; Horisberger, R.; Feltesse, J.; Perez, E.; Schoeffel, L.; Goerlich, L.; Mikocki, S.; Milcewicz-Mika, I.; Nowak, G.; Sopicki, P.; Turnau, J.; Grab, C.; Henderson, R.C.W.; Sloan, T.; Hennekemper, E.; Herbst, M.; Krueger, K.; Lendermann, V.; Schultz-Coulon, H.C.; Henschel, H.; Hiller, K.H.; Kostka, P.; Lange, W.; Naumann, T.; Herrera, G.; Lopez-Fernandez, R.; Huber, F.; Pirumov, H.; Sauter, M.; Schoening, A.; Joensson, L.; Jung, H.; Kapichine, M.; Morozov, A.; Nikitin, D.; Palichik, V.; Spaskov, V.; Landon, M.P.J.; Rizvi, E.; Traynor, D.; Martyn, H.U.; Mueller, K.; Robmann, P.; Straumann, U.; Truoel, P.; Stella, B.; Sykora, T.; Tsakov, I.; Wegener, D.; Collaboration: H1 Collaboration
2012-07-15
The diffractive process ep{yields}eXY, where Y denotes a proton or its low mass excitation with M{sub Y}<1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space region of the photon virtuality 3{<=}Q{sup 2}{<=} 1600 GeV {sup 2}, the square of the four-momentum transfer at the proton vertex vertical stroke t vertical stroke < 1.0 GeV {sup 2} and the longitudinal momentum fraction of the incident proton carried by the colourless exchange x{sub P}<0.05. Triple differential cross sections are measured as a function of x{sub P}, Q {sup 2} and {beta}=x/x{sub P} where x is the Bjorken scaling variable. These measurements are made after selecting diffractive events by demanding a large empty rapidity interval separating the final state hadronic systems X and Y. High statistics measurements covering the data taking periods 1999-2000 and 2004-2007 are combined with previously published results in order to provide a single set of diffractive cross sections from the H1 experiment using the large rapidity gap selection method. The combined data represent a factor between three and thirty increase in statistics with respect to the previously published results. The measurements are compared with predictions from NLO QCD calculations based on diffractive parton densities and from a dipole model. The proton vertex factorisation hypothesis is tested. (orig.)
Inclusive measurement of diffractive deep-inelastic scattering at HERA
Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (RU)] (and others)
2012-03-15
The diffractive process ep {yields} eXY, where Y denotes a proton or its low mass excitation with M{sub Y}<1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space region of the photon virtuality 3{<=} Q{sup 2} {<=}1600 GeV{sup 2}, the square of the four-momentum transfer at the proton vertex vertical stroke t vertical stroke <1.0 GeV{sup 2} and the longitudinal momentum fraction of the incident proton carried by the colourless exchange x{sub P}<0.05. Triple differential cross sections are measured as a function of x{sub P}, Q{sup 2} and {beta}=x/x{sub P} where x is the Bjorken scaling variable. These measurements are made after selecting diffractive events by demanding a large empty rapidity interval separating the final state hadronic systems X and Y. High statistics measurements covering the data taking periods 1999-2000 and 2004-2007 are combined with previously published results in order to provide a single set of diffractive cross sections from the H1 experiment using the large rapidity gap selection method. The combined data represent a factor between three and thirty increase in statistics with respect to the previously published results. The measurements are compared with predictions from NLO QCD calculations based on diffractive parton densities and from a dipole model. The proton vertex factorisation hypothesis is tested. (orig.)
Analysis of the role of diffraction in topographic site effects using boundary element techniques
Gomez, Juan; Restrepo, Doriam; Jaramillo, Juan; Valencia, Camilo
2013-10-01
The role played by the diffraction field on the problem of seismic site effects is studied. For that purpose we solve and analyze simple scattering problems under P and SV in-plane wave assumptions, using two well known direct boundary-element-based numerical methods. After establishing the difference between scattered and diffracted motions, and introducing the concept of artificious and physically based incoming fields, we obtain the amplitude of the Fourier spectra for the diffracted part of the response: this is achieved after establishing the connection between the spatial distribution of the transfer function over the studied simple topographies and the diffracted field. From the numerical simulations it is observed that this diffracted part of the response is responsible for the amplification of the surface ground motions due to the geometric effect. Furthermore, it is also found that the diffraction field sets in a fingerprint of the topographic effect in the total ground motions. These conclusions are further supported by observations in the time-domain in terms of snapshots of the propagation patterns over the complete computational model. In this sense the geometric singularities are clearly identified as sources of diffraction and for the considered range of dimensionless frequencies it is evident that larger amplifications are obtained for the geometries containing a larger number of diffraction sources thus resulting in a stronger topographic effect. The need for closed-form solutions of canonical problems to construct a robust analysis method based on the diffraction field is identified.
Tunable Beam Diffraction in Infiltrated Microstructured Fibers
Rosberg, Christian Romer; Bennet, Francis H.; Neshev, Dragomir N.;
We experimentally study beam propagation in two dimensional photonic lattices in microstructured optical fibers infiltrated with high index liquids. We demonstrate strongly tunable beam diffraction by dynamically varying the coupling between individual lattice sites....
Thermal diffractive corrections to Casimir energies
Kabat, Daniel
2011-01-01
We study the interplay of thermal and diffractive effects in Casimir energies. We consider plates with edges, oriented either parallel or perpendicular to each other, as well as a single plate with a slit. We compute the Casimir energy at finite temperature using a formalism in which the diffractive effects are encoded in a lower dimensional non-local field theory that lives in the gap between the plates. The formalism allows for a clean separation between direct or geometric effects and diffractive effects, and makes an analytic derivation of the temperature dependence of the free energy possible. At low temperatures, with Dirichlet boundary conditions on the plates, we find that diffractive effects make a correction to the free energy which scales as T^6 for perpendicular plates, as T^4 for slits, and as T^4 log T for parallel plates.
Atomic resolution 3D electron diffraction microscopy
Miao, Jianwei; Ohsuna, Tetsu; Terasaki, Osamu; O' Keefe, Michael A.
2002-03-01
Electron lens aberration is the major barrier limiting the resolution of electron microscopy. Here we describe a novel form of electron microscopy to overcome electron lens aberration. By combining coherent electron diffraction with the oversampling phasing method, we show that the 3D structure of a 2 x 2 x 2 unit cell nano-crystal (framework of LTA [Al12Si12O48]8) can be ab initio determined at the resolution of 1 Angstrom from a series of simulated noisy diffraction pattern projections with rotation angles ranging from -70 degrees to +70 degrees in 5 degrees increments along a single rotation axis. This form of microscopy (which we call 3D electron diffraction microscopy) does not require any reference waves, and can image the 3D structure of nanocrystals, as well as non-crystalline biological and materials science samples, with the resolution limited only by the quality of sample diffraction.
Diffractive waveplates for long wave infrared
Ouskova, Elena; Roberts, David; Tabiryan, Nelson; Steeves, D. M.; Kimball, B. R.
2017-05-01
We report about developing long-wave infrared diffractive optical components based on liquid crystals. The components show high efficiency and high transparency for the 10.6 μm wavelength of CO2 laser beam.
Kinematic Diffraction from a Mathematical Viewpoint
Baake, Michael
2011-01-01
Mathematical diffraction theory is concerned with the analysis of the diffraction image of a given structure and the corresponding inverse problem of structure determination. In recent years, the understanding of systems with continuous and mixed spectra has improved considerably. Simultaneously, their relevance has grown in practice as well. In this context, the phenomenon of homometry shows various unexpected new facets. This is particularly so for systems with stochastic components. After the introduction to the mathematical tools, we briefly discuss pure point spectra, based on the Poisson summation formula for lattice Dirac combs. This provides an elegant approach to the diffraction formulas of infinite crystals and quasicrystals. We continue by considering classic deterministic examples with singular or absolutely continuous diffraction spectra. In particular, we recall an isospectral family of structures with continuously varying entropy. We close with a summary of more recent results on the diffractio...
X-ray diffraction: instrumentation and applications.
Bunaciu, Andrei A; Udriştioiu, Elena Gabriela; Aboul-Enein, Hassan Y
2015-01-01
X-ray diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline materials. It provides information on structures, phases, preferred crystal orientations (texture), and other structural parameters, such as average grain size, crystallinity, strain, and crystal defects. X-ray diffraction peaks are produced by constructive interference of a monochromatic beam of X-rays scattered at specific angles from each set of lattice planes in a sample. The peak intensities are determined by the distribution of atoms within the lattice. Consequently, the X-ray diffraction pattern is the fingerprint of periodic atomic arrangements in a given material. This review summarizes the scientific trends associated with the rapid development of the technique of X-ray diffraction over the past five years pertaining to the fields of pharmaceuticals, forensic science, geological applications, microelectronics, and glass manufacturing, as well as in corrosion analysis.
Diffractive Optical Elements for Dynamic Optical Coupling
Changhe Zhou; Xin Zhao; Liren Liu
2003-01-01
Diffractive optical elements such as the complementary Dammann gratings are incorporated for dynamic optical fiber splitting and combining. Experimental results of 1′8 dynamic optical couplings are presented.
Diffractive Optical Elements for Dynamic Optical Coupling
无
2003-01-01
Diffractive optical elements such as the complementary Dammann gratings are incorporated for dynamic optical fiber splitting and combining. Experimental results of 1×8 dynamic optical couplings are presented.
Diffraction analysis of the microstructure of materials
Scardi, Paolo
2004-01-01
Diffraction Analysis of the Microstructure of Materials provides an overview of diffraction methods applied to the analysis of the microstructure of materials. Since crystallite size and the presence of lattice defects have a decisive influence on the properties of many engineering materials, information about this microstructure is of vital importance in developing and assessing materials for practical applications. The most powerful and usually non-destructive evaluation techniques available are X-ray and neutron diffraction. The book details, among other things, diffraction-line broadening methods for determining crystallite size and atomic-scale strain due, e.g. to dislocations, and methods for the analysis of residual (macroscale) stress. The book assumes only a basic knowledge of solid-state physics and supplies readers sufficient information to apply the methods themselves.
Simulating interference and diffraction in instructional laboratories
Maurer, L.
2013-03-01
Studieshave shown that standard lectures and instructional laboratory experiments are not effective at teaching interference and diffraction. In response, the author created an interactive computer program that simulates interference and diffraction effects using the finite difference time domain method. The software allows students to easily control, visualize and quantitatively measure the effects. Students collected data from simulations as part of their laboratory exercise, and they performed well on a subsequent quiz, showing promise for this approach.
[X-ray diffraction spectrum of heroin].
Hu, X; Kan, J; Yuan, B
1999-06-01
In this paper, practical measured X-ray diffraction spectra of heroin and opium are given and the parameters of each diffraction peak of the heroin are listed. The heroin belongs to orthorhombic crystal system; the basic vectors of the primitive cell are: a = 8.003, b = 14.373, c = 16.092 x 10(-10) m. As compared with the standard spectra of pure heroin and sucrose, the main doped additive checked by us, is sugar affirmatively.
Diffractive Leptoproduction of Vector Mesons in QCD
Brodsky, Stanley J.; Frankfurt, L.; Gunion, J. F.; Mueller, A.H.; Strikman, M.
1994-01-01
We demonstrate that the distinctive features of the forward differential cross section of diffractive leptoproduction of a vector meson can be legitimately calculated in perturbative QCD in terms of the light-cone $q \\bar q$ wave function of the vector meson and the gluon distribution of the target. In particular, we calculate the $Q^2$ and nuclear dependence of the diffractive leptoproduction of vector mesons and estimate the cross section. The production of longitudinally polarized vector m...
Unified QCD picture of hard diffraction
Navelet, H
2001-01-01
Using a combination of S-Matrix and perturbative QCD properties in the small x_{Bjorken} regime, we propose a formulation of hard diffraction unifying the partonic (Ingelman-Schlein) Pomeron, Soft Colour Interaction and QCD dipole descriptions. In particular, we show that all three approaches give an unique and mutually compatible formula for the proton diffractive structure functions incorporating perturbative and non perturbative QCD features.
Diffractive and ultraperipheral physics with ALICE
Schicker, Rainer
2008-01-01
The ALICE experiment consists of a central barrel, a muon spe ctrometer, zero degree calorimeters and additional detectors for trigger and event classificati on purposes. Such a geometry allows the implementation of a double gap trigger. A diffractive physi cs program of ALICE is outlined and a few specific reaction channels are discussed in order to ill ustrate the interest in such a diffractive physics program
When fast atom diffraction turns 3D
Zugarramurdi, Asier; Borisov, Andrei G., E-mail: andrei.borissov@u-psud.fr
2013-12-15
Fast atom diffraction at surfaces (FAD) in grazing incidence geometry is characterized by the slow motion in the direction perpendicular to the surface and fast motion parallel to the surface plane along a low index direction. It is established experimentally that for the typical surfaces the FAD reveals the 2D diffraction patterns associated with exchange of the reciprocal lattice vector perpendicular to the direction of fast motion. The reciprocal lattice vector exchange along the direction of fast motion is negligible. The usual approximation made in the description of the experimental data is then to assume that the effective potential leading to the diffraction results from the averaging of the 3D surface potential along the atomic strings forming the axial channel. In this work we use full quantum wave packet propagation calculations to study theoretically the possibility to observe the 3D diffraction in FAD experiments. We show that for the surfaces with large unit cell, such as can be the case for reconstructed or vicinal surfaces, the 3D diffraction can be observed. The reciprocal lattice vector exchange along the direction of fast motion leads to several Laue circles in the diffraction pattern.
Exclusive diffraction and Pomeron trajectory in ep collisions
Fazio, S
2008-01-01
The exclusive diffractive production of vector mesons and real photons in ep collisions has been studied at HERA in a wide kinematic range. Here we present the most recent experimental results together with a Regge-type model. We deduce the Pomeranchuk trajectory (Pomeron) by analyzing the HERA data on deeply virtual Compton scattering (DVCS), and then discuss its basic properties, namely its apparent "hardness" and its "non-flat" behavior, different from the claims of some authors.
Traceability of high focal length cameras with diffractive optical elements
Lages Martins, L.; Silva Ribeiro, A.; Sousa, J. Alves e.
2016-11-01
This paper describes the use of diffractive optical elements (DOEs) for metrological traceable geometrical testing of high focal length cameras applied in the observation of large- scale structures. DOEs and related mathematical models are briefly explained. Laboratorial activities and results are described for the case of a high focal length camera used for longdistance displacement measurement of a long-span (2278 m) suspension bridge.
Blazed Grating Resonance Conditions and Diffraction Efficiency Optical Transfer Function
Stegenburgs, Edgars
2017-01-08
We introduce a general approach to study diffraction harmonics or resonances and resonance conditions for blazed reflecting gratings providing knowledge of fundamental diffraction pattern and qualitative understanding of predicting parameters for the most efficient diffraction.
Neutron Diffraction and Magnetostriction of Cubic La(FexAl1-x)13 Intermetallic Compounds
Palstra, T.T.M.; Nieuwenhuys, G.J.; Mydosh, J.A.; Helmholdt, R.B.; Buschow, K.H.J.
1986-01-01
The ferromagnetic and antiferromagnetic states of La(FexAl1-x)13 were studied by neutron diffraction and magnetostriction measurements. We present a model for the magnetic structure of the antiferromagnetic state, consisting of ferromagnetic clusters, coupled antiferromagnetically. Magnetostriction
Effective grating theory for resonance domain surface-relief diffraction gratings.
Golub, Michael A; Friesem, Asher A
2005-06-01
An effective grating model, which generalizes effective-medium theory to the case of resonance domain surface-relief gratings, is presented. In addition to the zero order, it takes into account the first diffraction order, which obeys the Bragg condition. Modeling the surface-relief grating as an effective grating with two diffraction orders provides closed-form analytical relationships between efficiency and grating parameters. The aspect ratio, the grating period, and the required incidence angle that would lead to high diffraction efficiencies are predicted for TE and TM polarization and verified by rigorous numerical calculations.
The energy dependence of the diffraction minimum in the elastic scattering and new LHC data
Selyugin, O. V.
2017-03-01
The soft diffraction phenomena in the elastic proton-proton scattering are reviewed from the viewpoint of experiments at the LHC (TOTEM and ATLAS collaboration). In the framework of the High Energy Generalized Structure (HEGS) model the form of the diffraction minimum in the nucleon-nucleon elastic scattering in a wide energy region is analyzed. The energy dependencies of the main characteristics of the diffraction dip are obtained. The numerical predictions at LHC energies are presented. The comparison of the model predictions with the new LHC data at √{ s} = 13 TeV is made.
Remote Laser Diffraction PSD Analyzer
Batcheller, Thomas Aquinas; Huestis, Gary Michael; Bolton, Steven Michael
2000-06-01
Particle size distribution (PSD) analysis of radioactive slurry samples were obtained using a modified "off-the-shelf" classical laser light scattering particle size analyzer. A Horiba Instruments Inc. Model La-300 PSD analyzer, which has a 0.1 to 600 micron measurement range, was modified for remote application in a "hot cell" (gamma radiation) environment. The general details of the modifications to this analyzer are presented in this paper. This technology provides rapid and simple PSD analysis, especially down in the fine and microscopic particle size regime. Particle size analysis of these radioactive slurries down in this smaller range was not achievable - making this technology far superior than the traditional methods used previously. Remote deployment and utilization of this technology is in an exploratory stage. The risk of malfunction in this radiation environment is countered by gaining of this tremendously useful fundamental engineering data. Successful acquisition of this data, in conjunction with other characterization analyses, provides important information that can be used in the myriad of potential radioactive waste management alternatives.
Surface diffusion studies by optical diffraction techniques
Xiao, X.D.
1992-11-01
The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect.
Remote Laser Diffraction Particle Size Distribution Analyzer
Batcheller, Thomas Aquinas; Huestis, Gary Michael; Bolton, Steven Michael
2001-03-01
In support of a radioactive slurry sampling and physical characterization task, an “off-the-shelf” laser diffraction (classical light scattering) particle size analyzer was utilized for remote particle size distribution (PSD) analysis. Spent nuclear fuel was previously reprocessed at the Idaho Nuclear Technology and Engineering Center (INTEC—formerly recognized as the Idaho Chemical Processing Plant) which is on DOE’s INEEL site. The acidic, radioactive aqueous raffinate streams from these processes were transferred to 300,000 gallon stainless steel storage vessels located in the INTEC Tank Farm area. Due to the transfer piping configuration in these vessels, complete removal of the liquid can not be achieved. Consequently, a “heel” slurry remains at the bottom of an “emptied” vessel. Particle size distribution characterization of the settled solids in this remaining heel slurry, as well as suspended solids in the tank liquid, is the goal of this remote PSD analyzer task. A Horiba Instruments Inc. Model LA-300 PSD analyzer, which has a 0.1 to 600 micron measurement range, was modified for remote application in a “hot cell” (gamma radiation) environment. This technology provides rapid and simple PSD analysis, especially down in the fine and microscopic particle size regime. Particle size analysis of these radioactive slurries down in this smaller range was not previously achievable—making this technology far superior than the traditional methods used. Successful acquisition of this data, in conjunction with other characterization analyses, provides important information that can be used in the myriad of potential radioactive waste management alternatives.
Observation of the Quantum-Classical Transition via Electron Diffraction
Beierle, Peter; Batelaan, Herman
2016-05-01
A collimated electron beam with an energy ranging from .5 keV- 5 keV is passed over a 1 cm long conducting surface. The electrons are diffracted from a 100 nm periodic SiN free-standing grating. The surface is place within the electron near-field diffraction distance. The loss of visibility of the far-field diffraction pattern is measured, which indicates the amount of decoherence that the electrons experienced as they passed over the surface. It has been determined through the visibility as a function of the height with respect to the surface that a) one can observe the transition of the electron's behavior between classical and quantum mechanics, b) that our experiment can be used to rule out a classical theoretical model of the surface decohering mechanism (consistent with Hasselbach's work), and c) this experimental setup is simpler than the use of an interferometer. Comparing a silicon to a gold surface, we are in the process of testing a wider array of theoretical models for the mechanism of decoherence. This work is supported by the National Science Foundation under award number 1306565.
Measurement of diffractive and exclusive processes with the ATLAS detector
Gach, Grzegorz; The ATLAS collaboration
2015-01-01
The ATLAS collaboration has carried out a study diffractive dijet production at 7 TeV pp collisions at the LHC, i.e. events with a hadronic system containing at least two jets in addition to a large region of pseudorapidity devoid of hadronic activity. The data distributions are compared with Monte Carlo models and the rapidity gap survival probability has been estimated in the kinematic region with high diffractive contribution. Prospects for exclusive jet production studies with the forward proton tagging capability of the AFP sub-detector of ATLAS will be discussed. A first look at data taken jointly with the ATLAS and LHCf detectors in a p+Pb run will also be shown. In addition the measurement of the exclusive $\\gamma+\\gamma \\rightarrow ll$ production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been carried out.
Measurement of diffractive and exclusive processes with the ATLAS detector
Gach Grzegorz
2016-01-01
Full Text Available The ATLAS Collaboration has carried out a study of diffractive dijet production in proton–proton collisions at a centre-of-mass energy of √s = 7 TeV at the LHC. The data distributions are compared with Monte Carlo models and the rapidity gap survival probability has been estimated in the kinematic region with high diffractive contribution. Prospects for exclusive jet production studies with the forward proton tagging capability of the AFP sub-detector of ATLAS are also discussed. First results based on data taken jointly with the ATLAS and the LHCf detectors in a p+Pb run will also be shown. In addition, the measurement of the cross-section for the exclusive production of di-lepton pairs in pp collisions at √s = 7 TeV is discussed.
Diffraction-free beams in fractional Schr\\"odinger equation
Zhang, Yiqi; Belić, Milivoj R; Ahmed, Noor; Zhang, Yanpeng; Xiao, Min
2015-01-01
We consider the propagation of one-dimensional and two-dimensional (1D, 2D) Gaussian beams in FSE without a potential, analytically and numerically. Without chirp, a 1D Gaussian beam splits into two nondiffracting Gaussian beams during propagation, while a 2D Gaussian beam undergoes conical diffraction. When a Gaussian beam carries linear chirp, the 1D beam deflects along the trajectories $z=\\pm2(x-x_0)$, which are independent of the chirp. In the case of 2D Gaussian beam, the propagation is also deflected, but the trajectories align along the diffraction cone $z=2r$ and the direction is determined by the chirp. Both 1D and 2D Gaussian beams are diffractionless and display uniform propagation. The nondiffracting property discovered in this model applies to other beams as well. Based on this nondiffracting and splitting property, we introduce the Talbot effect of diffractionless beams in FSE.
Diffractive photoproduction of vector mesons at the LHC
Armesto, Néstor
2014-01-01
We confront saturation-based results for diffractive $\\psi(2s)$ and $\\rho$ production at HERA and $J/\\psi$ photoproduction with all available data including recent ones from HERA, ALICE and LHCb, finding a good agreement. We show that the $t$-distribution of differential cross-section of photoproduction of vector mesons offers a unique opportunity to discriminate among saturation and non-saturation models. This is due to emergence of a pronounced dip (or multiple dips) in the $t$-distribution of diffractive photoproduction of vector mesons at relatively large, but potentially accessible $|t|$ that can be traced back to the unitarity features of colour dipole amplitude in the saturation regime. We provide various predictions for exclusive (photo)-production of different vector mesons including the ratio of $\\psi(2s)/J/\\psi$ at HERA, the LHC and at future colliders.
Soft QCD in ATLAS: Minimum bias and diffraction studies
Sarkisyan-Grinbaum, EK; The ATLAS collaboration
2011-01-01
We present measurements on charged particle production in proton-proton collisions at centre-of-mass energies of root(s)= 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. Events were collected using a single-arm minimum bias trigger, charged tracks are measured with high precision in the inner tracking system. Minimum bias analysis uses data samples at all three energies, while diffractive events are studied using a sample of events at roo(s})= 7 TeV. To study diffractive interactions, the events that have hits on exactly one side of the ATLAS detector were selected. The charged particle multiplicity, pseudorapidity and transverse momentum spectra are analiyzed and compared to the predictions by various Monte Carlo models.
Measurement of diffractive and exclusive processes with the ATLAS detector
Gach, Grzegorz
2016-07-01
The ATLAS Collaboration has carried out a study of diffractive dijet production in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the LHC. The data distributions are compared with Monte Carlo models and the rapidity gap survival probability has been estimated in the kinematic region with high diffractive contribution. Prospects for exclusive jet production studies with the forward proton tagging capability of the AFP sub-detector of ATLAS are also discussed. First results based on data taken jointly with the ATLAS and the LHCf detectors in a p+Pb run will also be shown. In addition, the measurement of the cross-section for the exclusive production of di-lepton pairs in pp collisions at √s = 7 TeV is discussed.
Groove shape characteristics of echelle gratings with high diffraction efficiency
Zhang, Shanwen; Mi, Xiaotao; Zhang, Qian; Jirigalantu; Feng, Shulong; Yu, Haili; Qi, Xiangdong
2017-03-01
The groove shape characteristics of echelle gratings with high diffraction efficiency are investigated. Using the coordinate transformation method (C method), an r-2 aluminum echelle with 79 grooves/mm is optimized through rigorous numerical simulations and shows high diffraction efficiency of 76-81% in the high Littrow orders. A grating is found to be essentially an echelle if it contains a series of reflective facets with a specific tilt angle that are located far from the nonworking facet of the grating and have a deep groove depth; any groove shape that meets these conditions can be called an echelle grating. The underlying mechanism is analyzed phenomenologically using electromagnetic theory. The universal model proposed here, which represents a new cognitive understanding of the concept of the echelle, is ready for use in manufacturing applications and offers a new perspective for the fabrication of these gratings.
Random point sets and their diffraction
Baake, Michael
2010-01-01
The diffraction of various random subsets of the integer lattice $\\mathbb{Z}^{d}$, such as the coin tossing and related systems, are well understood. Here, we go one important step beyond and consider random point sets in $\\mathbb{R}^{d}$. We present several systems with an effective stochastic interaction that still allow for explicit calculations of the autocorrelation and the diffraction measure. We concentrate on one-dimensional examples for illustrative purposes, and briefly indicate possible generalisations to higher dimensions. In particular, we discuss the stationary Poisson process in $\\mathbb{R}^{d}$ and the renewal process on the line. The latter permits a unified approach to a rather large class of one-dimensional structures, including random tilings. Moreover, we present some stationary point processes that are derived from the classical random matrix ensembles as introduced in the pioneering work of Dyson and Ginibre. Their re-consideration from the diffraction point of view improves the intuiti...
Immobilizing Biomolecules Near the Diffraction Limit
Skovsen, Esben; Petersen, Maria Teresa Neves; Gennaro, Ane Kold Di
2009-01-01
Our group has previously shown that biomolecules containing disulfide bridges in close proximity to aromatic residues can be immobilized, through covalent bonds, onto thiol derivatized surfaces upon UV excitation of the aromatic residue(s). We have also previously shown that our new technology can...... be used to print arrays of biomolecules and to immobilize biomolecules according to any specific pattern on a planar substrates with micrometer scale resolution. In this paper we show that we can immobilize proteins according to diffraction patterns of UV light. We also show that the feature size...... of the immobilized patterns can be as small as the diffraction limit for the excitation light, and that the immobilized patterns correspond to the diffraction pattern used to generate it. The flexibility of this new technology will in principle make it possible to create any pattern of biomolecules onto a substrate...
Diffractive elements performance in chromatic confocal microscopy
Garzon, J; Duque, D; Alean, A; Toledo, M [Grupo de Optica y EspectroscopIa, Centro de Ciencia Basica, Universidad Pontificia Bolivariana. Medellin (Colombia); Meneses, J [Laboratorio de Optica y Tratamiento de Senales, Instituto de Fisica, Universidad Industrial de Santander, Bucaramanga (Colombia); Gharbi, T, E-mail: jgarzonr10@une.net.co [Laboratoire d' Optique P. M. Duffieux, UMR-6603 CNR/Universite de Franche-Comte. 16 route de Gray, 25030 Besancon Cedex (France)
2011-01-01
The Confocal Laser Scanning Microscopy (CLSM) has been widely used in the semiconductor industry and biomedicine because of its depth discrimination capability. Subsequent to this technique has been developed in recent years Chromatic Confocal Microscopy. This method retains the same principle of confocal and offers the added advantage of removing the axial movement of the moving system. This advantage is usually accomplished with an optical element that generates a longitudinal chromatic aberration and a coding system that relates the axial position of each point of the sample with the wavelength that is focused on each. The present paper shows the performance of compact chromatic confocal microscope when some different diffractive elements are used for generation of longitudinal chromatic aberration. Diffractive elements, according to the process and manufacturing parameters, may have different diffraction efficiency and focus a specific wavelength in a specific focal position. The performance assessment is carried out with various light sources which exhibit an incoherent behaviour and a broad spectral width.
Electron backscatter diffraction in materials characterization
Dejan Stojakovic
2012-03-01
Full Text Available Electron Back-Scatter Diffraction (EBSD is a powerful technique that captures electron diffraction patterns from crystals, constituents of material. Captured patterns can then be used to determine grain morphology, crystallographic orientation and chemistry of present phases, which provide complete characterization of microstructure and strong correlation to both properties and performance of materials. Key milestones related to technological developments of EBSD technique have been outlined along with possible applications using modern EBSD system. Principles of crystal diffraction with description of crystallographic orientation, orientation determination and phase identification have been described. Image quality, resolution and speed, and system calibration have also been discussed. Sample preparation methods were reviewed and EBSD application in conjunction with other characterization techniques on a variety of materials has been presented for several case studies. In summary, an outlook for EBSD technique was provided.
Forward energy flow and diffraction at ATLAS
Staroba, P; The ATLAS collaboration
2012-01-01
First measurements of forward energy flow and diffractive dissociation processes at ATLAS are presented. Measurements are based on 7 TeV minimum bias (7.1μb−1) and dijet (585μb−1) data samples taken during March-May 2010 in the low pileup accelerator setup. Measurement of transverse energy density as a function of pseudorapidity was performed using the full acceptance of ATLAS detectors. Stable charged particles with PT > 500 MeV and stable neutral particles with PT > 200 MeV were included. Manifestation of diffractive processes of three classes (single, double and central diffractive dissociation) was studied using inelastic differential cross section in forward rapidity gap size ΔηF bins. Experimental distributions are compared with several Monte Carlo predictions (PYTHIA6, PYTHIA8, PHOJET, HERWIG++ and EPOS) using different tunes.
Coherent Diffractive Imaging Using Randomly Coded Masks
Seaberg, Matthew H; Turner, Joshua J
2015-01-01
Coherent diffractive imaging (CDI) provides new opportunities for high resolution X-ray imaging with simultaneous amplitude and phase contrast. Extensions to CDI broaden the scope of the technique for use in a wide variety of experimental geometries and physical systems. Here, we experimentally demonstrate a new extension to CDI that encodes additional information through the use of a series of randomly coded masks. The information gained from the few additional diffraction measurements removes the need for typical object-domain constraints; the algorithm uses prior information about the masks instead. The experiment is performed using a laser diode at 532.2 nm, enabling rapid prototyping for future X-ray synchrotron and even free electron laser experiments. Diffraction patterns are collected with up to 15 different masks placed between a CCD detector and a single sample. Phase retrieval is performed using a convex relaxation routine known as "PhaseCut" followed by a variation on Fienup's input-output algorit...
Small angle electron diffraction and deflection
T. Koyama
2012-03-01
Full Text Available Electron optical system is constructed in order to obtain small angle diffraction and Lorentz deflection of electrons at the order of down to 10-6 radian in the reciprocal space. Long-distance camera length up to 3000 m is achieved in a conventional transmission electron microscope with LaB6 thermal emission type. The diffraction pattern at 5 × 10-6 radian is presented in a carbon replica grating with 500 nm lattice spacing while the magnetic deflection pattern at 2 × 10-5 radian is exhibited in Permalloy elements. A simultaneous recording of electron diffraction and Lorentz deflection is also demonstrated in 180 degree striped magnetic domains of La0.825Sr0.175MnO3.
Double diffraction in an atomic gravimeter
Malossi, Nicola; Merlet, Sébastien; Landragin, Arnaud; Santos, Franck Pereira Dos
2009-01-01
We demonstrate the realization of a new scheme for cold atom gravimetry based on the use of double diffraction beamsplitters recently demonstrated in \\cite{Leveque}, where the use of two retro-reflected Raman beams allows symmetric diffraction in $\\pm \\hbar k_{eff}$ momenta. Though in principle restricted to the case of zero Doppler shift, for which the two pairs of Raman beams are simultaneously resonant, we demonstrate that such diffraction pulses can remain efficient on atoms with non zero velocity, such as in a gravimeter, when modulating the frequency of one of the two Raman laser sources. We use such pulses to realize an interferometer insensitive to laser phase noise and some of the dominant systematics. This reduces the technical requirements and would allow the realization of a simple atomic gravimeter. We demonstrate a sensitivity of $1.2\\times10^{-7}g$ per shot.
Diffraction and interference of walking drops
Pucci, Giuseppe; Harris, Daniel M.; Bush, John W. M.
2016-11-01
A decade ago, Yves Couder and Emmanuel Fort discovered a wave-particle association on the macroscopic scale: a drop can bounce indefinitely on a vibrating bath of the same liquid and can be piloted by the waves that it generates. These walking droplets have been shown to exhibit several quantum-like features, including single-particle diffraction and interference. Recently, the original diffraction and interference experiments of Couder and Fort have been revisited and contested. We have revisited this system using an improved experimental set-up, and observed a strong dependence of the behavior on system parameters, including drop size and vibrational forcing. In both the single- and the double-slit geometries, the diffraction pattern is dominated by the interaction of the walking droplet with a planar boundary. Critically, in the double-slit geometry, the walking droplet is influenced by both slits by virtue of its spatially extended wave field. NSF support via CMMI-1333242.
Single Particle X-ray Diffractive Imaging
Bogan, M J; Benner, W H; Boutet, S; Rohner, U; Frank, M; Seibert, M; Maia, F; Barty, A; Bajt, S; Riot, V; Woods, B; Marchesini, S; Hau-Riege, S P; Svenda, M; Marklund, E; Spiller, E; Hajdu, J; Chapman, H N
2007-10-01
In nanotechnology, strategies for the creation and manipulation of nanoparticles in the gas phase are critically important for surface modification and substrate-free characterization. Recent coherent diffractive imaging with intense femtosecond X-ray pulses has verified the capability of single-shot imaging of nanoscale objects at sub-optical resolutions beyond the radiation-induced damage threshold. By intercepting electrospray-generated particles with a single 15 femtosecond soft-X-ray pulse, we demonstrate diffractive imaging of a nanoscale specimen in free flight for the first time, an important step toward imaging uncrystallized biomolecules.
Glancing angle synchrotron X-ray diffraction
Cernik, R.J. [Daresbury Lab., Warrington, WA (United States)
1996-09-01
This paper describes in basic detail some of the techniques that can be used to study thin films and surfaces. These are all in the X-ray region and cover reflectivity, diffraction form polycrystalline films, textured films and single crystal films. Other effects such as fluorescence and diffuse scattering are mentioned but not discussed in detail. Two examples of the reflectivity from multilayers and the diffraction from iron oxide films are discussed. The advantages of the synchrotron for these studies is stressed and the experimental geometries that can be employed are described i detail. A brief bibliography is provided at the end to accompany this part of the 1996 Frascati school.
Film thickness determination by grazing incidence diffraction
Battiston, G. A.; Gerbasi, R. [CNR, Padua (Italy). Istituto di Chimica e Tecnologie Inorganiche e dei Materiali Avanzati
1996-09-01
Thin films deposited via MOCVD (Metal Organic Chemical Vapour Deposition) are layers in the thickness range of a few manometers to about ten micrometers. An understanding of the physics and chemistry of films is necessary for a better comprehension of the phenomena involved in the film deposition procedure and its optimisation. Together with the crystalline phase a parameter that must be determined is the thickness of the layer. In this work the authors present a method for the measurement of the film thickness. This procedure, based on diffraction intensity absorption of the X-rays, both incident and diffracted in passing through the layers, resulted quite simple, rapid and non-destructive.
Atoms in static fields Chaos or Diffraction?
Dando, P A
1998-01-01
A brief review of the manifestations of classical chaos observed in atomic systems is presented. Particular attention is paid to the analysis of atomic spectra by periodic orbit-type theories. For diamagnetic non-hydrogenic Rydberg atoms, the dynamical explanation for observed spectral features has been disputed. By building on our previous work on the photoabsorption spectrum, we show how, by the addition of diffractive terms, the spectral fluctuations in the energy level spectrum of general Rydberg atoms can be obtained with remarkable precision from the Gutzwiller trace formula. This provides further evidence that non-hydrogenic systems are most naturally described in terms of diffraction rather than classical chaos.
Multiorder nonlinear diffraction in frequency doubling processes
Saltiel, Solomon M.; Neshev, Dragomir N.; Krolikowski, Wieslaw
2009-01-01
We analyze experimentally light scattering from 2 nonlinear gratings and observe two types of second-harmonic frequency-scattering processes. The first process is identified as Raman–Nath type nonlinear diffraction that is explained by applying only transverse phase-matching conditions. The angular...... position of this type of diffraction is defined by the ratio of the second-harmonic wavelength and the grating period. In contrast, the second type of nonlinear scattering process is explained by the longitudinal phase matching only, being insensitive to the nonlinear grating...
Diffraction of sound by nearly rigid barriers
Hadden, W. J., Jr.; Pierce, A. D.
1976-01-01
The diffraction of sound by barriers with surfaces of large, but finite, acoustic impedance was analyzed. Idealized source-barrier-receiver configurations in which the barriers may be considered as semi-infinite wedges are discussed. Particular attention is given to situations in which the source and receiver are at large distances from the tip of the wedge. The expression for the acoustic pressure in this limiting case is compared with the results of Pierce's analysis of diffraction by a rigid wedge. An expression for the insertion loss of a finite impedance barrier is compared with insertion loss formulas which are used extensively in selecting or designing barriers for noise control.
Focusing of light beyond the diffraction limit
Chen, K R
2009-01-01
Diffraction limits the behaviour of light in optical systems and sets the smallest achievable line width at half the wavelength. With a novel subwavelength plasmonic lens to reduce the diffraction via an asymmetry and to generate and squeeze the wave functions, an incident light is focused by the aperture to a single-line with its width beyond the limit outside the near zone. The fields focused are radiative and capable of propagating to the far zone. The light focusing process, besides being of academic interest, is expected to open up a wide range of application possibilities.
Wave diffraction by a cosmic string
Fernández-Núñez, Isabel
2016-01-01
We show that if a cosmic string exists, it may be identified through characteristic diffraction pattern in the energy spectrum of the observed signal. In particular, if the string is on the line of sight, the wave field is shown to fit the Cornu spiral. We suggest a simple procedure, based on Keller's geometrical theory of diffraction, which allows to explain wave effects in conical spacetime of a cosmic string in terms of interference of four characteristic rays. Our results are supposed to be valid for scalar massless waves, including gravitational waves, electromagnetic waves, or even sound in case of condensed matter systems with analogous topological defects.
Parabolic non-diffracting beams: geometrical approach
Sosa-Sánchez, Citlalli Teresa; Silva-Ortigoza, Gilberto; Alejandro Juárez-Reyes, Salvador; de Jesús Cabrera-Rosas, Omar; Espíndola-Ramos, Ernesto; Julián-Macías, Israel; Ortega-Vidals, Paula
2017-08-01
The aim of this work is to present a geometrical characterization of parabolic non-diffracting beams. To this end, we compute the corresponding angular spectrum of the separable non-diffracting parabolic beams in order to determine the one-parameter family of solutions of the eikonal equation associated with this type of beam. Using this information, we compute the corresponding wavefronts and caustic, and find that qualitatively the caustic corresponds to the maximum of the intensity pattern and the wavefronts are deformations of conical surfaces.
Wave diffraction by a cosmic string
Fernández-Núñez, Isabel; Bulashenko, Oleg
2016-08-01
We show that if a cosmic string exists, it may be identified through characteristic diffraction pattern in the energy spectrum of the observed signal. In particular, if the string is on the line of sight, the wave field is shown to fit the Cornu spiral. We suggest a simple procedure, based on Keller's geometrical theory of diffraction, which allows to explain wave effects in conical spacetime of a cosmic string in terms of interference of four characteristic rays. Our results are supposed to be valid for scalar massless waves, including gravitational waves, electromagnetic waves, or even sound in case of condensed matter systems with analogous topological defects.
Low missing mass, single- and double diffraction dissociation at the LHC
Jenkovszky, Laszlo; Orava, Risto; Salii, Andrii
2014-01-01
Low missing mass, single- and double diffraction dissociation is calculated for the LHC energies from a dual-Regge model, dominated by a Pomeron Regge pole exchange. The model reproduces the rich resonance structure in the low missing mass Mx region. The diffractionly excited states lie on the nucleon trajectory, appended by the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing mass dependence of the differential and integrated single- and double diffraction dissociation in the kinematical range of present and future LHC measurements are given. The model predicts a possible turn-down of the cross section towards, t -> 0 in a region probably accessible in future experiments in the nearly forward direction. The present work is a continuation and extension (e.g. with double diffraction) of a previous work using the dual Regge approach.
A neutron diffraction study of RMn2O5 multiferroics
Radaelli, P. G.; Chapon, L. C.
2008-10-01
The magnetic properties of RMn2O5 multiferroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram in both zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferroelectricity is discussed based on calculations of the ferroelectric polarization predicted by different microscopic coupling mechanisms (exchange-striction and cycloidal spin-orbit models). A minimal model containing a small set of parameters is also presented in order to understand the propagation of the magnetic structure along the c-direction.
Non-Diffracting Waves: A new introduction
Recami, E; Hernandez-Figuera, H E; Ambrosio, L A
2014-01-01
This work deals with exact solutions to the wave equations. We start by introducing the Non-Diffracting Waves (NDW), and by a definition of NDWs. Afterwards we recall -besides ordinary waves (gaussian beams, gaussian pulses)- the simplest non diffracting waves (Bessel beams, X-shaped pulses,...). In Sec.2 we show how to eliminate any backward-traveling components, first in the case of ideal NDW pulses, and then, in Sec.3, for realistic finite-energy NDW pulses. In particular, in subsec.3.1 we forward a general functional expression for any totally-forward non-diffracting pulses. Then, in Sec.4 an efficient method is set forth for the analytic description of truncated beams, a byproduct of its being the elimination of any need of lengthy numerical calculations. In Sec.5 we explore the question of the subluminal NDWs, or bullets, in terms of two different methods, the second one allowing the analytic description of non-diffracting waves with a static envelope ("Frozen Waves", FW), in terms of continuous Bessel ...
Diffraction in ALICE and trigger efficiencies
Navin, Sparsh; Lietava, Roman
ALICE is built to measure the properties of strongly interacting matter created in heavy-ion collisions. In addition, taking advantage of the low pT acceptance in the central barrel, ALICE is playing an important role in understanding pp collisions with minimum bias triggers at LHC energies. The work presented in this thesis is based on pp data simulated by the ALICE collaboration and early data collected at a center-of-mass energy of 7 TeV. A procedure to calculate trigger efficiencies and an estimate of the systematic uncertainty due to the limited acceptance of the detector are shown. A kinematic comparison between Monte Carlo event generators, PYTHIA 6, PYTHIA 8 and PHOJET is also presented. To improve the description of diffraction in PYTHIA, a hard diffractive component was added to PYTHIA 8 in 2009, which is described. Finally a trigger with a high efficiency for picking diffractive events is used to select a sample with an enhanced diffractive component from pp data. These data are compared to Monte ...
Diffractive Pedagogies: Dancing across New Materialist Imaginaries
Hickey-Moody, Anna; Palmer, Helen; Sayers, Esther
2016-01-01
We theorise an interdisciplinary arts practice university course and consider the forms of educational imaginary challenged by our curriculum. We argue for the disruptive and generative potential of what we call diffractive pedagogy as an example of the type of learning that can take place when materiality and entanglement are considered as vital…
Diffraction Anomalous Near-Edge Structure
Moltaji, Habib O., Jr.
1995-11-01
To determine the atomic structure about atom of an element in a sample of a condensed multicomponent single crystal, contrast radiation is proposed with the use of Diffraction Anomalous Near-Edge Structure (DANES), which combines the long-range order sensitivity of the x-ray diffraction and short-range order of the x-ray absorption near-edge techniques. This is achieved by modulating the photon energy of the x-ray beam incident on the sample over a range of energies near an absorption edge of the selected element. Due to anomalous dispersion, x-ray diffraction, and x-ray absorption, the DANES intensity with respect to the selected element is obtained in a single experiment. I demonstrate that synchrotron DANES measurements for the single crystal of thin film and the powder samples and provide the same local atomic structural information as the x-ray absorption near-edge with diffraction condition and can be used to provide enhanced site selectivity. I demonstrate calculations of DAFS intensity and measurements of polarized DANES and XANES intensity.
Diffractive leptoproduction of small masses in QCD
Gotsman, Errol; Maor, Uri [Tel Aviv Univ. (Israel). Raymond and Sackler Faculty of Exact Sciences. School of Physics and Astronomy; Levin, Eugene [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]|[Petersburg Nuclear Physics Inst., St. Petersburg (Russian Federation). Theory Dept.
1996-05-01
In this paper we consider the process of diffraction dissociation in deeply inelastic scattering in the region of small produced mass, which we define as production of q-bar q-pair and q-bar q G system in the final state. We show that the small distance contributions (r perpendicular is proportional to 1/Q) to the longitudinal polarised virtual photon dominate. Formulae for the cross section using the gluon structure function are written within the framework of perturbative QCD. It is shown that the production of small masses by the transverse polarized photo is concentrated at moderate values of r perpendicular to {approx} 1 GeV{sup -1}, where the p QCD approach can be applied. This could be responsible for a considerable part of the diffractive production. It is shown that only q-bar q pair production contribute to the diffraction dissociation at {beta} > 0.4, the possibility to extract the value of the gluon structure function from the measurements in this kinematic region is discussed. The evolution of the DD structure function is studied, and a solution to the DD evolution equations is proposed. Shadowing corrections are discussed for both the transverse and longitudinal polarised photon, and estimates of the different damping factors are given. The relation between diffractive production and the corrections to F2, is alluded to. (author). 45 refs., 16 figs.
Doubly diffracted ray from a hard quarterplane
Albertsen, Niels Christian
2000-01-01
The scattering of the electromagnetic field from a half wave dipole source around a quarterplane can be calculated from the solutions to two scalar problems, one with a soft quarterplane and one with a hard quarterplane. In both cases, a doubly diffracted ray may exist, but only in the case of th...
Accessing the diffracted wavefield by coherent subtraction
Schwarz, Benjamin; Gajewski, Dirk
2017-10-01
Diffractions have unique properties which are still rarely exploited in common practice. Aside from containing subwavelength information on the scattering geometry or indicating small-scale structural complexity, they provide superior illumination compared to reflections. While diffraction occurs arguably on all scales and in most realistic media, the respective signatures typically have low amplitudes and are likely to be masked by more prominent wavefield components. It has been widely observed that automated stacking acts as a directional filter favouring the most coherent arrivals. In contrast to other works, which commonly aim at steering the summation operator towards fainter contributions, we utilize this directional selection to coherently approximate the most dominant arrivals and subtract them from the data. Supported by additional filter functions which can be derived from wave front attributes gained during the stacking procedure, this strategy allows for a fully data-driven recovery of faint diffractions and makes them accessible for further processing. A complex single-channel field data example recorded in the Aegean sea near Santorini illustrates that the diffracted background wavefield is surprisingly rich and despite the absence of a high channel count can still be detected and characterized, suggesting a variety of applications in industry and academia.
Idealized powder diffraction patterns for cellulose polymorphs
Cellulose samples are routinely analyzed by X-ray diffraction to determine their crystal type (polymorph) and crystallinity. However, the connection is seldom made between those efforts and the crystal structures of cellulose that have been determined with synchrotron X-radiation and neutron diffrac...
Phase Transitions, Diffraction Studies and Marginal Dimensionality
Als-Nielsen, Jens Aage
1985-01-01
Continuous phase transitions and the associated critical phenomena have been one of the most active areas of research in condensed matter physics for several decades. This short review is only one cut through this huge subject and the author has chosen to emphasize diffraction studies as a basic...
Geometrical optics and the diffraction phenomenon
Timofeev, Aleksandr V [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)
2005-06-30
This note outlines the principles of the geometrical optics of inhomogeneous waves whose description necessitates the use of complex values of the wave vector. Generalizing geometrical optics to inhomogeneous waves permits including in its scope the analysis of the diffraction phenomenon. (methodological notes)
Development of Quantitative electron nano-diffraction
Kumar, V.
2009-01-01
This thesis is a step towards development of quantitative parallel beam electron nano-diffraction (PBED). It is focused on the superstructure determination of zig-zag and zig-zig NaxCoO2 and analysis of charge distribution in the two polymorphs Nb12O29 using PBED. It has been shown that quantitative
The Dynamical Theory of X Ray Diffraction
Balchin, A. A.; Whitehouse, C. R.
1974-01-01
Summarizes the Darwin theory of x-ray diffraction in thin crystals or crystals with a mosaic texture and its modified application to crystals with three-dimensional electrostatic dipoles. Indicates that the dynamical theory is brought into its present relevance by the improvement of single crystal growth techniques. (CC)
Concave diffraction gratings fabricated with planar lithography
Grabarnik, S.; Emadi, A.; Wu, H.; De Graaf, G.; Wolffenbuttel, R.F.
2008-01-01
This paper reports on the development and validation of a new technology for the fabrication of variable line-spacing non-planar diffraction gratings to be used in compact spectrometers. The technique is based on the standard lithographic process commonly used for pattern transfer onto a flat substr
Building X-ray Diffraction Calibration Software
Lande, Joshua; /Marlboro Coll.
2007-10-31
X-ray diffraction is a technique used to analyze the structure of crystals. It records the interference pattern created when x-rays travel through a crystal. Three dimensional structure can be inferred from these two dimensional diffraction patterns. Before the patterns can be analyzed, diffraction data must be precisely calibrated. Calibration is used to determine the experimental parameters of the particular experiment. This is done by fitting the experimental parameters to the diffraction pattern of a well understood crystal. Fit2D is a software package commonly used to do this calibration but it leaves much to be desired. In particular, it does not give very much control over the calibration of the data, requires a significant amount of manual input, does not allow for the calibration of highly tilted geometries, does not properly explain the assumptions that it is making, and cannot be modified. We build code to do this calibration while at the same time overcoming the limitations of Fit2D. This paper describes the development of the calibration software and the assumptions that are made in doing the calibration.
Diffraction traveltime approximation for TI media with an inhomogeneous background
Waheed, Umair bin
2013-09-01
Diffractions in seismic data contain valuable information that can help improve our modeling capability for better imaging of the subsurface. They are especially useful for anisotropic media because they inherently possess a wide range of dips necessary to resolve the angular dependence of velocity. We develop a scheme for diffraction traveltime computations based on perturbation of the anellipticity anisotropy parameter for transversely isotropic media with tilted axis of symmetry (TTI). The expansion, therefore, uses an elliptically anisotropic medium with tilt as the background model. This formulation has advantages on two fronts: first, it alleviates the computational complexity associated with solving the TTI eikonal equation, and second, it provides a mechanism to scan for the best-fitting anellipticity parameter η without the need for repetitive modeling of traveltimes, because the traveltime coefficients of the expansion are independent of the perturbed parameter η. The accuracy of such an expansion is further enhanced by the use of Shanks transform. We established the effectiveness of the proposed formulation with tests on a homogeneous TTI model and complex media such as the Marmousi and BP models.
A comment on the relation between diffraction and entropy
Baake, Michael
2012-01-01
Diffraction methods are used to detect atomic order in solids. While uniquely ergodic systems with pure point diffraction have zero entropy, the relation between diffraction and entropy is not as straightforward in general. In particular, there exist families of homometric systems, which are systems sharing the same diffraction, with varying entropy. We summarise the present state of understanding by several characteristic examples.
Transmissive Diffractive Optical Element Solar Concentrators
Baron, Richard; Moynihan, Philip; Price, Douglas
2008-01-01
Solar-thermal-radiation concentrators in the form of transmissive diffractive optical elements (DOEs) have been proposed as alternatives to mirror-type solar concentrators now in use. In comparison with functionally equivalent mirror-type solar concentrators, the transmissive, diffractive solar concentrators would weigh and cost less, and would be subject to relaxed mechanical tolerances. A DOE concentrator would be made from a thin, flat disk or membrane of a transmissive material having a suitable index of refraction. By virtue of its thinness, the DOE concentrator would have an areal mass density significantly less than that of a functionally equivalent conventional mirror. The DOE concentrator would have a relatively wide aperture--characterized by a focal-length/aperture-diameter ratio ('f number') on the order of 1. A kinoform (a surface-relief phase hologram) of high diffractive order would be microfabricated onto one face of the disk. The kinoform (see figure) would be designed to both diffract and refract incident solar radiation onto a desired focal region, without concern for forming an image of the Sun. The high diffractive order of this kinoform (in contradistinction to the low diffractive orders of some other kinoforms) would be necessary to obtain the desired f number of 1, which, in turn, would be necessary for obtaining a desired concentration ratio of 2,500 or greater. The design process of optimizing the concentration ratio of a proposed DOE solar concentrator includes computing convolutions of the optical bandwidth of the Sun with the optical transmission of the diffractive medium. Because, as in the cases of other non-imaging, light-concentrating optics, image quality is not a design requirement, the process also includes trading image quality against concentration ratio. A baseline design for one example calls for an aperture diameter of 1 m. This baseline design would be scalable to a diameter as large as 10 m, or to a smaller diameter for a
Localizer with high occlusion immunity using diffraction optics
Ditto, Thomas D.; Farges, Jacques
2004-10-01
The chromatic method of diffraction range finding can be exploited to construct a 3D localizer that tracks the position of a pointer, a 3-D scanner or a robotic end-effecter. A spectrogram is made using a diffraction grating as the primary objective of an optical system that tracks a broad band emitter such as a tungsten filament or white L.E.D. Image processing on the resulting spectra transforms the spectrogram at the input to distance and displacement at the output. The behavior conforms to geometric optics following the Diffraction Equation. This novel technique has unique features. For example, the number of samples increases with target distance, reversing the loss of resolution as a function of distance that is endemic to triangulation. The plurality of samples also can overcome occlusion liability common to time-of-flight range finders, since multiple paths exist between emitter and sensor. The grating can be made from inexpensive embossed plastic, and a wave length sensor can be constructed from garden variety color cameras. The method is robust at a grazing exodus angles that allow for a compact configuration of the receiver. In this paper we disclose the theory of operation including a mathematical model, and we demonstrate the method empirically.
Diffractive characteristics of the liquid crystal spatial light modulator
Cao Zhao-Liang; Mu Quan-Quan; Hu Li-Fa; Liu Yong-Gang; Xuan Li
2007-01-01
The liquid crystal spatial light modulator (LC SLM) is very suitable for wavefront correction and optical testing and can produce a wavefront with large phase change and high accuracy. The LC SLM is composed of thousands of pixels and the pixel size and shape have effects on the diffractive characteristics of the LC SLM. This paper investigates the pixel effect on the phase of the wavefront with the scalar diffractive theory. The results show that the maximum optical path difference modulation is 41 μm to produce the paraboloid wavefront with the peak to valley accuracy better than λ/10. Effects of the mismatch between the pixel and the period, and black matrix on the diffraction efficiency of the LC SLM are also analysed with the Fresnel phase lens model. The ability of the LC SLM is discussed for optical testing and wavefront correction based on the calculated results. It shows that the LC SLM can be used as a wavefront corrector and a compensator.
Dynamic color screening in diffractive deep inelastic scattering
Ingelman, Gunnar; Pasechnik, Roman; Werder, Dominik
2016-05-01
We present a novel Monte Carlo implementation of dynamic color screening via multiple exchanges of semisoft gluons as a basic QCD mechanism to understand diffractive electron-proton scattering at the HERA collider. Based on the kinematics of individual events in the standard QCD description of deep inelastic scattering at the parton level, which at low x is dominantly gluon initiated, the probability is evaluated for additional exchanges of softer gluons resulting in an overall color singlet exchange leading to a forward proton and a rapidity gap as the characteristic observables for diffractive scattering. The probability depends on the impact parameter of the soft exchanges and varies with the transverse size of the hard scattering subsystem and is therefore influenced by different QCD effects. We account for matrix elements and parton shower evolution either via conventional DGLAP log Q2 evolution with collinear factorization or CCFM small x evolution with k⊥ factorization and discuss the sensitivity to the gluon density distribution in the proton and the importance of large log x contributions. The overall result is, with only two model parameters which have theoretically motivated values, a satisfactory description of the observed diffractive cross section at HERA obtained in a wide kinematical range.
QUALITATIVE ANALYSIS OF A SERIE OF CEMENT BY X-RAY POWDER DIFFRACTION
Öztürk Yildirim, Sema; BULMUŞ, Tuğba
2009-01-01
Cement is now widely used in every aspect of daily life due to the development of technology and ecological consciousness. In this study, the qualitative analysis of a serie of cement samples were made by using X-ray powder diffraction. The powder diffraction patterns of samples were taken by using copper radiation [λ(CuKα) = 1.54056Å] at room temperature by the RIGAKU type D-MAX 220 model X-ray diffractometer. The data obtained from the powder diffraction patterns was evaluated and the subst...
Study of transmission grating diffraction efficiencies for soft X—ray
YANGJiamin; CUIMingqi; 等
1999-01-01
Tansmission grating spectrometers are extensively used to measure absolute X-ray spectra in a photon-energy range below 1000eV.the transmission grating,as its dispersive element,must be calibrated to obtain its diffraction efficiencies.Calibrations of absolute diffraction efficiencies of the transmission grating at photon energy of 844eV have been caried out on Bejing synchrotron Radiation Facility.With the aid of grating model,all of the grating structure parameters have been determined and the absolute diffraction efficeencies in a photon-energy range below 2000eV have also been calculated and discussed.
Ellipsometric and neutron diffraction study of pentane physisorbed on graphite.
Kruchten, Frank; Knorr, Klaus; Volkmann, Ulrich G; Taub, Haskell; Hansen, Flemming Y; Matthies, Blake; Herwig, Kenneth W
2005-08-02
High-resolution ellipsometry and neutron diffraction measurements have been used to investigate the structure, growth, and wetting behavior of fluid pentane (n-C(5)H(12)) films adsorbed on graphite substrates. We present isotherms of the thickness of pentane films adsorbed on the basal-plane surfaces of a pyrolytic graphite substrate as a function of the vapor pressure. These isotherms are measured ellipsometrically for temperatures between 130 and 190 K. We also describe neutron diffraction measurements in the temperature range 11-140 K on a deuterated pentane (n-C(5)D(12)) monolayer adsorbed on an exfoliated graphite substrate. Below a temperature of 99 K, the diffraction patterns are consistent with a rectangular centered structure. Above the pentane triple point at 143.5 K, the ellipsometric measurements indicate layer-by-layer adsorption of at least seven fluid pentane layers, each having the same optical thickness. Analysis of the neutron diffraction pattern of a pentane monolayer at a temperature of 130 K is consistent with small clusters having a rectangular-centered structure and an area per molecule of approximately 37 A(2) in coexistence with a fluid monolayer phase. Assuming values of the polarizability tensor from the literature and that the monolayer fluid has the same areal density as that inferred for the coexisting clusters, we calculate an optical thickness of the fluid pentane layers in reasonable agreement with that measured by ellipsometry. We discuss how these results support the previously proposed "footprint reduction" mechanism of alkane monolayer melting. In the hypercritical regime, we show that the layering behavior is consistent with the two-dimensional Ising model and determine the critical temperatures for layers n = 2-5.
Quantitative damage imaging using Lamb wave diffraction tomography
Zhang, Hai-Yan; Ruan, Min; Zhu, Wen-Fa; Chai, Xiao-Dong
2016-12-01
In this paper, we investigate the diffraction tomography for quantitative imaging damages of partly through-thickness holes with various shapes in isotropic plates by using converted and non-converted scattered Lamb waves generated numerically. Finite element simulations are carried out to provide the scattered wave data. The validity of the finite element model is confirmed by the comparison of scattering directivity pattern (SDP) of circle blind hole damage between the finite element simulations and the analytical results. The imaging method is based on a theoretical relation between the one-dimensional (1D) Fourier transform of the scattered projection and two-dimensional (2D) spatial Fourier transform of the scattering object. A quantitative image of the damage is obtained by carrying out the 2D inverse Fourier transform of the scattering object. The proposed approach employs a circle transducer network containing forward and backward projections, which lead to so-called transmission mode (TMDT) and reflection mode diffraction tomography (RMDT), respectively. The reconstructed results of the two projections for a non-converted S0 scattered mode are investigated to illuminate the influence of the scattering field data. The results show that Lamb wave diffraction tomography using the combination of TMDT and RMDT improves the imaging effect compared with by using only the TMDT or RMDT. The scattered data of the converted A0 mode are also used to assess the performance of the diffraction tomography method. It is found that the circle and elliptical shaped damages can still be reasonably identified from the reconstructed images while the reconstructed results of other complex shaped damages like crisscross rectangles and racecourse are relatively poor. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474195, 11274226, 11674214, and 51478258).
Diffractive di-jet production at the LHC with a Reggeon contribution
C. Marquet
2017-03-01
Full Text Available We study hard diffractive scattering in hadron–hadron collisions including, on top of the standard Pomeron-initiated processes, contributions due to the exchange of Reggeons. Using a simple model to describe the parton content of the Reggeon, we compute di-jet production in single diffractive and central diffractive events. We show that Reggeon contributions can be sizable at the LHC, and even sometimes dominant, and we identify kinematic windows in which they could be experimentally studied. We argue that suitable measurements must be performed in order to properly constrain the model, and be able to correctly account for Reggeon exchanges in the analysis of the many hard diffractive observables to be measured at the LHC.
Diffractive di-jet production at the LHC with a Reggeon contribution
Marquet, C.; Martins, D. E.; Pereira, A. V.; Rangel, M.; Royon, C.
2017-03-01
We study hard diffractive scattering in hadron-hadron collisions including, on top of the standard Pomeron-initiated processes, contributions due to the exchange of Reggeons. Using a simple model to describe the parton content of the Reggeon, we compute di-jet production in single diffractive and central diffractive events. We show that Reggeon contributions can be sizable at the LHC, and even sometimes dominant, and we identify kinematic windows in which they could be experimentally studied. We argue that suitable measurements must be performed in order to properly constrain the model, and be able to correctly account for Reggeon exchanges in the analysis of the many hard diffractive observables to be measured at the LHC.
Diffractive di-jet production at the LHC with a Reggeon contribution
Marquet, C; Pereira, A V; Rangel, M; Royon, C
2016-01-01
We study hard diffractive scattering in hadron-hadron collisions including, on top of the standard Pomeron-initiated processes, contributions due to the exchange of Reggeons. Using a simple model to describe the parton content of the Reggeon, we compute di-jet production in single diffractive and central diffractive events. We show that Reggeon contributions can be sizable at the LHC, and even sometimes dominant, and we identify kinematic windows in which they could be experimentally studied. We argue that suitable measurements must be performed in order to properly constrain the model, and be able to correctly account for Reggeon exchanges in the analysis of the many hard diffractive observables to be measured at the LHC.
Crystal structure of defect-containing semiconductor nanocrystals. An X-ray diffraction study
Buljan, Maja [Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni; Institut Rudjer Boskovic, Zagreb (Croatia); Desnica, Uros V.; Radic, Nikola [Institut Rudjer Boskovic, Zagreb (Croatia); Drazic, Goran [Institut Jozef Stefan, Ljubljana (Slovenia); Matej, Zdenek; Vales, Vaclav; Holy, Vaclav [Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni
2009-08-15
Defects of crystal structure in semiconductor nanocrystals embedded in an amorphous matrix are studied by X-ray diffraction and a full-profile analysis of the diffraction curves based on the Debye formula. A new theoretical model is proposed, describing the diffraction from randomly distributed intrinsic and extrinsic stacking faults and twin blocks in the nanocrystals. The application of the model to full-profile analysis of experimental diffraction curves enables the determination of the concentrations of individual defect types in the nanocrystals. The method has been applied for the investigation of selforganized Ge nanocrystals in an SiO{sub 2} matrix, and the dependence of the structure quality of the nanocrystals on their deposition and annealing parameters was obtained. (orig.)
Qin, Yi; Gong, Qiong; Wang, Zhipeng
2014-09-08
In previous diffractive-imaging-based optical encryption schemes, it is impossible to totally retrieve the plaintext from a single diffraction pattern. In this paper, we proposed a new method to achieve this goal. The encryption procedure can be completed by proceeding only one exposure, and the single diffraction pattern is recorded as ciphertext. For recovering the plaintext, a novel median-filtering-based phase retrieval algorithm, including two iterative cycles, has been developed. This proposal not only extremely simplifies the encryption and decryption processes, but also facilitates the storage and transmission of the ciphertext, and its effectiveness and feasibility have been demonstrated by numerical simulations.
Simulating multiple diffraction in imaging systems using a path integration method.
Mout, Marco; Wick, Michael; Bociort, Florian; Petschulat, Jörg; Urbach, Paul
2016-05-10
We present a method for simulating multiple diffraction in imaging systems based on the Huygens-Fresnel principle. The method accounts for the effects of both aberrations and diffraction and is entirely performed using Monte Carlo ray tracing. We compare the results of this method to those of reference simulations for field propagation through optical systems and for the calculation of point spread functions. The method can accurately model a wide variety of optical systems beyond the exit pupil approximation.
Interaction of cylindrically converging diffracted shock with uniform interface
Liang, Yu; Ding, Juchun; Zhai, Zhigang; Si, Ting; Luo, Xisheng
2017-08-01
The Richtmyer-Meshkov instability of an unperturbed air/SF6 interface subjected to a diffracted shock is experimentally studied by high-speed schlieren photography under cylindrical circumstances. The cylindrically converging diffracted shock (CCDS) is produced by a cylindrically uniform shock diffracting around a rigid cylinder(s), and the unperturbed interface is created by a soap film technique. The effects of coupling of multiple rigid cylinders and diverse spacings from the cylinder to interface on a flow field are highlighted. Schlieren images indicate that the amplitude of disturbances on the CCDS increases compared with the local shock radius. After the CCDS impact, a bulge is derived from the interface due to the shock-shock interaction inside the interface, and the number of bulges depends upon the number of cylinders. As the number of cylinders increases, the bulge becomes less pronounced, which is ascribed to additional shock-shock interactions inside the volume. As the distance between the cylinder and interface increases, an air cavity is first observed before the formation of a bulge. The amplitude of perturbation on the interface is found to reduce before the central reflected shock arrival because of the Rayleigh-Taylor stabilization effect. Through equating the pre-interface disturbance of the CCDS to the pre-shock perturbation of the perturbed interface, the initially linear growth rate is theoretically computed based on the impulsive model considering the Bell-Plesset effect. The theoretical results are found to deviate greatly from the experimental counterparts. Instead, taking the post-shock interface amplitude as an initial interface amplitude, the model works well. Therefore, the interface perturbations produced are notably smaller than the disturbances causing them. Moreover, the nonlinear behavior of perturbation growth is estimated by the model considering the Rayleigh-Taylor effect.
Pan, Meiyan, E-mail: yphantomohive@gmail.com; Zeng, Yingzhi; Huang, Zuohua, E-mail: zuohuah@163.com [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)
2014-09-15
A new method based on diffraction spectral analysis is proposed for the quantitative measurement of the phase variation amplitude of an ultrasonic diffraction grating. For a traveling wave, the phase variation amplitude of the grating depends on the intensity of the zeroth- and first-order diffraction waves. By contrast, for a standing wave, this amplitude depends on the intensity of the zeroth-, first-, and second-order diffraction waves. The proposed method is verified experimentally. The measured phase variation amplitude ranges from 0 to 2π, with a relative error of approximately 5%. A nearly linear relation exists between the phase variation amplitude and driving voltage. Our proposed method can also be applied to ordinary sinusoidal phase grating.
Qin, Yi; Wang, Zhipeng; Gong, Qiong
2014-07-01
In this paper, we propose a novel method for image encryption by employing the diffraction imaging technique. This method is in principle suitable for most diffractive-imaging-based optical encryption schemes, and a typical diffractive imaging architecture using three random phase masks in the Fresnel domain is taken for an example to illustrate it. The encryption process is rather simple because only a single diffraction intensity pattern is needed to be recorded, and the decryption procedure is also correspondingly simplified. To achieve this goal, redundant data are digitally appended to the primary image before a standard encrypting procedure. The redundant data serve as a partial input plane support constraint in a phase retrieval algorithm, which is employed for completely retrieving the plaintext. Simulation results are presented to verify the validity of the proposed approach.
Phase knife-edge laser Schlieren diffraction interferometry with boundary diffraction wave theory
Raj Kumar; D Mohan; Sushil K Kaura; D P Chhachhia; A K Aggarwal
2007-04-01
Within the framework of boundary diffraction wave theory it has been shown that the first bright fringe on either side of the central dark fringe of the phase knife-edge Fresnel diffraction pattern could be broadened to cover the whole field of view. Broadening of the first diffraction fringe, instead of conventionally modifying the spatial frequency spectrum, enhances the sensitivity of the Schlieren system. The use of phase knife-edge as viewing diaphragm in Schlieren diffraction interferometry not only enhances the fringe contrast but also avoids the loss in phase information as it lets through light from all parts of the test object and its thin interfacing makes the method suitable even for studying weak disturbances.
Measurement of dijet production in diffractive events with the ATLAS detector
AUTHOR|(INSPIRE)INSPIRE-00224260; The ATLAS collaboration
2015-01-01
A sample of pp collision data collected under low luminosity conditions at sqrt(s) = 7 TeV by the ATLAS detector at the Large Hadron Collider is used to study diffractive dijet production. Events containing at least two jets with pT > 20 GeV are selected and analysed in terms of variables which discriminate between diffractive and non-diffractive processes. Cross sections are measured differentially in \\Delta\\eta_F, the size of the observable forward region of pseudorapidity which is devoid of hadronic activity, and in an estimator, \\xi˜, of the fractional momentum loss of the proton assuming single diffractive dissociation (pp -> pX). Model comparisons indicate a dominant non-diffractive contribution up to moderately large \\Delta\\eta_F and small\\xi˜, with a diffractive contribution which is significant at the highest \\Delta\\etaF and the lowest \\xi˜. The rapidity gap survival probability is estimated from comparisons of the data in this latter region with predictions based on diffractive parton density fun...
Yu, Caixia; Wang, Yanfei; Zhao, Jingtao
2017-10-01
Seismic diffractions play a vital role in identifying discontinuous geological structures, such as tiny faults and cavities which are important because of their close relationship with the reservoir properties of oil and gas. In this paper, we focus on an extraction method for separation of seismic diffractions. The energy of reflection is usually much stronger than that of the diffraction, thus, removing reflection becomes a key problem for diffraction applications. In order to extract seismic diffractions accurately and stably, we propose an optimised regularisation method based on the local plane-wave equation. By considering two constraints arising from the Sobolev penalty function and the difference operator, we build a stable minimisation model for determining seismic slopes. In computation, an iterative method based on projection onto a convex set for solving the nonlinear minimisation is developed, which can provide fast and accurate solutions. Subtracting the predicted reflections from the seismic image, we can extract the seismic diffractions. Numerical experiments illustrate the effectiveness of the diffraction extraction method in separating tiny faults, scatterers and cavities. Finally, a carbonate reservoir field example is provided to demonstrate the high-resolution capability of the method in revealing small-scale discontinuous geological features.
Ultrafast Time Resolved X-ray Diffraction Studies of Laser Heated Metals and Semiconductors
Chen, Peilin; Tomov, I. V.; Rentzepis, P. M.
1998-03-01
Time resolved hard x-ray diffraction has been employed to study the dynamics of lattice structure deformation. When laser pulse energy is deposited in a material it generates a non uniform transient temperature distribution, which alters the lattice structure of the crystal. The deformed crystal lattice will change the angle of diffraction for a monochromatic x-ray beam. We report picosecond and nanosecond time resolved x-ray diffraction measurements of the lattice temperature distribution, transient structure and stress, in Pt (111) and GaAs (111) crystals, caused by pulsed UV laser irradiation. An ArF excimer laser operated at 300 Hz was used, both, to drive an x-ray diode with copper anode and heat the crystal. Bragg diffracted x-ray radiation was recorded by a direct imaging x-ray CCD. Changes in the diffraction patterns induced by a few millijouls pulse energy were observed at different time delays between the laser heating pulse and the x-ray probing pulse. A kinematical model for time resolved x-ray diffraction was used to analyze the experimental data. Good agreement between the measured and calculated scattered x-ray intensities profiles was achieved, indicating that detailed time resolved x-ray diffraction measurements can be made with nanosecond and picosecond resolution for small temperature changes. Our system can detect changes in the lattice spacing of about 10-3 A.
Ab initio structure determination via powder X-ray diffraction
Digamber G Porob; T N Guru Row
2001-10-01
Structure determination by powder X-ray diffraction data has gone through a recent surge since it has become important to get to the structural information of materials which do not yield good quality single crystals. Although the method of structure completion when once the starting model is provided is facile through the Rietveld refinement technique, the structure solution ab initio os still not push-button technology. In this article a survey of the recent development in this area is provided with an illustration of the structure determination of -NaBi3V2O10.
Diffraction of limit periodic point sets
Baake, Michael
2010-01-01
Limit periodic point sets are aperiodic structures with pure point diffraction supported on a countably, but not finitely generated Fourier module that is based on a lattice and certain integer multiples of it. Examples are cut and project sets with p-adic internal spaces. We illustrate this by explicit results for the diffraction measures of two examples with 2-adic internal spaces. The first and well-known example is the period doubling sequence in one dimension, which is based on the period doubling substitution rule. The second example is a weighted planar point set that is derived from the classic chair tiling in the plane. It can be described as a fixed point of a block substitution rule.
Laser diffraction analysis of colloidal crystals
Sogami, Ikuo S.; Shinohara, Tadatomi; Yoshiyama, Tsuyoshi [Kyoto Sangyo Univ., Department of Physics, Kyoto (Japan)
2001-10-01
Laser diffraction analysis is made on crystallization in salt-free aqueous suspensions of highly-charged colloidal particles for semi-dilute specimens of concentration 0.1-10.0 vol%. Kossel diffraction patterns which represent faithfully accurate information on lattice symmetries in the suspensions enable us to investigate the time evolution of colloidal crystals. The results show that the crystallization proceeds by way of the following intermediate phase transitions: two-dimensional hcp structure {yields} random layer structure {yields} layer structure with one sliding degree of freedom {yields} stacking disorder structure {yields} stacking structure with multivariant periodicity {yields} fcc twin structure with twin plane (111) {yields} normal fcc structure {yields} bcc twin structure with twin plane (11-bar2) or (1-bar12) {yields} normal bcc structure. For concentrated suspensions (>2 vol %), the phase transition ceases to proceed at the normal fcc structure. (author)
Diffractive and exclusive measurements at CDF
Gallinaro, Michele; /Rockefeller U.
2006-06-01
Experimental results from the CDF experiment at the Tevatron in p{bar p} collisions at {radical}s = 1.96 TeV are presented on the diffractive structure function at different values of the exchanged momentum transfer squared in the range 0 < Q{sup 2} < 10,000 GeV{sup 2}, on the four-momentum transfer |t| distribution in the region 0 < |t| < 1 GeV{sup 2} for both soft and hard diffractive events up to Q{sup 2} {approx} 4,500 GeV{sup 2}, and on the first experimental evidence of exclusive production in both dijet and diphoton events. A novel technique to align the Roman Pot detectors is also presented.
Hard diffraction in the QCD dipole picture
Bialas, A
1995-01-01
Using the QCD dipole picture of the BFKL pomeron, the gluon contribution to the cross-section for single diffractive dissociation in deep-inelastic high-energy scattering is calculated. The resulting contribution to the proton diffractive structure function integrated over t is given in terms of relevant variables, x_{\\cal P}, Q^2, and \\beta = x_{Bj}/x_{\\cal P}. It factorizes into an explicit x_{\\cal P}-dependent Hard Pomeron flux factor and structure function. The flux factor is found to have substantial logarithmic corrections which may account for the recent measurements of the Pomeron intercept in this process. The triple Pomeron coupling is shown to be strongly enhanced by the resummation of leading logs. The obtained pattern of scaling violation at small \\beta is similar to that for F_2 at small x_{Bj}.
Resonant diffraction of synchrotron radiation: New possibilities
Ovchinnikova, E. N.; Mukhamedzhanov, E. Kh.
2016-09-01
Resonant diffraction of synchrotron radiation (SR) is a modern method of studying the structure and properties of condensed matter that can be implemented on third-generation synchrotrons. This method allows one to investigate local properties of media (including magnetic and electronic ones) and observe thermal vibrations, defects, and orbital and charge orderings. A brief review of the advance provided by SR resonant diffraction is presented, and the capabilities of this method for analyzing phase transitions are considered in more detail by the example of potassium dihydrogen phosphate and rubidium dihydrogen phosphate crystals. It is shown that the investigation of the temperature dependence of forbidden reflections not only makes it possible to observe the transition from para- to ferroelectric phase, but also gives information about the proton distribution at hydrogen bonds.
Photoelectron diffraction and holography: Some new directions
Fadley, C.S. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Davis, CA (United States). Dept. of Physics
1993-08-01
Photoelectron diffraction has by now become a versatile and powerful technique for studying surface structures, with special capabilities for resolving chemical and magnetic states of atoms and deriving direct structural information from both forward scattering along bond directions and back-scattering path length differences. Further fitting experiment to theory can lead to structural accuracies in the {plus_minus}0.03 ){Angstrom} range. Holographic inversions of such diffraction data also show considerable promise for deriving local three-dimensional structures around a given emitter with accuracies of {plus_minus}0.2--0.3 {Angstrom}. Resolving the photoelectron spin in some way and using circularly polarized radiation for excitation provide added dimensions for the study of magnetic systems and chiral experimental geometries. Synchrotron radiation with the highest brightness and energy resolution, as well as variable polarization, is crucial to the full exploitation of these techniques.
Neutron diffraction of cell membranes (myelin).
Parsons, D F; Akers, C K
1969-09-05
Small-angle neutron diffraction (wavelength 4.05 angstroms) of human and rabbit sciatic nerve has been carried out by means of the Brookhaven high flux beam reactor with an automated slit camera. Most of the free water of the nerves was substituted in order to minimize incoherent scatter of hydrogen atoms. The differences in amplitude and phase shifts between neutrons and x-rays resulted in a neutron diffraction pattern that was completely different from the x-ray pattern. The neutron pattern consisted of a single peak of about 89-angstrom spacing in the region examined (up to 6-angstrom spacing). The strong third, fourth, and fifth order reflections (about 60, 45, and 36 angstroms) seen in the x-ray pattern were suppressed. The neutron data indicated a strong scattering from one portion of the membrane.
When holography meets coherent diffraction imaging
Latychevskaia, Tatiana; Fink, Hans-Werner
2011-01-01
In understanding the physical, chemical and biological properties of a molecule by obtaining detailed information about its structure, there is an ultimate wish: the visualization of this very molecule in three dimensions at atomic scale, rather than obtaining structural information by averaging over an ensemble of molecules. Coherent diffraction imaging (CDI) is a modern lens-less imaging technique promising exactly that: visualizing an individual molecule at the highest possible resolution solely limited by the radiation wavelength. Individual bacteria and viruses have been imaged by CDI employing coherent X-rays and recently, CDI has been extended to recover the three-dimensional shape of objects from a single diffraction pattern. Higher resolution is expected with the implementation of bright coherent radiation from X-ray free electron lasers. Since detectors are only sensitive to intensity, the phase of the wave is missing and must somehow be recovered to reconstruct the molecule's anatomy. There are two...
Antonov, S. N.; Vainer, A. V.; Proklov, V. V.; Rezvov, Yu. G.
2010-03-01
Bragg’s acoustooptic diffraction in an acoustically anisotropic medium is considered taking into account the two-dimensional spatial diffraction structure of the acoustic beam. The conditions are determined under which reverse transfer of optical power from the diffracted to the transmitted beam in the regime of 100% efficiency of diffraction is considerably suppressed. It is shown that this effect is due to diffraction bending of wave fronts of the acoustic beam in the acoustooptic diffraction plane. The problem of optimization of the piezoelectric transducer size and the spatial position of the input light beam is solved using the criterion of the minimal required power of the acoustic field. The results of simulation in a wide range of the acoustooptic interaction parameters for a Gaussian light beam are reported. The correctness of the model is confirmed experimentally. Recommendations for designers of acoustooptic devices are formulated.
Neutron forward diffraction by single crystal prisms
Sohrab Abbas; Apoorva G Wagh; Markus Strobl; Wolfgang Treimer
2008-11-01
We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to the incidence angle. We have measured the variation of neutron deflection and transmission across a Bragg reflection, for several single crystal prisms. The results agree well with theory.
Multidataset Refinement Resonant Diffraction, and Magnetic Structures
Attfield, J. Paul
2004-01-01
The scope of Rietveld and other powder diffraction refinements continues to expand, driven by improvements in instrumentation, methodology and software. This will be illustrated by examples from our research in recent years. Multidataset refinement is now commonplace; the datasets may be from different detectors, e.g., in a time-of-flight experiment, or from separate experiments, such as at several x-ray energies giving resonant information. The complementary use of x rays and neutrons is exe...
Giacovazzo, C. [Bari Univ. (Italy). Dip. Geomineralogico
1996-09-01
The basic concepts of X-ray diffraction may be more easily understood if it is made preliminary use of a mathematical background. In these pages the authors will first define the delta function and its use for the representation of a lattice. Then the concepts of Fourier transform and convolution are given. At the end of this talk one should realize that a crystal is the convolution of the lattice with a function representing the content of the unit cell.
ATLAS results on diffraction and exclusive production
AUTHOR|(INSPIRE)INSPIRE-00224260; The ATLAS collaboration
2017-01-01
Various aspects of forward physics have been studied by the ATLAS collaboration using data from Run I at the LHC. In this text, main results of three published analyses are summarized, based on data from proton-proton collisions at $\\sqrt{s} = 7$ or 8 TeV collected between 2010 and 2012. One analysis deals with diffractive signature with at least two jets in the final state, the other two study exclusive production of a pair of leptons or W bosons.
Theoretical and measured performance of diffraction gratings
Bowler, M.A. E-mail: m.bowler@dl.ac.uk; Finetti, P.; Holland, D.M.P.; Humphrey, I.; Quinn, F.M.; Roper, M.D
2001-07-21
At the SRS at Daresbury Laboratory, we are undertaking a programme comparing the results from efficiency calculations of diffraction gratings, mainly using the GRADIF code of Neviere, with measured efficiencies. The deviations from the predicted performance are larger for higher orders than for first order. Higher order contamination is important in determining the usability of the beamline for certain types of experiments, particularly at energies below 100 eV.
Theoretical and measured performance of diffraction gratings
Bowler, M A; Holland, D M P; Humphrey, I; Quinn, F M; Röper, M D
2001-01-01
At the SRS at Daresbury Laboratory, we are undertaking a programme comparing the results from efficiency calculations of diffraction gratings, mainly using the GRADIF code of Neviere, with measured efficiencies. The deviations from the predicted performance are larger for higher orders than for first order. Higher order contamination is important in determining the usability of the beamline for certain types of experiments, particularly at energies below 100 eV.
Diffraction studies of papaya mosaic virus.
Tollin, P; Bancroft, J B; Richardson, J F; Payne, N C; Beveridge, T J
1979-10-15
X-ray and optical diffraction studies of the flexuous papaya mosaic virus are described. The virus is constructed so that there are 35 coat protein subunits in 4 turns of the helix. The virus contains about 1410 protein subunits and 6800 nucleotides and has a molecular weight of about 33 x 10(6). The structure of tubes assembled in vitro from coat protein both in the presence and absence of nucleic acid resembles that of the native virus.
New Forward and Diffractive Physics at CMS
Santoro, Alberto
2011-04-01
Forward and Diffractive Physics (FWP) in LHC is a new open window to understand this type of strong interactions. We will present a didactic description of the topics being developed at CMS. As we know there still is no new results to present for FWP. We are accumulating data to have soon new results. We will show a number of topics and the detectors properties to do the observation of several topologies. We expect to give an optimistic view of the area.
Optimizing Crystal Volume for Neutron Diffraction Studies
Snell, E. H.
2003-01-01
For structural studies with neutron diffraction more intense neutron sources, improved sensitivity detector and larger volume crystals are all means by which the science is being advanced to enable studies on a wider range of samples. We have chosen a simplistic approach using a well understood crystallization method, with minimal amounts of sample and using design of experiment techniques to maximize the crystal volume all for minimum effort. Examples of the application are given.
Metamaterial hyperlens demonstration of propagation without diffraction
Fleming, Simon
2017-03-01
Metamaterials are a topic of much research interest because they have such extraordinary properties. Such materials are generally difficult and expensive to make and to characterize, and thus beyond the reach of undergraduate classes. This paper describes a metamaterial hyperlens, fabricated in about an hour from materials costing about one dollar, which permits an experimental demonstration of propagation without diffraction using common undergraduate laboratory microwave equipment.
Diffraction Measurements on CPF Steel Fatigue Samples
1995-05-30
I I I I I I I I I I I I I I I I I I I - 535 - Diffraction Measurements on CPF Steel Fatigue Samples by Percy Clark*, Tom...to the formation of a detectable fatigue crack, a series of hourglass shaped specimens were fabricated from 350WT steel , cyclically loaded to...were made between these experiments and earlier less successful similar experiments conducted on HY80 samples. The limitations and potential for the
Diffractive D{sup *}-mesons production in DIS at HERA
Vinokurova, Svetlana
2010-05-15
This thesis presents a measurement of the cross sections for the production of the charmed mesons in diffractive deep inelastic positron-proton scattering (DIS) interactions of the type ep{yields}eXY, where the system X is separated from a low-mass system Y, by a large rapidity gap where no particles are observed. These diffractive processes can be explained as a result of the exchange of a strongly interacting colour singlet object between the final state particles. In this measurement data taken with the H1 detector in the years 1999-2000, corresponding to an integrated luminosity of L{sub int}=46.7 pb{sup -1} are used. Inclusive DIS events are selected in the kinematic range with the momentum transfer Q{sup 2} element of [2;100] GeV and inelasticity y{sub bj} element of [0.05;07]. The charm quark is tagged by requiring a D{sup *} meson decaying into the channel D{sup *}{yields}D{sup 0}{pi}{sub slow}{yields}K{pi}{pi}{sub slow} inside the central tracking system with transverse momenta p{sub t}(D{sup *})>2 GeV. The forward components of the H1 detector are used to select genuine diffractive events on the basis of the forward sub-detectors activity and of the presence a large rapidity gap in the final state hadrons. The visible charm production cross sections are measured in the diffractive kinematic range M{sub Y} < 1.6 GeV, vertical stroke t vertical stroke < 1 GeV{sup 2} and x{sub P} < 0.04 to be {sigma}(ep{yields}e{sup '}(D{sup *}X)Y)=249{+-}31(stat.){+-}30(sys) pb, where the first uncertainty is statistical and the second systematic. The shape of the differential distributions for diffractive D{sup *} production are well described by the collinear factorisation model which is implemented in the Monte Carlo simulation RAPGAP. (orig.)
Non-diffractive beam in random media
Shiina, Tatsuo
2017-09-01
Beam propagation has been given important attention in a variety of applications in medicine, remote sensing and information science. Especially, the beam propagation in highly scattering media, which is called random media, is important. In general, the multiple scattering gets rid of beam characteristics, e.g., intensity distribution, phase front, and polarization. In this study, self-converging effect of annular beam was applied in random media. Diluted milk was used as random media, and the transmitted light was detected with a narrow view angle of 5.5mrad. The collimated annular beam of a few tens millimeters takes a few hundred meters to transform its beam shape into the non-diffractive beam in free space, while this transformation was shorten only to 20 cm in random media, that is, the collimated annular beam caused its transformation at only 20 cm in random media. The transformed beam kept its optical characteristics of ;non-diffractive beam;. Such transformation of the annular beam needs the appropriate condition of random media. Media concentration and propagation distance control the generation of the center peak intensity of the transformed beam. This study indicates the generation of the non-diffractive beam in random media and reveals its appropriate condition.
New approaches in diffraction based optical metrology
Ebert, M.; Vanoppen, P.; Jak, M.; v. d. Zouw, G.; Cramer, H.; Nooitgedagt, T.; v. d. Laan, H.
2016-03-01
Requirements for on-product overlay, focus and CD uniformity continue to tighten in order to support the demands of 10nm and 7nm nodes. This results in the need for simultaneously accurate, robust and dense metrology data as input for closed-loop control solutions thereby enabling wafer-level control and high order corrections. In addition the use of opaque materials and stringent design rules drive the need for expansion of the available measurement wavelengths and metrology target design space. Diffraction based optical metrology has been established as the leading methodology for integrated as well as standalone optical metrology for overlay, focus and CD monitoring and control in state of the art chip manufacturing. We are presenting the new approaches to diffraction based optical metrology designed to meet the processing diffraction based metrology signals. In this paper we will present the new detection principle and its impact on key performance characteristics of overlay and focus measurements. We will also describe the wide range of applications of a newly introduced increased measurement spot size, enabling significant improvements to accuracy and process robustness of overlay and focus measurements. With the YS350E the optical CD measurement capability is also extended, to 10x10μm2 targets. We will discuss the performance and value of small targets in after-develop and after-etch applications.
Shock Wave Diffraction Phenomena around Slotted Splitters
Francesca Gnani
2015-01-01
Full Text Available In the field of aerospace engineering, the study of the characteristics of vortical flows and their unsteady phenomena finds numerous engineering applications related to improvements in the design of tip devices, enhancement of combustor performance, and control of noise generation. A large amount of work has been carried out in the analysis of the shock wave diffraction around conventional geometries such as sharp and rounded corners, but the employment of splitters with lateral variation has hardly attracted the attention of researchers. The investigation of this phenomenon around two-dimensional wedges has allowed the understanding of the basic physical principles of the flow features. On the other hand, important aspects that appear in the third dimension due to the turbulent nature of the vortices are omitted. The lack of studies that use three-dimensional geometries has motivated the current work to experimentally investigate the evolution of the shock wave diffraction around two splitters with spike-shaped structures for Mach numbers of 1.31 and 1.59. Schlieren photography was used to obtain an insight into the sequential diffraction processes that take place in different planes. Interacting among them, these phenomena generate a complicated turbulent cloud with a vortical arrangement.
DNA hydration studied by neutron fiber diffraction
Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J. [Keele Univ. (United Kingdom)] [and others
1994-12-31
The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix.
Integrated Diffractive Optics for Surface Ion Traps
Streed, Erik; Ghadimi, Moji; Blums, Valdis; Norton, Benjamin; Connor, Paul; Amini, Jason; Volin, Curtis; Lobino, Mirko; Kielpinski, David
2016-05-01
Photonic interconnects are a bottleneck to achieving large-scale trapped ion quantum computing. We have modified a Georgia Tech Research Institute microwave chip trap by using e-beam lithography to write reflective diffractive collimating optics (80 μm x 127 μm, f=58.6 μm, λ=369.5nm) on the center electrode. The optics have an NA of 0.55 x 0.73, capturing 13.2% of the solid angle. To evaluate the optics 174Yb+ was loaded by isotope selective photo-ionization from a thermal oven and then shuttled to imaging sites. Near diffraction limited sub-wavelength ion images were obtained with an observed spot sized FWHM of 338 nm x 268 nm vs. a diffraction limit of 336 nm x 257 nm. The total photon collection efficiency was measured to be 5.2+/-1.2%. Coupling into a single mode fiber of up to 2.0+/-0.6% was observed, limited by mismatch in the coupling optics. Image mode quality indicates coupling up to 4% may be possible. Funding from Australian Research Council and IARPA.
Microstructure of Horseshoe Nails Using Neutron Diffraction
Goossens, D. J.; Studer, A. J.; Stachurski, Z. H.
2010-04-01
Neutron diffraction allows nondestructive testing of the bulk microstructure of mechanical components. The microstructures of horseshoe nails made through three different processes have been explored as a function of position along the nail. Despite all nails being made of similar plain low-carbon steel and being process annealed after manufacture, the microstructures are far from the same. Nails made from strip, using a cold forging stamping process, show narrower diffraction peaks indicating a narrower distribution of lattice parameters and also show diffraction peak intensity ratios closer to those expected for unstrained steel. Thus, the distribution of the orientation of grains in these nails is closer to that of undistorted steel compared to nails made through the other two processes considered—one a drawing from wire and the other a combination of rolling and cold forging. The blades of the drawn nails showed little preferred orientation but the converse was true in the heads. Differing patterns of preferred orientation suggest that the various manufacturing approaches result in substantially different mechanical advantages for the three types of nails, a result in accord with mechanical testing.
Wave diffraction by a cosmic string
Fernández-Núñez, Isabel [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Institut de Ciències del Cosmos (ICCUB), Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Bulashenko, Oleg, E-mail: oleg.bulashenko@ub.edu [Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain)
2016-08-26
We show that if a cosmic string exists, it may be identified through characteristic diffraction pattern in the energy spectrum of the observed signal. In particular, if the string is on the line of sight, the wave field is shown to fit the Cornu spiral. We suggest a simple procedure, based on Keller's geometrical theory of diffraction, which allows to explain wave effects in conical spacetime of a cosmic string in terms of interference of four characteristic rays. Our results are supposed to be valid for scalar massless waves, including gravitational waves, electromagnetic waves, or even sound in case of condensed matter systems with analogous topological defects. - Highlights: • Gravitational waves could help us to reveal cosmic strings – topological defects of early Universe. • Wave diffraction in conical spacetime of a cosmic string is solved analytically. • The Cornu spiral is shown to appear when the string is on the line of sight. • For a string located within our galaxy, the highest amplification would occur at a frequency range of LIGO detector.
Enhanced high-speed coherent diffraction imaging
Potier, Jonathan; Fricker, Sebastien; Idir, Mourad
2011-03-01
Due to recent advances in X-ray microscopy, we are now able to image objects with nanometer resolution thanks to Synchrotron beam lines or Free Electron Lasers (FEL). The PCI (Phase Contrast Imaging) is a robust technique that can recover the wavefront from measurements of only few intensity pictures in the Fresnel diffraction region. With our fast straightforward calculus methods, we manage to provide the phase induced by a microscopic specimen in few seconds. We can therefore obtain high contrasted images from transparent materials at very small scales. To reach atomic resolution imaging and thus make a transition from the near to the far field, the Coherent Diffraction Imaging (CDI) technique finds its roots in the analysis of diffraction patterns to obtain the phase of the altered complex wave. Theoretical results about existence and uniqueness of this retrieved piece of information by both iterative and direct algorithms have already been released. However, performances of algorithms remain limited by the coherence of the X-ray beam, presence of random noise and the saturation threshold of the detector. We will present reconstructions of samples using an enhanced version of HIO algorithm improving the speed of convergence and its repeatability. As a first step toward a practical X-Ray CDI system, initial images for reconstructions are acquired with the laser-based CDI system working in the visible spectrum.
Walczak, Michał; Grubmüller, Helmut
2014-08-01
We developed a Bayesian method to extract macromolecular structure information from sparse single-molecule x-ray free-electron laser diffraction images. The method addresses two possible scenarios. First, using a "seed" structural model, the molecular orientation is determined for each of the provided diffraction images, which are then averaged in three-dimensional reciprocal space. Subsequently, the real space electron density is determined using a relaxed averaged alternating reflections algorithm. In the second approach, the probability that the "seed" model fits to the given set of diffraction images as a whole is determined and used to distinguish between proposed structures. We show that for a given x-ray intensity, unexpectedly, the achievable resolution increases with molecular mass such that structure determination should be more challenging for small molecules than for larger ones. For a sufficiently large number of recorded photons (>200) per diffraction image an M^{1/6} scaling is seen. Using synthetic diffraction data for a small glutathione molecule as a challenging test case, successful determination of electron density was demonstrated for 20000 diffraction patterns with random orientations and an average of 82 elastically scattered and recorded photons per image, also in the presence of up to 50% background noise. The second scenario is exemplified and assessed for three biomolecules of different sizes. In all cases, determining the probability of a structure given set of diffraction patterns allowed successful discrimination between different conformations of the test molecules. A structure model of the glutathione tripeptide was refined in a Monte Carlo simulation from a random starting conformation. Further, effective distinguishing between three differently arranged immunoglobulin domains of a titin molecule and also different states of a ribosome in a tRNA translocation process was demonstrated. These results show that the proposed method is
Fernandes, P
2007-04-15
This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B{sub 2} liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B{sub 2} phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation.
Choi, Hun-Kook [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Chosun University, Gwangju (Korea, Republic of); Jung, Deok; Sohn, Ik-Bu; Noh, Young-Chul; Lee, Yong-Tak [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kim, Jin-Tae [Chosun University, Gwangju (Korea, Republic of); Ahsan, Shamim [Khulna University, Khulna (Bangladesh)
2014-11-15
This research demonstrates laser-assisted fabrication of high-efficiency diffraction gratings in fused-silica glass samples. Initially, femtosecond laser pulses are used to engrave diffraction gratings on the glass surfaces. Then, these micro-patterned glass samples undergo CO{sub 2} laser polishing process. unpolished diffraction gratings encoded in the glass samples show an overall diffraction efficiency of 18.1%. diffraction gratings imprinted on the glass samples and then polished four times by using a CO{sub 2} laser beam attain a diffraction efficiency of 32.7%. We also investigate the diffraction patterns of the diffraction gratings encoded on fused-silica glass surfaces. The proposed CO{sub 2} laser polishing technique shows great potential in patterning high-efficiency diffraction gratings on the surfaces of various transparent materials.
Materials identification using a small-scale pixellated x-ray diffraction system
O'Flynn, D.; Crews, C.; Drakos, I.; Christodoulou, C.; Wilson, M. D.; Veale, M. C.; Seller, P.; Speller, R. D.
2016-05-01
A transmission x-ray diffraction system has been developed using a pixellated, energy-resolving detector (HEXITEC) and a small-scale, mains operated x-ray source (Amptek Mini-X). HEXITEC enables diffraction to be measured without the requirement of incident spectrum filtration, or collimation of the scatter from the sample, preserving a large proportion of the useful signal compared with other diffraction techniques. Due to this efficiency, sufficient molecular information for material identification can be obtained within 5 s despite the relatively low x-ray source power. Diffraction data are presented from caffeine, hexamine, paracetamol, plastic explosives and narcotics. The capability to determine molecular information from aspirin tablets inside their packaging is demonstrated. Material selectivity and the potential for a sample classification model is shown with principal component analysis, through which each different material can be clearly resolved.
Observation of parametric X-ray radiation in an anomalous diffraction region
Alexeyev, V. I.; Eliseyev, A. N.; Irribarra, E.; Kishin, I. A.; Kubankin, A. S.; Nazhmudinov, R. M.
2016-08-01
A new possibility to expand the energy region of diffraction processes based on the interaction of relativistic charged particles with crystalline structures is presented. Diffracted photons related to parametric X-ray radiation produced by relativistic electrons are detected below the low energy threshold for the X-ray diffraction mechanism in crystalline structures for the first time. The measurements were performed during the interaction of 7 MeV electrons with a textured polycrystalline tungsten foil and a highly oriented pyrolytic graphite crystal. The experiment results are in good agreement with a developed model based on the PXR kinematical theory. The developed experimental approach can be applied to separate the contributions of real and virtual photons to the total diffracted radiation generated during the interaction of relativistic charged particles with crystalline targets.
X-Ray and Neutron Diffraction Studies on Thermal Parameters of Thalous Bromide
无
2003-01-01
Thermal parameters of TIBr were determined using both X-ray and neutron diffraction techniques. The data was analysed by Rietveld profile refinement procedure. From the neutron diffraction data, due to weak odd-order reflections, it was not possible to determine the individual thermal parameters. The X-ray diffraction measurements yielded BT1=0.296(5) nm2 and BBr=0.162(5) nm2. The overall isotropic value, B was 0.252(7) nm2 which is in good agreement with B=0.230(8) nm2 obtained from present neutron diffraction measurements. The present values are also in good agreement with theoretical estimates obtained from the shell models.
Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry.
Vadilonga, Simone; Zizak, Ivo; Roshchupkin, Dmitry; Evgenii, Emelin; Petsiuk, Andrei; Leitenberger, Wolfram; Erko, Alexei
2017-04-01
X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (La3Ga5SiO14) modulated by Λ = 3 µm Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice. Experimental results are compared with the corresponding theoretical model that exploits the kinematical diffraction theory. This experiment shows that the propagation of the surface acoustic waves creates a dynamical diffraction grating on the crystal surface, and this can be used for space-time modulation of an X-ray beam.
Stress in Thin Films; Diffraction Elastic Constants and Grain Interaction
无
2002-01-01
Untextured bulk polycrystals usually possess macroscopically isotropic elastic properties whereas for most thin films transverse isotropy is expected, owing to the limited dimensionality. The usually applied models for the calculation of elastic constants of polycrystals from single crystal elastic constants (so-called grain interaction models) erroneously predict macroscopic isotropy for an (untextured) thin film. This paper presents a summary of recent work where it has been demonstrated for the first time by X-ray diffraction analysis of stresses in thin films that elastic grain interaction can lead to macroscopically elastically anisotropic behaviour (shown by non-linear sin2ψ plots). A new grain interaction model, predicting the macroscopically anisotropic behaviour of thin films, is proposed.
An efficient and accurate method for calculating nonlinear diffraction beam fields
Jeong, Hyun Jo; Cho, Sung Jong; Nam, Ki Woong; Lee, Jang Hyun [Division of Mechanical and Automotive Engineering, Wonkwang University, Iksan (Korea, Republic of)
2016-04-15
This study develops an efficient and accurate method for calculating nonlinear diffraction beam fields propagating in fluids or solids. The Westervelt equation and quasilinear theory, from which the integral solutions for the fundamental and second harmonics can be obtained, are first considered. A computationally efficient method is then developed using a multi-Gaussian beam (MGB) model that easily separates the diffraction effects from the plane wave solution. The MGB models provide accurate beam fields when compared with the integral solutions for a number of transmitter-receiver geometries. These models can also serve as fast, powerful modeling tools for many nonlinear acoustics applications, especially in making diffraction corrections for the nonlinearity parameter determination, because of their computational efficiency and accuracy.
Diffractive Dijet Photoproduction in ep Collisions at HERA
Aaron, F.D.; Andreev, V.; Backovic, S.; Baghdasaryan, A.; Barrelet, E.; Bartel, W.; Begzsuren, K.; Belousov, A.; Bizot, J.C.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Bunyatyan, A.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; Delcourt, B.; Delvax, J.; De Wolf, E.A.; Diaconu, C.; Dobre, M.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eliseev, A.; Elsen, E.; Falkiewicz, A.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, Samvel; Glazov, A.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Huber, F.; Jacquet, M.; Janssen, X.; Jonsson, L.; Jung, A.W.; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kluge, T.; Knutsson, A.; Kogler, R.; Kostka, P.; Kraemer, M.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kutak, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Lendermann, V.; Levonian, S.; Lipka, K.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, M.U.; Mudrinic, M.; Muller, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nowak, K.; Olsson, J.E.; Osman, S.; Ozerov, D.; Pahl, P.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Perez, E.; Petrukhin, A.; Picuric, I.; Piec, S.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Polifka, R.; Povh, B.; Radescu, V.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Tabasco, J.E.Ruiz; Rusakov, S.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.C.; Sefkow, F.; Shaw-West, R.N.; Shtarkov, L.N.; Shushkevich, S.; Sloan, T.; Smiljanic, Ivan; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Staykova, Z.; Steder, M.; Stella, B.; Stoicea, G.; Straumann, U.; Sunar, D.; Sykora, T.; Thompson, G.; Thompson, P.D.; Toll, T.; Tran, T.H.; Traynor, D.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Trevino, A.Vargas; Vazdik, Y.; von den Driesch, M.; Wegener, D.; Wunsch, E.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zohrabyan, H.; Zomer, F.
2010-01-01
Measurements are presented of single and double-differential dijet cross sections in diffractive photoproduction based on a data sample with an integrated luminosity of 47 pb^-1. The events are of the type ep -> eXY, where the hadronic system X contains at least two jets and is separated by a large rapidity gap from the system Y, which consists of a leading proton or low-mass proton excitation. The dijet cross sections are compared with QCD calculations at next-to-leading order and with a Monte Carlo model based on leading order matrix elements with parton showers. The measured cross sections are smaller than those obtained from the next-to-leading order calculations by a factor of about 0.6. This suppression factor has no significant dependence on the fraction x_gamma of the photon four-momentum entering the hard subprocess. Ratios of the diffractive to the inclusive dijet cross sections are measured for the first time and are compared with Monte Carlo models.
Diffractive dijet photoproduction in ep collisions at HERA
Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (RU)] (and others)
2010-03-15
Measurements are presented of single and double-differential dijet cross sections in diffractive photoproduction based on a data sample with an integrated luminosity of 47 pb{sup -1}. The events are of the type ep{yields}eXY, where the hadronic system X contains at least two jets and is separated by a large rapidity gap from the system Y, which consists of a leading proton or low-mass proton excitation. The dijet cross sections are compared with QCD calculations at next-to-leading order and with a Monte Carlo model based on leading order matrix elements with parton showers. The measured cross sections are smaller than those obtained from the next-to-leading order calculations by a factor of about 0.6. This suppression factor has no significant dependence on the fraction x{sub {gamma}} of the photon four-momentum entering the hard subprocess. Ratios of the diffractive to the inclusive dijet cross sections are measured for the first time and are compared with Monte Carlo models. (orig.)
Nonlinear diffraction effects around a surface-piercing structure
Lalli, F.; Mascio, A. Di; Landrini, M. [Istituto Nazionale per Studi ed Esperienze di Architettura Navale, Rome (Italy)
1995-12-31
In the present paper the interaction of a wave system with a submerged or surface piercing body is studied. The wave diffraction caused by a cylinder in finite depth water and by a shoal is been computed and the results are compared with analytical solutions and experimental data. The problem is analyzed numerically in the frame of irrotational incompressible flow hypothesis. Both the linearized and the fully nonlinear mathematical models are studied. The numerical solution is gained by means of a mixed panel-desingularized formulation. An explicit time-marching algorithm updates the wave elevation and the potential at the free surface. In all cases, the numerical simulation mirrors the experimental data. In the case of the diffraction around a cylinder, the simulation confirms and extends the theoretical results of the second order analysis (Kriebel 1990, 1992): the linear model yields a very good estimation of the force amplitude acting on the body, while the wave profiles are poorly predicted when compared with the fully nonlinear simulation and the experimental data.
He, Yunteng; Zhang, Jie; Kong, Wei
2016-07-01
We demonstrate the practicality of electron diffraction of single molecules inside superfluid helium droplets using CBr4 as a testing case. By reducing the background from pure undoped droplets via multiple doping, with small corrections for dimers and trimers, clearly resolved diffraction rings of CBr4 similar to those of gas phase molecules can be observed. The experimental data from CBr4 doped droplets are in agreement with both theoretical calculations and with experimental results of gaseous species. The abundance of monomers and clusters in the droplet beam also qualitatively agrees with the Poisson statistics. Possible extensions of this approach to macromolecular ions will also be discussed. This result marks the first step in building a molecular goniometer using superfluid helium droplet cooling and field induced orientation. The superior cooling effect of helium droplets is ideal for field induced orientation, but the diffraction background from helium is a concern. This work addresses this background issue and identifies a possible solution. Accumulation of diffraction images only becomes meaningful when all images are produced from molecules oriented in the same direction, and hence a molecular goniometer is a crucial technology for serial diffraction of single molecules.
High pressure x-ray diffraction techniques with synchrotron radiation
刘景
2016-01-01
This article summarizes the developments of experimental techniques for high pressure x-ray diffraction (XRD) in diamond anvil cells (DACs) using synchrotron radiation. Basic principles and experimental methods for various diffraction geometry are described, including powder diffraction, single crystal diffraction, radial diffraction, as well as coupling with laser heating system. Resolution in d-spacing of different diffraction modes is discussed. More recent progress, such as extended application of single crystal diffraction for measurements of multigrain and electron density distribution, time-resolved diffraction with dynamic DAC and development of modulated heating techniques are briefl y introduced. The current status of the high pressure beamline at BSRF (Beijing Synchrotron Radiation Facility) and some results are also presented.
Diffractive vector meson leptoproduction and spin effects
Goloskokov, S V
2006-01-01
We analyse spin effects in diffractive vector meson leptoproduction at small $x$ on the basis of the generalized parton distribution (GPD) approach. We take into account quark transverse degrees of freedom in the hard subprocess. We calculate amplitudes for the longitudinally and transversely polarized photons and vector mesons. Our results on the cross section and spin density matrix elements (SDME) are in fair agreement with the DESY experiments. Predictions for HERMES and COMPASS energy range are made. The predicted double spin longitudinal $A_{LL}$ asymmetry is not small at HERMES energies
Survival probability in diffractive dijet photoproduction
Klasen, M
2009-01-01
We confront the latest H1 and ZEUS data on diffractive dijet photoproduction with next-to-leading order QCD predictions in order to determine whether a rapidity gap survival probability of less than one is supported by the data. We find evidence for this hypothesis when assuming global factorization breaking for both the direct and resolved photon contributions, in which case the survival probability would have to be E_T^jet-dependent, and for the resolved or in addition the related direct initial-state singular contribution only, where it would be independent of E_T^jet.
Optical image encryption based on diffractive imaging.
Chen, Wen; Chen, Xudong; Sheppard, Colin J R
2010-11-15
In this Letter, we propose a method for optical image encryption based on diffractive imaging. An optical multiple random phase mask encoding system is applied, and one of the phase-only masks is selected and laterally translated along a preset direction during the encryption process. For image decryption, a phase retrieval algorithm is proposed to extract a high-quality plaintext. The feasibility and effectiveness of the proposed method are demonstrated by numerical results. The proposed method can provide a new strategy instead of conventional interference methods, and it may open up a new research perspective for optical image encryption.
Oblique Water Wave Diffraction by a Step
Dolai P.
2017-02-01
Full Text Available This paper is concerned with the problem of diffraction of an obliquely incident surface water wave train on an obstacle in the form of a finite step. Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the physical parameters reflection and transmission coefficients in terms of integrals. Appropriate multi-term Galerkin approximations involving ultraspherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for reflection and transmission coefficients which are depicted graphically. From these figures various interesting results are discussed.
Flexible filamentous virus structure from fiber diffraction
Stubbs, Gerald; Kendall, Amy; McDonald, Michele; Bian, Wen; Bowles, Timothy; Baumgarten, Sarah; McCullough, Ian; Shi, Jian; Stewart, Phoebe; Bullitt, Esther; Gore, David; Ghabrial, Said (IIT); (BU-M); (Vanderbilt); (Kentucky)
2008-10-24
Fiber diffraction data have been obtained from Narcissus mosaic virus, a potexvirus from the family Flexiviridae, and soybean mosaic virus (SMV), a potyvirus from the family Potyviridae. Analysis of the data in conjunction with cryo-electron microscopy data allowed us to determine the symmetry of the viruses and to make reconstructions of SMV at 19 {angstrom} resolution and of another potexvirus, papaya mosaic virus, at 18 {angstrom} resolution. These data include the first well-ordered data ever obtained for the potyviruses and the best-ordered data from the potexviruses, and offer the promise of eventual high resolution structure determinations.
Elastic and diffractive scattering at D0
Edwards, Tamsin; /Manchester U.
2004-04-01
The first search for diffractively produced Z bosons in the muon decay channel is presented, using a data set collected by the D0 detector at the Fermilab Tevatron at {radical}s = 1.96 TeV between April and September 2003, corresponding to an integrated luminosity of approximately 110 pb{sup -1}. The first dN/d|t| distribution for proton-antiproton elastic scattering at this c.o.m. energy is also presented, using data collected by the D0 Forward Proton Detector between January and May 2002. The measured slope is reproduced by theoretical predictions.
The basics of crystallography and diffraction
Hammond, C
2015-01-01
This title provides a clear and very broadly based introduction to crystallography, light, X-ray, and electron diffraction; a knowledge of which is essential to students in a wide range of scientific disciplines but which is otherwise generally covered in subject-specific and more mathematically detailed texts. The book is also designed to appeal to the more general reader since it shows, by historical and biographical references, how the subject has developed from the work and insights of successive generations of crystallographers and scientists.
Oblique Water Wave Diffraction by a Step
Dolai, P.
2017-02-01
This paper is concerned with the problem of diffraction of an obliquely incident surface water wave train on an obstacle in the form of a finite step. Havelock expansions of water wave potentials are used in the mathematical analysis to obtain the physical parameters reflection and transmission coefficients in terms of integrals. Appropriate multi-term Galerkin approximations involving ultraspherical Gegenbauer polynomials are utilized to obtain a very accurate numerical estimate for reflection and transmission coefficients which are depicted graphically. From these figures various interesting results are discussed.
Quantum Theory for Large Molecules $C_{60}$ Diffraction
Wu, Xiang-Yao; Liu, Xiao-Jing; Ba, Nuo; Wu, Yi-Heng; Tang, Hou-Li; Wang, Jing; Zhang, Si-Qi
2011-01-01
Diffraction phenomena of large molecules have been studied in many experiments, and these experiments are described by many theoretical works. In this paper, we study $C_{60}$ molecules single and double-slit diffraction with quantum theory approach, and we pay close attention to the $C_{60}$ diffraction experiment carried out by A.Zeilinger et.at in 1999. In double-slit diffraction, we consider the decoherence effect, and find the theoretical results are good agreement with experimental data.
A Comment on the Relation between Diffraction and Entropy
Michael Baake
2012-05-01
Full Text Available Diffraction methods are used to detect atomic order in solids. While uniquely ergodic systems with pure point diffraction have zero entropy, the relation between diffraction and entropy is not as straightforward in general. In particular, there exist families of homometric systems, which are systems sharing the same diffraction, with varying entropy. We summarise the present state of understanding by several characteristic examples.
Diffractive electroproduction of {rho} and {phi} mesons at HERA
Aaron, F.D. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Aldaya Martin, M. [DESY Hamburg (Germany); Alexa, C. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (RO)] (and others)
2009-06-15
Diffractive electroproduction of {rho} and {phi} mesons is measured at HERA with the H1 detector in the elastic and proton dissociative channels. The data correspond to an integrated luminosity of 51 pb{sup -1}. About 10500 {rho} and 2000 {phi} events are analysed in the kinematic range of squared photon virtuality 2.5{<=}Q{sup 2}{<=}60 GeV{sup 2}, photon-proton centre of mass energy 35{<=}W{<=}180 GeV and squared four-momentum transfer to the proton vertical stroke 3 vertical stroke {<=} GeV{sup 2}. The total, longitudinal and transverse cross sections are measured as a function of Q{sup 2}, W and vertical stroke 3 vertical stroke. The measurements show a transition to a dominantly ''hard'' behaviour, typical of high gluon densities and small q anti q dipoles, for Q{sup 2} larger than 10 to 20 GeV{sup 2}. They support flavour independence of the diffractive exchange, expressed in terms of the scaling variable (Q{sup 2}+M{sub V}{sup 2})/4, and proton vertex factorisation. The spin density matrix elements are measured as a function of kinematic variables. The ratio of the longitudinal to transverse cross sections, the ratio of the helicity amplitudes and their relative phases are extracted. Several of these measurements have not been performed before and bring new information on the dynamics of diffraction in a QCD framework. The measurements are discussed in the context of models using generalised parton distributions or universal dipole cross sections. (orig.)
Diffractive electroproduction of {rho} and {phi} mesons at HERA
Aaron, F.D. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Aldaya Martin, M. [DESY Hamburg (Germany); Alexa, C. [National Inst. for Physics and Nuclear Engineering (NIPNE), Bucharest (RO)] (and others)
2009-06-15
Diffractive electroproduction of {rho} and {phi} mesons is measured at HERA with the H1 detector in the elastic and proton dissociative channels. The data correspond to an integrated luminosity of 51 pb{sup -1}. About 10500 {rho} and 2000 {phi} events are analysed in the kinematic range of squared photon virtuality 2.5{<=}Q{sup 2}{<=}60 GeV{sup 2}, photon-proton centre of mass energy 35{<=}W{<=}180 GeV and squared four-momentum transfer to the proton vertical stroke 3 vertical stroke {<=} GeV{sup 2}. The total, longitudinal and transverse cross sections are measured as a function of Q{sup 2}, W and vertical stroke 3 vertical stroke. The measurements show a transition to a dominantly ''hard'' behaviour, typical of high gluon densities and small q anti q dipoles, for Q{sup 2} larger than 10 to 20 GeV{sup 2}. They support flavour independence of the diffractive exchange, expressed in terms of the scaling variable (Q{sup 2}+M{sub V}{sup 2})/4, and proton vertex factorisation. The spin density matrix elements are measured as a function of kinematic variables. The ratio of the longitudinal to transverse cross sections, the ratio of the helicity amplitudes and their relative phases are extracted. Several of these measurements have not been performed before and bring new information on the dynamics of diffraction in a QCD framework. The measurements are discussed in the context of models using generalised parton distributions or universal dipole cross sections. (orig.)
Lentz, Martin; Klaus, Manuela; Coelho, Rodrigo S.; Schaefer, Nobert; Schmack, Florian; Reimers, Walter; Clausen, Bjørn
2014-11-01
The deformation behavior of the Mg-RE alloys ME21 and WE54 was investigated. Although both alloys contain rare earth elements, which alter and weaken the texture, the flow curves of the alloys deviate significantly, especially in uniaxial compression test. Apart from the higher strength of the WE54 alloy, the compression flow curve does not exhibit the typical sigmoidal shape, which is associated with tension twinning. However, optical microscopy, X-ray texture measurements, and EBSD analysis reveal the activity of tension twinning. The combination of in situ energy-dispersive X-ray synchrotron diffraction and EPSC modeling was used to analyze these differences. The investigation reveals that twin propagation is decelerated in the WE54 alloy, which requires a change of the twinning scheme from the `finite initial fraction' to the `continuity' assumption. Furthermore, an enhanced activity of the pyramidal slip system was observed in case of the WE54 alloy.
Theory of groove-envelope phase effects in self-diffraction
Reislöhner, Jan; Pfeiffer, Adrian N
2016-01-01
If two laser beams cross in a medium under shallow angle, the laser-induced grating consists of only a few grooves. In this situation, the phase between the grooves of the grating and its envelope is a decisive parameter for nonlinear effects. Here, models are established for reproducing the groove-envelope phase effects that have been observed in the interference pattern of self-diffraction. Four-wave mixing leads to interferences that are dominant in the spatial region between the orders of diffraction and with tilted interference fringes in the diagram of transverse coordinate vs. pulse delay. The vertical interference fringes that are dominant directly on the diffraction orders, experimentally observed at high intensity close to the damage threshold, require a model beyond four-wave mixing. A model is suggested that is based on optical transmission changes with confinement to regions in the medium that are smaller than the groove spacing.
Single and double diffraction dissociation at the LHC
Fiore, Roberto; Jenkovszky, László; Mieskolainen, Mikael; Orava, Risto
2017-03-01
Single and double diffraction dissociation at the LHC is studied in a factorizable Regge-pole model, dominated by a Pomeron pole exchange in the t channel. While the contribution from secondary reggeon exchanges at the LHC is negligible, they are indispensable to match the lower-energy, ISR and FNAL data. To this end we append to the leading Pomeron exchange an effective reggeon. The main emphasis in our study is on the nucleon resonances in missing masses, that are accounted for by a dual model of the inelastic pP → MX vertex, similar to the DIS structure function, known from HERA, with a non-linear nucleon, N∗ trajectory in the direct, MX2 channel. Regge factorization and its breakdown due to a renormalization factor, tempering the energy rise is discussed.
Synchrotron powder diffraction on Aztec blue pigments
Sanchez del Rio, M. [European Synchrotron Radiation Facility, B.P. 220, Grenoble Cedex (France); Gutierrez-Leon, A.; Castro, G.R.; Rubio-Zuazo, J. [Spanish CRG Beamline at the European Synchrotron Radiation Facility, SpLine, B.P. 220, Grenoble Cedex (France); Solis, C. [Universidad Nacional Autonoma de Mexico, Instituto de Fisica, Mexico, D.F. (Mexico); Sanchez-Hernandez, R. [INAH Subdireccion de Laboratorios y Apoyo Academico, Mexico, D.F. (Mexico); Robles-Camacho, J. [INAH Centro Regional Michoacan, Morelia, Michoacan (Mexico); Rojas-Gaytan, J. [INAH Direccion de Salvamento Arqueologico, Naucalpan de Juarez (Mexico)
2008-01-15
Some samples of raw blue pigments coming from an archaeological rescue mission in downtown Mexico City have been characterized using different techniques. The samples, some recovered as a part of a ritual offering, could be assigned to the late Aztec period (XVth century). The striking characteristic of these samples is that they seem to be raw pigments prior to any use in artworks, and it was possible to collect a few {mu}g of pigment after manual grain selection under a microscopy monitoring. All pigments are made of indigo, an organic colorant locally known as anil or xiuhquilitl. The colorant is always found in combination with an inorganic matrix, studied by powder diffraction. In one case the mineral base is palygorskite, a rare clay mineral featuring micro-channels in its structure, well known as the main ingredient of the Maya blue pigment. However, other samples present the minerals sepiolite (a clay mineral of the palygorskite family) and calcite. Another sample contains barite, a mineral never reported in prehispanic paints. We present the results of characterization using high resolution powder diffraction recorded at the European Synchrotron Radiation Facility (BM25A, SpLine beamline) complemented with other techniques. All of them gave consistent results on the composition. A chemical test on resistance to acids was done, showing a high resistance for the palygorskite and eventually sepiolite compounds, in good agreement with the excellent resistance of the Maya blue. (orig.)
Imaging molecular structure with photoelectron diffraction
Boll, Rebecca
2014-07-02
The possibility to study the structure of polyatomic gas-phase molecules by photoelectron diffraction is investigated with the goal of developing a method capable of imaging ultrafast photochemical reactions with femtosecond temporal and sub-Angstroem spatial resolution. The fluorine 1s-level of adiabatically laser-aligned 1-ethynyl-4-fluorobenzene (C{sub 8}H{sub 5}F) molecules was ionized by X-ray pulses from the Linac Coherent Light Source Free-Electron Laser, and the angular distributions of photoelectrons with kinetic energies between 30 and 60 eV were recorded by velocity map imaging. Comparison with density functional theory calculations allows relating the measured distributions to the molecular structure. The results of an IR-pump, X-ray-probe experiment on aligned 1,4-dibromobenzene (C{sub 6}H{sub 4}Br{sub 2})molecules are presented to explore the potential of photoelectron diffraction for time-resolved imaging. The influence of the alignment laser pulse on the pumping and probing step is discussed. Laser-alignment is contrasted with determination of the molecular orientation by photoelectron-photoion coincidences for an exemplary data set on 1-ethynyl-4-fluorobenzene molecules recorded at the PETRA III synchrotron. Both methods are evaluated with respect to their applicability to record time-dependent snapshots of molecular structure. The results obtained in this work indicate possible future avenues for investigating ultrafast molecular dynamics using X-ray Free-Electron Lasers.
Multidataset Refinement Resonant Diffraction, and Magnetic Structures.
Attfield, J Paul
2004-01-01
The scope of Rietveld and other powder diffraction refinements continues to expand, driven by improvements in instrumentation, methodology and software. This will be illustrated by examples from our research in recent years. Multidataset refinement is now commonplace; the datasets may be from different detectors, e.g., in a time-of-flight experiment, or from separate experiments, such as at several x-ray energies giving resonant information. The complementary use of x rays and neutrons is exemplified by a recent combined refinement of the monoclinic superstructure of magnetite, Fe3O4, below the 122 K Verwey transition, which reveals evidence for Fe(2+)/Fe(3+) charge ordering. Powder neutron diffraction data continue to be used for the solution and Rietveld refinement of magnetic structures. Time-of-flight instruments on cold neutron sources can produce data that have a high intensity and good resolution at high d-spacings. Such profiles have been used to study incommensurate magnetic structures such as FeAsO4 and β-CrPO4. A multiphase, multidataset refinement of the phase-separated perovskite (Pr0.35Y0.07Th0.04Ca0.04Sr0.5)MnO3 has been used to fit three components with different crystal and magnetic structures at low temperatures.
Applications of TOF neutron diffraction in archaeometry
Kockelmann, W. [Rutherford Appleton Laboratory, ISIS Facility, Chilton (United Kingdom); Siano, S.; Bartoli, L. [Istituto di Fisica Applicata - CNR, Sesto Fiorentino (Italy); Visser, D. [Rutherford Appleton Laboratory, ISIS Facility, Chilton (United Kingdom); Netherlands Organisation for Scientific Research (NWO), Den Haag (Netherlands); Hallebeek, P. [Netherlands Institute for Cultural Heritage (ICN), Amsterdam (Netherlands); Traum, R. [Kunsthistorisches Museum Wien, Muenzkabinett, Vienna (Austria); Linke, R.; Schreiner, M. [Akademie der Bildenden Kuenste, Institut fuer Wissenschaften und Technologien in der Kunst, Vienna (Austria); Kirfel, A. [Universitaet Bonn, Mineralogisch-Petrologisches Institut, Bonn (Germany)
2006-05-15
Neutron radiation meets the demand for a versatile diagnostic probe for collecting information from the interior of large, undisturbed museum objects or archaeological findings. Neutrons penetrate through coatings and corrosion layers deep into centimetre-thick materials, a property that makes them ideal for non-destructive examination of objects for which sampling is impractical or unacceptable. A particular attraction of neutron techniques for archaeologists and conservation scientists is the prospect of locating hidden materials and structures inside objects. Time-of-flight (TOF) neutron diffraction allows for the examination of mineral and metal phase contents, crystal structures, grain orientations, and microstructures as well as micro- and macro strains. A promising application is texture analysis which may provide clues to the deformation history of the material, and hence to specific working processes. Here we report on instructive examples of TOF neutron diffraction, including phase analyses of medieval Dutch tin-lead spoons, texture analyses of bronze specimens as well as of 16th-century silver coins. (orig.)
Neutron diffraction study of austempered ductile iron
Choi, C. S.; Sharpe, W.; Barker, J.; Fields, R. J.
1996-04-01
Crystallographic properties of an austempered ductile iron (ADI) were studied by using neutron diffraction. A quantitative phase analysis based on Rietveld refinements revealed three component phases, α-Fe (ferrite), γ-Fe (austenite), and graphite precipitate, with weight fractions of 66.0, 31.5, and 2.5 pct, respectively. The ferrite phases of the samples were found to be tetragonal, 14/mmm, with a c/a ratio of about 0.993, which is very close to the body-centered cubic (bcc) structure. The austenite phase had C atoms occupying the octahedral site of the face-centered cubic (fcc) unit cell with about 8 pct occupancy ratio. A strong microstrain broadening was observed for the two Fe phases of the samples. The particle sizes of the acicular ferrite phase were studied by using small angle neutron scattering. The analysis suggested a mean rod diameter of 700 A. The scattering invariant predicts a ferrite volume fraction consistent with the powder diffraction analysis. A textbook case of nodular graphite segregation, with average diameters ranging from 10 to 20 μm, was observed by optical micrography.
Diffraction limited spectro-polarimeter - Phase I
Sankarasubramanian, Kasiviswanathan; Elmore, David F.; Lites, Bruce W.; Sigwarth, Michael; Rimmele, Thomas R.; Hegwer, Steven L.; Gregory, Scott; Streander, Kim V.; Wilkins, Lawrence M.; Richards, K.; Berst, C.
2003-02-01
A diffraction limited spectro-polarimeter is under construction at the National Solar Observatory in collaboration with the High Altitude Observatory. The scientific objective of the project is to measure the magnetic fields on the Sun up to the diffraction limit of the Dunn Solar Telescope. The same instrument would also measure the magnetic field of large sunspots or sunspot groups with reasonable spatial resolution. This requires a flexible image scale which cannot be obtained with the current Advanced Stokes Polarimeter (ASP) without loosing 50% of the light. The new spectro-polarimeter is designed in such a way that the image scale can be changed without loosing much light. It can work either in high-spatial resolution mode (0.09 arcsec per pixel) with a small field of view (FOV: 65 arcsec) or in large FOV mode (163 arcsec) with low-spatial resolution (0.25 arcsec per pixel). The phase-I of this project is to design and build the spectrograph with flexible image scale. Using the existing modulation, calibration optics of the ASP and the ASP control and data acquisition system with ASP-CHILL camera, the spectrograph was tested for its performance. This paper will concentrate on the performance of the spectrograph and will discuss some preliminary results obtained with the test runs.
Crystal diffraction lens for medical imaging
Smither, Robert K.; Roa, Dante E.
2000-04-01
A crystal diffraction lens for focusing energetic gamma rays has been developed at Argonne National Laboratory for use in medical imaging of radioactivity in the human body. A common method for locating possible cancerous growths in the body is to inject radioactivity into the blood stream of the patient and then look for any concentration of radioactivity that could be associated with the fast growing cancer cells. Often there are borderline indications of possible cancers that could be due to statistical functions in the measured counting rates. In order to determine if these indications are false or real, one must resort to surgical means and take tissue samples in the suspect area. We are developing a system of crystal diffraction lenses that will be incorporated into a 3- D imaging system with better sensitivity (factors of 10 to 20) and better spatial resolution (a few mm in both vertical and horizontal directions) than most systems presently in use. The use of this new imaging system will allow one to eliminate 90 percent of the false indications and both locate and determine the size of the cancer with mm precision. The lens consists of 900 single crystals of copper, 4 mm X 4 mm on a side and 2 - 4 mm thick, mounted in 13 concentric rings.
Impact of Casimir-Polder interaction on Poisson-spot diffraction at a dielectric sphere
Hemmerich, Joshua L.; Bennett, Robert; Reisinger, Thomas; Nimmrichter, Stefan; Fiedler, Johannes; Hahn, Horst; Gleiter, Herbert; Buhmann, Stefan Yoshi
2016-08-01
Diffraction of matter waves is an important demonstration of the fact that objects in nature possess a mixture of particlelike and wavelike properties. Unlike in the case of light diffraction, matter waves are subject to a vacuum-mediated interaction with diffraction obstacles. Here we present a detailed account of this effect through the calculation of the attractive Casimir-Polder potential between a dielectric sphere and an atomic beam. Furthermore, we use our calculated potential to make predictions about the diffraction patterns to be observed in an ongoing experiment where a beam of indium atoms is diffracted around a silicon-dioxide sphere. The result is an amplification of the on-axis bright feature, which is the matter-wave analog of the well-known "Poisson spot" from optics. Our treatment confirms that the diffraction patterns resulting from our complete account of the sphere Casimir-Polder potential are indistinguishable from those found via a large-sphere nonretarded approximation in the discussed experiments, establishing the latter as an adequate model.
Influence of Carrier Transport on Diffraction Efficiency of Steady-State Photocarrier Grating
Sun, Q. M.; Wang, Y. F.; Gao, C. M.; Cui, H.
2015-06-01
A two-dimensional theoretical model of a diffractive steady-state photocarrier grating (SSPCG) has been developed. The carrier diffusion equation with a spatially periodic excitation source was solved, and an analytical expression of the carrier density distribution was obtained. Based on the band-filling theory and the Kramers-Kronig relation, the carrier-induced refractive index change of SSPCG was estimated, and the refractive index profile was determined. The diffraction efficiency of the SSPCG was calculated by multilevel rigorous coupled-wave analysis. Simulations were carried out to investigate the influence of the carrier transport properties on the diffraction efficiency of the SSPCG. The results show that a semiconductor material with a longer lifetime and a smaller diffusivity will have a higher diffraction efficiency. The spatial amplitude of the carrier density and the grating strength of the SSPCG are closely related to the grating period. For an InP-based SSPCG, the diffraction efficiency of the transmitted wave reaches its maximum value (25 %) when the grating provides a phase shift. The theoretical analysis and conclusions are helpful for material selection and experimental parameter determination of a diffractive SSPCG.
High-resolution diffraction grating interferometric transducer of linear displacements
Shang, Ping; Xia, Haojie; Fei, Yetai
2016-01-01
A high-resolution transducer of linear displacements is presented. The system is based on semiconductor laser illumination and a diffraction grating applied as a length master. The theory of the optical method is formulated using Doppler description. The relationship model among the interference strips, measurement errors, grating deflection around the X, Y and Z axes and translation along the Z axis is built. The grating interference strips' direction and space is not changed with movement along the X (direction of grating movement), Y (direction of grating line), Z axis, and the direction and space has a great effect when rotating around the X axis. Moreover the space is little affected by deflection around the Z axis however the direction is changed dramatically. In addition, the strips' position shifted rightward or downwards respectively for deflection around the X or Y axis. Because the emitted beams are separated on the grating plane, the tilt around the X axis error of the stage during motion will lead to the optical path difference of the two beams resulting in phase shift. This study investigates the influence of the tilt around the X axis error. Experiments show that after yaw error compensation, the high-resolution diffraction grating interferometric transducer readings can be significantly improved. The error can be reduced from +/-80 nm to +/-30 nm in maximum.
Automated twin identification technique for use with electron backscatter diffraction.
Henrie, B. L. (Benjamin Lyman); Mason, T. A. (Thomas A.); Bingert, J. F. (John F.)
2004-01-01
Historically, twinning information has been obtained by optical microscopy, TEM, and neutron diffraction. Recent research has shown that automated electron backscatter diffraction (EBSD) can be used to extract reliable twinning statistics. An automated twin identification technique for use with EBSD has facilitated a greater understanding of deformation twinning in materials. The key features of this automated framework are the use of the crystallographic definition of twin relationships, the inclination of the common K, plane at a twin boundary, and the correct identification of the parent orientation in a parent/twin pair. The complex nature of the parent/twin interactions required the use of a voting scheme to correctly identify parent orientations. In those few cases were the voting scheme was unable to determine parent orientation (< 2 pct) the algorithm allows for manual selection. Twin area fractions are categorized by operative twin systems along with secondary and tertiary twinning. These statistics are reported for {alpha}-zirconium and 316L stainless steel. These improved twin statistics can help quantify deformation processes as well as provide validation of plasticity models for materials that exhibit deformation twinning.
A new bridge technique for neutron tomography and diffraction measurements
Burca, G., E-mail: G.Burca@open.ac.uk [Materials Engineering, Open University, Milton Keynes, MK7 6AA (United Kingdom); James, J.A. [Materials Engineering, Open University, Milton Keynes, MK7 6AA (United Kingdom); Kockelmann, W. [ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom); Fitzpatrick, M.E. [Materials Engineering, Open University, Milton Keynes, MK7 6AA (United Kingdom); Zhang, S.Y. [ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom); Hovind, J. [Paul Scherrer Institute (PSI), CH-5232, Villigen (Switzerland); Langh, R. van [Delft University of Technology, Department of Materials Science, Faculty 3mE, Mekelweg 2, 2628 CD Delft (Netherlands); Rijksmuseum Amsterdam, P.O. Box 74888, 1070 DN Amsterdam (Netherlands)
2011-09-21
An attractive feature of neutron techniques is the ability to identify hidden materials and structures inside engineering components and objects of art and archaeology. Bearing this in mind we are investigating a new technique, 'Tomography Driven Diffraction' (TDD), that exploits tomography data to guide diffraction experiments on samples with complex structures and shapes. The technique can be used utilising combinations of individual tomography and diffraction instruments, such as NEUTRA (PSI, CH) and ENGIN-X (ISIS, UK), but is also suitable for new combined imaging and diffraction instruments such as the JEEP synchrotron engineering instrument (DIAMOND, UK) and the proposed IMAT neutron imaging and diffraction instrument (ISIS, UK).
The energy dependence of the diffraction minimum and new LHC data
Selyugin, O V
2016-01-01
The soft diffraction phenomena in the elastic proton-proton scattering are reviewed from the viewpoint of experiments at the LHC (TOTEM and ATLAS collaboration). In the framework of the High Energy Generalized Structure (HEGS) model the form of the diffraction minimum in the nucleon-nucleon elastic scattering in a wide energy region is analyzed. The numerical predictions at LHC energies are presented. The comparison of the model predictions with the new LHC data at $\\sqrt{s}=13$ TeV is made.
Derrick, Malcolm; Magill, S; Mikunas, D; Musgrave, B; Repond, J; Stanek, R; Talaga, R L; Zhang, H; Ayad, R; Bari, G; Basile, M; Bellagamba, L; Boscherini, D; Bruni, A; Bruni, G; Bruni, P; Cara Romeo, G; Castellini, G; Chiarini, M; Cifarelli, Luisa; Cindolo, F; Contin, A; Corradi, M; Gialas, I; Giusti, P; Iacobucci, G; Laurenti, G; Levi, G; Margotti, A; Massam, Thomas; Nania, R; Nemoz, C; Palmonari, F; Polini, A; Sartorelli, G; Timellini, R; Zamora-Garcia, Yu E; Zichichi, Antonino; Bargende, A; Crittenden, James Arthur; Desch, Klaus; Diekmann, B; Doeker, T; Eckert, M; Feld, L; Frey, A; Geerts, M; Geitz, G; Grothe, M; Haas, T; Hartmann, H; Haun, D; Heinloth, K; Hilger, E; Jakob, H P; Katz, U F; Mari, S M; Mass, A; Mengel, S; Mollen, J; Paul, E; Rembser, C; Schattevoy, R; Schramm, D; Stamm, J; Wedemeyer, R; Campbell-Robson, S; Cassidy, A; Dyce, N; Foster, B; George, S; Gilmore, R; Heath, G P; Heath, H F; Llewellyn, T J; Morgado, C J S; Norman, D J P; O'Mara, J A; Tapper, R J; Wilson, S S; Yoshida, R; Rau, R R; Arneodo, M; Iannotti, L; Schioppa, M; Susinno, G; Bernstein, A M; Caldwell, A; Cartiglia, N; Parsons, J A; Ritz, S; Sciulli, F; Straub, P B; Wai, L; Yang, S; Zhu, Q; Borzemski, P; Chwastowski, J; Eskreys, Andrzej; Piotrzkowski, K; Zachara, M; Zawiejski, L; Adamczyk, L; Bednarek, B; Jelen, K; Kisielewska, D; Kowalski, T; Rulikowska-Zarebska, E; Suszycki, L; Zajac, J; Kotanski, Andrzej; Przybycien, M B; Bauerdick, L A T; Behrens, U; Beier, H; Bienlein, J K; Coldewey, C; Deppe, O; Desler, K; Drews, G; Flasinski, M; Gilkinson, D J; Glasman, C; Göttlicher, P; Grosse-Knetter, J; Gutjahr, B; Hain, W; Hasell, D; Hessling, H; Iga, Y; Joos, P; Kasemann, M; Klanner, Robert; Koch, W; Köpke, L; Kötz, U; Kowalski, H; Labs, J; Ladage, A; Löhr, B; Loewe, M; Lüke, D; Manczak, O; Monteiro, T; Ng, J S T; Nickel, S; Notz, D; Ohrenberg, K; Roco, M T; Rohde, M; Roldán, J; Schneekloth, U; Schulz, W; Selonke, F; Stiliaris, E; Surrow, B; Voss, T; Westphal, D; Wolf, G; Youngman, C; Zhou, J F; Grabosch, H J; Kharchilava, A I; Leich, A; Mattingly, M C K; Meyer, A; Schlenstedt, S; Wulff, N; Barbagli, G; Pelfer, P G; Anzivino, Giuseppina; Maccarrone, G D; De Pasquale, S; Votano, L; Bamberger, Andreas; Eisenhardt, S; Freidhof, A; Söldner-Rembold, S; Schröder, J; Trefzger, T M; Brook, N H; Bussey, Peter J; Doyle, A T; Fleck, I; Saxon, D H; Utley, M L; Wilson, A S; Dannemann, A; Holm, U; Horstmann, D; Neumann, T; Sinkus, R; Wick, K; Badura, E; Burow, B D; Hagge, L; Lohrmann, E; Mainusch, J; Milewski, J; Nakahata, M; Pavel, N; Poelz, G; Schott, W; Zetsche, F; Bacon, Trevor C; Butterworth, Ian; Gallo, E; Harris, V L; Hung, B Y H; Long, K R; Miller, D B; Morawitz, P P O; Prinias, A; Sedgbeer, J K; Whitfield, A F; Mallik, U; McCliment, E; Wang, M Z; Wang, S M; Wu, J T; Zhang, Y; Cloth, P; Filges, D; An Shiz Hong; Hong, S M; Nam, S W; Park, S K; Suh, M H; Yon, S H; Imlay, R; Kartik, S; Kim, H J; McNeil, R R; Metcalf, W; Nadendla, V K; Barreiro, F; Cases, G; Graciani, R; Hernández, J M; Hervás, L; Labarga, L; Del Peso, J; Puga, J; Terrón, J; De Trocóniz, J F; Smith, G R; Corriveau, F; Hanna, D S; Hartmann, J; Hung, L W; Lim, J N; Matthews, C G; Patel, P M; Sinclair, L E; Stairs, D G; Saint-Laurent, M G; Ullmann, R T; Zacek, G; Bashkirov, V; Dolgoshein, B A; Stifutkin, A; Bashindzhagian, G L; Ermolov, P F; Gladilin, L K; Golubkov, Yu A; Kobrin, V D; Kuzmin, V A; Proskuryakov, A S; Savin, A A; Shcheglova, L M; Solomin, A N; Zotov, N P; Botje, M; Chlebana, F S; Dake, A P; Engelen, J; De Kamps, M; Kooijman, P M; Kruse, A; Tiecke, H G; Verkerke, W; Vreeswijk, M; Wiggers, L; De Wolf, E; Van Woudenberg, R; Acosta, D; Bylsma, B G; Durkin, L S; Honscheid, K; Li Chuan; Ling, T Y; McLean, K W; Murray, W N; Park, I H; Romanowsky, T A; Seidlein, R; Bailey, D S; Blair, G A; Byrne, A; Cashmore, Roger J; Cooper-Sarkar, A M; Daniels, D C; Devenish, R C E; Harnew, N; Lancaster, M; Luffman, P; Lindemann, L; McFall, J D; Nath, C; Noyes, V A; Quadt, A; Uijterwaal, H; Walczak, R; Wilson, F F; Yip, T; Abbiendi, G; Bertolin, A; Brugnera, R; Carlin, R; Dal Corso, F; De Giorgi, M; Dosselli, U; Limentani, S; Morandin, M; Posocco, M; Stanco, L; Stroili, R; Voci, C; Bulmahn, J; Butterworth, J M; Feild, R G; Whitmore, J; D'Agostini, Giulio; Marini, G; Nigro, A; Tassi, E; Hart, J C; McCubbin, N A; Prytz, K; Shah, T P; Short, T L; Barberis, E; Dubbs, T; Heusch, C A; Van Hook, M; Hubbard, B; Lockman, W; Rahn, J T; Sadrozinski, H F W; Seiden, A; Biltzinger, J; Seifert, R J; Walenta, Albert H; Zech, G; Abramowicz, H; Briskin, G M; Dagan, S; Levy, A; Hasegawa, T; Hazumi, M; Ishii, T; Kuze, M; Mine, S; Nagasawa, Y; Nakao, M; Susuki, I; Tokushuku, K; Yamada, S; Yamazaki, Y; Chiba, M; Hamatsu, R; Hirose, T; Homma, K; Kitamura, S; Nakamitsu, Y; Yamauchi, K; Cirio, R; Costa, M; Ferrero, M I; Lamberti, L; Maselli, S; Peroni, C; Sacchi, R; Solano, A; Staiano, A; Dardo, M; Bailey, D C; Bandyopadhyay, D; Bénard, F; Brkic, M; Crombie, M B; Gingrich, D M; Hartner, G F; Joo, K K; Levman, G M; Martin, J F; Orr, R S; Sampson, C R; Teuscher, R; Catterall, C D; Jones, T W; Kaziewicz, P B; Lane, J B; Saunders, R L; Shulman, J; Blankenship, K; Lu, B; Mo, L W; Bogusz, W; Charchula, K; Ciborowski, J; Gajewski, J; Grzelak, G; Kasprzak, M; Krzyzanowski, M; Muchorowski, K; Nowak, R J; Pawlak, J M; Tymieniecka, T; Wróblewski, A K; Zakrzewski, J A; Zarnecki, A F; Adamus, M; Eisenberg, Y; Karshon, U; Revel, D; Zer-Zion, D; Ali, I; Badgett, W F; Behrens, B H; Dasu, S; Fordham, C; Foudas, C; Goussiou, A; Loveless, R J; Reeder, D D; Silverstein, S; Smith, W H; Vaiciulis, A W; Wodarczyk, M; Tsurugai, T; Bhadra, S; Cardy, M L; Fagerstroem, C P; Frisken, W R; Furutani, K M; Khakzad, M; Schmidke, W B
1995-01-01
Inclusive transverse momentum spectra of charged particles in photoproduction events in the laboratory pseudorapidity range -1.2<\\eta<1.4 have been measured up to p_{T}=8\\GeV using the ZEUS detector. Diffractive and non--diffractive reactions have been selected with an average \\gamma p centre of mass (c.m.) energy of \\langle W \\rangle = 180\\GeV. For diffractive reactions, the p_{T} spectra of the photon dissociation events have been measured in two intervals of the dissociated photon mass with mean values \\langle M_{X} \\rangle = 5 GeV and 10 GeV. The inclusive transverse momentum spectra fall exponentially in the low p_{T} region. The non--diffractive data show a pronounced high p_{T} tail departing from the exponential shape. The p_{T} distributions are compared to lower energy photoproduction data and to hadron--hadron collisions at a similar c.m. energy. The data are also compared to the results of a next--to--leading order QCD calculation.
Neutron diffraction of unidirectional fiber-composites
Ochiai, Shojiro; Hojo, Masaki; Iwasaki, Naoya; Sawada, Takehiro; Inoue, Takashi; Tanaka, Mototsugu; Okumura, Ikuo; Ono, Masayoshi [Kyoto Univ. (Japan)
1997-06-01
Nb-Ti/Cu and Nb{sub 3}Al/Cu superconductive fiber-composites were studied by a neutron diffraction method. The results obtained showed that the aggregate structures were formed in the direction of <100> and <111> for copper and <110> for Nb-Ti filament. Nb{sub 3}Al grew up to the radius direction and formed the side face (210). Residual strain and stress of Cu in Nb-Ti/Cu and Nb{sub 3}Al/Cu composite were measured by TOF and PSD method. The value before smoothing treatment was 96 MPa, but the value after smoothing treatment became 40 MPa, near estimated value. (S.Y.)
Diffraction limited optics for single atom manipulation
Sortais, Y R P; Browaeys, A; Fournet, P; Grangier, P; Lamare, M; Lance, A M; Marion, H; Mercier, R; Messin, G; Tuchendler, C
2006-01-01
We present an optical system designed to capture and observe a single neutral atom in an optical dipole trap, created by focussing a laser beam using a large numerical aperture N.A.=0.5 aspheric lens. We experimentally evaluate the performance of the optical system and show that it is diffraction limited over a broad spectral range (~ 200 nm) with a large transverse field (+/- 25 microns). The optical tweezer created at the focal point of the lens is able to trap single atoms of 87Rb and to detect them individually with a large collection efficiency. We measure the oscillation frequency of the atom in the dipole trap, and use this value as an independent determination of the waist of the optical tweezer. Finally, we produce with the same lens two dipole traps separated by 2.2 microns and show that the imaging system can resolve the two atoms.
Electron Backscatter Diffraction in Low Vacuum Conditions
El-Dasher, B S; Torres, S G
2008-07-17
Most current scanning electron microscopes (SEMs) have the ability to analyze samples in a low vacuum mode, whereby a partial pressure of water vapor is introduced into the SEM chamber, allowing the characterization of nonconductive samples without any special preparation. Although the presence of water vapor in the chamber degrades electron backscatter diffraction (EBSD) patterns, the potential of this setup for EBSD characterization of nonconductive samples is immense. In this chapter we discuss the requirements, advantages and limitations of low vacuum EBSD (LV-EBSD), and present how this technique can be applied to a two-phase ceramic composite as well as hydrated biominerals as specific examples of when LV-EBSD can be invaluable.
Diffraction radiation from relativistic heavy ions
Potylitsyna, N. A.
2001-01-01
In recent years, the relativistic heavy ion beams at new accelerator facilities are allowed to obtain some new interesting results (see, for instance, Datz et al., Phys. Rev. Lett. 79 (18) (1997) 3355; Ladyrin et al., Nucl. Instr. and Meth. A 404 (1998) 129). The problem of non-destructive heavy ion beam diagnostics at these accelerators is highly pressing. The authors of the papers (Rule et al., Proceedings of the Seventh Beam Instrumentation Workshop, Argonne IL, AIP Conference Proceedings, Vol. 390, NY, 1997; Castellano, Nucl. Instr. and Meth. A 394 (1997) 275) suggested to use diffraction radiation (DR) appearing when a charge moves close to a conducting surface (Bolotovskii and Voskresenskii, Sov. Phys. Usp. 9 (1966) 73) for non-destructive electron beam diagnostics. The DR characteristics are defined by both Lorentz-factor and the particle charge, and do not depend on its mass. The estimation of feasibility of using DR for relativistic ion beam diagnostics is undoubtedly interesting.
Flat hat glass diffractive optical beam shaper
Reichel, Steffen; Petzold, Uwe; Biertuempfel, Ralf; Vogt, Helge
2009-02-01
Many laser applications need a homogeneous - so called flat hat - light distribution in the application area. However, many laser emit Gaussian shaped light. The technology of diffractive optical elements (DOE) can be used to shape the Gaussian beam into a flat hat beam at a compact length. SCHOTT presents a DOE design of a flat hat DOE beam shaper made out of optical glass. Here the material glass has the significant advantage of high laser durability, low scattering losses, high resistance to temperature, moisture, and chemicals compared to polymer DOEs. Simulations and measurements on different DOEs for different wavelength, laser beam width, and laser divergence are presented. Surprisingly the flat hat DOE beam shaper depends only weakly on wavelength and beam width but strongly on laser divergence. Based on the good agreement between simulation and measurement an improved flat hat DOE beam shaper is also presented.
Suppression factors in diffractive photoproduction of dijets
Klasen, Michael; Kramer, Gustav
2010-11-01
Now that new publications of H1 data for the diffractive photoproduction of dijets, which overlap with the earlier published H1 data and the recently published data of the ZEUS collaboration, have appeared, we have recalculated the cross sections for this process in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that the NLO cross sections disagree with the data, showing that factorization breaking occurs at that order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut. However, by suppressing only the resolved contribution, also reasonably good agreement with all the data is found with a suppression factor independent of the transverse-energy cut.
Suppression factors in diffractive photoproduction of dijets
Klasen, Michael [Universite Joseph Fourier/CNRS-IN2P3/INPG, Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Kramer, Gustav [Universitaet Hamburg, II. Institut fuer Theoretische Physik, Hamburg (Germany)
2010-11-15
Now that new publications of H1 data for the diffractive photoproduction of dijets, which overlap with the earlier published H1 data and the recently published data of the ZEUS collaboration, have appeared, we have recalculated the cross sections for this process in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that the NLO cross sections disagree with the data, showing that factorization breaking occurs at that order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut. However, by suppressing only the resolved contribution, also reasonably good agreement with all the data is found with a suppression factor independent of the transverse-energy cut. (orig.)
Suppression factors in diffractive photoproduction of dijets
Klasen, M
2010-01-01
After new publications of H1 data for the diffractive photoproduction of dijets, which overlap with the earlier published H1 data and the recently published data of the ZEUS collaboration, have appeared, we have recalculated the cross sections for this process in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that the NLO cross sections disagree with the data, showing that factorization breaking occurs at that order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut. However, by suppressing only the resolved contribution, also reasonably good agreement with all the data is found with a suppression factor independent of the transverse-energy cut.
Suppression factors in diffractive photoproduction of dijets
Klasen, Michael [Joseph Fourier Univ./CNRS-IN2P3/INPG, 38 - Grenoble (France). Lab. de Physique Subatomique et de Cosmologie; Kramer, Gustav [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik
2010-06-15
After new publications of H1 data for the diffractive photoproduction of dijets, which overlap with the earlier published H1 data and the recently published data of the ZEUS collaboration, have appeared, we have recalculated the cross sections for this process in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that the NLO cross sections disagree with the data, showing that factorization breaking occurs at that order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut. However, by suppressing only the resolved contribution, also reasonably good agreement with all the data is found with a suppression factor independent of the transverse-energy cut. (orig.)
Amplitude image processing by diffractive optics.
Cagigal, Manuel P; Valle, Pedro J; Canales, V F
2016-02-22
In contrast to the standard digital image processing, which operates over the detected image intensity, we propose to perform amplitude image processing. Amplitude processing, like low pass or high pass filtering, is carried out using diffractive optics elements (DOE) since it allows to operate over the field complex amplitude before it has been detected. We show the procedure for designing the DOE that corresponds to each operation. Furthermore, we accomplish an analysis of amplitude image processing performances. In particular, a DOE Laplacian filter is applied to simulated astronomical images for detecting two stars one Airy ring apart. We also check by numerical simulations that the use of a Laplacian amplitude filter produces less noisy images than the standard digital image processing.
Phase retrieval from single biomolecule diffraction pattern.
Ikeda, Shiro; Kono, Hidetoshi
2012-02-13
In this paper, we propose the SPR (sparse phase retrieval) method, which is a new phase retrieval method for coherent x-ray diffraction imaging (CXDI). Conventional phase retrieval methods effectively solve the problem for high signal-to-noise ratio measurements, but would not be sufficient for single biomolecular imaging which is expected to be realized with femto-second x-ray free electron laser pulses. The SPR method is based on the Bayesian statistics. It does not need to set the object boundary constraint that is required by the commonly used hybrid input-output (HIO) method, instead a prior distribution is defined with an exponential distribution and used for the estimation. Simulation results demonstrate that the proposed method reconstructs the electron density under a noisy condition even some central pixels are masked.
Improved accuracy in nano beam electron diffraction
Beche, A; Rouviere, J-L [CEA, INAC, SP2M, LEMMA, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Clement, L, E-mail: armand.beche@cea.f, E-mail: jean-luc.rouviere@cea.f [ST Microelectronics, 850 rue Jean Monnet, F-38920 Crolles (France)
2010-02-01
Nano beam electron diffraction (NBD or NBED) is applied on a well controlled sample in order to evaluate the limit of the technique to measure strain. Measurements are realised on a 27nm thick Si{sub 0.7}Ge{sub 0.3} layer embedded in a silicon matrix, with a TITAN microscope working at 300kV. Using a standard condenser aperture of 50{mu}m, a probe size diameter of 2.7 nm is obtained and a strain accuracy of 6x10{sup -4} (mean root square, rms) is achieved. NBED patterns are acquired along a [110] direction and the bidimensionnal strain in the (110) plane is measured. Finite element simulations are carried out to check experimental results and reveal that strain relaxation and probe averaging in a 170nm thick TEM lamella reduces strain by 15%.
Virtual input device with diffractive optical element
Wu, Ching Chin; Chu, Chang Sheng
2005-02-01
As a portable device, such as PDA and cell phone, a small size build in virtual input device is more convenient for complex input demand. A few years ago, a creative idea called 'virtual keyboard' is announced, but up to now there's still no mass production method for this idea. In this paper we'll show the whole procedure of making a virtual keyboard. First of all is the HOE (Holographic Optical Element) design of keyboard image which yields a fan angle about 30 degrees, and then use the electron forming method to copy this pattern in high precision. And finally we can product this element by inject molding. With an adaptive lens design we can get a well correct keyboard image in distortion and a wilder fan angle about 70 degrees. With a batter alignment of HOE pattern lithography, we"re sure to get higher diffraction efficiency.
Coherent diffractive imaging using randomly coded masks
Seaberg, Matthew H., E-mail: seaberg@slac.stanford.edu [CNRS and D.I., UMR 8548, École Normale Supérieure, 45 Rue d' Ulm, 75005 Paris (France); Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); D' Aspremont, Alexandre [CNRS and D.I., UMR 8548, École Normale Supérieure, 45 Rue d' Ulm, 75005 Paris (France); Turner, Joshua J. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)
2015-12-07
We experimentally demonstrate an extension to coherent diffractive imaging that encodes additional information through the use of a series of randomly coded masks, removing the need for typical object-domain constraints while guaranteeing a unique solution to the phase retrieval problem. Phase retrieval is performed using a numerical convex relaxation routine known as “PhaseCut,” an iterative algorithm known for its stability and for its ability to find the global solution, which can be found efficiently and which is robust to noise. The experiment is performed using a laser diode at 532.2 nm, enabling rapid prototyping for future X-ray synchrotron and even free electron laser experiments.
Generalized Backpropagation Algorithms for Diffraction Tomography
Paladhi, Pavel Roy; Tayebi, Amin; Udpa, Lalita
2016-01-01
Filtered backpropagation (FBPP) is a well-known technique used for Diffraction Tomography (DT). For accurate reconstruction of a complex image using FBPP, full $360^{\\circ}$ angular coverage is necessary. However, it has been shown that using some inherent redundancies in projection data in a tomographic setup, accurate reconstruction is still possible with $270^{\\circ}$ coverage which is called the minimal-scan angle range. This can be done by applying weighing functions (or filters) on projection data of the object to eliminate the redundancies and accurately reconstruct the image from this lower angular coverage. This paper demonstrates procedures to generate many general classes of these weighing filters. These are all equivalent at $270^{\\circ}$ coverage but would perform differently at lower angular coverages and under presence of noise. This paper does a comparative analysis of different filters when angular coverage is lower than minimal-scan angle of $270^{\\circ}$. Simulation studies have been done t...
Diffractive optical elements written by photodeposition
Baal-Zedaka, I.; Hava, S.; Mirchin, N.; Margolin, R.; Zagon, M.; Lapsker, I.; Azoulay, J.; Peled, A.
2003-03-01
In this work direct laser writing of diffractive optical elements (DOE) by photodeposition (PD) of amorphous selenium (a-Se) from colloid solutions has been investigated. We used a computer controlled laser scanner for patterning thin film micro-profiles creating thus planar optical elements by direct beam writing on surfaces immersed in a liquid phase PD cell. The laser employed was an argon ion laser at 488 nm wavelength, with powers up to 55 mW, for writing typically 25-250 μm wide lines of 200 nm thickness at rates of about 150 μm/s. Various elements made of photodeposited thin films on polymethyl-methacrylate (PMMA) substrates were produced for prototyping microlenses, linear grating arrays, cylindrical and circular profiled DOE patterns.
Diffractive optical elements written by photodeposition
Baal-Zedaka, I.; Hava, S.; Mirchin, N.; Margolin, R.; Zagon, M.; Lapsker, I.; Azoulay, J.; Peled, A
2003-03-15
In this work direct laser writing of diffractive optical elements (DOE) by photodeposition (PD) of amorphous selenium (a-Se) from colloid solutions has been investigated. We used a computer controlled laser scanner for patterning thin film micro-profiles creating thus planar optical elements by direct beam writing on surfaces immersed in a liquid phase PD cell. The laser employed was an argon ion laser at 488 nm wavelength, with powers up to 55 mW, for writing typically 25-250 {mu}m wide lines of 200 nm thickness at rates of about 150 {mu}m/s. Various elements made of photodeposited thin films on polymethyl-methacrylate (PMMA) substrates were produced for prototyping microlenses, linear grating arrays, cylindrical and circular profiled DOE patterns.
Lobato, I; Van Dyck, D
2015-08-01
The steadily improving experimental possibilities in instrumental resolution as in sensitivity and quantization of the data recording put increasingly higher demands on the precision of the scattering factors, which are the key ingredients for electron diffraction or high-resolution imaging simulation. In the present study, we will systematically investigate the accuracy of fitting of the main parameterizations of the electron scattering factor for the calculation of electron diffraction intensities. It is shown that the main parameterizations of the electron scattering factor are consistent to calculate electron diffraction intensities for thin specimens and low angle scattering. Parameterizations of the electron scattering factor with the correct asymptotic behavior (Lobato and Dyck [5], Kirkland [4], and Weickenmeier and Kohl [2]) produce similar results for both the undisplaced lattice model and the frozen phonon model, except for certain thicknesses and reflections.
Nuclear dynamical diffraction using synchrotron radiation
Brown, D.E.
1993-05-01
The scattering of synchrotron radiation by nuclei is extensively explored in this thesis. From the multipole electric field expansion resulting from time-dependent nonrelativistic perturbation theory, a dynamical scattering theory is constructed. This theory is shown, in the many particle limit, to be equivalent to the semi-classical approach where a quantum mechanical scattering amplitude is used in the Maxwell inhomogeneous wave equation. The Moessbauer specimen whose low-lying energy levels were probed is a ferromagnetic lattice of {sup 57}Fe embedded in a yttrium iron garnet (YIG) crystal matrix. The hyperfine fields in YIG thin films were studied at low and room temperature using time-resolved quantum beat spectroscopy. Nuclear hyperfine structure quantum beats were measured using a fast plastic scintillator coincidence photodetector and associated electronics having a time resolution of 2.5 nsec. The variation of the quantum beat patterns near the Bragg [0 0 2] diffraction peak gave a Lamb-Moessbauer factor of 8.2{plus_minus}0.4. Exploring characteristic dynamical features in the higher order YIG [0 0 10] reflection revealed that one of the YIG crystals had bifurcated into two different layers. The dynamics of nuclear superradiance was explored. This phenomenon includes the radiative speedup exhibited by a collective state of particles, and, in striking concurrence, resonance frequency shifts. A speedup of a factor of 4 in the total decay rate and a beat frequency shift of 1{1/2} natural resonance linewidths were observed. Nuclear resonance scattering was also found to be a useful way of performing angular interferometry experiments, and it was used to observe the phase shift of a rotated quantum state. On the whole, nuclear dynamical diffraction theory has superbly explained many of the fascinating features of resonant magnetic dipole radiation scattered by a lattice of nuclei.
Lobato, I., E-mail: Ivan.Lobato@uantwerpen.be; Van Dyck, D.
2015-08-15
The steadily improving experimental possibilities in instrumental resolution as in sensitivity and quantization of the data recording put increasingly higher demands on the precision of the scattering factors, which are the key ingredients for electron diffraction or high-resolution imaging simulation. In the present study, we will systematically investigate the accuracy of fitting of the main parameterizations of the electron scattering factor for the calculation of electron diffraction intensities. It is shown that the main parameterizations of the electron scattering factor are consistent to calculate electron diffraction intensities for thin specimens and low angle scattering. Parameterizations of the electron scattering factor with the correct asymptotic behavior (Lobato and Dyck [5], Kirkland [4], and Weickenmeier and Kohl [2]) produce similar results for both the undisplaced lattice model and the frozen phonon model, except for certain thicknesses and reflections. - Highlights: • Parameterizations of the electron scattering factor with the correct asymptotic behavior produce similar electron diffraction intensities. • Peng et al. parameterization is not adequate for calculations that involves higher-order Laue zones reflections. • Electron diffraction calculations of Cu-crystal with and without inclusion of phonons.
Phase retrieval methods for surface x-ray diffraction
Saldin, D.K.; Harder, R.J.; Shneerson, V.L. [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI (United States); Moritz, W. [Institute of Crystallography and Applied Mineralogy, University of Munich, Munich (Germany)
2001-11-26
We develop an iterative input-output feedback method for the phasing of surface x-ray diffraction (SXRD) amplitudes that relies on successive operations in real and reciprocal space. We demonstrate its use for the recovery of the real and positive electron density of a surface unit cell from simulated SXRD intensities. We have successfully recovered the entire surface electron density in a case where the two-dimensional surface unit cell is the same as that of the bulk and also in one where the surface unit cell is four times larger than that of the bulk. We show that the exponential modelling algorithm for structure completion derived earlier from maximum entropy theory may be regarded as a special case of an input-output phasing algorithm with a particular form of object-domain operations. (author)
Review of factorization breaking in diffractive photoproduction of dijets
Klasen, M
2008-01-01
After the final analyses of the H1 and ZEUS collaborations for the diffractive photoproduction of dijets have appeared, we have recalculated these cross sections in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that at NLO the cross sections disagree with the data, showing that factorization breaking occurs at this order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut and is 0.42 for the H1 and 0.71 for the ZEUS analysis. However, by suppressing only the resolved contribution by a factor of approximately three, also reasonably good agreement with all the data is found. The size of the factorization breaking effects for resolved photons agrees with absorptive-model predictions.
Review of factorization breaking in diffractive photoproduction of dijets
Klasen, Michael [Grenoble Univ. (France). Lab. de Physique Subatomique et de Cosmologie; Kramer, Gustav [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2008-06-13
After the final analyses of the H1 and ZEUS collaborations for the diffractive photoproduction of dijets have appeared, we have recalculated these cross sections in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that at NLO the cross sections disagree with the data, showing that factorization breaking occurs at this order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse energy cut and is 0.42 for the H1 and 0.71 for the ZEUS analysis. However, by suppressing only the resolved contribution by a factor of approximately three, also reasonably good agreement with all the data is found. The size of the factorization breaking effects for resolved photons agrees with absorptive-model predictions. (orig.)
Review of Factorization Breaking in Diffractive Photoproduction of Dijets
Klasen, Michael; Kramer, Gustav
After the final analyses of the H1 and ZEUS collaborations for the diffractive photoproduction of dijets have appeared, we have recalculated these cross sections in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that at NLO the cross sections disagree with the data, showing that factorization breaking occurs at this order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut and is 0.42 for the H1 and 0.71 for the ZEUS analysis. However, by suppressing only the resolved contribution by a factor of approximately three, also reasonably good agreement with all the data is found. The size of the factorization breaking effects for resolved photons agrees with absorptive-model predictions.
Microscopic Description of Diffractive Deuteron Breakup by He-3 Nuclei
Kovalchuk, Valery
2016-01-01
A microscopic formalism for describing observed cross sections for deuteron breakup by three-nucleon nuclei was developed on the basis of the diffraction nuclear model. A general formula that describes the amplitude for the reaction d+3He->3He+p+n and which involves only one adjustable parameter was obtained by using expansions of the integrands involved in terms of a Gaussian basis. This formula was used to analyze experimental data on the exclusive cross sections for deuteron breakup by He-3 nuclei at the projectile energy of 89.4 MeV. The importance of employing, in calculations, a deuteron wave function that has a correct asymptotic behavior at large nucleon-nucleon distances was demonstrated.
Revealing proton shape fluctuations with incoherent diffraction at high energy
Mäntysaari, Heikki; Schenke, Björn
2016-08-01
The differential cross section of exclusive diffractive vector meson production in electron proton collisions carries important information on the geometric structure of the proton. More specifically, the coherent cross section as a function of the transferred transverse momentum is sensitive to the size of the proton, while the incoherent or proton dissociative cross section is sensitive to fluctuations of the gluon distribution in coordinate space. We show that at high energies the experimentally measured coherent and incoherent cross sections for the production of J /Ψ mesons are very well reproduced within the color glass condensate framework when strong geometric fluctuations of the gluon distribution in the proton are included. For ρ meson production, we also find reasonable agreement. We study in detail the dependence of our results on various model parameters, including the average proton shape, analyze the effect of saturation scale and color charge fluctuations and constrain the degree of geometric fluctuations.
Revealing proton shape fluctuations with incoherent diffraction at high energy
Mäntysaari, Heikki
2016-01-01
The differential cross section of exclusive diffractive vector meson production in electron proton collisions carries important information on the geometric structure of the proton. More specifically, the coherent cross section as a function of the transferred transverse momentum is sensitive to the size of the proton, while the incoherent, or proton dissociative cross section is sensitive to fluctuations of the gluon distribution in coordinate space. We show that at high energies the experimentally measured coherent and incoherent cross sections for the production of $J/\\Psi$ mesons are very well reproduced within the color glass condensate framework when strong geometric fluctuations of the gluon distribution in the proton are included. For $\\rho$ meson production we also find reasonable agreement. We study in detail the dependence of our results on various model parameters, including the average proton shape, analyze the effect of saturation scale and color charge fluctuations and constrain the degree of g...
Yang Jia-Min; Hu Zhi-Min; Wei Min-Xi; Zhang Ji-Yan; Yi Rong-Qing; Gan Xin-Shi; Zhao Yang; Cui Ming-Qi; Zhu Tuo; Zhao Yi-Dong; Sun Li-Juan; Zheng Lei; Yan Fen
2011-01-01
Integral diffraction coefficients of the crystal are the essential data of a crystal spectrometer which is extensively used to measure quantitative x-ray spectra of high temperature plasmas in kilo-electron-volt region. An experimental method has been developed to measure the integral diffraction coefficients of crystals on beamline 4B7 of Beijing Synchrotron Radiation Facility. The integral diffraction coefficients of several crystals including polyethylene terephthalate (PET), thallium acid phthalate (TIAP) and rubidium acid phthalate (RAP) crystals have been measured in the x-ray energy range 2100-5600 eV and compared with the calculations of the 'Darwin Prins' and the 'Mosaic' models. It is shown that the integral diffraction coefficients of these crystals are between the calculations of the 'Darwin Prins' and the 'Mosaic' models, but more close to the 'Darwin Prins' model calculations.
Workshop on industrial application of neutron diffraction. Stress measurement by neutron diffraction
Minakawa, N; Morii, Y; Oyama, Y
2002-01-01
This workshop was planned to make use of the neutron from the reactor and the pulse neutron source JSNS for the industrial world. Especially, this workshop focused on the stress measurement by the neutron diffraction and it was held on the Tokai JAERI from October 15 to 16, 2001. The participant total was 93 and 40 participated from the industrial world. The introduction of the residual stress development of measurement technique by the neutron diffraction method and a research of the measurement of the residual stress such as the nuclear reactor material, the ordinary structure material, the composite material, the quenching steel, the high strength material were presented and discussed in this workshop. Moreover, it was introduced for the industrial world that an internal stress measurement is important for development of new product or an improvement of a manufacturing process. The question from the industrial world about which can be measured the product form, the size, the measurement precision, the reso...
Kolyuchkin, V. V.; Odinokov, S. B.
2016-08-01
The method of security hologram quality inspection, in which the relief phase parameters are determined by registering results of the intensity distribution in diffraction orders, is known. The profile of relief as a harmonious distribution is represented. Deviation of the real relief profile from the ideal profile, another words phase relief noise, influence on the accuracy of this method. In the paper, on the assumption of homogeneity of the phase relief noise, the mathematical expressions for evaluating the influence of the phase relief noise on the intensity distribution in the diffraction orders are represented. Parameters of the correlation functions approximation describing the phase relief noise are determined. The dependence of the intensity values from the standard deviation of the phase relief noise is represented.
Diffraction Ellipsometry Studies on Insect Flight Muscle
Shen, Sui
Characterization of the orientation and distribution of myosin cross-bridge at rigor, relax, low ionic strength (36 mM) and activation (pCa 4.3) conditions are of great interest since these states have been proposed to be transient steps in the cyclical interaction of myosin heads with actin during contraction. Measurements sensitive to the cross-bridge orientation in chemically skinned single muscle fibers of the insect, Lethocerus collossicus have been performed under various physiological conditions using laser diffraction ellipsometry. Determination of both the total birefringence, Deltan, and the differential field ratio, rm DFR (defined as {E_parallel -E_|over E_parallel-E _|}),is necessary for complete characterization of the optical polarization state. For rigor insect fiber, the birefringence value was close to the value we obtained from chemically skinned frog muscle fibers. However, the differential field ratio, DFR, was a negative value for insect fiber, while we always measured a positive value from frog muscle fibers. Polarization states of light diffracted from fibers exhibited a dependence on configurations of structural proteins at different conditions: fluid index matching using o-toluidine, alpha -chymotrypsin cleavage, KCl myosin extraction, rigor state, relaxed state, exogenous S-1 binding on rigor fiber, low ionic strength state, activation state at resting or stretched length. Results of our data analysis suggested that: (1) the negative DFR value of the insect flight muscle was contributed by alpha-actinin arranged perpendicular to the fiber axis in the Z-line, (2) in rigor fiber, 70% of myosin heads are doubly bound (45^circ and 90^ circ) while the rest of 30% are in single head binding configuration (90^circ), (3) myosin heads are randomly oriented in relaxed fiber, (4) mean axial angle is about 62^ circ for exogenous myosin heads binding on rigor fiber, (5) at low ionic strength, 25% of the total myosin heads are weakly attached to actin
Quantum Theory of Electronic Double-Slit Diffraction
WU Xiang-Yao; GUO Yi-Qing; ZHANG Bai-Jun; LI Hai-Bo; LU Jing-Bin; LIU Xiao-Jing; WANG Li; ZHANG Chun-Li; LIU Bing; FAN Xi-Hui
2007-01-01
Phenomena of electron, neutron, atomic and molecular diffraction have been studied in many experiments, and these experiments have been explained by some theoretical works. We study electronic double-slit diffraction with a quantum mechanical approach and obtain the following results: (1) When the ratio of d + a/a = n (n = 1, 2, 3,...),orders n, 2n, 3n,...are missing in diffraction pattern. (2) When the ratio of d+a/a ≠ n (n = 1, 2, 3,...), there is not missing order in diffraction pattern. (3) The slit thickness c has a large affect on the electronic diffraction pattern, which is a new quantum effect. We believe that all the predictions in our work can be tested by the electronic double slit diffraction experiment.
Optical generation of non-diffracting beams via photorefractive holography
Vieira, Tarcio A; Gesualdi, Marcos R R; Zamboni-Rached, Michel
2015-01-01
This work presents, for the first time the optical generation of non-diffracting beams via photorefractive holography. Optical generation of non-diffracting beams using conventional optics components is difficult and, in some instances, unfeasible, as it is wave fields given by superposition of non-diffracting beams. It is known that computer generated holograms and spatial light modulators (SLMs) successfully generate such beams. With photorefractive holography technique, the hologram of a non-diffracting beam is constructed (recorded) and reconstructed (reading) optically in a nonlinear photorefractive medium. The experimental realization of a non-diffracting beam was made in a photorefractive holography setup using a photorefractive Bi12SiO20 (BSO) crystal as the holographic recording medium, where the non-diffracting beams, the Bessel beam arrays and superposition of co-propagating Bessel beams (Frozen Waves) were obtained experimentally. The experimental results are in agreement with the theoretically pr...
Multi-Slit Diffraction of Evanescent Electromagnetic Waves
SONG Zhen-Ming; CHEN Yong-Yao; XU Bo; LI Yan-Feng; HU Ming-Lie; XING Qi-Rong; ZHANG Zhi-Gang; CHAI Lu; WANG Qing-Yue
2008-01-01
The well-known Fraunhofer multi-slit diffraction is described as the multi-slit interference modulated by the single-slit diffraction, namely the multiplication between the single-slit diffraction factor and the multi-slit interference factor. By considering the simplified argument we show that the multi-slit diffraction of evanescent waves which are in the near-field region also has the interference and diffraction effects, and that this two-fold effect can be expressed as the convolution of the diffraction factor and the interference factor. Our conclusion could be helpful to understand the contribution of evanescent waves to the optical responses of sub-wavelength structures such as slits and grooves.
X-ray diffraction imaging of material microstructures
Varga, Laszlo
2016-10-20
Various examples are provided for x-ray imaging of the microstructure of materials. In one example, a system for non-destructive material testing includes an x-ray source configured to generate a beam spot on a test item; a grid detector configured to receive x- rays diffracted from the test object; and a computing device configured to determine a microstructure image based at least in part upon a diffraction pattern of the x-rays diffracted from the test object. In another example, a method for determining a microstructure of a material includes illuminating a beam spot on the material with a beam of incident x-rays; detecting, with a grid detector, x-rays diffracted from the material; and determining, by a computing device, a microstructure image based at least in part upon a diffraction pattern of the x-rays diffracted from the material.
Digital Diffractive Optics: An Introduction to Planar Diffractive Optics and Related Technology
Kress, B.; Meyrueis, P.
2000-10-01
Diffractive optical elements (DOEs) are becoming more and more widely used in a braod range of fields, including telecommunications, optical computing, consumer electronics, laser material processing and the biomedical sciences, to manipulate light through micro-optical systems. In order to get the most out of such DOEs, knowledge of the design process, fabrication, packaging in a particular system, and operation is required. Digital Diffractive Optics discusses in detail the design and simulation of DOEs, before considering the main fabrication techniques. The increasingly important CAD/CAM tool requirements for the production of DOEs are covered, and a chapter is devoted to the crucial area of systematic fabrication error compensation. Finally, the integration and use of DOEs in a number of different systems, including various opto-electronic and opto-mechanical systems, are discussed. Digital Diffractive Optics will be of great interest to all those involved in the fields of optical engineering and photonics. It presents a clear view of the whole process, from design to fabrication and application, without overstressing the, often complex, mathematics, and will thus be accessible to postgraduate students and those entering the field, as well as more experienced engineers and scientists.
Single-pulse x-ray diffraction using polycapillary optics for in situ dynamic diffraction.
Maddox, B R; Akin, M C; Teruya, A; Hunt, D; Hahn, D; Cradick, J; Morgan, D V
2016-08-01
Diagnostic use of single-pulse x-ray diffraction (XRD) at pulsed power facilities can be challenging due to factors such as the high flux and brightness requirements for diffraction and the geometric constraints of experimental platforms. By necessity, the x-ray source is usually positioned very close, within a few inches of the sample. On dynamic compression platforms, this puts the x-ray source in the debris field. We coupled x-ray polycapillary optics to a single-shot needle-and-washer x-ray diode source using a laser-based alignment scheme to obtain high-quality x-ray diffraction using a single 16 ns x-ray pulse with the source >1 m from the sample. The system was tested on a Mo sample in reflection geometry using 17 keV x-rays from a Mo anode. We also identified an anode conditioning effect that increased the x-ray intensity by 180%. Quantitative measurements of the x-ray focal spot produced by the polycapillary yielded a total x-ray flux on the sample of 3.3 ± 0.5 × 10(7) molybdenum Kα photons.
Optimal implementation of a microspectrometer based on a single flat diffraction grating
Grabarnik, S.; Emadi, A.; Sokolova, E.; Vdovin, G.; Wolffenbuttel, R.F.
2008-01-01
An analytical model has been developed and applied to explore the limits in the design of a highly miniaturized planar optical microspectrometer based on an imaging diffraction grating. This design tool has been validated as providing the smallest possible dimensions while maintaining acceptable spe
Determination of the Cu(110)-c(6X2)-O structure by x-ray diffraction
Feidenhans'l, R.; Grey, F.; Johnson, R.L.
1991-01-01
We have performed a structural determination of the Cu(110)-c(6 X 2)-O surface by x-ray diffraction. A model including only copper atoms is found on the basis of the Patterson function; the positions of the oxygen atoms are revealed in an electron-density-difference map. The final structure has a...
An engineered design of a diffractive mask for high precision astrometry
Dennison, Kaitlin; Ammons, S. Mark; Garrel, Vincent; Marin, Eduardo; Sivo, Gaetano; Bendek, Eduardo; Guyon, Oliver
2016-07-01
AutoCAD, Zemax Optic Studio 15, and Interactive Data Language (IDL) with the Proper Library are used to computationally model and test a diffractive mask (DiM) suitable for use in the Gemini Multi-Conjugate Adaptive Optics System (GeMS) on the Gemini South Telescope. Systematic errors in telescope imagery are produced when the light travels through the adaptive optics system of the telescope. DiM is a transparent, flat optic with a pattern of miniscule dots lithographically applied to it. It is added ahead of the adaptive optics system in the telescope in order to produce diffraction spots that will encode systematic errors in the optics after it. Once these errors are encoded, they can be corrected for. DiM will allow for more accurate measurements in astrometry and thus improve exoplanet detection. The mechanics and physical attributes of the DiM are modeled in AutoCAD. Zemax models the ray propagation of point sources of light through the telescope. IDL and Proper simulate the wavefront and image results of the telescope. Aberrations are added to the Zemax and IDL models to test how the diffraction spots from the DiM change in the final images. Based on the Zemax and IDL results, the diffraction spots are able to encode the systematic aberrations.
Waal, van de B.W.
1999-01-01
An up-to-date overview of recent developments in the structure elucidation of large ArN-clusters (103
Sokolov, Yu
2016-08-01
The compact diffraction circuit controlling small angular movements with small errors (2 ") and implementation simplicity is considered. The mathematical model describing the radiation intensity distribution in a receiver is obtained. The experiment results (at TU Ilmenau, Germany) confirmed the basic theoretical principles described in the paper.
A greedy method for reconstructing polycrystals from three-dimensional X-ray diffraction data
Kulshreshth, Arun Kumar; Alpers, Andreas; Herman, Gabor T.
2009-01-01
An iterative search method is proposed for obtaining orientation maps inside polycrystals from three-dimensional X-ray diffraction (3DXRD) data. In each step, detector pixel intensities are calculated by a forward model based on the current estimate of the orientation map. The pixel at which the ...
[The coding correction of slit diffraction in Hadamard transform spectrometer].
Li, Bo; Wang, Shu-Rong; Huang, Yu; Wang, Jun-Bo
2013-08-01
According to the principles of Hadamard transform spectrometer and the slit diffraction characteristics, the influence of spectrometer entrance slit diffraction of Hadamard transform spectrometer on the measurement result was analyzed, for the diffraction case, the Hadamard transform spectrometer instrument structure matrix was studied, and the Hadamard transform spectrometer encoding/decoding method was established. The analysis of incident spectral verified the correctness of the coding/ decoding. This method is very important for the high precision measurement of Hadamard transform spectrometer.
On the Intensity Distribution Function of Blazed Reflective Diffraction Gratings
Casini, R.; Nelson, P G
2014-01-01
We derive from first principles the expression for the angular/wavelength distribution of the intensity diffracted by a blazed reflective grating, according to a scalar theory of diffraction. We considered the most common case of a groove profile with rectangular apex. Our derivation correctly identifies the geometric parameters of a blazed reflective grating that determine its diffraction efficiency, and fixes an incorrect but commonly adopted expression in the literature. We compare the pre...
High-mass diffraction in the QCD dipole picture
Bialas, A; Peschanski, R
1998-01-01
Using the QCD dipole picture of the BFKL pomeron, the cross-section of single diffractive dissociation of virtual photons at high energy and large diffractively excited masses is calculated. The calculation takes into account the full impact-parameter phase-space and thus allows to obtain an exact value of the triple BFKL Pomeron vertex. It appears large enough to compensate the perturbative 6-gluon coupling factor (alpha/pi)^3 thus suggesting a rather appreciable diffractive cross-section.
Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams
Hastings, J.B.; /SLAC; Rudakov, F.M.; /Brown U.; Dowell, D.H.; Schmerge, J.F.; /SLAC; Cardoza, J.D.; /Brown U.; Castro, J.M.; Gierman, S.M.; Loos, H.; /SLAC; Weber, P.M.; /Brown U.
2006-10-24
An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.
Induced Diffraction in Phase-Mismatched Second-Harmonic Generation
SU Wen-Hua; QIAN Lie-Jia; FU Xi-Quan; YANG Hua; ZHU He-Yuan
2007-01-01
We show analytically that in phase-mismatched second-harmonic generation,an effective diffraction is induced at the second-harmonic (SH) frequency.Numerical simulation results agree with the analytical predictions.Compared to the case of linear propagation,the effect of the overall diffraction at the SH frequency becomes doubled due to the induced diffraction,which causes an interesting result that the SH beam width will be larger than that of the fundamental field.