Instrumental line shapes in neutron powder diffraction with focusing monochromators

2000 ◽  
Vol 33 (1) ◽  
pp. 137-146 ◽  
Author(s):  
A. D. Stoica ◽  
M. Popovici ◽  
W. B. Yelon
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Powder Diffraction ◽  
Analytical Approximation ◽  
Neutron Powder Diffraction ◽  
Computational Results ◽  
Line Shapes ◽  
Bent Crystal ◽  
Instrumental Line ◽  
Position Sensitive

The optics of neutron powder diffractometers with bent-crystal monochromators is considered with respect to the computation of instrumental line shapes, accounting for second-order aberrations. A procedure of Monte Carlo simulation of instrumental line shapes has been developed. An analytical approximation of these shapes is described. Computational results for the case of the MURR diffractometer with position-sensitive detection and a focusing silicon monochromator are presented.

Monte-Carlo simulation of single-line resonance scattering in a rarefied gas

1991 ◽  
Vol 69 (8-9) ◽  
pp. 1146-1153 ◽  
Author(s):  
I. D. Lockerbie ◽  
W. S. C. Brooks ◽  
P. How ◽  
E. J. Llewellyn
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Multiple Scattering ◽  
Rarefied Gas ◽  
Resonant Scattering ◽  
Resonance Scattering ◽  
Single Line ◽  
Gas Temperature ◽  
Line Shapes ◽  
Simulation Results

A Monte-Carlo simulation of single-line resonant scattering in a rarefied gas is presented and the technique is applied to the interpretation of a rocket-borne resonance-lamp experiment. The simulation examines the case of an emitting and absorbing gas at the same temperature for a number of detector and source configurations. The distance from the last scatter point, the angular distribution of the detected scattered photons, and the line shape formed by the scattered photons, at the detector, are evaluated for these different configurations. The simulation results suggest that the scattering of the detected photon occurs very near to the rocket, and not necessarily in the traditional scattering region at the intersection of the detector and emitter normals. It is observed that multiple scattering plays an important role in the number of photons detected and that the apparent gas temperature, as exhibited by the line shapes of the scattered photons, is dependent upon the configuration of the experiment. The simulation results suggest that, for a resonance-scattering experiment to measure constituent concentrations, the experimental design must optimize the return signal and minimize the effect of multiple scattering. The results also suggest that the calibration procedures for resonance-scattering experiments must be made with a physical configuration and environment that is identical to that expected in the rocket flight.

Reverse Monte Carlo modelling of neutron powder diffraction data

1999 ◽  
Vol 55 (5) ◽  
pp. 783-789 ◽  
Author(s):  
A. Mellergård ◽  
R. L. McGreevy
Keyword(s):  
Monte Carlo ◽  
Powder Diffraction ◽  
Direct Calculation ◽  
Neutron Powder Diffraction ◽  
Reverse Monte Carlo ◽  
Powder Diffraction Data ◽  
Crystalline Materials ◽  
Neutron Powder Diffraction Data ◽  
Magnetic Disorder ◽  
Initial Results

A new reverse Monte Carlo (RMC) method for modelling both lattice and magnetic disorder in powder crystalline materials by direct calculation of the structure factor has been developed. The method, the program and the basic theory are described in some detail. Initial results from modelling the lattice and magnetic structure of MnO around the Néel temperature are also presented.

Estimation of Compton imager using single 3D position-sensitive LYSO scintillator: Monte Carlo simulation

2017 ◽  
Vol 71 (2) ◽  
pp. 70-76 ◽  
Author(s):  
Taewoong Lee ◽  
Hyounggun Lee ◽  
Younghak Kim ◽  
Wonho Lee
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Position Sensitive

scholarly journals Conditional Disconnection Probability in Star Graphs

VLSI Design ◽  
1993 ◽  
Vol 1 (1) ◽  
pp. 61-70
Author(s):  
Walid Najjar ◽  
Pradip K. Srimani
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Fault Tolerance ◽  
Vlsi Design ◽  
Analytical Approximation ◽  
Network Resilience ◽  
Probabilistic Measure ◽  
Star Graphs ◽  
Network Fault Tolerance ◽  
Network Fault

Recently a new interconnection topology has been proposed which compares very favorably with the well known n-cubes (hypercubes) in terms of degree, diameter, fault-tolerance and applicability in VLSI design. In this paper we use a new probabilistic measure of network fault tolerance expressed as the probability of disconnection to study the robustness of star graphs. We derive analytical approximation for the disconnection probability of star graphs and verify it with Monte Carlo simulation. We then compare the results with hypercubes [4]. We also use the measures of network resilience and relative network resilience to evaluate the effects of the disconnection probability on the reliability of star graphs.

Double Bent Crystal Monochromator for High Resolution Neutron Powder Diffraction

2013 ◽  
Vol 28 (S2) ◽  
pp. S351-S359 ◽  
Author(s):  
P. Mikula ◽  
M. Vrána ◽  
J. Šaroun ◽  
B.S. Seong ◽  
W. Woo
Keyword(s):  
High Resolution ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Angular Resolution ◽  
Polycrystalline Sample ◽  
Neutron Powder Diffraction ◽  
Diffraction Experiment ◽  
Neutron Diffraction Experiment ◽  
Bent Crystal ◽  
Neutron Wavelength

Recent results of focusing and reflectivity properties of the dispersive double-bent-crystal monochromator have shown that it could be succesfully used in high resolution neutron diffraction experiment. By using a standard polycrystalline sample of α-Fe, the resolution of the diffraction performance in the vicinity of the scattering angle 2θS = 90o for the neutron wavelength λ= 0.162 nm was tested in detail. It has been found that for thin (1.3 mm) bent second crystal the angular resolution represented by FWHM of diffraction profiles was 1x10−3 rad for 211 and 200 reflections and about 3x10−3 rad for 220 reflection.

scholarly journals C-type related order in the defective fluorites La2Ce2O7 and Nd2Ce2O7 studied by neutron scattering and ab initio MD simulations

2016 ◽  
Vol 18 (34) ◽  
pp. 24070-24080 ◽  
Author(s):  
Liv-Elisif Kalland ◽  
Stefan T. Norberg ◽  
Jakob Kyrklund ◽  
Stephen Hull ◽  
Sten G. Eriksson ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Powder Diffraction ◽  
Structural Investigation ◽  
Md Simulations ◽  
Neutron Powder Diffraction ◽  
Reverse Monte Carlo ◽  
X Ray ◽  
Ab Initio Md ◽  
Reverse Monte Carlo Method

We present a structural investigation of La2−xNdxCe2O7 using molecular dynamics, in addition to X-ray powder diffraction and total scattering neutron powder diffraction, analysed using Rietveld refinement and the reverse Monte Carlo method.

Monte Carlo simulation of charged‐particle‐analyzer line shapes

1986 ◽  
Vol 57 (11) ◽  
pp. 2780-2785
Author(s):  
Ronald E. Negri ◽  
James W. Taylor
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Charged Particle ◽  
Line Shapes
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