scholarly journals Novel reference-free methods for the determination of the instrumental response of Laue-type bent crystal spectrometers

2019 ◽  
Vol 34 (11) ◽  
pp. 2325-2332
Author(s):  
Monika Szlachetko ◽  
Joanna Hoszowska ◽  
Jakub Szlachetko ◽  
Jean-Claude Dousse
Keyword(s):  
Instrumental Response ◽  
Bent Crystal ◽  
Instrumental Resolution ◽  
Type Crystal

This paper presents two novel reference-free methods for the determination of the instrumental resolution of Laue-type crystal spectrometers.

Effects of source size and wavefront propagation on the energy resolution of a bent-crystal polychromator

2010 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
J. P. Sutter ◽  
M. Amboage ◽  
S. Hayama ◽  
S. Díaz-Moreno
Keyword(s):  
Energy Resolution ◽  
Silicon Crystal ◽  
X Rays ◽  
Pixel Size ◽  
X Ray ◽  
Bent Crystal ◽  
Full Wave ◽  
Instrumental Resolution ◽  
Optical Treatment ◽  
X Ray Absorption

Polychromators, or elliptically bent diffracting crystals that focus a broad-bandwidth X-ray beam onto a sample, have become a common device at synchrotron beamlines specializing in X-ray absorption spectroscopy (XAS) because they allow a full absorption spectrum to be collected in one shot. Such a device is being planned for the XAS beamline I20 of the Diamond Light Source. A bent silicon crystal diffracting 7 keV X-rays with the (1 1 1) reflection is taken as a model for the simulations of this report. Instrumental resolution is determined by the demagnification of the source, the spread of the diffracted beam during propagation and the pixel size of the position-sensitive detector placed behind the sample. The first is calculated by geometrical optics. The second is calculated by a full wave-optical treatment, which includes Takagi–Taupin integration to find the diffracted amplitude at the crystal's surface and Huygens–Fresnel propagation of the diffracted wave to the sample or detector. This sets the polychromator's intrinsic energy resolution. The pixel size of the detector is then added to find the total instrumental resolution at various sample–detector distances.

scholarly journals Angular distribution and asymmetries in the decay of the polarized charmed baryon Λc+ → K−Δ++ → K−pπ+

2020 ◽  
Vol 35 (11n12) ◽  
pp. 2050060
Author(s):  
A. Yu. Korchin ◽  
V. A. Kovalchuk
Keyword(s):  
Angular Distribution ◽  
Decay Rate ◽  
Asymmetry Parameter ◽  
Polarization Vector ◽  
Pole Model ◽  
Precession Angle ◽  
Charmed Baryon ◽  
Bent Crystal ◽  
Final Particles

Angular distribution of the final particles in the decay [Formula: see text] of the polarized charmed baryon is discussed. Asymmetries are proposed that allow for determination of the components of the [Formula: see text] polarization vector. The precession angle of the polarization in the process of baryon channeling in a bent crystal is directly related to these asymmetries. The decay rate and asymmetry parameter for the [Formula: see text] decay are calculated in the pole model and compared with experiment.

Determination of Constant Strain Gradients of Elastically Bent Crystal Using X-ray Mirage Fringes

2012 ◽  
Vol 51 ◽  
pp. 076702 ◽  
Author(s):  
Sukswat Jongsukswat ◽  
Tomoe Fukamachi ◽  
Kenji Hirano ◽  
Dongying Ju ◽  
Riichirou Negishi ◽  
...  
Keyword(s):  
Strain Gradients ◽  
X Ray ◽  
Bent Crystal

Digital Measurement of Radio Source Positions

1967 ◽  
Vol 1 (1) ◽  
pp. 32-33
Author(s):  
H. S. Murdoch ◽  
M. I. Large
Keyword(s):  
High Resolution ◽  
Radio Source ◽  
Radio Telescope ◽  
Instrumental Response ◽  
Response Pattern ◽  
Accurate Determination ◽  
Analysis Procedure ◽  
Digital Measurement ◽  
Critical Stage

The accurate determination of radio source positions is one of the principal uses of high resolution instruments such as the Molonglo Radio Telescope. A critical stage in this process familiar to all radio astronomers involves the measurement of the instrumental response pattern relative to some accurate time or position marker. Ideally, the analysis procedure should introduce no further errors either random or systematic beyond those which are already present in the data. This is virtually impossible with chart analysis.

Line Broadening Analysis Using FullProf*: Determination of Microstructural Properties

2004 ◽  
Vol 443-444 ◽  
pp. 123-126 ◽  
Author(s):  
Juan Rodríquez-Carvajal ◽  
T. Roisnel
Keyword(s):  
Rietveld Method ◽  
Structural Defects ◽  
Microstructural Properties ◽  
Line Broadening ◽  
Resolution Function ◽  
Short Account ◽  
Profile Matching ◽  
Instrumental Resolution ◽  
Diffraction Patterns

A short account of the methodology used within FullProf to extract average micro-structural properties from the analysis of broadened lines of constant wavelength diffraction patterns is presented. The approach is based on the Voigt approximation and can be combined with the Rietveld method as well as with the profile matching (Le Bail fit) procedure. Both the instrumental and sample profiles are supposed to be well described by Voigt functions. To get reliable sample parameters a good knowledge of the Instrumental Resolution Function (IRF) is needed. Only a phenomenological treatment, in terms of coherent size domains and strains due to structural defects, is performed.

Determination of Constant Strain Gradients of Elastically Bent Crystal Using X-ray Mirage Fringes

2012 ◽  
Vol 51 (7R) ◽  
pp. 076702 ◽  
Author(s):  
Sukswat Jongsukswat ◽  
Tomoe Fukamachi ◽  
Kenji Hirano ◽  
Dongying Ju ◽  
Riichirou Negishi ◽  
...  
Keyword(s):  
Strain Gradients ◽  
X Ray ◽  
Bent Crystal

Experimental determination of resolution function parameters from small-angle neutron scattering data of a colloidal SiO2dispersion

2010 ◽  
Vol 43 (4) ◽  
pp. 686-692 ◽  
Author(s):  
T. Vad ◽  
W. F. C. Sager ◽  
J. Zhang ◽  
J. Buitenhuis ◽  
A. Radulescu
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Scattering Data ◽  
Resolution Function ◽  
Correlation Peak ◽  
Particle Correlation ◽  
Instrumental Resolution ◽  
Silica Dispersion

A dilute dispersion of charge-stabilized, monodisperse silica nanoparticles has been used to determine the instrumental resolution function parameters of a conventional small-angle neutron scattering instrument in pinhole geometry over the entire accessible range of momentum transferq. Independent determination of the structure parameters of the colloidal silica dispersion by small-angle X-ray scattering enables refinement of both theq-independent geometric and theq-dependent (wavelength spread or polychromaticity of the neutron beam) contributions to the resolution function. The procedure described is appropriate if no further instrumental characterization is available. It is demonstrated that the sample used for refining the resolution function parameters has to exhibit sharp structural scattering features such as Bragg reflections, form factor maxima and minima, or an inter-particle correlation peak for each instrumental configuration at which the measurements have been performed to cover aqrange of two orders of magnitude (0.03 <q< 3.2 nm−1).

Time Variations of the Calcium Elemental Abundance in Flares from NOAA Active Regions 2562 and 2779

1988 ◽  
Vol 102 ◽  
pp. 189-193
Author(s):  
J. Sylwester ◽  
M.-C. Zolcinski-Couet ◽  
R.D. Bentley ◽  
J.R. Lemen
Keyword(s):  
Solar Maximum ◽  
Active Regions ◽  
Elemental Abundance ◽  
Crystal Spectrometer ◽  
Solar Maximum Mission ◽  
Bent Crystal ◽  
Time Variations ◽  
Abundance Variation ◽  
Future Work

AbstractAnalysis of flare spectra obtained with the Bent Crystal Spectrometer aboard the Solar Maximum Mission (SMM) satellite enables the determination of the fluxes in the resonance (w) line of Ca XIX and the near-by continuum. The line-to-continuum intensity ratio is a sensitive measure of the calcium elemental abundance (Aca) relative to hydrogen in the emitting plasma. In previous investigations we found the calcium abundance varies from flare to flare. In the present investigation we analyse the variations ofAcafor flares which occurred in two active regions well observed bySMM. We conclude that it is not possible to correlate the abundance variations with the time of the flare occurrence as suggested in an earlier paper for flares produced from a single active region. Further, we find no convincing correlation of abundance variation with any other flare characteristics. This negative result will stimulate future work on the physical interpretation of the calcium abundance variation.

X-ray focusing properties of doubly bent crystals

2017 ◽  
Vol 50 (4) ◽  
pp. 1104-1116 ◽  
Author(s):  
Golamreza Askari Germi ◽  
Sayyed Jalal Pestehe ◽  
Alireza Rastkar Ebrahimzadeh
Keyword(s):  
General Relation ◽  
General Point ◽  
Detector Plane ◽  
Linear Source ◽  
X Ray ◽  
Bent Crystal ◽  
Exact Determination ◽  
Bent Crystals ◽  
Focusing Properties

The focusing properties of several bent crystal geometries, including the newly introduced Pestehe & Askari general point-focusing system [Pestehe & Askari Germi (2012),Opt. Soc. Am. A,29, 68–77; Pestehe & Askari Germi (2012),J. Appl. Cryst.45, 890–901], on an arbitrarily positioned detector plane are investigated and illustrated. The properties of the focal points and the generated images are theoretically related to the local, ℓ, and directional, γ, positions of the detector plane for a given position of a point source on the Rowland circle. A general relation is derived for the detector positioning to obtain a specially focused image. This formula for the polar position of the detector plane, given by the two ℓ and γ variables, enables the exact determination of the system astigmatism and the exact calculation of the sagittal and meridional image positions for the spectrometer under study. The astigmatisms of the above-mentioned bent crystal geometries have been studied, and their sagittal and meridional focal positions and characteristics have been obtained and are illustrated. It is also shown that there is a possibility of designing a spectrometer to focus rays from a linear source onto a point on the Rowland circle.

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