X-ray measurement of laser fusion targets using least squares fitting

1979 ◽  
Vol 18 (24) ◽  
pp. 4116 ◽  
Author(s):  
Russell M. Singleton ◽  
Berthold W. Weinstein ◽  
Charles D. Hendricks
Keyword(s):  
Least Squares ◽  
Laser Fusion ◽  
X Ray ◽  
Least Squares Fitting

Thermal expansion coefficients and Gruneisen parameters of quartz at high temperature by X-ray method

1994 ◽  
Vol 9 (2) ◽  
pp. 148-150
Author(s):  
Nabil N. Rammo ◽  
Saad B. Farid
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Ambient Temperature ◽  
Least Squares ◽  
Temperature Variation ◽  
Ray Method ◽  
X Ray ◽  
Least Squares Fitting ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

The temperature variation of the interplanar spacings (101), (112), and (211) of 325 mesh quartz was determined in the range 300–966 °K using X-ray powder diffractometry. The measured lattice parameters have been found to increase nonlinearly with temperature, and the dependence has been expressed by a polynomial of second degree from the least-squares fitting of the data, the results of which are presented herein. Values are given for the thermal expansion coefficients and Gruneisen parameter in the range 300 to 768 °K. In the range 768–966 °K, the expansion is zero. The derivatives dαa/dT, dαc/dT, and dαv/dT at ambient temperature are also given.

scholarly journals Experimental Determination of Scan-truncation Losses from Low-temperature (16 K) Single-crystal X-ray Measurements

1988 ◽  
Vol 41 (3) ◽  
pp. 503 ◽  
Author(s):  
Riccardo Destro
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Experimental Determination ◽  
Least Squares ◽  
Spectral Distribution ◽  
Experimental Measurements ◽  
Fourier Methods ◽  
X Ray ◽  
Least Squares Fitting

Model intensity profiles have been obtained for biscarbonyl[ 14]annulene by convoluting the Mo Ka spectral distribution with two functions derived from experimental measurements at 16(1) K, up to 26Mo = 110�, of a spherical crystal mounted on a four-circle diffractometer equipped with the Samson low-temperature apparatus. The process includes accurate measurement of the inherent background, treatment of the profiles by numerical Fourier methods, and least-squares fitting. Owing to the instrumental configuration of the diffractometer used in this investigation, the first step of the process has required a careful determination of the X dependence of the background, besides the usual 26 dependence. Truncation losses for the crystal under study, evaluated for several scan ranges, are far larger than usually assumed or predicted.

An X-ray determination of the thermal expansion of the intermetallic compound Ni3Zr

1983 ◽  
Vol 16 (6) ◽  
pp. 645-646 ◽  
Author(s):  
S. K. Shadangi ◽  
S. C. Panda ◽  
S. Bhan
Keyword(s):  
Thermal Expansion ◽  
Intermetallic Compound ◽  
Least Squares ◽  
Temperature Interval ◽  
X Ray ◽  
Least Squares Fitting ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Ray Methods

The lattice spacings of the intermetallic compound Ni3Zr have been measured by X-ray methods in the temperature interval 298–1033 K using a Debye–Scherrer camera. In all the cases the measured lattice spacings have been found to increase non-linearly with temperature and the dependence has been expressed by a polynomial of second degree from the least-squares fitting of the data. The thermal expansion coefficients for both parameters have been found to decrease with increase in temperature.

scholarly journals Evaluation of uncertainty in the energy dispersive X-ray fluorescence determination of platinum in alumina

2015 ◽  
Vol 7 (12) ◽  
pp. 5345-5351 ◽  
Author(s):  
P. S. Remya Devi ◽  
A. C. Trupti ◽  
A. Nicy ◽  
A. A. Dalvi ◽  
K. K. Swain ◽  
...  
Keyword(s):  
Least Squares ◽  
Energy Dispersive ◽  
Weighted Regression ◽  
Calibration Function ◽  
X Ray ◽  
Least Squares Fitting ◽  
Fluorescence Determination ◽  
Analytical Result ◽  
Fitting In

Uncertainty, the most important characteristic of an analytical result, has been evaluated using a bottom-up approach during EDXRF determination of Pt in alumina. The calibration function of the EDXRF spectrometer was derived through bivariate least squares fitting, in combination with weighted regression of the residuals.

Wavelength Calibration of Flat-Crystal and Convex Curved-Crystal X-Ray Spectrographs

1979 ◽  
Vol 33 (1) ◽  
pp. 19-25 ◽  
Author(s):  
J. W. Criss
Keyword(s):  
Least Squares ◽  
Crystal Surface ◽  
Detector Array ◽  
Reflection Mode ◽  
Wavelength Calibration ◽  
X Ray ◽  
Least Squares Fitting ◽  
Intensity Measurements ◽  
Fitting Method ◽  
Calibration Equations

Fixed-crystal spectrographs must be calibrated in terms of wavelength vs position on the film or detector array. This can be done either from the measured positions of lines with known wavelengths or from the geometrical design of the instrument. It is more accurate, however, to combine both kinds of information in a least-squares fitting method. This paper presents techniques for several spectrograph geometries, including flat and convex-curved crystals in reflection mode, with both flat and cylindrical film. Also treated is a less common case where the diffracting planes are inclined to the crystal surface. Uses of the calibration equations in wavelength determinations, resolution studies, and intensity measurements are discussed.

X-ray emission from laser fusion targets

1981 ◽  
Author(s):  
V. W. Slivinsky
Keyword(s):  
Laser Fusion ◽  
X Ray
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