An empirical derivation of the X-ray optic transmission profile used in calibrating the Planetary Instrument for X-ray Lithochemistry (PIXL) for Mars 2020

2018 ◽  
Vol 33 (2) ◽  
pp. 162-165 ◽  
Author(s):  
C. M. Heirwegh ◽  
W. T. Elam ◽  
D. T. Flannery ◽  
A. C. Allwood

Calibration of the prototype Planetary Instrument for X-ray Lithochemistry (PIXL) selected for Mars 2020 has commenced with an empirical derivation of the X-ray optic transmission profile. Through a straightforward method of dividing a measured “blank” spectrum over one calculated assuming no optic influence, a rudimentary profile was formed. A simple boxcar-smoothing algorithm was implemented to approximate the complete profile that was incorporated into PIQUANT. Use of this form of smoothing differs from the more conventional approach of using a parameter-based function to complete the profile. Comparison of element-specific correction factors, taken from a measurement of NIST SRM 610, was used to assess the accuracy of the new profile. Improvement in the low- to mid-energy portion of the data was apparent though the high-energy region diverged from unity, and thus, requires further refinement.

1998 ◽  
Vol 5 (3) ◽  
pp. 1007-1009 ◽  
Author(s):  
Y. Nishihata ◽  
O. Kamishima ◽  
Y. Kubozono ◽  
H. Maeda ◽  
S. Emura

XAFS (X-ray absorption fine-structure) spectra were measured near K-absorption edges of Ce (40.5 keV), Dy (53.8 keV), Ta (67.4 keV) and Pt (78.4 keV). The blunt K-edge jump due to the finite lifetime of the core hole was observed. This makes it difficult to extract EXAFS (extended X-ray absorption fine-structure) functions at low k values. Local structure parameters can be evaluated from the EXAFS spectra above K-absorption edges in the high-energy region as well as from those above L III-edges. It was found that the finite-lifetime effect of the core hole is effectively taken into the photoelectron mean-free-path term, as predicted theoretically.


2001 ◽  
Vol 48 (4) ◽  
pp. 1179-1183 ◽  
Author(s):  
D Siodłak ◽  
M A Broda ◽  
B Rzeszotarska ◽  
A E Kozioł ◽  
I Dybała

Conformational preferences of Ac-deltaAla-NMe2 and Ac-(Z)-deltaPhe-NMe2 were studied and compared with those of their monomethyl counterparts as well as with those of their saturated analogues. X-Ray data and energy calculations revealed a highly conservative conformation of the dehydro dimethylamides, which is located in a high-energy region of the Ramachandran map.


2021 ◽  
Vol 11 (9) ◽  
pp. 4010
Author(s):  
Seon-Chil Kim

In the field of medical radiation shielding, there is an extensive body of research on process technologies for ecofriendly shielding materials that could replace lead. In particular, the particle size and arrangement of the shielding material when blended with a polymer material affect shielding performance. In this study, we observed how the particle size of the shielding material affects shielding performance. Performance and particle structure were observed for every shielding sheet, which were fabricated by mixing microparticles and nanoparticles with a polymer material using the same process. We observed that the smaller the particle size was, the higher both the clustering and shielding effects in the high-energy region. Thus, shielding performance can be improved. In the low-dose region, the effect of particle size on shielding performance was insignificant. Moreover, the shielding sheet in which nanoparticles and microsized particles were mixed showed similar performance to that of the shielding sheet containing only microsized particles. Findings indicate that, when fabricating a shielding sheet using a polymer material, the smaller the particles in the high-energy region are, the better the shielding performance is. However, in the low-energy region, the effect of the particles is insignificant.


1957 ◽  
Vol 18 (3) ◽  
pp. 264-268 ◽  
Author(s):  
Daisuke Ito ◽  
Tetsuro Kobayashi ◽  
Miwae Yamazaki ◽  
Shigeo Minami

Author(s):  
A. Fasso ◽  
K. Göbel ◽  
M. Höfert ◽  
J. Ranft ◽  
G. Stevenson

1987 ◽  
Vol 36 (4) ◽  
pp. 1656-1662 ◽  
Author(s):  
G. C. Saha ◽  
Shyamal Datta ◽  
S. C. Mukherjee

Sign in / Sign up

Export Citation Format

Share Document