Axel: A Balloon-borne X-ray Astronomy Experiment

1996 ◽  
Vol 13 (2) ◽  
pp. 156-161 ◽  
Author(s):  
R. K. Sood ◽  
J. Panettieri ◽  
D. Grey ◽  
G. Woods ◽  
J. Hoffmann ◽  
...  
Keyword(s):  
High Pressure ◽  
Large Area ◽  
X Ray ◽  
Ultra High Pressure ◽  
Successful Program ◽  
Proportional Counters ◽  
Experimental Laboratory ◽  
Scintillator Detector

AbstractFollowing a successful program to investigate the physics of ultra-high-pressure proportional counters, a counter array has been developed for hard X-ray astronomy. A parallel investigation has evaluated the performance of a large-area phoswich scintillator detector for the same purpose. The two detectors have been integrated in a balloon-borne payload, the Astrophysical X-ray Experimental Laboratory (AXEL). This paper describes the instrumentation aboard the payload.

An ultra high pressure xenon detector for hard x-ray astronomy

1991 ◽  
Vol 11 (8) ◽  
pp. 421-424 ◽  
Author(s):  
R.K. Sood ◽  
R.K. Manchanda ◽  
Z. Ye
Keyword(s):  
High Pressure ◽  
X Ray ◽  
Ultra High Pressure

Crystal-to-Crystal Diastereoselective Transformation of 2,4,6-Triisopropyl-4'-(S)-phenylalaninocarbonylbenzophenone Methyl Ester

1998 ◽  
Vol 54 (6) ◽  
pp. 907-911 ◽  
Author(s):  
H. Hosomi ◽  
Y. Ito ◽  
S. Ohba
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Methyl Ester ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
Pass Filter ◽  
X Ray ◽  
Ultra High Pressure ◽  
Phenylalanine Methyl Ester

Dissymmetry of the photoproduct was induced by using a chiral substituent, (S)-methylphenylalanine, in the title compound {N-4-(2,4,6-triisopropylbenzoyl)benzoyl]-(S)-phenylalanine methyl ester (I)}. On irradiation with light from a 250 W ultra-high-pressure Hg lamp for 7 h through a long-pass filter, the photoreaction in a crystal was 100% complete without the loss of crystallinity. The crystal structures (I), before, and (II) {N-[4-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoyl]-(S)-phenylalanine methyl ester}, after photocyclization, have been determined by X-ray diffraction. For comparison, a crystal structure analysis has also been carried out for the photoproduct (III) of the 3′-COOMe derivative after recrystallization {methyl 3-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoate}. The dihedral angle between the central carbonyl plane and the triisopropylphenyl ring deviates from 90° by 10 (1)° in (I), which makes an imbalance in the intramolecular O(carbonyl)...H(methine) distances of the isopropyl groups at positions 2 and 6. The crystal structure of (II) indicates that the nearer methine H was predominantly abstracted by the carbonyl O atom in the reaction. The absolute configuration around the asymmetric C atom in the cyclobutenol ring of the product is S.

scholarly journals X-Ray Astronomy Satellite Ginga

1990 ◽  
Vol 123 ◽  
pp. 41-48
Author(s):  
F. Makino
Keyword(s):  
Gamma Ray ◽  
Effective Area ◽  
X Rays ◽  
Scientific Instruments ◽  
Large Area ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Proportional Counters ◽  
Main Instrument

AbstractThe X-ray astronomy satellite Ginga carries three scientific instruments, the Large Area proportional Counters (LAC), All Sky X-ray Monitor (ASM) and Gamma-ray Burst Detector (GBD). The LAC is the main instrument with an effective area of 4000 cm2 giving it the highest sensitivity to hard X-rays so far achieved. Ginga observed about 250 targets up to the end of 1989.

A Focusing System for X-ray Diffraction Studies of Materials Under High Pressure in the Diamond Cell

1990 ◽  
Vol 34 ◽  
pp. 437-446 ◽  
Author(s):  
Y. Wu ◽  
A. C. Thompson ◽  
J. H. Underwood ◽  
H. K. Mao ◽  
Y. W. Fei ◽  
...  
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Sample Volume ◽  
Small Samples ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultra High Pressure ◽  
High Pressure Studies ◽  
Invaluable Tool ◽  
Spherical Mirrors

Recent advances in techniques to generate static ultra-high pressure (>100 GPa) in the diamond anvil cell have significantly enhanced our understanding of the properties of solids under these extreme conditions. In order to characterize the structure of solids at these pressures, X-ray diffraction using synchrotron radiation has become an invaluable tool. Since the highest pressures are attained at the expense of sample volume (~ 100 μm3) , it is best to use the intense radiation available from a synchrotron to study the very small samples used in ultra-high pressure studies. Even with the intense x-ray beams currently available, it is still often desirable to focus the x-ray beam to increase the available flux. We have developed a focusing system which uses multilayer coated spherical mirrors. With this system, intense x-ray beams with sizes smaller than 10 μm by 10 μm can be achieved at a synchrotron radiation beamline. Previously, we used the focusing system for x-ray microprobe experiments.

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