J. S. Yadav
Articles written in Journal of Astrophysics and Astronomy
Volume 15 Issue 1 March 1994 pp 85-94
The Anuradha cosmic ray experiment in Spacelab-3, flown in the orbit at 350 km with an inclination of 57° for about six days, was used to measure the low energy galactic cosmic ray (GCR) heavy ions using a specially designed CR-39 detector module incorporating the arrival time information of the particles. The abundances of sub-iron (Sc-Cr) and iron particles in the low energy interval of 30–300 MeV/N were determined from the measurements made in four different depths of the CR-39 detector module of 150 layers. From these studies we obtained sub-iron (Sc-Cr) to iron abundance ratios of 0.8 to 1.2 in 30–300 MeV/N energy range. It is found that these ratios are enhanced by a factor of two as compared to interplanetary ratios of about 0.5. It is shown that the enhancement of the ratio inside the earth’s magnetosphere is probably due to the degree of ionization of low energy Sc to Cr and Fe ions in the galactic cosmic rays and to the rigidity filtering effects of the geomagnetic field. Further studies are needed to understand fully the phenomena and their implications.
Volume 38 Issue 2 June 2017 Article ID 0030 Review Article
P. C. Agrawal J. S. Yadav H. M. Antia Dhiraj Dedhia P. Shah Jai Verdhan Chauhan R. K. Manchanda V. R. Chitnis V. M. Gujar Tilak Katoch V. N. Kurhade P. Madhwani T. K. Manojkumar V. A. Nikam A. S. Pandya J. V. Parmar D. M. Pawar Jayashree Roy B. Paul Mayukh Pahari Ranjeev Misra M. H. Ravichandran K. Anilkumar C. C. Joseph K. H. Navalgund R. Pandiyan K. S. Sarma K. Subbarao
Large area X-ray propositional counter (LAXPC) instrument on AstroSat is aimed at providing high time resolution X-ray observations in 3–80 keV energy band with moderate energy resolution. To achieve large collecting area, a cluster of three co-aligned identical LAXPC detectors, is used to realize an effective area in access of ∼6000cm2 at 15 keV. The large detection volume of the LAXPC detectors, filled with xenon gas at ∼2 atmosphere pressure, results in detection efficiency greater than 50%, above 30 keV. In this article, we present salient features of the LAXPC detectors, their testing and characterization in the laboratory prior to launch and calibration in the orbit. Some preliminary results on timing and spectral characteristics of a few X-ray binaries and other type of sources, are briefly discussed to demonstrate that the LAXPC instrument is performing as planned in the orbit.
Volume 41, 2020
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