Development of the hard x-ray detector for the ASTRO-E mission

The ASTRO-E satellite is scheduled for launch in 2000 by the Institute of Space and Astronautical Science (ISAS). In this paper the design and performance of the hard x ray detector (HXD) developed for ASTRO-E are described. The HXD is a combination of YAP/BGO phoswich scintillators and silicon PIN diodes covering a wide energy band of 10 - 700 keV. The detector background is reduced down to several times 10-6c/s/cm2/keV, and the sensitivity of the HXD is more than one order of magnitude higher than any other past missions in the range of a few 10 keV to several 100 keV. Thus ASTRO-E HXD is expected to achieve an extreme high performance for detecting cosmic hard x rays and low-energy gamma rays. Astrophysics to be explored with the HXT are expected to be extremely widespread and rich.