Tadayuki Takahashi

Abstract The Hard X-ray Detector (HXD) on board Suzaku covers a wide energy range from 10 keV to 600 keV by the combination of silicon PIN diodes and GSO scintillators. The HXD is designed to achieve an extremely low in-orbit background based on a combination of new techniques, including the concept of a well-type active shield counter. With an effective area of $142 \,\mathrm{cm}^{2}$ at 20 keV and $273 \,\mathrm{cm}^{2}$ at 150 keV, the background level at sea level reached $\sim 1 \times 10^{

Cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) have been regarded as promising semiconductor materials for hard X-ray and /spl gamma/-ray detection. The high atomic number of the materials (Z/sub Cd/=48, Z/sub Te/=52) gives a high quantum efficiency in comparison with Si. The large bandgap energy (Eg/spl sim/1.5 eV) allows us to operate the detector at room temperature. However, a considerable amount of charge loss in these detectors produces a reduced energy resolution. This probl

We observed the BL Lac object Mrk 421 with the X-ray satellite ASCA in 1994 as part of a multifrequency observation. The 24 hr observation was conducted 1 day after the onset of a TeV flare detected by the Whipple Observatory and detected an X-ray flare, with no apparent variability in the optical, UV, and EGRET GeV flux. The ASCA 2-10 keV flux peaked at 3.7 × 10-10 ergs cm-2 s-1 and then decreased to 1.8 × 10-10 ergs cm-2 s-1 with a doubling timescale of ~12 hr. The shape of the X-ray spectrum

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusin