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Proceedings Paper

The hard x-ray imager (HXI) onboard ASTRO-H
Author(s): Kazuhiro Nakazawa; Goro Sato; Motohide Kokubun; Teruaki Enoto; Yasushi Fukazawa; Kouichi Hagino; Atsushi Harayama; Katsuhiro Hayashi; Jun Kataoka; Junichiro Katsuta; Philippe Laurent; François Lebrun; Olivier Limousin; Kazuo Makishima; Tsunefumi Mizuno; Kunishiro Mori; Takeshi Nakamori; Toshio Nakano; Hirofumi Noda; Hirokazu Odaka; Masanori Ohno; Masayuki Ohta; Shinya Saito; Rie Sato; Hiroyasu Tajima; Hiromitsu Takahashi; Tadayuki Takahashi; Shin'ichiro Takeda; Yukikatsu Terada; Hideki Uchiyama; Yasunobu Uchiyama; Shin Watanabe; Kazutaka Yamaoka; Yoichi Yatsu; Takayuki Yuasa
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Paper Abstract

Hitomi X-ray observatory launched in 17 February 2016 had a hard X-ray imaging spectroscopy system made of two hard X-ray imagers (HXIs) coupled with two hard X-ray telescopes (HXTs). With 12 m focal length, they provide fine (2' half-power diameter; HPD) imaging spectroscopy at 5 to 80 keV. The HXI main imagers are made of 4 layers of Si and a CdTe semiconductor double-sided strip detectors, stacked to enhance detection efficiency as well as to enable photon interaction-depth sensing. Active shield made of 9 BGO scintillators surrounds the imager to provide with low background. Following the deployment of the Extensible Optical Bench (EOB) on 28 February, the HXI was gradually turned on. Two imagers successfully started observation on 14 March, and was operational till the incident lead to Hitomo loss, on 26 March. All detector channels, 1280 ch of imager and 11 channel of active shields and others each, worked well and showed performance consistent with those seen on ground. From the first light observation of G21.5-0.9 and the following Crab observations, 5-80 keV energy coverage and good detection efficiency were confirmed. With blank sky observations, we checked our background level. In some geomagnetic region, strong background continuum, presumably caused by trapped electron with energy ~100 keV, is seen. But by cutting the high-background time-intervals, the background became significantly lower, typically with 1-3 x 10-4 counts s-1 keV-1 cm-2 (here cm2 is shown with detector geometrical area). Above 30 keV, line and continuum emission originating from activation of CdTe was significantly seen, though the level of 1-4 x 10-4 counts s-1 keV-1 cm-2 is still comparable to those seen in NuSTAR. By comparing the effective area and background rate, preliminary analysis shows that the HXI had a statistical sensitivity similar to NuSTAR for point sources, and more than twice better for largely extended sources.

Paper Details

Date Published: 25 July 2016
PDF: 13 pages
Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, 990511 (25 July 2016); doi: 10.1117/12.2231176
Show Author Affiliations
Kazuhiro Nakazawa, Univ. of Tokyo (Japan)
Goro Sato, Institute of Space and Astronautical Science, JAXA (Japan)
Motohide Kokubun, Institute of Space and Astronautical Science, JAXA (Japan)
Teruaki Enoto, Kyoto Univ. (Japan)
Yasushi Fukazawa, Hiroshima Univ. (Japan)
Kouichi Hagino, Institute of Space and Astronautical Science, JAXA (Japan)
Atsushi Harayama, Hiroshima Univ. (Japan)
Katsuhiro Hayashi, Nagoya Univ. (Japan)
Jun Kataoka, Waseda Univ. (Japan)
Junichiro Katsuta, Hiroshima Univ. (Japan)
Philippe Laurent, APC/ IRFU / Service d'Astrophysique, CEA Saclay (France)
François Lebrun, APC/ IRFU / Service d'Astrophysique, CEA Saclay (France)
Olivier Limousin, APC/ IRFU / Service d'Astrophysique, CEA Saclay (France)
Kazuo Makishima, Global Research Cluster, The Institute of Physical and Chemical Research (Japan)
Tsunefumi Mizuno, Hiroshima Univ. (Japan)
Kunishiro Mori, Institute of Space and Astronautical Science, JAXA (Japan)
Takeshi Nakamori, Yamagata Univ. (Japan)
Toshio Nakano, Nishina Ctr., The Institute of Physical and Chemical Research (Japan)
Hirofumi Noda, Tohoku Univ. (Japan)
Hirokazu Odaka, Stanford Univ. (United States)
Masanori Ohno, Hiroshima Univ. (Japan)
Masayuki Ohta, Institute of Space and Astronautical Science, JAXA (Japan)
Shinya Saito, Rikkyo Univ. (Japan)
Rie Sato, Institute of Space and Astronautical Science, JAXA (Japan)
Hiroyasu Tajima, Nagoya Univ. (Japan)
Hiromitsu Takahashi, Hiroshima Univ. (Japan)
Tadayuki Takahashi, Institute of Space and Astronautical Science, JAXA (Japan)
Shin'ichiro Takeda, Okinawa Institute of Science and Technology (Japan)
Yukikatsu Terada, Saitama Univ. (Japan)
Hideki Uchiyama, Shizuoka Univ. (Japan)
Yasunobu Uchiyama, Rikkyo Univ. (Japan)
Shin Watanabe, Institute of Space and Astronautical Science, JAXA (Japan)
Kazutaka Yamaoka, Nagoya Univ. (Japan)
Yoichi Yatsu, Tokyo Institute of Technology (Japan)
Takayuki Yuasa, Nishina Ctr., The Institute of Physical and Chemical Research (Japan)


Published in SPIE Proceedings Vol. 9905:
Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray
Jan-Willem A. den Herder; Tadayuki Takahashi; Marshall Bautz, Editor(s)

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