The hard x-ray imager (HXI) onboard ASTRO-H
The hard x-ray imager (HXI) onboard ASTRO-H
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DOI：
10.1117/12.2231176
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发表时间：
2016-07
影响因子：
1.4
通讯作者：
K. Nakazawa;G. Sato;M. Kokubun;T. Enoto;Y. Fukazawa;K. Hagino;A. Harayama;Katsuhiro Hayashi;J. Kataoka;J. Katsuta;P. Laurent;F. Lebrun;O. Limousin;K. Makishima;T. Mizuno;K. Mori;T. Nakamori;T. Nakano;H. Noda;H. Odaka;M. Ohno;M. Ohta;S. Saito;R. Sato;H. Tajima;H. Takahashi;Tadayuki Takahashi;S. Takeda;Y. Terada;H. Uchiyama;Y. Uchiyama;S. Watanabe;K. Yamaoka;Y. Yatsu;T. Yuasa
中科院分区：
文献类型：
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作者：
K. Nakazawa;G. Sato;M. Kokubun;T. Enoto;Y. Fukazawa;K. Hagino;A. Harayama;Katsuhiro Hayashi;J. Kataoka;J. Katsuta;P. Laurent;F. Lebrun;O. Limousin;K. Makishima;T. Mizuno;K. Mori;T. Nakamori;T. Nakano;H. Noda;H. Odaka;M. Ohno;M. Ohta;S. Saito;R. Sato;H. Tajima;H. Takahashi;Tadayuki Takahashi;S. Takeda;Y. Terada;H. Uchiyama;Y. Uchiyama;S. Watanabe;K. Yamaoka;Y. Yatsu;T. Yuasa
日立X射线观测站于2016年2月17日发射，其硬X射线成像光谱学系统由两台硬X射线成像仪(HXI)和两台硬X射线望远镜(HXT)组成。它们的焦距为12米，可在5-80keV范围内提供精细的(2‘半次方直径；HPD)成像光谱。HXI主成像器由4层硅和一个CdTe半导体双面条形探测器组成，堆叠在一起既可以提高探测效率，也可以实现光子相互作用深度传感。由9个BGO闪烁体制成的主动屏蔽层环绕着成像器，以提供低背景。在2月28日部署了可扩展光学工作台(EOB)后，HXI逐渐开启。两台成像仪于3月14日成功开始观测，并一直运行到3月26日导致Hitomo损失的事件。所有探测器通道，包括1280通道成像仪和11通道主动屏蔽以及其他通道，工作正常，表现出与地面上看到的一致的性能。从G21.5-0.9的第一次光观测和随后的Crab观测，证实了5-80keV的能量覆盖和良好的探测效率。在空白的天空观测中，我们检查了我们的背景水平。在某些地磁区，可以看到很强的本底连续体，可能是由能量约为100keV的俘获电子引起的。但通过削减高本底时间间隔，本底变得明显较低，通常为1-3×10-4计数S-1keV-1厘米-2(这里用探测器几何面积表示厘米2)。在30keV以上，虽然1-4×10~(-4)个S~(-1)keV~(-1)cm~(-2)的能级仍可与在新星上看到的水平相当，但仍能明显地观察到来自于镉镉激活的线状和连续发射。通过比较有效面积和背景率，初步分析表明，对于点源，HXI具有与NuSTAR相似的统计敏感性，而对于大范围扩展源，HXI的统计敏感性要好两倍以上。
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.