Origin of the in-orbit instrumental background of the Hard X-ray Imager onboard Hitomi
Origin of the in-orbit instrumental background of the Hard X-ray Imager onboard Hitomi
复制标题
瞳号硬X射线成像仪在轨仪器背景的起源
DOI：
10.1117/1.jatis.6.4.046003
复制
发表时间：
2020
影响因子：
2.3
通讯作者：
and other 40 authors
中科院分区：
文献类型：
--
作者：
Hagino K.;Odaka H.;Sato G.;Sato T.;and Terada Y.(39th);and other 40 authors
了解和减少在轨仪器背景对于实现硬 X 射线天文观测的高灵敏度至关重要。瞳卫星上的硬X射线成像仪（HXI）的观测数据由于其具有不同原子序数的多层配置而提供了有关背景成分的有用信息：HXI由四层Si（Z= 14）探测器和一层碲化镉（CdTe）（Z= 48, 52）探测器的堆叠组成，周围环绕着井型Bi4Ge3O12有源屏蔽。根据观测数据，推断顶部 Si 层、下面的三个 Si 层和 CdTe 层的背景分别由不同的成分主导，即低能电子、反照率中子和质子诱发的放射性激活。对HXI在轨背景的蒙特卡罗模拟很好地再现了观测到的各层背景光谱，从而定量验证了上述假设。此外，我们建议添加电子屏蔽以减少背景。
Understanding and reducing in-orbit instrumental backgrounds are essential to achieving high sensitivity in hard x-ray astronomical observations. The observational data of the Hard X-ray Imager (HXI) onboard the Hitomi satellite provide useful information on the background components due to its multilayer configuration with different atomic numbers: the HXI consists of a stack of four layers of Si (Z= 14) detectors and one layer of cadmium telluride (CdTe) (Z= 48, 52) detector surrounded by well-type Bi4Ge3O12active shields. Based on the observational data, the backgrounds of the top Si layer, the three underlying Si layers, and the CdTe layer are inferred to be dominated by different components, namely, low-energy electrons, albedo neutrons, and proton-induced radioactivation, respectively. Monte Carlo simulations of the in-orbit background of the HXI reproduce the observed background spectrum of each layer well, thereby quantitatively verifying the above hypothesis. In addition, we suggest the inclusion of an electron shield to reduce the background.