Development and calibration of fine collimators for the ASTRO-H Soft Gamma-ray Detector
Development and calibration of fine collimators for the ASTRO-H Soft Gamma-ray Detector
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ASTRO-H 软伽马射线探测器精细准直器的开发和校准
DOI：
10.1117/12.2054649
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Taka
中科院分区：
文献类型：
--
作者：
Mizuno;T.;Kimura;D.;Fukazawa;Y.;Furui;S.;Goto;K.;Hayashi;T.;Kawabata;K. S.; Kawano;T.;Kitamura;Y.;Shirakawa;H.;Tanabe;T.;Makishima;K.;Nakajima;K.;Nakazawa; K.;Fukuyama;T.;Ichinohe;Y.;Ishimura;K.;Ohta;M.;Sato;T.;Taka
软伽马射线探测器(SGD)是一个被厚厚的BGO主动屏蔽层包围的Si/CdTe康普顿望远镜，计划于2015年发射时搭载在ASTRO-H卫星上。SGD的能量范围从40到600keV，具有很高的灵敏度，这使得我们可以研究宇宙中的非热现象。SGD使用具有窄视场(FOV)概念的康普顿相机，以减少非X射线背景(NXB)并提高灵敏度。由于SGD本质上是一台非成像仪器，它还必须处理FOV内的宇宙X射线背景(CXB)。该探测器采用被称为“精细准直器”的被动屏蔽层，将低能光子(≤100keV)的视场限制在≤0.6°以内，从而将来自CXB的污染降至低于预期的水平。虽然FC的概念已经被铃鹿号上的硬X射线探测器采用，但SGD的FCS尺寸大约大四倍，技术上更难操作。我们为SGD开发了FCS，并通过对其进行X射线测试和环境测试(如振动测试)来确认原型功能符合要求。我们还开发了一套自准直仪系统，它使用可见光来确定透过率和光轴，并根据X射线测试的数据进行了校准。飞行模型的验收测试于2013年12月开始：六个飞行模型中有五个被认为是可以接受的，另一个单元目前正在生产中。在质子束实验的基础上对其活化特性进行了研究，并将结果用于估算在轨NXB。
The Soft Gamma-ray Detector (SGD) is a Si/CdTe Compton telescope surrounded by a thick BGO active shield and is scheduled to be onboard the ASTRO-H satellite when it is launched in 2015. The SGD covers the energy range from 40 to 600 keV with high sensitivity, which allows us to study nonthermal phenomena in the universe. The SGD uses a Compton camera with the narrow field-of-view (FOV) concept to reduce the non-Xray background (NXB) and improve the sensitivity. Since the SGD is essentially a nonimaging instrument, it also has to cope with the cosmic X-ray background (CXB) within the FOV. The SGD adopts passive shields called “fine collimators” (FCs) to restrict the FOV to ≤ 0.6° for low-energy photons (≤ 100 keV), which reduces contamination from CXB to less than what is expected due to NXB. Although the FC concept was already adopted by the Hard X-ray Detector onboard Suzaku, FCs for the SGD are about four times larger in size and are technically more difficult to operate. We developed FCs for the SGD and confirmed that the prototypes function as required by subjecting them to an X-ray test and environmental tests, such as vibration tests. We also developed an autocollimator system, which uses visible light to determine the transmittance and the optical axis, and calibrated it against data from the X-ray test. The acceptance tests of flight models started in December 2013: five out of six FCs were deemed acceptable, and one more unit is currently being produced. The activation properties were studied based on a proton-beam test and the results were used to estimate the in-orbit NXB.