The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes
The low Earth orbit radiation environment and its impact on the prompt background of hard x-ray focusing telescopes
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近地轨道辐射环境及其对硬X射线聚焦望远镜瞬发背景的影响
DOI：
10.1117/12.926248
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发表时间：
2012
影响因子：
4.8
通讯作者：
F. Gianotti
中科院分区：
文献类型：
--
作者：
V. Fioretti;A. Bulgarelli;G. Malaguti;V. Bianchin;M. Trifoglio;F. Gianotti
为了在硬 X 射线波段达到深灵敏度水平，背景最小化是科学驱动的必要条件，这是硬 X 射线望远镜（例如 NuSTAR、ASTRO-H）的关键科学要求之一。它需要对辐射环境和屏蔽系统的新概念进行仔细建模。我们利用 Bologna Geant4 多任务模拟器 (BoGEMMS) 功能来评估低地球轨道 (LEO) 辐射环境对混合 Si/CdTe 软硬 X 射线探测组件以及组合式主动和被动屏蔽系统的即时背景水平的影响。对于每一类粒子，模拟背景通量的光谱分布，探索不同材料（塑料与无机活性闪烁体）和配置（封闭或被主动屏蔽包围的被动吸收器）对背景计数率的影响。虽然主动屏蔽可以有效去除质子，但外部被动屏蔽会导致反照率电子和正电子成为背景的主要来源。相反，反照率中子与主动屏蔽的相互作用很弱，它们通过弹性散射导致低于 10 keV 的强烈背景水平。就背景和主动屏蔽计数率而言，最佳屏蔽配置是通过放置在无源层内的无机闪烁体给出的，并添加无源材料来吸收主动屏蔽的强荧光线并避免 CdTe 探测器上的逃逸峰。
The background minimization is a science-driven necessity in order to reach deep sensitivity levels in the hard X-ray band, one of the key scientific requirements for hard X-ray telescopes (e.g. NuSTAR, ASTRO-H). It requires a careful modeling of the radiation environment and new concepts of shielding systems. We exploit the Bologna Geant4 Multi-Mission Simulator (BoGEMMS) features to evaluate the impact of the Low Earth Orbit (LEO) radiation environment on the prompt background level for a hybrid Si/CdTe soft and hard X-ray detection assembly and a combined active and passive shielding system. For each class of particles, the spectral distribution of the background flux is simulated, exploring the effect of different materials (plastic vs inorganic active scintillator) and configurations (passive absorbers enclosing or surrounded by the active shielding) on the background count rate. While protons are efficiently removed by the active shielding, an external passive shielding causes the albedo electrons and positrons to be the primary source of background. Albedo neutrons are instead weakly interactive with the active shielding, and they cause an intense background level below 10 keV via elastic scattering. The best shielding configuration in terms of background and active shielding count rates is given by an inorganic scintillator placed inside the passive layers, with the addition of passive material to absorb the intense fluorescence lines of the active shielding and avoid escape peaks on the CdTe detector.
DOI：
10.1111/j.1365-2966.2007.11746.x
发表时间：
2006-08
影响因子：
4.8
作者：
S. Sazonov;E. Churazov;R. Sunyaev;M. Revnivtsev
通讯作者：
S. Sazonov;E. Churazov;R. Sunyaev;M. Revnivtsev