A magnetic diverter for charged particle background rejection in the SIMBOL-X telescope
A magnetic diverter for charged particle background rejection in the SIMBOL-X telescope
复制标题
用于 SIMBOL-X 望远镜中带电粒子背景抑制的磁偏转器
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
A. Tiengo
中科院分区：
文献类型：
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作者：
D. Spiga;V. Fioretti;A. Bulgarelli;E. Dell’Orto;L. Foschini;G. Malaguti;G. Pareschi;G. Tagliaferri;A. Tiengo
最小化X射线望远镜中的带电粒子背景是一个众所周知的问题。自然存在于宇宙环境中的带电粒子（主要是质子和电子）在与X射线探测器碰撞时构成了重要的背景源。更糟糕的是，在钱德拉和牛顿-XMM中观察到X射线探测器的光谱性能严重退化，这是由掠入射镜收集的动能在100 keV和一些MeV之间的软质子引起的，并通过漏斗进入探测器。对于像SIMBOL-X这样的聚焦望远镜，软X射线探测器暴露在质子通量下会显著增加仪器背景，从而导致灵敏度下降。在最坏的情况下，它还可能严重损害检测器的持续时间。可以采取的一个众所周知的对策是实施适当设计的磁转向器，这应该可以防止高能粒子到达SIMBOL-X的焦平面仪器。虽然Newton-XMM和Swift-XRT配备了电子的磁转向器，但所使用的磁场不足以有效地作用于质子。在本文中，我们模拟的行为磁分流器的SIMBOL-X，包括商业可用的永磁体。SIMBOL-X光学器件的影响通过GEANT 4库进行模拟，而所需的强磁场的影响则通过沿着IDL中专门编写的数值代码进行模拟。
Minimization of charged particle background in X-ray telescopes is a well known issue. Charged particles (chiefly protons and electrons) naturally present in the cosmic environment constitute an important background source when they collide with the X-ray detector. Even worse, a serious degradation of spectroscopic performances of the X-ray detector was observed in Chandra and Newton-XMM, caused by soft protons with kinetic energies ranging between 100 keV and some MeV being collected by the grazing-incidence mirrors and funneled to the detector. For a focusing telescope like SIMBOL-X, the exposure of the soft X-ray detector to the proton flux can increase significantly the instrumental background, with a consequent loss of sensitivity. In the worst case, it can also seriously compromise the detector duration. A well-known countermeasure that can be adopted is the implementation of a properly-designed magnetic diverter, that should prevent high-energy particles from reaching the focal plane instruments of SIMBOL-X. Although Newton-XMM and Swift-XRT are equipped with magnetic diverters for electrons, the magnetic fields used are insufficient to effectively act on protons. In this paper, we simulate the behavior of a magnetic diverter for SIMBOL-X, consisting of commercially-available permanent magnets. The effects of SIMBOL-X optics is simulated through GEANT4 libraries, whereas the effect of the intense required magnetic fields is simulated along with specifically-written numerical codes in IDL.