Modeling charge transfer inefficiency in the Chandra Advanced CCD Imaging Spectrometer
Modeling charge transfer inefficiency in the Chandra Advanced CCD Imaging Spectrometer
复制标题
对 Chandra 高级 CCD 成像光谱仪中的电荷转移低效率进行建模
DOI：
10.1016/s0168-9002(01)02156-8
复制
发表时间：
2001
影响因子：
1.4
通讯作者：
G. Garmire
中科院分区：
文献类型：
--
作者：
L. Townsley;P. Broos;J. Nousek;G. Garmire
钱德拉X射线天文台（Chandra）先进CCD成像光谱仪（ACIS）中的前照式（FI）CCD在地球辐射带的极端环境中被损坏，导致电荷陷阱，导致并行读取期间增强的电荷转移效率（CTI）。这会导致行相关增益、事件等级“变形”（电荷的空间再分布）和能量分辨率降低。ACIS背照式（BI）CCD由于其制造也表现出明显的CTI。这是不够温和的位置依赖的能量分辨率是看不到的，但它是目前在并行和串行寄存器。该CTI还以空间复杂的方式改变增益和事件等级，因为并行CTI和串行CTI相互作用。鉴于这些现实，我们已经开发和调整了一个现象学模型的CTI FI和BI CCD，并将其纳入我们的Monte Carlo模拟的ACIS CCD。它模拟电荷损失和电荷的空间重新分布（拖尾），从而再现所有ACIS CCD中的空间相关增益和等级分布以及FI设备中的行相关能量分辨率。在这里，我们探讨CTI的证据，比较我们的模拟数据，并提出了一种技术，CTI校正的基础上，正演模拟。
The front-illuminated (FI) CCDs in the Advanced CCD Imaging Spectrometer (ACIS) on the Chandra X-ray Observatory (Chandra) were damaged in the extreme environment of the Earth's radiation belts, causing charge traps that result in enhanced charge transfer inefficiency (CTI) during parallel readout. This causes row-dependent gain, event grade ‘morphing’ (spatial redistribution of charge) and energy resolution degradation. The ACIS back-illuminated (BI) CCDs also exhibit pronounced CTI due to their manufacturing. It is mild enough that position-dependent energy resolution is not seen, but it is present in both parallel and serial registers. This CTI also changes the gain and event grades, in a spatially complicated way as parallel and serial CTI interact. Given these realities, we have developed and tuned a phenomenological model of CTI for both FI and BI CCDs and incorporated it into our Monte Carlo simulations of the ACIS CCDs. It models charge loss and the spatial redistribution of charge (trailing), thus reproducing the spatially dependent gain and grade distribution seen in all ACIS CCDs and the row-dependent energy resolution seen in the FI devices. Here we explore the evidence for CTI, compare our simulations to data, and present a technique for CTI correction based on forward modeling.