The Cadmium Zinc Telluride (CZT) Imager onboard AstroSat consists of pixelated CZT detectors, which are sensitive to hard X-rays above 20 keV. The individual pixels are triggered by ionising events occurring in them, and the detectors operate in a self-triggered mode, recording each event separately with information about its time of incidence, detector co-ordinates, and channel that scales with the amount of ionisation. The detectors are sensitive not only to photons from astrophysical sources of interest, but also prone to a number of other events like background X-rays, cosmic rays, and noise in detectors or the electronics. In this work, a detailed analysis of the effect of cosmic rays on the detectors is made and it is found that cosmic rays can trigger multiple events which are closely packed in time (called ‘bunches’). Higher energy cosmic rays, however, can also generate delayed emissions, a signature previously seen in the PICsIT detector on-board INTEGRAL. An algorithm to automatically detect them based on their spatial clustering properties is presented. Residual noise events are examined using examples of Gamma Ray Bursts as target sources.

AstroSat 机载镉锌碲化物 (CZT) 成像仪由像素化 CZT 探测器组成，它们对 20 keV 以上的硬 X 射线敏感。单个像素由发生在其中的电离事件触发，探测器以自触发模式运行，分别记录每个事件的发生时间、探测器坐标和随电离量缩放的通道等信息。探测器不仅对来自感兴趣的天体物理源的光子敏感，而且容易受到许多其他事件的影响，如背景 X 射线、宇宙射线和探测器或电子设备中的噪声。在这项工作中，对宇宙射线对探测器的影响进行了详细分析，发现宇宙射线可以触发时间上紧密堆积的多个事件（称为“束”）。然而，更高能量的宇宙射线也会产生延迟发射，这是以前在 INTEGRAL 上的 PICsIT 探测器中看到的特征。提出了一种基于它们的空间聚类特性自动检测它们的算法。使用伽马射线爆发的例子作为目标源来检查残余噪声事件。