We are currently developing Cadmium Zinc Telluride (CZT) detectors for a next-generation space-borne hard X-ray telescope which can follow up on the highly successful NuSTAR (Nuclear Spectroscopic Telescope Array) mission. Since the launch of NuSTAR in 2012, there have been major advances in the area of X-ray mirrors, and state-of-the-art X-ray mirrors can improve on NuSTAR’s angular resolution of $\sim$ 1arcmin Half Power Diameter (HPD) to 15” or even 5” HPD. Consequently, the size of the detector pixels must be reduced to match this resolution. This paper presents detailed simulations of relatively thin (1mm thick) CZT detectors with hexagonal pixels at a next-neighbor distance of 150 $\mu$m. The simulations account for the non-negligible spatial extent of the deposition of the energy of the incident photon, and include detailed modeling of the spreading of the free charge carriers as they move toward the detector electrodes. We discuss methods to reconstruct the energies of the incident photons, and the locations where the photons hit the detector. We show that the charge recorded in the brightest pixel and six adjacent pixels suffices to obtain excellent energy and spatial resolutions. The simulation results are being used to guide the design of a hybrid application-specific integrated circuit (ASIC)-CZT detector package.

我们目前正在为下一代星载硬X射线望远镜开发碲化镉锌（CZT）探测器，该探测器可以跟进非常成功的NuSTAR（核光谱望远镜阵列）任务。自2012年推出NuSTAR以来，X射线反射镜领域取得了重大进步，而最新的X射线反射镜可以改善NuSTAR的角分辨率，$〜$1arcmin半功率直径（HPD）至15英寸甚至5英寸HPD。因此，必须减小检测器像素的大小以匹配此分辨率。本文详细介绍了相对较薄（1mm厚）的CZT检测器的仿真，该检测器在相邻邻居距离为150时具有六角形像素 $\mu$米 该模拟解释了入射光子能量沉积的不可忽略的空间范围，并且包括当自由电荷载流子移向检测器电极时其扩散的详细模型。我们讨论了重建入射光子能量的方法，以及光子撞击探测器的位置。我们表明，记录在最亮的像素和六个相邻像素中的电荷足以获得出色的能量和空间分辨率。仿真结果正用于指导混合专用集成电路（ASIC）-CZT检测器套件的设计。