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用于太阳X射线观测的碲锌镉探测器原型读出电子学系统设计

Design of a Prototype Readout Electronics System for CZT Detectors in Solar X-ray Observation

  • 摘要: X射线成像望远镜(X-ray Imaging Telescope, XIT)作为太阳极轨天文台(Solar Polar Observatory, SPO)的科学载荷之一,主要承担太阳X射线观测任务,实现对全日面爆发事件的监测与小尺度活动的X射线能谱获取。碲锌镉(CdZnTe, CZT)晶体材质轻、平均原子序数高、与光子相互作用截面大,广泛用于多个空间天文卫星载荷。针对XIT载荷的原型验证需求,本文设计并实现了一套碲锌镉探测器原型读出电子学系统。该系统使用专用集成电路(Application-Specific Integrated Circuit, ASIC) VATA461.3芯片对碲锌镉信号进行采集处理。该芯片是一款电荷测量专用芯片,具备低功耗、低噪声、高集成度的特点,适用于空间任务。本文实现了碲锌镉探测器读出电子学的硬件设计、FPGA固件开发及上位机软件开发。实验测试结果表明,该系统的电子学等效噪声电荷(Equivalent Noise Charge, ENC)范围为154~201 e,32个通道的积分非线性(Integral Non-Linearity, INL)优于4.33%。大像素与小像素的能量分辨率分别为3.94 keV@59.5 keV和3.14 keV@59.5 keV,均满足技术指标4 keV@59.5 keV。

     

    Abstract: The X-ray Imaging Telescope (XIT) is one of the scientific payloads of the Solar Polar Observatory (SPO), primarily tasked with solar X-ray observations. It aims to monitor full-disk eruptive events and obtain X-ray spectra of small-scale solar activities. CdZnTe (CZT) crystals, known for their lightweight nature, high average atomic number, and large photon interaction cross-section, have been widely used in multiple space astronomical satellite payloads. To meet the prototype validation requirements of the XIT payload, this paper designs and implements a prototype readout electronics system for CdZnTe detectors. The system employs the Application-Specific Integrated Circuit (ASIC) VATA461.3 chip to acquire and process signals from CdZnTe detectors. The chip is a special chip for charge measurement, with low power consumption, low noise, and high integration, suitable for space missions. In this paper, the hardware design of the detector readout electronics, the firmware development of the FPGA, and the implementation of the host computer software, have been achieved. Experimental test results indicate that the equivalent noise charge (ENC) of the system ranges from 154 to 201 e. The integral non-linearity (INL) of the 32 channels is better than 4.33%. The energy resolutions of large and small pixels are 3.94 keV@59.5 keV and 3.14 keV@59.5 keV, respectively, both satisfying the technical requirement of 4 keV@59.5 keV.

     

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