基于THGEM的X射线光电偏振测量技术基础研究

Polarimetry is a powerful observational technique in X-ray astronomy, useful to enhance our understanding of the geometry, magnetic field arrangement and emission mechanisms of many compact objects. Due to the lack of high sensitive instrumentation, the only unambiguous detection of X-ray polarization has been obtained from observations of the Crab Nebula in 1970s. Only recently, with the development of Micro-Pattern Gas Detector (MPGD), the possibility to exploit the photoemission process to measure the photon polarization has become a reality. Currently, X-ray photoelectric Polarimetry is developing with the performances of high sensitivity, wide X-ray energy band and large field of view. In this project, the X-ray photoelectric polarimeter with THGEM is studied by using Monte Carlo simulation and experimental measurement. Photoelectric Polarimetry will be tested to achieve high sensitivity and large field of view for the observation of GRBs, supernova shock breakout and tidal disruption of stars et al..

X射线偏振与高能天体的几何结构，周围的磁场强度，辐射机制等重要信息相关，可以提供光谱和时变观测所不能提供的关键信息，是人们理解天体基本物理参数的重要手段。由于缺乏高灵敏度的偏振观测设备，目前对天体的X射线偏振观测仍停留在上世纪70年代对蟹状星云上。近10年来，微型结构气体探测器的发明推动了光电偏振仪的迅速发展。目前，高性能的X射线光电偏振探测装置仍是国际上的研究热点。X射线偏振测量技术中，高灵敏度、宽波段、宽视场仍是丞待解决的关键科学问题。 本项目以自主研发的THGEM为技术基础，采用探测器响应模拟与实验研究相结合的技术路线，开展高灵敏、宽视场X射线光电偏振探测器基础研究，并探索其在伽玛射线暴、超新星激波暴、恒星潮汐瓦解事件等暂现源X射线偏振探测中应用。

本项目围绕着空间X射线偏振探测需求，开展了X射线偏振探测技术研究，从实验上比较了THGEM+CCD光读出和THGEM+像素电子学读出两种技术方案，成功研制高信噪比的基于THGEM像素电子学读出的X射线光电偏振探测器原理样机，并开展在不同工作气体，不同气压下的X射线光电子径迹测量研究，编写重建算法，实现光电子径迹起始点及出射方向重建。另外，还开展了THGEM新工艺研究，大面积THGEM探测器以及新型探测器研制，开展了基于THGEM的二维探测器应用研究，包括地面宇宙线晶体量能器标定系统，紧凑型THGEM衍射仪，α源表面污染检测仪，数字强子量能器灵敏层探测器等。