【摘要】 偏振测量X射线聚焦望远镜阵列(PFA)属于增强型X射线时变与偏振空间天文台(eXTP)有效载荷之一，其位于焦平面的气体像素探测器(GPD)用于测量处于极端条件下天体辐射的软X射线偏振度等物理参数。GPD采用单层气体电子倍增器(GEM)作为气体放大级，有效面积为(15.5×15.5)mm~2,孔型为双锥形结构，相邻孔间间距为50μm,孔外直径为30μm,锥角约为10°;该GEM孔采用非聚焦激光辐照技术制作成型，生产时由于激光非均匀性以及辐照区域重叠，将引起不同孔的锥角出现差异，造成孔间增益不均匀。基于GPD基线设计参数，通过构建GPD-GEM模拟框架，验证了模拟的有效增益和文献测试结果的一致性；在相同工作电压下，0°～10°范围内不同锥角对应的GPD-GEM有效增益基本呈线性关系。该结果表明GPD-GEM孔型最优为圆柱形结构，为其生产工艺提供了优化方向。更多还原

【Abstract】 The Polarimetry Focusing Array(PFA)is one of the payloads in the enhance X-ray Timing and Polarimetry mission(eXTP),each telescope in the PFA contains a Gas Pixel Detector(GPD)which locates in the focal plane and will give the polarized degree of soft X-ray sources from celestial objects under extreme conditions.The GPD consists of a single Gas Electron Multiplier(GEM)foil with an effective area of(15.5×15.5)mm~2 and holes of double conical shape as the amplification stage.The GEM foil with a pitch of 50 μm, a hole diameter of 30 μm, and a cone degree of 10 ° is fabricated by laser-etched technique.The non-uniform intensity of the laser and overlap in some irradiation areas causes different gain values among the holes during the GEM fabricates.In this study, we constructed a simulation framework for the GPD-GEM based on the baseline design and obtain a consistent trend of the effective gain measured in the reference, giving the linear relationship between the cone angle of holes and the gain under a condition of the same voltage.The studies illustrate the cylindrical shape of the GPD-GEM is a better option and provide an optimal design of it.更多还原