根据Vernier型光子技术探测器的工作原理,论述了电子云质心解码与阳极面板形成的微小极间电容和电路前端噪声有着密切的关系;根据泊松方程,建立了Vernier阳极的数学模型.利用有限元软件ANSYS计算出同面多电极不规则图形的电容值与极间电容值,解决了如何计算不规则形状电容值的问题;利用皮秒激光器在镀有金膜的石英基底上刻蚀出与仿真参数一致的Vernier型阳极,并测量其电容值.将测量电容值与仿真值进行比较,验证了建立模型的正确性,优化了Vernier阳极的设计参数.
According to the principle of Vernier anode photon counting detector, in this paper we discuss a decoding algorithm of caculating centroid location and interelectrode capacitance between electrodes, which has a close relationship with preamplifier circuit noise. Based on the Poisson's equation, the theoretical model of Vernier anode is established. The method of calculating the irregular shape uniplanar self-capacitance and interelectrode capacitance between electrodes using ANSYS finite element analysis is introduced. In addition, a Vernier anode plate is manufactured with picosecond laser micromachining process on a 1.5 mm thick quartz substrate with gold film as conductors. The Vernier anode pattern has a pitch of 9.9 mm, an active area of 19.8 mm × 19.8 mm, insulation channel depth of 10 9m, and insulation channel width of 30 μm. Comparing the simulated capacitances with the measured capacitances, the validity of the threedimensional finite-element method is proved. A simulation study on the effects of substrate permittivity, insulation channel width and depth on capacitance change is carried out. The simulation result provides a basis for structure design of Vernier anodes.