【摘要】 硅漂移探测器(Silicon Drift Detector,SDD)中电荷包的漂移时间(μs·cm-1)与粒子入射位置到读出电极距离有关,而且通常不能直接测量,其不确定性是影响探测器时间分辨的主要原因。漂移时间和电荷灵敏放大器(Charge Sensitive Amplifier,CSA)输出信号上升时间之间有明显的对应关系,利用三角成形和梯形成形信号的脉冲幅度比可测量上升时间,从而得到漂移时间。对脉冲幅度比测量网络进行了建模仿真,研究了脉冲幅度比与CSA输出信号间的关系,以及SDD和CSA电子学噪声对脉冲幅度比的影响。结果显示:脉冲幅度比只与上升时间有关,可通过幅度比测量漂移时间。通过优化成形网络的成形参数可以控制电子学噪声的影响,使修正后的到达时间测量精度提高一个数量级左右。更多还原

【Abstract】 [Background] The silicon drift detector(SDD) has been widely used in space exploration in recent years. The SDD has outstanding energy resolution, but its time resolution is not very satisfactory. The charge packet generated by the interaction between the incident photon and the detector takes some time to drift to anode. The drift time depends on the distance between the interaction position and the anode, and usually can’t be measured directly.Therefore, the uncertainty of drift time is the main factor that affects the time resolution of the SDD system.[Purpose] This study aims to propose a method called pulse amplitude ratio to measure the drift time so as to improve the time resolution of the SDD system. [Methods] The correspondence between the drift time and the rise time of the output signal of the charge sensitive amplifier(CSA) was made use of. The rise time was measured by the pulse amplitude ratio of triangular and trapezoidal shaping, hence the drift time was obtained by measuring the pulse amplitude ratio. Matlab/Simulink module and Xilinx module of system generator were used to build the system for simulation of the readout chain for pulse amplitude ratio measurement. The relationship between pulse amplitude ratio and CSA output signal, and the influence of SDD and CSA electronic noise on pulse amplitude ratio were investigated in details. [Results] Simulation results show that the pulse amplitude ratio of the shaping network only depends on the rise time, and the electronic noise of SDD and CSA can cause the measurement error. [Conclusions]The influence of electronic noise of SDD can be reduced by using optimized parameters of the shaping network, and the accuracy of the corrected arrival time can be improved by about one order of magnitude.更多还原