【摘要】 使用不同的方法来确定La Br3晶体信号的到达时间。在文中信号经过光电倍增管的放大之后由DSR4测试板进行数字采集,其中DRS4是由瑞士PSI研究所生产的高带宽、低功耗以及快读出时间的开关电容阵列。这些优势使得DRS4很具有吸引力,很多实验将传统的ADC与TDC替换为DRS4。采集的波形可以通过不同的方法进行后续处理。其中包括:(1)恒分甄别、(2)波形拟合、(3)PMT脉冲模型法以及(4)均值过滤法。文中实现的恒分甄别的时间分辨与使用模拟电路获取的平均时间分辨相比没有提高。高斯波形拟合法虽然与数字CFD的结果相当,但是却更加耗时。均值滤波法虽然容易实现,但是通过这个方法得到的时间分辨与采样时间在一个量级。而PMT脉冲模型法得到的平均时间分辨为195.4 ps,优于模拟信号的恒分甄别的时间分辨254.7 ps。更多还原

【Abstract】 Various digital methods were examined for determining the relative arrival times of pulses from ?20 mm × 5 mm La Br3 scintillators. In this study, pulses from the photomultiplier tubes(PMTs)were digitized by DRS4 evaluation board, a switched capacitor array(SCA) produced by the Paul Scherrer Institute(PSI). The high bandwidth, low power consumption and short readout time make DRS4 attractive for many experiments, replacing traditional ADCs and TDCs. The sampling signals were post processed with multiple techniques. These techniques include:(1) constant-fraction discrimination(CFD),(2) pulse-shape fitting,(3) mean PMT pulse model and(4) median filtered zero crossing method.The implemented CFD in the digital regimes did not improve the resolution of using analog equipment with average time resolution. The pulse-shape fitting yielded as good resolution as digital CFD, however,is much more time consuming. The median filtered method were easy to implement, and had a resolution on the order of sampling time. Average timing resolutions of 195.4 ps were obtained with mean PMT pulse model, which is better than the analog constant-fraction-zero-crossing with average resolution of254.7 ps.更多还原