数字上升时间法甄别LaBr_(3):Ce探测器α本底研究

Discrimination of Intrinsic Alpha Background in LaBr_(3):Ce Detector by Digital Rise Time Method

为甄别LaBr_(3):Ce晶体本底γ和α事件,使用数字化仪采集探测器阳极信号,基于数字上升时间法(DRTM)进行脉冲的离线分析,考察了积分后脉冲幅度的上下恒比点和垂直采样最低有效位对甄别品质因子(FOM)的影响,并比较了数字上升时间法与数字电荷比较法(DCCM)的α-γ甄别性能。结果表明:DRTM的甄别效果主要取决于上恒比点的选取,下恒比点对结果的影响较小;垂直采样精度的提升可显著改善FoM值;相同条件下DRTM的α-γ甄别性能优于DCCM。

In order to discriminate the background events from gamma and alpha decay in a LaBr_(3):Ce crystal,the signals from the anode of detector were sampled by digitizer DT5730B,and then analyzed with the digital rise time method offline.The influences from the upper and lower constant fraction points of the integrated pulse amplitude and the vertical sampling least significant bit of digitizer on the figure of merit(FoM)value were investigated.Furthermore,the performance of the digital rise time method was compared with the digital charge comparison method which has been widely used.The results show that:the performance of the digital rise time method mainly depends on the selection of the upper constant fraction point,and the lower constant fraction point has less influence.The enhance of the vertical sampling accuracy could significantly improve the FoM value.The discrimination effects of the digital rise time method is better than the digital charge comparison method under the same condition.