塑料闪烁体探测器测量宇宙射线μ子寿命实验

Experimental measurement of the lifetime of cosmic ray muon by plastic scintillation detector

本文设计了基于快时间响应的塑料闪烁体和光电倍增管组成的宇宙射线μ子探测器.带电粒子在探测器中产生的电脉冲信号波形由数字化仪读出并记录在计算机.通过离线数据分析完成μ子衰变事例选择、脉冲信号定时和寿命拟合等步骤.实验中脉冲信号上升时间小于20 ns,噪声小于3 mV,经估算使用前沿定时方法得到的探测器时间分辨率可达到纳秒量级.μ子平均寿命测量值为2.188±0.045μs,与粒子数据表(PDG)给出的μ子寿命测量值在误差范围内是符合的.

In this experiment,a cosmic ray muon detector is designed based on plastic scintillator and photomultiplier with fast time response.The waveform of electrical pulse signal produced by charged particle in the detector is read out and recorded in computer by a digitizer.Through offline data analysis,the procedures of muon decay event selection,timing of pulse signal and lifetime fitting are completed.In this experiment,the rise time of pulse signal is less than 20 ns,and the noise is less than 3 mV.It is estimated that the time resolution of detector can reach an order of nano second by using leading-edge timing method.The measured average lifetime of the muon is 2.188±0.045μs,which is consistent with the world average of muon lifetime with respect to the experimental error.