一种基于SiPM的具有高能量分辨率的紧凑型溴化镧γ谱仪

辐射防护 ›› 2020, Vol. 40 ›› Issue (3): 193-197.

一种基于SiPM的具有高能量分辨率的紧凑型溴化镧γ谱仪

石伯轩¹, 刘立业², 曹勤剑², 夏三强², 王晓龙²

1.中核环保工程有限公司, 北京 100191;
2.中国辐射防护研究院, 太原 030006

收稿日期:2019-09-03 发布日期:2020-07-10
通讯作者: 刘立业。E-mail:liuliye@cirp.org.cn
作者简介:石伯轩(1983—),男,2003年毕业于清华大学工程物理系核工程与核技专业,2007年毕业于日本东京大学系统量子工学系,获硕士学位,2010年毕业于日本东京力学原子力国际核工程与核技术专业,获博士学位,高级工程师。E-mail:shi_boxuan@163.com

A compact LaBr₃:Ce gamma spectrometer based on SiPM with high energy resolution

SHI Boxuan¹, LIU Liye², CAO Qinjian², XIA Sanqiang², WANG Xiaolong²

1. CNNC Environmental protection Engineering Co. Ltd. , Beijing 100191;
2. China Institute for Radiation Protection, Taiyuan 030006

Received:2019-09-03 Published:2020-07-10

摘要/Abstract

摘要： 基于光电倍增管(photomultiplier tube,简称PMT)的LaBr₃:Ce γ谱仪具有比NaI(Tl)γ谱仪更高的能量分辨率,但具有体积大、对磁场敏感、需要高电压等缺点。硅光电倍增管(Silicon photomultiplier tube,简称SiPM)具有与PMT相近的增益和效率,同时具有诸如高定时分辨率、抗磁场能力强、低偏压和紧凑尺寸等优良特性。本文将LaBr₃:Ce晶体与SiPM阵列耦合,设计研制基于SiPM的紧凑型LaBr₃:Ce γ谱仪,通过降噪、优化工作电压等措施改善SiPM的缺点对γ谱仪性能的影响。工作电压的噪声会导致能量分辨率发生恶化,通过设计无源滤波电路CLC π型滤波器,利用其对直/交流阻抗的不同特性,滤除高频纹波,工作电压的信噪比从未降噪前的62.6 dB提高到74.64 dB;能量分辨率最优值对应于表示暗噪声、串扰、光电探测效率和SiPM增益之间折衷的最佳工作电压。通过实验给出不同工作电压下的能量分辨率,确定最佳工作电压为54.8 V,该电压下的能量分辨率为3.06%(@662 keV),结果与使用光电倍增管(PMT)测量的2.89％非常接近。

关键词: γ谱仪, LaBr₃:Ce晶体, SiPM

Abstract: The PMT-based LaBr₃:Ce gamma spectrometer has higher energy resolution than NaI gamma spectrometer, but it has the disadvantages such as large volume, sensitive to magnetic field and high voltage demand. Silicon photomultiplier tube (SiPM) has similar gain and efficiency as PMT, while offering excellent characteristics such as high timing resolution, high magnetic field resistance, low bias and compact size. In this paper, the LaBr₃:Ce crystal is coupled with the SiPM array, and the compact LaBr₃:Ce γ spectrometer based on SiPM is designed and developed to improve the impact of the shortcomings of SiPM on the performance of gamma spectrometer by reducing noise, optimizing the operating voltage.The noise of working voltage will lead to the deterioration of energy resolution. By designing the CLC-type π filter with passive filter circuit, the high frequency ripple can be filtered by using its different characteristics of DC/AC impedance and the signal-to-noise ratio of working voltage can be increased from 62.6 dB to 74.64 dB before the noise reduction. The minimum energy resolution corresponds to the optimum operating voltage representing a compromise between dark noise, crosstalk, photodetection efficiency, and SiPM gain. The energy resolution at different working voltages is given by experiment, and the optimal working voltage is determined to be 54.8 V. The energy resolution at this voltage is 3.06% (@662 keV), the result of which is very close to 2.89% measured by photomultiplier tube (PMT).

Key words: gamma spectrometer, LaBr₃:Ce crystal, SiPM

中图分类号:

TL817

石伯轩, 刘立业, 曹勤剑, 夏三强, 王晓龙. 一种基于SiPM的具有高能量分辨率的紧凑型溴化镧γ谱仪[J]. 辐射防护, 2020, 40(3): 193-197.

SHI Boxuan, LIU Liye, CAO Qinjian, XIA Sanqiang, WANG Xiaolong. A compact LaBr₃:Ce gamma spectrometer based on SiPM with high energy resolution[J]. RADIATION PROTECTION, 2020, 40(3): 193-197.