便携式γ能谱仪闪烁探头改进设计及性能研究

为满足当前便携式γ能谱仪对高性能闪烁探头的需要，本文提出了采用CsI(Tl)晶体耦合雪崩光电二极管的方式代替NaI(Tl)晶体耦合光电倍增管以构成新的闪烁探测器，并设计了低噪声电荷灵敏放大器作为探测器读出电路。根据唯一变量原则分别测试了能量分辨率随温度与偏压的变化规律，并对多种放射源的γ射线进行能谱响应实验。实验结果表明：当温度为23 ℃且偏压为370 V时，该闪烁探头对¹³⁷Cs、²²⁶Ra、⁶⁰Co和¹⁵²Eu源的γ射线具备优异的能谱响应特性，其中，对¹³⁷Cs源的γ射线能量分辨率可达4.98%，输出信号信噪比可达21∶1，上升时间为80 ns。可见，改进后的闪烁探头的性能有大幅提升，具备能量分辨率更佳、体积更小、抗机械性能与适用性更强等优点。

Improved Design and Performance Research on Portable γ Spectrometry Scintillation Probe

In order to fill the need of high-performance scintillation probe for the current portable γ spectrometry,the CsI(Tl)crystal coupled with avalanche photo diode was adopted to constitute a new scintillation detector instead of NaI(Tl)crystal coupled with photomultiplier,also a low-noise charge sensitive amplifier was designed to serve as a readout circuit for the detector.For researching the performance of the improved scintillation probe,the regularity of the energy resolution changing with the temperature and the bias voltage was tested respectively based on the unique variable principle and experiments with spectrum response of γ ray for various radiation sources.The results show that the scintillation probe has a excellent characteristic of spectrum response for 137Cs,226Ra,60Co and 152Eu sources when the temperature is 23 ℃ and the bias voltage is 370 V.Especially,the energy resolution is 4.98％,the SNR of the output signal is 21:1 and the rise time is 80 ns for 137Cs.Thus it can be seen that the improved scintillation probe,which has better energy resolution,smaller size and stronger performance of anti-mechanical and applicability,is significantly more excellent than the conventional one.