水体γ放射性测量中高纯锗探测效率刻度

摘要

水体放射性测量中要得到核素的活度,就必须知道核素的探测效率,而探测效率的影响因素较多,所以,对高纯锗探测装置进行效率刻度具有重要的实际意义.本文选用的高纯锗探测装置是基于一种水体放射性的实时在线监测系统,将待监测水域中的水样采样到低本底铅室中,利用高纯锗探测器对水中放射性核素进行探测.实验采用KCl配制了一定比活度的40K液体源,测量其 γ 能谱,并计算40K的探测效率.同时根据厂家给的具体参数,对整个水体监测系统进行了建模和计算,模拟计算了能量在59.5?2614.7 keV范围内的 γ 射线的全能峰探测效率并得到效率曲线.通过对比40K的探测效率,发现其实验测量结果和模拟计算结果的偏差为0.018%.验证了使用蒙特卡罗模拟高纯锗探测装置效率刻度方法的可行性和准确性.%Background: To obtain the activity of nuclide in the radioactive measurement of water, it is necessary to know the detection efficiency of nuclide which may be influenced by many factors. Purpose: It is of great practical significance to carry out the efficiency scale of high purity germanium detection device. The high purity germanium detection device selected is based on a real-time on-line monitoring system for the radioactivity of water bodies. Methods: The water samples in the monitored waters were sampled into the low-lead lead rooms, and the radionuclides in water were detected by high purity germanium detectors. The 40K liquid source with a specific activity was prepared using KCl. The γ spectrum was measured and the detection efficiency of 40K was calculated. At the same time, the whole water body monitoring system was modeled and calculated according to the specific parameters given by the manufacturers. The energy efficiency of the γ ray in the range of 59.5?2614.7 keV was simulated and the efficiency curve was obtained. Results: The deviation of detection efficiency of 40K is found to be 0.018% between the simulation and experimental results. Conclusion: The results verify the feasibility and accuracy of Monte Carlo method in simulating the efficiency scale of high purity germanium detection devices.