高纯锗探测器的效率刻度

Calibration of HPGe Detector Efficiency

探测效率是高纯锗谱仪的重要性能指标,探测器的效率刻度具有重要的意义。针对新购置的高纯锗谱议,采用多线法和距离变换相结合的实验方法,刻度了高纯锗探测器在不同源距下的全能峰效率曲线,并利用厂家提供的探头结构尺寸,采用MCNP5程序模拟计算了该探测器对不同能量γ射线的全能峰效率。将模拟计算效率和实验效率进行对比,模拟计算的全能峰效率和实验测定的全能峰效率具有一定偏差,经分析偏差主要原因是探测器内部结构尺寸不够精确,通过调节死层厚度和冷指尺寸,使得模拟计算效率和实验效率很好符合。

Efficiency is one of the important performance of detector ,and efficiency calibration of detector is very important .According to the need of the HPGe detector which is bought recently , we calibrate the efficiency of HPGe detector with passive and active method .The curves of efficiency of the coaxial HPGe detector with sever-al distances between the radioactive source and the detector are calibrated .Meanwhile, using the dimensions of the detect-head provided by the producer , and using MCNP5 code based on the Monte Carlo method , we sim-ulate and calculate the full -energy efficiency of the γ-ray,establish the MCNP model of the curve of detected efficiency.Then, the calculated values of efficiency with the experimental ones are compared .The simulated efficiency and the experimental efficiency has some deviation , we change the thickness of dead layer and the size of cold-finger, the efficiency curves are more consistent .The results show that when the HPGe detector dead layer thickness is 0.17 cm, the thickness and length of cold -finger size are 0.625 cm and 4.53 cm, The simulated efficiencies are consistent with the experimental ones .