CdZnTe伽马射线探测器的能谱特性分析

Analysis on Energy Spectra for CdZnTe Gamma Ray Detector

CdZnTe(CZT)探测器目前在国内外天体物理研究中占有重要的地位。本文采用蒙特卡洛软件GEANT4模拟了CZT伽马射线探测器对伽马射线的能谱响应,研究了电子和空穴的输运特性、外加偏压、探测器厚度等因素对平面型探测器的能谱特性的影响规律。结果表明,在电子收集效率较高时,能量分辨率明显受迁移率寿命积比值((μτ)_(e)/(μτ)_(h))的影响,比值越小,能量分辨率越好。增加工作电压可以提高载流子的收集效率和探测器的能量分辨率。在电子收集效率较高时,增大厚度可以弱化空穴信号贡献,提高能量分辨率。漂移程与晶体厚度之比(μτ)_(e)E/d可以用来估算平面型CZT探测器对低能射线的收集效率,并计算出其对应关系。

CdZnTe detectors play an important role in international astronomy research.In this paper,the spectra response of CdZnTe planar detector forγ-ray was numerically simulated using GEANT4 Monte-Carlo simulation toolkit,and the influence of the factors,such as transport properties of electrons and holes,applied bias voltage,thickness of detector and other factors were studied.The calculated results show that when the charge collection efficiency(CCE)of electron is high,the dependence of energy resolution on the ratio of electron and hole mobility-lifetime product((μτ)_(e)/(μτ)_(h))is strong,and the resolution increases with the decrease of the ratio.The energy resolution and CCE of carrier can be improved by raising up the bias.When the CCE of electron is high,increasing thickness can weaken the hole signal contribution to the total induced charge,and improve the energy resolution.The value of(μτ)_(e)E/d can be used to evaluate CCE of planar CdZnTe detectors for rays of low energy,and the corresponding relationship was calculated.