基于硅光电二极管的低吸收剂量率实时在线探测器

在核医学和空间地面模拟实验中有着强烈的较低和极低吸收剂量率探测需求,但是现有的吸收剂量计在极低剂量率的探测方面存在精度低、价格高、无法在线等问题。建立了一种在线电流测量系统,研究了硅光电二极管XRB 100sCB380开路光生电流和γ吸收剂量率之间的关系,探索了硅光电二极管作为低吸收剂量率实时在线探测器的可能性。实验表明:XRB 100S-CB380对60Coγ射线有良好的响应,在10-9~10^-5Gy·min^-1和10-5~10-1Gy·min^-1两个吸收剂量率范围内其光生电流与吸收剂量率的关系符合线性规律,具有作为实时在线低吸收剂量率探测器的潜质。但在低吸收剂量率下,该种光电二极管表现出低剂量率损伤增强效应,致使其吸收剂量率探测能力下降,在标定和在线连续测量时需考虑该效应的影响。

Real-time online low dose rate detectors based on silicon photodiodes

Detections of dose rate is the basic request for researches in nuclear medicine and ground simulation of aerospace.However,the low and extremely low dose rate dosimeters have shortcomings of large error,expensive costs and inconvenience for real-time online applications.Here a real-time current monitoring system was established to analyze the influence ofγdose rate on the open circuit photocurrent of silicon-based photodiodes XRB 100 s-CB380.The photocurrent of XRB 100 s-CB380 was found to be sensitive toγdose rate of 60Co field,and it obeyed linear law in the dose rate ranges of 10^-9-10^-5 Gy·min^-1 and 10^-5-10^-1 Gy·min^-1.Therefore,photodiodes XRB 100 s-CB380 might be a promised real-time online detector for the low and extremely low dose rate measurements.However,the decreased detection efficiency,due to the enhanced low dose rate sensitivity effect in the photodiodes under low and extremely low dose rates,must be considered for calibration and continual n-line measurements.