基于G-M管的伸缩式γ剂量率探头设计及性能分析

Design and Performance Analysis of Telescopic Gamma Dose-rate Probe Based on G-M Tube

目前,对于测量未知剂量水平或者明显高于本底剂量率水平的辐射场所使用的γ剂量率设备大多需要现场测量,可能造成操作人员接触超剂量辐射。设计一种基于G-M计数管的带有伸缩结构的γ剂量率探头可以有更好的防护距离,有效避免测量人员受到强辐射场的照射,降低风险。结合现场需求反馈及参考国内外相似设备,设计适合的伸缩式结构,同时对选用G-M管的能响补偿条件进行分析,选取适合的补偿条件,并设计一种脉冲检测电路解决以往G-M管漏计数的问题。通过对使用补偿后G-M管的伸缩式γ探头进行性能测试,结果表明该γ剂量率探头在满足相对响应范围的能量条件下,在±45°范围内的相对响应为0.77~1.06。在有效测量范围内由非线性产生的剂量率响应的相对变化范围为-9.30%~+11.84%,同时在接收到大剂量率照射时也会有过载提示。可见探头的各项物理性能均满足并优于参考标准,符合设计要求。

At present,mostγ-dose rate devices used in radiation sites for measuring unknown dose levels or significantly higher than the background dose rate level require on-site measurement,which may expose operators to excessive doses of radiation.A gamma-dose rate probe with a retractable design could reduce the risk.A telescopic gamma dose-rate probe based on G-M tube is designed,which can have a better protective distance and effectively avoid the strong radiation field exposure to the operator.Without telescopic structure,it can also be used as a general portable dose-rate meter.Combined with the field demand feedback and reference to similar equipment at home and abroad,design a suitable telescopic structure,at the same time to select the G-M tube energy response compensation conditions are analyzed,select the appropriate compensation conditions,and design a pulse detection circuit to solve the problem of the previous G-M tube leakage counting.The results show that the angular response of theγdose-rate probe ranges from 0.77 to 1.06 in the range of±45°when the energy of the relative response range is satisfied.Within the effective range of measurement,the relative variation of the dose rate response generated by nonlinearity ranges from-9.30%to+11.84%.At the same time,there will be overload warning when receiving large dose rate irradiation.The test performance of the probe meets and outperforms the reference standard and meets the design requirements.