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为开展环境γ辐射剂量仪的现场校准,研制了一套辐照装置,其辐射场空气比释动能率可在0.27-34.86μGy·h~(-1)范围内通过距离与减弱器来调节。基于大量Geant4蒙特卡罗模拟设计了一种轻便型辐射准直器,在保证辐射场品质的前提下,大大降低了准直器重量,更适用于现场校准。此外,还研制了一套自动化支撑平台与三片曲面辐射减弱器,可远程实现辐射装置空间定位以及辐射场强度和空间的调节,曲面辐射减弱器有利于保证辐射场均匀性。测试实验及蒙特卡罗模拟结果显示,该辐射装置辐射场再现性、自散射、均匀性等性能良好,通过系统地计算地面散射对辐射场的影响,可为现场校准提供指导。
In order to carry out on-site calibration of environmental γ-radiation dosimeter, a set of irradiation device was developed. The rate of air kerma can be adjusted by distance and attenuator in the range of 0.27-34.86μGy · h -1. Based on a large number of Geant4 Monte Carlo simulations, a portable radiation collimator is designed. It greatly reduces collimator weight while ensuring the quality of the radiation field and is more suitable for field calibration. In addition, a set of automated support platform and three-piece curved radiation attenuator have also been developed to remotely position the radiation device and adjust the intensity and the space of the radiation field. The curved radiation attenuator helps to ensure uniformity of the radiation field. Experimental results and Monte Carlo simulation results show that the radiating system has good reproducibility, self-scattering and uniformity of radiation field. It can provide guidance for on-site calibration by systematically calculating the influence of surface scattering on the radiation field.