Development of a personal dosimeter applied for the photon and fast-neutron fields in high-energy accelerator facilities

1.作为开发适用于快中子（能量> 10 MeV）的个人剂量计的第一步，我们测试了使用两层CR-39堆（厚度为0.9 mm x 2）测量0.25、0.55、5和15 MeV快中子产生的二次带电粒子LET分布的可行性。探测器的前层充当辐射器，后层充当中子探测器。结果表明：对于亚MeV中子，要获得正确的LET分布和剂量，化学刻蚀的长度应小于5 μ m;现有CR-39探测器系统和化学腐蚀条件（体蚀刻~15 μm）适用于5 MeV中子剂量测定，LET > 10 keV/μm时的剂量当量和平均品质因子与ICRP 74中子注量-剂量转换因子和ICRP 60辐射加权因子一致，分别为：15 MeV中子剂量测定需要~2 mm厚的辐射体。虽然目前的测量部分， ...更多信息 由于不能得到正确的低能短程带电粒子LET值，我们认为，改进CR-39探测器系统和化学腐蚀条件，可以提高亚MeV至数十MeV能量范围内快中子剂量学LET分布测量的准确性.研制了一种用于测量大量核径迹蚀刻探测器的自动扫描系统。研究了高能重离子和快中子辐照CR-39塑料样品的扫描性能。包括样品转移、样品ID识别、图像采集和图像分析在内的整体扫描速度令人满意。该系统允许在一天内处理100个样品，扫描面积为4 cm 2/样品，用于中子剂量测定。开发了一种新的个人剂量测定软件“LETDose”。该软件将TLD测量的吸收剂量和CR-39径迹探测器测量的LET分布相结合，用于估算光子和快中子辐射场的吸收剂量和剂量当量。少

1. As a first step toward developing a personal dosimeter applicable for fast neutrons (energy > 10 MeV), we tested the feasibility of using two-layer CR-39 stacks (0.9 mm in thickness x 2) to make LET distribution measurements for secondary charged particles due to fast neutrons of 0.25, 0.55, 5 and 15 MeV. The front layers of the detectors act as a radiator and the back layers act as a neutron detector. The results indicated the following: chemical etching shorter than 5 um is needed to obtain the correct LET distribution and dose for sub MeV neutrons; the present CR-39 detector system and chemical etching condition (bulk etch ~15 μm) are appropriate for 5 MeV neutron dosimetry, and measured dose equivalents and averaged quality factors for LET > 10 keV/μm agreed with the ICRP 74 neutron-fluence-to-dose conversion factor and the ICRP 60 radiation weighting factor, respectively; a thick radiator of ~2 mm is required for 15 MeV neutron dosimetry. Although the present measurements partl … More y failed to obtain correct LET values for the low-energy and short-range charged particles induced by fast neutrons, we conclude that modifications of the CR-39 detector system and chemical etching condition should improve the accuracy of LET distribution measurement for fast neutron dosimetry in the sub MeV to tens MeV energy range.2. An automated scanning system was developed for measuring a large number of nuclear track-etch detectors. We investigated scanning performance using CR-39 plastic samples irradiated by high-energy heavy ions and fast neutrons. Overall scanning speed including sample transfer, sample ID recognition, image acquisition and image analysis was satisfactorily high. The system allowed the processing of 100 samples with scan areas of 4 cm2/sample in one day for neutron dosimetry.3. A new software "LETDose" was developed for personal dosimetry. The software combines absorbed doses measured by TLDs and the LET distributions measured by CR-39 track detectors for estimating absorbed doses and dose equivalents for radiation fields consisting of photons and fast neutrons. Less