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本文介绍了一种新研制的适用于铀矿山测量氡及其子体的个人α累积暴露量装置。它系用聚碳酸酯材料作为α粒子的固体径迹探测器的探测基片,将辐照后的基片,加以适当地化学蚀刻和电化学蚀刻相间处理,可使本底径迹降到7.5±3个/cm~2;探测效率可达13％以上;最低可测下限为0.5WLH(工作水平小时);最高可测上限为50WLM(工作水平月)。该探测器在一个工作水平(WL)条件下可连续工作一万小时左右,积累一个月可测最低环境氡浓度为1×10~(-13)居里/升。 探测器外形尺寸为φ24×4.5毫米,类似一个微章,小巧易于佩带;探测器取样是被动式的,没有抽气泵的取样系统。 为了提高探测效率,除在蚀刻条件上找出最佳蚀刻条件外,还设计了合理的结构。 本文给出的最佳预蚀刻条件,用含乙醇的6.5NKOH溶液将基片于61℃下蚀刻3小时。电化学蚀刻条件为,用6.5NKOH:乙醇=5.5:2(体积);电压350V(基片厚约140μm);频率为1kHz;电蚀刻时间2小时;温度61℃。
This paper presents a newly developed personal α cumulative exposure device suitable for the measurement of radon and its daughters in uranium mines. It is a solid substrate with polycarbonate particles as the detector track detection substrate, the irradiated substrate, the appropriate chemical etching and electrochemical etching phase processing, the background track can be reduced to 7.5 ± 3 / cm ~ 2; detection efficiency of up to 13% or more; minimum detectable limit of 0.5WLH (working hours); maximum limit of 50WLM (working level month). The detector can work continuously for about 10,000 hours at a working level (WL), and has a measurable minimum ambient radon concentration of 1 × 10 ~ (-13) Curie / liter for one month of accumulation. Detector size φ24 × 4.5 mm, similar to a micro-chapter, small and easy to wear; detector sampling is passive, no suction pump sampling system. In order to improve the detection efficiency, in addition to find the best etching conditions in the etching conditions, but also designed a reasonable structure. For the best pre-etching conditions given here, the substrate was etched for 3 hours at 61 ° C with a solution of ethanol in 6.5 N KOH. Electrochemical etching conditions were 6.5 N KOH: ethanol = 5.5: 2 by volume; voltage 350 V (substrate thickness about 140 μm); frequency 1 kHz; electrical etching time 2 hours; temperature 61 ° C.