In this study, a portable cascade impactor was developed to more efficiently determine the activity size distribution of attached radon and thoron progeny in a natural environment. The developed impactor consisted of four stages with a backup filter stage for collection of the aerosol samples. The aerosol cut points were set for 10, 2.5, 1, and 0.5 μm at a sampling rate of 4 L min⁻¹. Five CR-39 chips were used as alpha detectors for each stage. To separate the alpha particles emitted from radon and thoron progeny, the CR-39 detectors were covered with aluminium-vaporized Mylar films. The thickness of each film was adjusted to allow alpha particles emitted from radon and thoron progeny to reach the surface of the CR-39 detectors. The particle cut-off characteristics of each stage were determined by mono-dispersive aerosols with particle sizes ranging from 0.1 to 1.23 μm from the collection efficiency curve. The test results showed that the respective cut-off size of stages 3 and 4 were close to the designed cut-points. Validation of the technique by comparison with two commercial devices confirmed that the developed technique could provide the necessary information to estimate the activity size distribution of attached radon and thoron progeny for dose assessment, especially, in a field survey where direct electric power is not available.

在这项研究中，便携式级联撞击器被开发来更有效地确定在自然环境中附着的ra和的后代的活动大小分布。开发的撞击器包括四个阶段，其中一个备用过滤器阶段用于收集气溶胶样品。以4 L min ^-1的采样率将气溶胶切点设置为10、2.5、1和0.5μm。每个阶段使用五个CR-39芯片作为alpha探测器。为了分离ra和子后代发出的α粒子，CR-39检测器上覆盖了铝蒸发的聚酯薄膜。调整每个膜的厚度，以使从from和子后代发出的α粒子到达CR-39检测器的表面。由收集效率曲线通过粒径为0.1至1.23μm的单分散气溶胶确定每个阶段的颗粒截留特性。测试结果表明，第3阶段和第4阶段各自的截止尺寸接近设计的截止点。