总Thα活度测量的意义和方法

THE SIGNIFICANCE AND METHOD OF MEASURING THE TOTAL THORIUM α-ACTIVITY

了解Th同位素对人体的照射剂量，关键是测量230Th和228STh的量，因而获得总α活度的数据比起用化学分析只得到总Th含量更为重要。测量方法很简便，只需把化学分析用过的显色液，转换为放射性测量样品并掺入ZnS（Ag），用内问法测量。其4π探测效率为（95±1）％，计数本底为3×10－4Bq。

Determining the content of 230Th and 228Th is the key for understanding the exposure dose of the thorium isotopes. To obtain the date about the total α-activity of the thorium is more important than to analyze chemically the total content of thorium. A very simple method used to measure total a-activity of the thorium is proposed. It need only collect the showing colour liquid which was used, convert into the sample used for measuring α-radiation, mixe with Zns (Ag),and then measure with inner scintillation. The efficiency of detection is (95 ± 1 ) %,and background count is 3 × 10-4 Bq.