微少量環境試料測定用井戸型Ge検出器の効率特性

抄録

A well-type Ge detector was studied to use for determining radioactivities of U and T h-series nuclides in small amount of environmental samples. Peak efficiencies of the well-type detector decreased against the height of sample (relative variation rate (a'/Eff (_at24mm) ) was about -1%/ mm in this study) . The principal reason is thought to be in self-absorption. It is convenient to use the first-order regression formula to calculate the efficiencies if sample height is lower than the well depth. This technique was applied to lake core samples to determine sedimentation rate, and a good result was obtained.