现在常用的测镭方法均需将样品密封1～3倍氡的半衰期（约3～10天），这不可避免地带来分析周期长、由于密封而可能产生漏气以及样品周围介质对氡的吸收和渗透等缺点。样品不经密封而直接测定其镭浓度的方法，已成为一些放射性分析工作者探索的目标之一。有的作者已提出用Ge（Li）探测器测量镭的186keV特征光峰，从而有可能直接测定镭浓度

[1

2]

；也有的作者曾用放化方法直接测镭本身的

α

放射性

[3]

。但由于Ge（Li）探测器的灵敏体积小，需低温设备，成本昂贵以及化学处理手续繁杂等缺点，使得它们目前在生产中难于推广。有人认为使用NaI（T1）探测器是乏味费时和损失精度的

[4]

。本实验则试用普通的NaI（T1）闪烁体和简单的单道能谱仪进行此项工作，并对某些影响因素作了初步探讨。

In this experiment a ST-402 plastic scintillator (

ϕ

100×0.3mm) and a NaI(Tl) crystal (

ϕ

100×25mm) were used as the

β

and

γ

ray detectors respectively.

The 186 keV photo peak was chosen as radium channel. The unsealed samples were measured with

β-γ

spectrometry. The counting time was 10 min for each sample. The advantages and disadvantages of this method were discussed at the end of the paper.