论文部分内容阅读
一、引言 象氡一样,氦是未出露的铀或钍矿床的一种示踪元素,其最大优点是He~4很稳定,并能通过大多数岩石或矿物迅速扩散。此外,由于它溶解度极小,因此对进入地下水中比较小的He~4流量也能检测出来。近年来,精确分析氦同位素的质谱计,已经发展到这样一种程度,即对20克水样中溶解氦的He~3/He~4比值都很容易测量,其精度大约为0.2％(与大气氦相比)。
I. INTRODUCTION Like radon, helium is a tracer element of unexposed uranium or thorium deposits. Its greatest advantage is that He ~ 4 is stable and can rapidly diffuse through most rocks or minerals. In addition, due to its very low solubility, it is also possible to detect the smaller flow He ~ 4 into the groundwater. In recent years, the mass spectrometer for accurate analysis of helium isotopes has evolved to such an extent that the He ~ 3 / He ~ 4 ratio of dissolved helium in 20 grams of water can be easily measured with an accuracy of about 0.2% (and Atmospheric helium).