在原子核物理实验和放射性同位素应用中,有时需要用非常薄的入射窗的气体计数管(正比计数管、盖革计数管)来记录低能入射粒子。因为窗很薄,所以在这种计数管內,只能充很低气压的气体,以保证不损坏薄窗。因此就需要了解低气压气体计数管的特性。我们对充少量多原子分子蒸汽(纯酒精蒸汽)的低气压气体计数管的特性进行了初步的测量。结果表明,低 In nuclear physics experiments and radioisotope applications, it is sometimes necessary to record low-energy incident particles with gas-counting tubes (proportional counters, geiger counting tubes) with very thin entrance windows. Because the window is thin, only a very low pressure gas can be charged in this counter tube to ensure that the thin window is not damaged. Therefore, we need to know the characteristics of low pressure gas counter. We performed a preliminary measurement of the characteristics of a low pressure gas counter tube filled with a small amount of polyatomic molecular vapor (pure alcohol vapor). The results show that low