Theoretical Calculation of the Number of α-ray Track in a Petri Dish-type Cloud Chamber with Monazite Source

Abstract

In the case of petri dish-type cloud chamber with an α-ray source of monazite sphere(2.5mm diameter), the expected number of the α-ray tracks was theoretically calculated using Bethe formula and compared with the reported experimental value. The validity of the calculation method was firstly confirmed. The theoretically calculated number of α-ray tracks(0.208 per second) in a cloud chamber was fairly agreed with experimental value(0.383 per second). During the observation of the tracks, the surface of the source was gradually wet with ethanol-liquid. The thickness of the liquid layer was estimated to be 6μm by comparing the calculated escape probability of the α-rays and the experimental value under having the liquid layer on the source surface.