An experimental technique for determining the ranges of alpha particles in different gases

n apparatus has been built to determine accurately alpha-particle ranges experimentally by using a weightless isotropic alpha-particle source and a large area scintillation detector. An alpha particle source is placed at a fixed distance from a large area ZnS(Ag) detector in an enclosed chamber. Ranges of the alpha particle in various gases are obtained by varying the pressure of the gas within the chamber and observing the alpha counting rate as a function of pressure.;Because the experiment was performed without a detector window and because counting rates were extrapolated to a zero threshold setting, values were obtained for the true mean ranges rather than effective ranges. Mean ranges were obtained for alpha particles from...