Decay Constant of Radium C'

Abstract

IN previous notes¹ an account has been given of a measurement of the decay constant of radium C'. The method consisted in determinations of the number of particles emitted from a beam of recoil atoms from radium C at various distances from the source. For the half period a value of the order 10⁵ sec. was found. During a continuation of these experiments, it was found that the number of particles emitted from a beam of recoil atoms depended greatly on the temperature of the walls of the apparatus. When the walls were cooled by liquid air, the source being at room temperature, a large number of particles were emitted from the wall facing the source. From these experiments it was concluded that, at room temperature, the recoil atoms are at least partly reflected from the walls of the apparatus. The dependence of the number of particles emitted from the recoil atoms on the temperature of the walls indicated that the shape of the decay curve was complicated by the reflection of the recoil atoms from the walls.