Capture of Electrons by α-Particles

Abstract

EXPERIMENTS, similar to those of Davis and Barnes (Phys. Rev., 34, 152, 1929; 35, 217, 1930), have been made, in which a beam of α-particles passed through a stream of electrons, moving parallel to the α-particles. The apparatus differed from that of Davis and Barnes chiefly in that a Geiger counter, with mechanical recording system, was used in place of a scintillation screen, and that the polonium was inside the evacuated vessel. The number of singly-charged particles was always about one per cent of the total. The numbers of both doubly- and singly-charged particles were found to be entirely unaffected by the electron stream throughout the voltage range investigated, namely, from 450 to 750 volts. In particular, no capture was observed when the velocities of α-particles and electrons were nearly equal. Capture by the doubly-charged particles to an extent of less than 0.5 per cent would probably not have been defected, on account of probability error. N. A. de Bruyne was associated with me during part of this work.