The nuclear scattering of electrons and positrons at 0·7 and 1·4 MeV

Abstract

An experiment is described in which electrons and positrons are scattered, under identical conditions, at energies of 0·7 and 1·4 MeV by foils of aluminium, silver and gold. Both the incident and scattered particles are counted by making use of the fast response and good energy resolution of anthracene crystals. The incident beam, which is in the form of a divergent hollow cone of semi-vertical angle of near 10°, and of 5% energy spread, is provided by using radioactive sources in a β-ray spectrometer. Effective angles of scattering of 22·8, 34·5 and 47·5° are employed. It is concluded that, within the experimental accuracy of about ±5% , the results are in accordance with predictions of the Dirac theory.