Small terms in the beta-decay spectrum of tritium

Abstract

The electron energy spectrum in the beta decay of tritium is considered with particular attention to factors that may influence that spectrum in the neighbourhood of the end-point as is of importance in studies directed to the question of a possible finite mass for the electron anti-neutrino. In addition to the conventional Fermi function the following effects are evaluated: the effect of the finite nuclear size on the solution of the Dirac equation for the electron; screening of the latter by the orbital electron; exchange between the beta particle and the orbital electron; convolution of the lepton and nucleonic wavefunctions through the nuclear volume; the recoil of the He ion in its generation of the Coulomb field; the effect of the finite nuclear mass in the energy dependence of the phase space; V-A interference; weak magnetism; radiative corrections.