Recoil by -Decay

Abstract

IF one investigates the recoil of a light nucleus by emission of an electron and a neutrino, it is important to consider that for a given direction of the electron the angular distribution of the neutrino is not isotropic. The details of the decay naturally depend on the assumptions made about the interaction between the heavy particle and the electron-neutrino field; in particular, they determine the energy distribution of the electron. But even if this distribution were known, apart from any theory, the recoil would still depend on the special form of the interaction energy, in so far as this form also determines the coupling between the directions of electron and neutrino. Such a coupling is a general consequence of the theory of decay, although the wave-lengths have to be assumed to be large compared with the nuclear dimensions. In the case of the two forms of interaction proposed by Fermi¹ and Konopinski and Uhlenbeck² of the type (0,0) and (0,1) respectively³, the coupling is due to the fact that the four amplitudes of the wave-functions depend on the direction of the particles. For the type (1,1) as well as in the case of higher derivatives, the coupling appears explicitly in the interaction energy.