On the theory of beta-radioactivity III : The influence of electric and magnetic fields on polarized electron beams

Abstract

The influence of electric and magnetic fields on the spin orientation (polarization) of electrons in a beam is calculated according to the Pauli spin theory and the Dirac theory. For the cases, where the field is perpendicular or parallel to a polarized electron beam, the following results are found.

Transverse electric field. In the non-relativistic approximation the spin orientation remains constant in space, even if the beam is deflected; the relativistic formula gives for the ratio of the rotation of the spin orientation and the angle of deflection of the beam: Ekin/E (ratio of kinetic energy and total energy, i.e., including the rest mass).

Transverse magnetic field. The spin orientation does not change in relation to the direction of propagation.

Longitudinal electric field. Though the beam is accelerated (or retarded) the spin orientation remains constant in space.

Longitudinal magnetic field. The spin orientation rotates about the direction of propagation.

It is shown that longitudinal polarization of electron beams (spins parallel or antiparallel to the direction of propagation) can be observed by means of an electric deflection of the beam and a scattering experiment in succession.