Change in Neutron Polarization Induced by a Superconductor Rotated in a Magnetic Field

Abstract

Neutron depolarization (i.e. the change in the polarization vector projection onto the applied magnetic field) depends on neutron Larmor frequency ω L in the superconductor and on a frequency ω 1 ω being related to the directional variation of the magnetic induction inside the superconductor. Depolarization is small if η = ω L /ω » 1. In the opposite limit η « 1, the depolarization is due to neutron spin rotation about the magnetic flux, which, in turn, rigidly rotates with a superconductor. A total spin reversal is possible at η = 1. Depolarization at a stationary rotation angle in a superconducting plate carrying a transport critical current in a magnetic field is considered as well. Depolarisation is determined by either longitudinal or transversal critical currents depending on the angle between the applied field and the critical current direction.