J. Phys. I France
Volume 7, Numéro 1, January 1997
Page(s) 177 - 185
DOI: 10.1051/jp1:1997132
J. Phys. I France 7 (1997) 177-185

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

V.N.K. Zhuchenko

Petersburg Nuclear Physics Institute, St Petersburg district, 188350, Russia

(Received 18 November 1996, revised 2 September 1996, accepted 17 September 1996)

Neutron depolarization (i.e. the change in the polarization vector projection onto the applied magnetic field) depends on neutron Larmor frequency $\omega_{\rm L}$ in the superconductor and on a frequency $\omega$, $\omega$ being related to the directional variation of the magnetic induction inside the superconductor. Depolarization is small if $\eta = \omega_{\rm L}/\omega \gg 1$. In the opposite limite $\eta \ll 1$, 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 $\eta = 1$. 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.

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