Multilayer neutron polarizing mirrors working under a low external magnetic field less than 100 gausses

Abstract

We have developed multilayer neutron polarizing mirrors which are controlled under an external magnetic field less than 100 gausses. Multilayers of Permalloy-Ge and Fe-Ge have been evaporated on Si wafers in the magnetic field of about 130 gausses parallel to the surface of the wafer. The polarizing efficiencies of Fe-Ge and Permalloy-Ge multilayer mirrors were 95% and 91% respectively under a low external magnetic field of 80 gausses. Under a very low external field of 50 gausses, the polarizing efficiency was 90% in case of Permalloy-Ge.

A neutron pulse was obtained by applying a pulsed magnetic field of about 50 gausses parallel to the Permalloy-Ge polarizing mirror. The pulse rise time is the order of 100μs in the present pulsed magnetic devices.