Neutron polarization control by interferometer

A neutron interference experiment of the magnetic double refraction phenomenon was made in order to control the neutron spins. The experiment was carried out using an LLL type interferometer on HT-11 station at JRR-2 of JAERI where an apparatus for precise neutron optics is installed. A magnetic phase shifter made of Permalloy and a nuclear phase shifter made of Al were inserted between the interferometer's crystal slabs. When the magnetic phase shifter was set at an appropriate angle an interference fringe produced by rotation of the nuclear phase shifter disappeared due to the magnetic double refraction. However, the fringe was recovered after the neutron beam was reflected from a spin analyzing crystal. This shows that the polarization state of the neutron beam outgoing from the interferometer is continuously changed by controlling the magnetic and nuclear phase shifters. (author)