Preliminary Experiment of Magnetic Imaging Using Polarized Pulsed Neutrons at HUNS

Imaging using polarized neutrons is one of the most attractive techniques in the neutron imaging field, because of its capability to visualize magnetic field inside materials or spaces by analyzing neutron polarization. An advanced method, which can quantify the magnetic field by combining the time-of-flight method with a polarization analysis of pulsed neutrons, has been developed at J-PARC. To introduce this method to the compact accelerator-driven neutron source, we have started the magnetic imaging experiments at Hokkaido University Neutron Source (HUNS). Using an experimental system consisting of a pair of magnetic super-mirrors as a polarizer and an analyzer, a spin flipper, and a two-dimensional neutron detector, we obtained the polarization of 90% at the wavelength over 6 Å. The first demonstration experiments were performed for coil samples. As a result, an oscillatory behaviour of polarization depending on the wavelength due to the neutron spin's Larmor precession was clearly observed.