Polarization analysis for magnetic field imaging at RADEN in J-PARC/MLF

Shinohara, Takenao   ; Hiroi, Kosuke  ; Hayashida, Hirotoshi*; Kai, Tetsuya   ; Parker, J. D.*; Oikawa, Kenichi   ; Kiyanagi, Yoshiaki*

Polarized neutron imaging is an attractive method to visualize magnetic fields in a bulk object or space. Recently a new imaging instrument "RADEN" has been constructed at the beam line of BL22 of the Materials and Life Science Experimental Facility (MLF) at J-PARC, which is dedicated to the energy-resolved neutron imaging experiments. In this instrument, polarization analysis apparatus for magnetic field imaging has been installed and the commissioning study has been going. As a demonstration study, a ring-shaped electric steel was measured and an oscillatory behavior was clearly observed in the wavelength dependence of neutron polarization. The period of polarization oscillation corresponded with that expected from the magnetization of the sample. In addition, a change of domain structure was observed by changing the applied field to the steel sample. In the presentation, we introduce our new system and show recent results on polarized neutron imaging experiments.