Optimization of the magnetic field environment in the polarization analysis system of BL22 "RADEN" at J-PARC/MLF (Contract research)

Energy resolved neutron imaging techniques have been developed at BL22 "RADEN" installed in the Materials and Life Science Experimental Facility (MLF) of J-PARC. A polarized neutron imaging technique, which is one of the energy-resolved neutron imaging techniques, attracts much attention as a magnetic imaging method that enables to obtain a quantitative magnetic field distribution in an industrial product under driving state. At RADEN, a polarization analysis apparatus for polarized neutron imaging experiments has been prepared, but its performance was not fully achieved due to imperfectness of the field connection between devices. To improve the performance of polarization analysis system at RADEN, we performed magnetic field simulation of this system, and optimized the magnetic field environment by evaluating the magnetic field connection. After the optimization, we rearranged devices of the system, and confirmed that uniform polarization distribution could be obtained within 4 x 4 cm² field of view. (author)