Development of a polarized-neutron imaging technique at the China Advanced Research Reactor

摘要: In contrast to conventional neutron imaging by measuring the attenuation contrast, polarized-neutron imaging (PNI) has proven to be a powerful tool for investigating the spatial distribution of magnetic fields inside and around bulk samples owing to the intrinsic magnetic moment of neutrons. This technique benefits from the measurement of the cumulative precession of the neutron polarization passing through a magnetic field. We report the recent development of the PNI capability at the China Advanced Research Reactor (CARR), where two neutron-imaging instruments (thermal and cold) have been established. To further develop and realize the PNI technique, a PNI facility consisting of a double-crystal pyrolytic graphite monochromator, supermirror polarizer with three parallel V-cavities, and an in-situ optically pumped 3He neutron spin filter as a neutron spin analyzer was successfully developed and tested based on an established cold neutron-imaging instrument. This setup will be beneficial for enhancing neutron imaging and neutron optics in CARR in the future.