A large area polarized 3He neutron spin filter

A large area polarized He-3 neutron spin filter has been developed and tested in long-term operation. The polarizer cells have area 50 cm(2) and larger allowing access to a large area neutron beam. Polarization of He-3 up to 57 +/- 1% was measured by monitoring the neutron transmission through the He-3. The polarization was maintained over the course of several weeks, but the maximum attainable polarization declined over the course of a year-long run as the cell degraded, possibly due to long-term exposure to the neutron beam at high temperatures. The resulting neutron polarization and transmission are velocity dependent and are optimized for 5 angstrom. Cell construction, polarizer design, performance, and polarimetry are described in this paper. (C) 2007 Published by Elsevier B.V.