Spin exchange optical pumping based polarized ³He filling station for the Hybrid Spectrometer at the Spallation Neutron Source

The Hybrid Spectrometer (HYSPEC) is a new direct geometry spectrometer at the Spallation Neutron Source at the Oak Ridge National Laboratory. This instrument is equipped with polarization analysis capability with 60° horizontal and 15° vertical detector coverages. In order to provide wide angle polarization analysis for this instrument, we have designed and built a novel polarized ³He filling station based on the spin exchange optical pumping method. It is designed to supply polarized ³He gas to HYSPEC as a neutron polarization analyzer. In addition, the station can optimize the ³He pressure with respect to the scattered neutron energies. The depolarized ³He gas in the analyzer can be transferred back to the station to be repolarized. We have constructed the prototype filling station. Preliminary tests have been carried out demonstrating the feasibility of the filling station. Here, we report on the design, construction, and the preliminary results of the prototype filling station.