In situ SEOP polarised He-3 neutron spin filter for incident beam polarisation and polarisation analysis on neutron scattering instruments

摘要

We discuss the development and characterisation of a new in situ spin exchange optical pumping (SEOP) based He-3 neutron spin filter polarisation device. We present results from a recent test of the prototype system developed with the Institut Laue-Langevin. The polariser was installed on the polarised reflectometer CRISP at ISIS in the analyser position. The He-3 was pumped continuously in situ on the beamline. The system also integrated a He-3 adiabatic fast passage spin flipper that allowed reversal of the He-3 and therefore neutron polarisation state, allowing for measurement of all four polarisation cross-sections. The system was run for a number of days reaching a He-3 polarisation of 63%.