Neutron Beam Effects on Spin Exchange Polarized He-3

Abstract

We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal-spin-exchange polarized He-3 cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable He-3 polarization and was attributed to a decrease of alkali-metal polarization, which led us to directly measure alkali-metal polarization and spin relaxation over a range of neutron fluxes at LANSCE and ILL. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as the square root of the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the recombination-limited ion concentration, but is much larger than expected from earlier work.

submitted to Physical Review Letters

References in corpus (2)

• Characterization of a ballistic supermirror neutron guide
• Upper Bounds on Parity Violating Gamma-Ray Asymmetries in Compound Nuclei from Polarized Cold Neutron Capture

Cited by in corpus (6)

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• Search for a T-odd, P-even Triple Correlation in Neutron Decay
• High level of ${}^3$He polarization of 81\% Maintained in an on-beam ${}^3$He spin filter using SEOP
• ANNI - A pulsed cold neutron beam facility for particle physics at the ESS
• Effects of Nitrogen Quenching Gas on Spin-Exchange Optical Pumping of He-3
• Measurement of the absolute neutron beam polarization from a supermirror polarizer and the absolute efficiency of a neutron spin rotator for the NPDGamma experiment using a polarized ${}^3$He neutron spin-filter