Neutron beam effects on spin-exchange-polarized 3He.
We have observed depolarization effects when high intensity cold neutron beams are incident on alkali-metal spin-exchange-polarized 3He cells used as neutron spin filters. This was first observed as a reduction of the maximum attainable 3He 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 Los Alamos Neutron Science Center and Institute Laue-Langevin. The data reveal a new alkali-metal spin-relaxation mechanism that approximately scales as sqrt[phi_{n}], where phi_{n} is the neutron capture-flux density incident on the cell. This is consistent with an effect proportional to the concentration of electron-ion pairs but is much larger than expected from earlier work.
Sharma
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FOCUS Center and Physics Department, University of Michigan, Ann Arbor, Michigan 48104, USA.
Babcock
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Andersen
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Barrón-Palos
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Becker
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Boag
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Chen
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Chupp
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Danagoulian
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Gentile
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Klein
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Penttila
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Petoukhov
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Soldner
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Tardiff
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Walker
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Wilburn
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