Dec 7 – 8, 2021 Online only
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Measurement of the Pseudmagnetic precession of polarized 3He

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Dec 7, 2021, 1:40 PM
Talk Nuclear, Particle, and Astrophysics Nuclear, Particle, and Astrophysics


Earl Babcock


The pseudomagnetic precession of neutrons in polarized nuclei is caused by the incoherent neutron scattering cross section and leads to a real spin rotation of polarized neutrons. This precession however does not come from “magnetic fields” but directly from scattering at the nucleus. The pseudomagnetic precession of 3He is itself of high for few-body nuclear effective field theories to test nuclear flied models and to understand neutron scattering from quantum liquids. Novel neutron optics using polarized media for “pseudomagnetic neutron prisms” and could be the focus of future studies. However, the two main experimental results for the incoherent scattering cross section of 3He at the ILL and NIST disagree by bout 2 sigma. As a “calibration” for experiments with polarized 129Xe and 131Xe we briefly measured the 3He cross section a recent experiment. Our result, while having very low statistical error, gave a value several sigma (of the statistical error) below the other published results. Consequently, more work is justified. Given the on-site resources for 3He polarization at the JCNS, the JNSE is ideal to attempt to resolve the discrepancy between the published 3He results. Even at a reduced cold neutron flux of the FRM2 without its cold source, viable experiments can indeed be conducted as we measure the direct beam. This would make a topic of good scientific interest with good experimental feasibility to conduct within the next years it JNSE.

Primary authors

Dr Boyd Goodson (Southern Illinois University) Earl Babcock Mr Hao Lu (Indiana University) Olaf Holderer Dr William M Snow (University of Indiana)

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