Absolute magnetization calibration of polarized 131Xe for measurement of the 131Xe nuclear pseudomagnetism using neutron spin echo

We will investigate T violation in neutron interactions with heavy nuclei at a compound nuclear p-wave resonance by searching for a P-odd and T-odd term in the neutron forward scattering amplitude. Thew 131Xe P-odd effects have already been measured, however the previously unmeasured neutron incoherent scattering length of the polarized 131Xe target, would be a large systematic error because of the resulting pseudomagnetic precession. Measurement of this incoherent neutron scattering length requires absolute polarimetry of 131Xe. Here neutrons provide us a method for NMR calibration using hyperpolarized 3He as the standard instead of the more typical thermally polarized 1H sample. Since the 3He polarization dependent neutron absorption cross section is accurately known, measurement of neutron absorption of the polarized 3He gives an absolute NMR calibration. The absolute 131Xe polarimetry/magnetization used to determine the neutron incoherent scattering length of 131Xe as measured from its pseudomagnetic precession observed in measurements on the JNSE instrument at the FRMII is discussed [1]. [1] Heinz Maier-Leibnitz Zentrum. (2015). J-NSE: Neutron spin echo spectrometer. Journal of large-scale research facilies, 1, A11. http://dx.doi.org/10.17815/jlsf-1-34