Neutron Polarimetry Using a Polarized 3He Cell for the aCORN Experiment

Abstract

The neutron polarization of the NG-C beamline at the NIST Center for Neutron Research was measured as part of the aCORN neutron beta decay experiment. Neutron transmission through a polarized 3He spin filter cell was recorded while adiabatic fast passage (AFP) nuclear magnetic resonance (NMR) reversed the polarization direction of the 3He in an eight-step sequence to account for drifts. The dependence of the neutron transmission on the spin filter direction was used to calculate the neutron polarization. The time dependent transmission was fit to a model which included the neutron spectrum, and 3He polarization losses from spin relaxation and AFP-NMR. The polarization of the NG-C beamline was found to be $\mid P_{\mathrm{n}}\mid \le 4\times 10^{-4}$ with 90 % confidence.

arXiv comment14 pages, 3 figures

References in corpus (6)

• Optically Polarized ${}^3$He
• Improved determination of the $\beta$-${\overline{\nu }}_e$ angular correlation coefficient $a$ in free neutron decay with the $a$SPECT spectrometer
• Measurement of the neutron decay electron-antineutrino angular correlation by the aCORN experiment
• 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
• aCORN: an experiment to measure the electron-antineutrino correlation coefficient in free neutron decay
• The aCORN Backscatter-Suppressed Beta Spectrometer

Cited by in corpus (2)

• Measurement of the neutron decay electron-antineutrino angular correlation by the aCORN experiment
• First Use of a Polarized ${}^3$He Neutron Spin Filter on the Back-n White Neutron Source of CSNS