Measurements of the Total Cross Section for the Scattering of Polarized Neutrons from Polarized ${}^3$He

Abstract

Measurements of polarized neutron--polarized ${}^3$He scattering are reported. The target consisted of cryogenically-polarized solid ${}^3$He, thickness 0.04 atom/b and polarization 40%. The longitudinal and transverse total cross-section differences $\Delta {\sigma }_L$ and $\Delta {\sigma }_T$ were measured for incident neutron energies 2-8 MeV. The results are compared to phase-shift predictions based on four different analyses of n-${}^3$He scattering. The best agreement is obtained with a recent R-matrix analysis of A=4 scattering and reaction data, lending strong suport to the ${}^4$He level scheme obtained in that analysis.

arXiv comment19 pages RevTeX style, 5 postscript figures, excepted for publication in the Aug96 issue of Phys. Rev. C. Revised version includes correct version of 1 postscript figure