Measurements of the total cross section for the scattering of polarized neutrons from polarized He-3

Measurements of polarized-neutron-polarized-He-3 scattering are reported. The target consisted of cryogenically polarized solid He-3, with thickness 0.04 atom/b and polarization similar to 0.4. Polarized neutrons were produced via the H-3((p) over right arrow,(n) over right arrow)He-3 or H-2((d) over right arrow (n) over right arrow)He-3 polarization-transfer reactions. The longitudinal and transverse total cross-section differences Delta sigma(L) at and a 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-He-3 scattering. The best agreement is obtained with a recent R-matrix analysis of A=4 scattering and reaction data, lending strong support to the He-4 level scheme obtained in that analysis. Discrepancies with other phase-shift parametrizations of n-He-3 scattering exist, attributable in most instances to one or two particular partial waves.