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

Measurements of polarized-neutron–polarized-³He scattering are reported. The target consisted of cryogenically polarized solid ³He, with thickness 0.04 atom/b and polarization ∼0.4. Polarized neutrons were produced via the ³H(p→,n→)³He or ²H(d→,n→)³He polarization-transfer reactions. The longitudinal and transverse total cross-section differences Δσ_L and Δσ_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-³He scattering. The best agreement is obtained with a recent R-matrix analysis of A=4 scattering and reaction data, lending strong support to the ⁴He level scheme obtained in that analysis. Discrepancies with other phase-shift parametrizations of n-³He scattering exist, attributable in most instances to one or two particular partial waves. © 1996 The American Physical Society.