Measurement of the relative longitudinal spin-dependent total cross-section difference in n→-d→ scattering

We report relative measurements of the n→-d→ longitudinal spin-dependent total cross-section difference (ΔσL)d, at En(lab) = 5.0, 6.88, and 9.0 MeV. The deuteron target was polarized via dynamic nuclear polarization at 250 mK in a 2.5-T external magnetic field. The target polarization was monitored by nuclear magnetic resonance and was calibrated by a (ΔσL)d measurement at En(lab) = 1.18 MeV. The polarized neutron beams were produced through the H3(p→,n→)He3 and H2(d→,n→) He3 reactions. The neutron polarizations were determined either by direct measurement or from known or calculated polarization-transfer coefficients. The results for (ΔσL)d show agreement with theoretical calculations based on nucleon-nucleon potential models but are not of sufficient precision to distinguish the presence or absence of three-nucleon force contributions to the cross sections.