0° polarization transfer in H²(p→,n→)pp at 54 and 71 MeV

Results of measurements of the transverse polarization transfer coefficients K_y^y′(0°) for H²(p→,n→)pp at 54 and 71 MeV are presented. The magnitude and energy dependence of this parameter have been determined with sufficient precision (4%) to permit the use of this reaction as a source of nearly monoenergetic polarized neutrons in precise measurements. K_y^y′(0°) is found to have a significant dependence on excitation energy. The results at low excitation energy are in agreement with calculations in the impulse approximation using the nucleon-nucleon phase shifts obtained from the Bonn or Paris potentials. A substantial difference from the results obtained using the empirical phase shifts is found. Results of measurements of the longitudinal polarization transfer coefficient K_z^z′(0°) at 54 MeV are also presented.