Abstract:
Measurements of neutron-deuteron (n-d) analyzing power A(y)(theta) at E-n = 19.0 MeV are reported at 16 angles from theta(c.m.) = 46.7 to 152.0 degrees. The objective of the experiment is to better characterize the discrepancies between n-d data and the predictions of three-nucleon calculations for neutron energies above 16.0 MeV. The experiment used a shielded neutron source, which produced polarized neutrons via the H-2((d) over right arrow,(n) over right arrow)He-3 reaction, a deuterated liquid scintillator center detector ( CD) and liquid-scintillator neutron side detectors. A coincidence between the CD and the side detectors isolated the elastic-scattering events. The CD pulse height spectrum associated with each side detector was sorted by using pulse-shape discrimination, time-of-flight techniques, and by removing accidental coincidences. A Monte Carlo computer simulation of the experiment accounted for effects due to finite geometry, multiple scattering, and CD edge effects. The resulting high-precision data ( with absolute uncertainties ranging from 0.0022 to 0.0132) have a somewhat lower discrepancy with the predictions of three-body calculations, as compared to those found at lower energies.
