MEASUREMENT OF T-20(90-DEGREES) IN THE H-1((D)OVER-RIGHT-ARROW,GAMMA)HE-3 REACTION BELOW DEUTERON BREAKUP THRESHOLD

The tensor analyzing powers of the H-1((d) over tilde, gamma)He-3 reac tion are sensitive to the tensor component of the nucleon-nucleon forc e, which mixes the L=2 D state into the He-3 ground state wave functio n. Modern Faddeev calculations of this reaction allow a quantitative c omparison to the parametrization of the tensor force in the trinucleon system. The T-20 analyzing power was measured at an incident beam ene rgy of 5.25 MeV and a laboratory angle of 90 degrees (theta(c.m.) = 92 .9 degrees), where the comparison to theory is especially rigorous. Th e measured value of T-20(90 degrees(lab)) is -0.035 +/- 0.04, which di ffers by approximate to 3 sigma from a recent Faddeev calculation whic h uses the separable expansion of the Paris potential.