Spin polarization effects in the 3He(d, 3He p)n and the 3He(d, t p)p reactions at Ed = 17 MeV

Abstract

Triple-differential cross sections and vector analyzing powers were measured for the 3He(d, 3He p)n and the 3He(d, t p)p reactions at E d = 17 MeV. Data are presented for four pairs of coplanar detection angles for the 3He/triton and proton where quasi-free scattering (QFS) or quasi-free reaction (QFR) processes are expected to be dominant, and for five sets of angles where the kinematics favor the nucleon-nucleon final-state interaction (NN FSI). Tensor-analyzing-power measurements, T 20 and T 22, are also presented for two sets of angles. For the angle pairs where the QFS/QFR mechanism is important, the data are compared with the predictions of PWIA and DWIA calculations. While both calculations are only partly successful in describing the shapes of the quasi-free peaks, the DWIA better predicts their magnitudes. The vector analyzing powers (VAP) in the quasi-free region are at best only qualitatively reproduced by both calculations for the QFS, while for the QFR there is quantitative agreement between both calculations and the data only in the energy region near the center of the QFR maximum. Data obtained for the angle pairs where the NN FSI is present are compared to the predictions of a simple two-step model. The reaction is assumed to proceed by pickup of a nucleon from the 3He by the deuteron, followed by breakup of the recoil dinucleon system. These calculations describe the shapes and magnitudes of the NN FSI peaks reasonably well. The VAP predictions are for the most part also consistent with the two-step assumption. In all of the data, strong contributions are present from nucleon-trion FSI corresponding to the 0 − and 2 − resonances in 4He at E x = 21.1 and 22.1 MeV, respectively.