Polarization effects in the 2H( 3He, tp)p reaction at E = 33 MeV

Abstract

Triple-differential cross sections and vector analyzing powers have been measured for the 2H( 3He, tp)p reaction at E He = 32.5 MeV. Data are presented for ten pairs of lab angles in the range θ t = 15°–30°, θ p = 20°–55°, most of which correspond to the kinematic region in which the quasi-free 3He + n → t + p reaction with the unobserved proton as spectator is expected to be the dominant mechanism. In addition to the usual QFR maximum, most of the energy-sharing distributions of cross section exhibit a smaller maximum at lower energy along the kinematic locus in the E t, E p plane. The analyzing power is generally negative in the vicinity of the QFR peak, but exhibits a maximum in the region between the two peaks in the cross section. This behavior is reproduced by distorted-wave impulse-approximation calculations which include coherently amplitudes corresponding to the cases in which each of the two protons in the final state are the spectator. The best agreement with the data is obtained when the radial integrals are cut off at a maximum radius of ~ 15 fm. The predicted analyzing powers show little sensitivity to the parameters of the two-body reaction, but rather depend almost entirely on the spin-orbit terms in the distorting potentials, a behavior which is similar to that observed in nucleon-transfer reactions involving a transferred orbital angular momentum of zero.