Nuclear reactions producing 2He and excited states of 4He as unbound outgoing systems

A system has been developed to detect the unbound outgoing reaction products 2He (1S0 state of the pp system) and α* (excited states of 4He below E/sub x/ = 25 MeV) by way of a kinematically complete coincidence measurement of the breakup particles p + p and p + t, respectively. Projected proton energy spectra from three different reactions producing 2He showed the characteristic enhancement of the cross section over the phase space distribution, which is caused by the final-state interaction between the two protons in the 1S0 state of 2He and is well accounted for by the theory of Watson and Migdal. Energy spectra from the (3He, 2He) reaction were taken at E3/sub He/ = 60 MeV on targets of 6Li, 7Li, 9Be, 12C, and 13C. Angular distributions were measured for the 12C and 13C targets at E3/sub He/ = 50 MeV and were found to be in excellent agreement with exact finite-range (EFR) and zero-range distorted-wave Born-approximation (DWBA) calculations. Energy spectra from the (α, 2He) reaction were collected on targets of 12C, 13C, 14N, 15N, 16O, 18O, 20Ne, 26Mg, 28Si, 29Si, 32S, 36Ar, and 38Ar at E/sub α/ = 65 MeV and on 24Mg and 40Ca at E/sub α/ = 55 MeV. One observed preferential population of 2n states with dominant configurations (d/sub 5/2)42+, (d/sub 3/2/f/sub 7/2/)5- and f/sub 7/2/)62+, many of which were previously unknown