High-spin states in the direct 12, 13C(α, p) 15, 16N reactions

Abstract

The 12, 13C(α, p) reactions at E α = 35 MeV are used to study high-spin states in 15N and 16N. Theoretical prescriptions are given for normalizing DWBA predictions in a semi-microscopic model and for comparing differential cross sections in the two reactions. Angular distributions are presented for many states, with DWBA analyses for those of high spin, from 10.7 to 15.4 MeV in 15N and from 0 to 11.8 MeV in 16N. The observed magnitudes are larger than predicted. In 16N, a 4 − state is observed at 6.17 MeV, and theoretical comparisons indicate that a member of the strong triplet of states at 7.6 MeV, resolved in this study, has also a 4 − spin. Strong peaks are observed at 15.42 MeV in 15N and at 11.75 MeV in 16N, but neither peak can be explained by our theoretical analysis. The DWBA angular distributions depend sensitively on the choice of the α-particle optical potential.