A confirmative spin-parity assignment for the key 6.15 MeV state in 18Ne of astrophysical importance
Abstract
Proton resonant states in 18Ne have been investigated by the resonant elastic scattering of 17F+p. The 17F beam was separated by the CNS radioactive ion beam separator (CRIB), and bombarded a thick H2 gas target at 3.6 MeV/nucleon. The recoiled light particles were measured by using three sets of E-E Si telescope at scattering angles of θlab≈ 3, 10 and 18, respectively. Four resonances, i.e., at Ex=6.15, 6.30, 6.85, and 7.05 MeV, were observed clearly. By R-matrix analysis of the excitation functions, Jπ=1- was firmly assigned to the 6.15 MeV state which is a key state in calculating the reaction rate of 14O(α,p)17F reaction. This reaction was thought to be one of the most probable key reactions for the breakout from the hot-CNO cycle to the rp-process in type I x-ray bursts In addition, a new excited state observed at Ex=6.85 MeV was tentatively assigned as 0-, which could be the analog state of 6.880 MeV, 0- in mirror 18O.