Isobaric spin selection rule in the N 14(d, α)C 12 reaction

Abstract

The N 14(d, α)C 12 reaction leading to the 15.11 MeV and 16.11 MeV ( T=1) levels of C 12 violates conservation of isobaric spin. The cross section of the reaction to the 15.11 MeV level was measured by observing the alpha particles with solid state detectors and with broad-range spectrographs and by observing the 15.11 MeV gamma rays from the decay of the state. A gamma ray yield curve was taken from 3 MeV to 12 MeV and shows strong resonance structure. Angular distributions of alpha particles leading to the 12.71, 15.11 and 16.11 MeV levels were measured at 7.18 MeV deuteron energy and to the 12.71 MeV level at 5.93 MeV. At 7.18 MeV the total cross sections to the 15.11 MeV and 16.11 MeV levels are respectively 3.1% and approximately 4% of the cross section for the reaction leading to the 12.71 MeV ( T = 0) state. Contrary to other (d, α) reactions in which the selection rule was observed to hold, neither initial nor final states have J π = 0 + in this case.