Proton decay of 26Si via the 28Si(p,t)26Si Reaction and Implications for 25Al(p,g)26Si

The rate of the 25Al(p,g)26Si reaction in novae is important to the production of galactic 26Al, an important astronomical observable for its 1.809 MeV gamma ray. 26Al has been catalogued near massive stars and found in presolar grains. The 25Al proton capture reaction serves to bypass 26Alg:s: production since the subsequent 26Si beta decay preferentially populates instead the isomeric state of 26Al. Several recent studies have aimed to locate and characterize the first l = 0 resonances in 26Si above the 25Al+p threshold, which would dominate the reaction rate at nova temperatures. We have studied several resonances in 25Al(p,g)26Si via the 28Si(p,t)26Si* reaction at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Several higherenergy states in 26Si are given spin and parity assignments for the first time, and possible new states are observed. In addition to measuring the angular distributions of the tritons, a partial implementation of the Oak Ridge Rutgers University Barrel Array (ORRUBA) was used to measure the coincident protons emitted from the decay of states in 26Si above the proton threshold. We observe that the first l = 0 state above the proton threshold decays essentially 100% of the time via proton emission, resultingmore » in a proton branching ratio consistent with one.« less