High-precision ( p,t) reaction to determine 25Al( p,γ )26Si reaction rates

Since the identification of ongoing 26Al production in the universe, the reaction sequence 24Mg(p,γ )25Al(β+ν)25Mg(p,γ )26Al has been studied intensively. At temperatures where the radiative capture on 25Al (t1/2 = 7.2 s) becomes faster than the β+ decay, the production of 26Al can be reduced due to the depletion of 25Al. To determine the resonances relevant for the 25Al(p,γ )26Si bypass reaction, we measured the 28Si(p,t )26Si reaction with high-energy precision using the Grand Raiden spectrometer at the Research Center for Nuclear Physics, Osaka. Several new energy levels were found above the p threshold and for known states excitation energies were determined with smaller uncertainties. The calculated stellar rates of the bypass reaction agree well with previous results, suggesting that these rates are well established.