Proton Unbound States in T=3/2 and T=2 Nuclei and the Reaction Rates for Sequential Two-proton Capture Reactions in the rp-Process

Proton capture reactions on T=l nuclei (e.g. 22Mg, 26Si, 30S, and 34Ar) are considered the main impedance on the rp-process reaction below A=46. Low proton-capture Q-values result in large inverse photodisintegration rates at the typical temperature and density conditions in explosive hydrogen burning scenarios. As a consequence most of the processed material remains stored in the T=l nuclei until they undergo P-decay (waiting points) . It was pointed out3 that a rapid subsequent proton capture on the low abundance T=3/2 nuclei (e.g. 23Al, 27P, 31Cl, and 35K) may bridge these waiting points. This will reduce the timescale of the rp-process considerably and may increase the production rate of heavy elements during explosive hydrogen burning. It will also strongly reduce the final abundances of the T=l nuclei, which is of particular importance in the case of "Mg and 26Si, the progenitors of the long lived y-ray sources 2 2 ~ a and 26A1. To study these effects in dynamic nucleosynthesis models, it is necessary to determine the reaction rates for proton capture on T=l and T=3/2 neutron-deficient nuclei below mass A=46. The resonant reaction rate for proton-capture processes as a function of temperature Tg (in units of GK),