Impact of the New As-65(p,gamma)Se-66 Reaction Rate on the Two-proton Sequential Capture of Ge-64, Weak GeAs Cycles, and Type I X-Ray Bursts Such as the Clocked Burster GS 1826-24

We reassess the As-65(p,gamma)Se-66 reaction rates based on a set of proton thresholds of Se-66, S (p)(Se-66), estimated from the experimental mirror nuclear masses, theoretical mirror displacement energies, and full p f-model space shell-model calculation. The self-consistent relativistic Hartree-Bogoliubov theory is employed to obtain the mirror displacement energies with much reduced uncertainty, and thus reducing the proton-threshold uncertainty up to 161 keV compared to the AME2020 evaluation. Using the simulation instantiated by the one-dimensional multi-zone hydrodynamic code, Kepler, which closely reproduces the observed GS 1826-24 clocked bursts, the present forward and reverse As-65(p,gamma)Se-66 reaction rates based on a selected S (p)(Se-66) = 2.469 +/- 0.054 MeV, and the latest Mg-22(alpha,p)Al-25, Ni-56(p,gamma)Cu-57, Cu-57(p,gamma)Zn-58, Ni-55(p,gamma)Cu-56, and Ge-64(p,gamma)As-65 reaction rates, we find that though the GeAs cycles are weakly established in the rapid-proton capture process path, the As-65(p,gamma)Se-66 reaction still strongly characterizes the burst tail end due to the two-proton sequential capture on Ge-64, not found by the Cyburt et al. sensitivity study. The As-65(p,gamma)Se-66 reaction influences the abundances of nuclei A = 64, 68, 72, 76, and 80 up to a factor of 1.4. The new S (p)(Se-66) and the inclusion of the updated Mg-22(alpha,p)Al-25 reaction rate increases the production of C-12 up to a factor of 4.5, which is not observable and could be the main fuel for a superburst. The enhancement of the C-12 mass fraction alleviates the discrepancy in explaining the origin of the superburst. The waiting point status of and two-proton sequential capture on Ge-64, the weak-cycle feature of GeAs at a region heavier than Ge-64, and the impact of other possible S (p)(Se-66) are also discussed.