Advancement of Photospheric Radius Expansion and Clocked Type-I X-Ray Burst Models with the New 22Mg (α,p)25Al Reaction Rate Determined at the Gamow Energy

We report the first (in)elastic scattering measurement of 25Al + p with the capability to select and measure in a broad energy range the proton resonances in 26Si contributing to the 22Mg (α,p) reaction at type I x-ray burst energies. We measured spin-parities of four resonances above the α threshold of 26Si that are found to strongly impact the 22Mg ( α , p ) rate. The new rate advances a state-of-the-art model to remarkably reproduce light curves of the GS 1826 – 24 clocked burster with mean deviation < 9 % and permits us to discover a strong correlation between the He abundance in the accreting envelope of the photospheric radius expansion burster and the dominance of 22Mg ( α , p ) branch.