High-precision mass measurement of Si24 and a refined determination of the rp process at the A=22 waiting point

Abstract

We report a high-precision mass measurement of $^{24}\mathrm{Si}$, performed with the Low Energy Beam and Ion Trap (LEBIT) facility at the National Superconducting Cyclotron Laboratory. The atomic mass excess, $10\phantom{\rule{0.16em}{0ex}}753.8$(37) keV, is a factor of 5 more precise than previous results. This substantially reduces the uncertainty of the $^{23}\mathrm{Al}(p,\ensuremath{\gamma})^{24}\mathrm{Si}$ reaction rate, which is a key part of the rapid proton capture ($rp$) process powering type I x-ray bursts. The updated rate constrains the onset temperature of the $(\ensuremath{\alpha},p)$ process at the $^{22}\mathrm{Mg}$ waiting point to a precision of 9%.