High-precision mass measurement of Si-24 and a refined determination of the rp process at the A=22 waiting point

We report a high-precision mass measurement of Si-24, performed with the Low Energy Beam and Ion Trap (LEBIT) facility at the National Superconducting Cyclotron Laboratory. The atomic mass excess, 10753.8(37) keV, is a factor of 5 more precise than previous results. This substantially reduces the uncertainty of the Al-23(p, gamma) Si-24 reaction rate, which is a key part of the rapid proton capture (r p) process powering type I x-ray bursts. The updated rate constrains the onset temperature of the (alpha, p) process at the Mg-22 waiting point to a precision of 9%.