The image rp-process waiting-point nucleus 68Se and its astrophysical implications Original Research Article

Precise mass measurements of nuclei along the N=Z line are important input parameters for simulations of the rp-process. Of particular interest is the mass of the 6834Se34 rp-process waiting point nucleus for determining the possibility of a two-proton capture branch bypassing its slow β-decay. The mass of 68Se was measured via the β-decay endpoint. 68Se was produced by the 12C(58Ni, 2n)68Se reaction and subsequently implanted onto a moving tape system using the fragment mass analyzer at the ATLAS facility of Argonne National Laboratory. A mass excess value of (−54189±240) keV was determined from the β-endpoint measurement of QEC=4710(200) keV. Evaluations of proton separation energies based on the measured mass were used in a one zone type I X-ray burst model. It is concluded that the N=Z=34 isotope 68Se is a waiting point for the rp-process.