High-precision mass measurements for the rp-process at JYFLTRAP

Abstract

The double Penning trap JYFLTRAP at the University of Jyvaskyla has been successfully used to achieve high-precision mass measurements of nuclei involved in the rapid proton-capture (rp) process. A precise mass measurement of 31 Cl is essential to estimate the waiting point condition of 30 S in the rp-process occurring in type I x-ray bursts (XRBs). The mass-excess of 31 C1 measured at JYFLTRAP, -7034.7(3.4) keV, is 15 more precise than the value given in the Atomic Mass Evaluation 2012. The proton separation energy S p determined from the new mass-excess value confirmed that 30 S is a waiting point, with a lower-temperature limit of 0.44 GK. The mass of 52 Co effects both 51 Fe( p,γ ) 52 Co and 52 Co( p,γ ) 53 Ni reactions. The mass-excess value measured, - 34 331.6(6.6) keV is 30 times more precise than the value given in AME2012. The Q values for the 51 Fe( p,γ ) 52 Co and 52 Co( p,γ ) 53 Ni reactions are now known with a high precision, 1418(11) keV and 2588(26) keV respectively. The results show that 52 Co is more proton bound and 53 Ni less proton bound than what was expected from the extrapolated value.