High-precision mass measurements for the isobaric multiplet mass equation at A=52

Abstract

Masses of Co-52, (52)Com, Fe-52, Fe-52(m), and Mn-52 have been measured with the JYFLTRAP double Penning trap mass spectrometer. The isobaric multiplet mass equation for the T = 2 quintet at A = 52 has been studied employing the new mass values. No significant breakdown (beyond the 3 sigma level) of the quadratic form of the IMME was observed (chi(2)/n = 2.4). The cubic coefficient was 6.0(32) keV (chi(2)/n = 1.1). The excitation energies for the isomer and the T = 2 isobaric analog state in Co-52 have been determined to be 374(13) keV and 2922(13) keV, respectively. The measured mass values for Co-52 and (52)Com are 29(10) keV and 16(15) keV higher, respectively, than obtained in a recent storage-ring experiment, and significantly lower than predicted by extrapolations. Consequently, this has an impact on the proton separation energies for Co-52 and Ni-53 relevant for the astrophysical rapid proton capture process. The Q value for the proton decay from the 19/2(-) isomer in Co-53 has been determined with an unprecedented precision, Q(p) = 1558.8(17) keV.