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

Abstract

Masses ofCo m have been experimentally determined for the first time and found to be more bound than predicted by extrapolations. 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 3σ level) of the quadratic form of the IMME was observed (χ 2 /n = 2.4). The cubic coefficient was 6.0(32) keV (χ 2 /n = 1.1). The excitation energies for the isomer and the T = 2 isobaric analogue state in 52 Co have been determined to be 374(13) keV and 2922(13) keV, respectively. The Q value for the proton decay from the 19/2 − isomer in 53 Co has been determined with an unprecedented precision, Qp = 1558.8(17) keV. The proton separation energies of 52 Co and 53 Ni relevant for the astrophysical rapid proton capture process have been experimentally determined for the first time.

Isospin-symmetry breaking in masses of N≃Z nuclei

“…In particular, in Table 2 we present predictions of mass excesses of 52 Co, 56 Cu, and 73 Rb, whose masses were in AME2012 [25] derived from systematics, and 44 V, whose ground-state mass measurement is uncertain. Recently, the mass excess of 52 Co was measured as −34361(8) [43] or −34331.6(66) keV [44]. These values are in excellent agreement with our prediction, even though the difference between them is still far beyond the estimated (much smaller) experimental uncertainties.…”

“…The obtained values of t II 0 and t III 0 turn out to not agree with the NN ISB interactions (NN scattering lengths) in the 1 S 0 channel. We predicted mass excesses of 52 Co, 56 Cu, 73 Rb, and 44 V, and for 52 Co and 56 Cu we obtained excellent agreement with the recently measured values [37,43,44]. To better pin down the ISB effects, accurate mass measurements of the other two nuclei are very much called for.…”

“…For SV ISB T , the fitting procedure was performed for ground-state configurations regardless of their alignment. This led to antialigned configurations in A = 12,20,24,36,40,44,48, and 56, and to aligned ones in the remaining A = 4n triplets. In the A = 4n triplets, the obtained values of K quantum numbers (projections of the angular momentum on the symmetry axis) agree with the experimental values of angular momentum I.…”

“…Unfortunately, for certain values of A, we were unable to find solutions for all orientations. The missing solutions were: for SV ISB T , A = 12 and 16; for SkM* ISB , A = 12, 16,20,24,28,32,40,44, and 52; for SLy4 ISB , A = 12, 16, 28, 32, 40, and 52. Furthermore, for SkM* ISB and SLy4 ISB , solutions for A = 30 and 36 triplets turned out to be spherically symmetric, which led to unexpectedly large values of TDE.…”

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

“…The TOF-ICR technique has been applied with a 100 ms long quadrupolar radiofrequency (RF) excitation. A new massexcess value for 52 Co was measured: -34 331.6(6.6) keV [6]. The proton-capture Q values for 51 Fe(p,γ) 52 Co and 52 Co(p,γ) 53 Ni are 1418(11) keV and 2588(26) keV, respectively.…”