Mass measurements in the vicinity of the doubly-magic waiting point 56Ni

TL;DR

This study precisely measured nuclear masses and Q values near the doubly-magic nucleus 56Ni, significantly improving data critical for astrophysical rp-process modeling and nuclear structure understanding.

Contribution

The paper provides highly precise mass measurements and Q values for several isotopes near 56Ni, including the first direct measurements of proton-capture Q values for key isotopes, enhancing nuclear data accuracy.

Findings

Proton-capture Q value for 56Ni(p,gamma)57Cu improved by a factor of 37.

Precise excitation energy of 53Co^m measured at 3174.3 keV.

Mass values adjusted within a network of 17 frequency ratio measurements.

Abstract

Masses of 56,57Fe, 53Co^m, 53,56Co, 55,56,57Ni, 57,58Cu, and 59,60Zn have been determined with the JYFLTRAP Penning trap mass spectrometer at IGISOL with a precision of dm/m \le 3 x 10^{-8}. The QEC values for 53Co, 55Ni, 56Ni, 57Cu, 58Cu, and 59Zn have been measured directly with a typical precision of better than 0.7 keV and Coulomb displacement energies have been determined. The Q values for proton captures on 55Co, 56Ni, 58Cu, and 59Cu have been measured directly. The precision of the proton-capture Q value for 56Ni(p,gamma)57Cu, Q(p,gamma) = 689.69(51) keV, crucial for astrophysical rp-process calculations, has been improved by a factor of 37. The excitation energy of the proton emitting spin-gap isomer 53Co^m has been measured precisely, Ex = 3174.3(10) keV, and a Coulomb energy difference of 133.9(10) keV for the 19/2- state has been obtained. Except for 53Co, the mass values have been adjusted within a network of 17 frequency ratio measurements between 13 nuclides which allowed also a determination of the reference masses 55Co, 58Ni, and 59Cu.