Coulomb energy difference as a probe of isospin-symmetry breaking in the upper fp-shell nuclei

Abstract

The anomaly in Coulomb energy differences (CED) between the isospin T=1 states in the odd-odd N=Z nucleus 70Br and the analogue states in its even-even partner 70Se has remained a puzzle. This is a direct manifestation of isospin-symmetry breaking in effective nuclear interactions. Here, we perform large-scale shell-model calculations for nuclei with A=66-78 using the new filter diagonalization method based on the Sakurai-Sugiura algorithm. The calculations reproduce well the experimental CED. The observed negative CED for A=70 are accounted for by the cross-shell neutron excitations from the fp-shell to the g9/2 intruder orbit with the enhanced electromagnetic spin-orbit contribution at this special nucleon number.

4 pages, 4 figures, accepted for publication in Physical Review Letters

References in corpus (4)

• Phase transition in exotic nuclei along the $N=Z$ line
• Coulomb shifts and shape changes in the mass 70 region
• Isospin symmetry breaking at high spins in the mirror pair 67Se and 67As
• Filter diagonalization of shell-model calculations

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• Shape coexistence and isospin symmetry in $A=70$ nuclei: Spectroscopy of the $T_z=-1$ nucleus ${}^{70}$Kr
• Effects of Coulomb and isospin symmetry breaking interactions on neutron-skin thickness
• Isospin effects in N~Z nuclei in extended Density Functional Theory
• High precision mass measurements of the isomeric and ground states of ${}^{44}$V: improving constraints on the IMME parameters of the A=44, ${\text{0}}^{\text{+}}$ quintet
• Search for the $\alpha$ + core structure in the ground state bands of $22\le Z\le 42$ even-even nuclei
• Neutrino Spectra from Nuclear Weak Interactions in $sd$-Shell Nuclei Under Astrophysical Conditions
• Exploring isospin-nonconserving effects in the upper $fp$ shell with new mass measurements
• Relativistic correction of the Coulomb interaction in the local density approximation for energies and radii in doubly-magic nuclei