Dipole and quadrupole moments of Cu73–78 as a test of the robustness of the Z=28 shell closure near

R. P. de Groote

¹

,

T. Day Goodacre

²

,

Kieran Flanagan

³

et al.

Abstract

Nuclear spins and precise values of the magnetic dipole and electric quadrupole moments of the ground states of neutron-rich 73-78 Cu isotopes were measured using the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the CERN On-Line Isotope Mass Separator (ISOLDE) facility. The nuclear moments of the less exotic 73,75 Cu isotopes were remeasured with similar precision, yielding values that are consistent with earlier measurements. The moments of the odd-odd isotopes, and 78 29 Cu (N = 49) in particular, are used to investigate excitations of the assumed doubly magic 78 Ni core through comparisons with large-scale shell-model calculations. Despite the narrowing of the Z = 28 shell gap between N ∼ 45 and N = 50, the magicity of Z = 28 and N = 50 is restored toward 78 Ni. This is due to weakened dynamical correlations, as clearly probed by the present moment measurements.

Investigating the large deformation of the 5/2+ isomeric state in Zn73 : An indicator for triaxiality

“…It illustrates that in 73m Zn a certain degree of proton excitations across the closed Z = 28 shell and neutron excitations across the N = 50 shell gaps are important. This was also observed recently in the neutron-rich Cu isotopes via mass and moment measurements [17,36]. The most noteworthy conclusion from Fig.…”

“…Measurements of ground state properties from laser spectroscopy have also provided considerable nuclear structure information in this region [14][15][16][17][18][19]. With one proton above Z = 28, a study of Cu isotopes revealed a primarily single-particle nature and a weak "magic" behavior around N = 40 from the spins, moments, and charge radii, but also showed a nonnegligible contribution from NN correlations and cross-shell excitations [14,16,17].…”

“…With one proton above Z = 28, a study of Cu isotopes revealed a primarily single-particle nature and a weak "magic" behavior around N = 40 from the spins, moments, and charge radii, but also showed a nonnegligible contribution from NN correlations and cross-shell excitations [14,16,17]. In contrast, with two and three protons above Z = 28, the collective behavior above N > 40 is significantly enhanced in the Zn and Ga isotopic chains, as indicated by their measured quadrupole moments [15,19].…”

Skyrme density functional description of the double magic Ni78 nucleus

“…At the same time the production of copper isotopes 75−79 Cu at the CERN-ISOLDE facility supports the doubly magic character of 78 Ni [4]. The magnetic dipole and the electric quadrupole moments of 78 29 Cu and other Cu isotopes, measured using the CRIS experiment at the CERN-ISOLDE facility suggests that the magicity of Z = 28 and N = 50 is restored towards 78 Ni [5].…”

Precision measurements of the charge radii of potassium isotopes

“…Precision laser spectroscopy can simultaneously measure multiple nuclear properties of isotopes in a nuclear modelindependent way, such as nuclear spins, electromagnetic moments, and changes in the mean-square charge radii. This makes such measurements a major ingredient for nuclear structure studies in different regions of the nuclear chart, providing important benchmarks for testing and developing state-of-the-art nuclear theories [1][2][3][4][5][6][7][8].…”