Evolution of the nuclear structure approachingNi78:βdecay ofCu

Abstract

A β-decay study of the even mass 74,76,78 Cu isotopes toward levels in 74,76,78 Zn was performed at the ISOLDE mass separator. The copper isotopes were produced in proton-or neutron-induced fission reactions on 238 U, laser ionized, mass separated, and sent to a β-γ detection system. Half-lives, decay schemes, and possible spin configurations were obtained for the copper isotopes. The results are compared with calculations using schematic forces as well as large-scale shell-model calculations with realistic forces.

β-decay study ofCu77

“…The 772 keV (1/2 − isomeric state, T 1/2 = 1.05 ± 0.10 s) has been identified in Ref. [29] and the 114.7 keV level together with the 800 keV level has been identified in the β-delayed neutron emission of 78 Cu [15]. Only recently, more levels were identified in a decay study at HRIBF [30,31].…”

“…6 could be constructed based on the coincidence relations given in Table II. Furthermore, use has been made of the β-delayed neutron-decay data from 78 Cu [15] (see also Fig. 7).…”

“…A more detailed description of the experimental setup can be found in Refs. [15,18,19]. In this subtracted spectrum the activity coming from the β decay of 77 Cu can be easily identified (labeled by numbers).…”

“…On the same ground, recent mass measurements in this region show a very weak irregularity in the two-neutron-separation energies around N = 40 giving no evidence for a well-established shell closure [7,8]. The same mass region was further studied by means of Coulomb excitation and β-decay experiments in neighboring Cu and Zn neutron-rich isotopes [9][10][11][12][13][14][15]. From those studies the fragile nature of the N = 40 subshell closure was confirmed and the key role of the g 9/2 orbit was revealed in the systematics.…”

Investigating nuclear shell structure in the vicinity ofNi78: Low-lying excited states in the neutron-rich isotopesZn80,82<

“…The observed peaks exhibit a significance larger than 3σ . In Table I, the γ -ray intensities (I γ ) are given relative to the 2 [31,[42][43][44][45]. In the 82 Zn spectrum [ Fig.…”