Comparative study of rotational bands in theA≈60mass region: Modification of Nilsson parameters

Abstract

The large number of high-spin bands that have been observed in A = 56-62 nuclei are analyzed systematically within the cranked Nilsson-Strutinsky approach. Optimized Nilsson single-particle parameters are derived from investigations of energy differences between experimental and calculated rotational bands. Specifically, the relative energies of bands in neighboring nuclei whose configurations differ by having a high-j orbital either filled or empty are analyzed. The level schemes calculated with the new Nilsson parameters are compared with those using standard Nilsson parameters. Some configuration assignments are revised.

Single-particle and collective excitations inNi62

“…18 of Ref. [50]. These differences are in line with the expected average pairing energy as calculated for 161 Lu and 138 Nd in Refs.…”

“…IVB of Ref. [51] in the case of the 62 Zn nucleus, the number of g 9/2 particles in a configuration can generally be correlated with the spin value I 0 at the minimum of the E − E rld curve. According to the CNS calculations, this is true also for the low-lying collective bands in 62 Ni, which are formed in configurations with two f 7/2 proton holes.…”

“…The calculations were performed with the single-particle parameters used recently to interpret high-spin sequences in 63 Ni [22]. Those parameters were fitted originally to the high-spin bands of A = 56-62 nuclei [50]. In the CNS formalism, pairing effects are neglected as they are expected to play a minor role at high spin (>15h).…”

“…Hence, p 1 (n 1 ) denotes the number of holes in the orbitals of f 7/2 character and p 2 (n 2 ) refers to the number of particles in orbitals of g 9/2 parentage for protons (neutrons) relative to a closed 56 Ni core [48]. For an odd number of (f p) protons or neutrons, the (±) notation is added to specify the signature of these nucleons, where (f p) refers to the orbitals of p 3/2 f 5/2 character [50]. The number of protons and neutrons in these orbitals is determined by the condition that Z = 28 and N = 34.…”

Terminating states in the positive-parity structures of As67

“…Studies of high-angularmomentum states in proton-rich nuclei in the mass 60-75 region have revealed evidence for structures that reach their maximum spin state in different ways. For example, with only a few particles outside the 56 Ni core, the valence space configurations terminate in a noncollective state as seen, for example, in 62 Zn [2,3]. Furthermore, in 62 Zn, the same type of termination also occurs if one or two particles are excited across the N = Z = 28 shell gap.…”