The doubly-magic character of146Gd and its relation to208Pb

Abstract

Recent experiments indicate the possibility of a doubly-magic character for the nucleus ~46Gd (Z=64, N=82). In this work the results of a large-scale shell-model study on the nucleus 146Gd and its neighbouring nuclei 145Eu, ~4SGd, 147Gd and 147Tb are presented. The configurations taken into account include up to 2p-2h excitations for protons and/or neutrons. The calculated spectra and static moments are compared with the experimental data. Finally, the present results on shell closure in 146Gd are discussed in connection with those derived from a similar approach applied to the well-known doubly-magic nucleus 2~

Extended shell model calculation for even N = 82 isotones with a realistic effective interaction

“…Small but important differences in the single-particle spectra are found between [23][24][25] and speculations about the size of the single-particle energy gap at Z = 64. However, it now seems clear that 146 Gd has doubly magic properties, but the subshell closure does not appear as pronounced as for 208 Pb [2].…”

“…Abbas [1] even goes as far as to claim that all the N = 82 and Z = 58, 60, 62, 64, 66, 68, 70 nuclei were doubly magic. At least for 146 Gd the doubly magic character and the subshell closure at Z = 64 is rather well established [2,3].…”

Evidence for single particle structure of high spin states inPm144andPm<

“…4i (2) 93 (4) 41 (2) 34s(so) i16(s) 4S9(22) 72(3} ia2 (6) i66 ( o.av (16) 0.84 (20) o.4s (11) 0.55 (13) 0.465 ( Intensities from coincidence data (85 MeV).…”

“…With the discovery of the Z = 64 subshell closure [19] it became possible to discuss properties of nuclei near sGd in terms of a small number of valence protons or proton holes. Even though the proton-shell closure becomes less pronounced when neutrons are coupled to the Z = 64, K = 82 core [20], Z = 64 nuclei remain spherical for N ( 86 and do not become well deformed until N ) 90 [1]. As a result, a shell-model-like description is possible for nuclei close to the N = 82 shell closure.…”

Occupation probabilities of single particle levels using the microscopic interacting boson model: Application to some nuclei of interest in neutrinoless double-βdecay

“…The isovector SDI strength A 1 was fitted to reproduce the excitation energy of the 2 + 1 state in 134 Te. We have also considered an alternative set of proton particle energies suitable for A = 150 based on the assumption of a subshell closure at Z = 64 [35][36][37][38][39][40]. They were extracted from the excitation spectrum of 147 Tb.…”