Coulomb and nuclear excitations of Zn70 and Ni68 at intermediate energy

Abstract

The reduced transition probabilities B(E2; 0 + g.s. → 2 + 1 , 2 + 2 ) in 70 Zn and the full B(E2; 0 + g.s. → 2 + ) strength up to Sn=7.79 MeV in 68 Ni have been determined at the LISE/GANIL facility using the Coulomb-excitation technique at intermediate beam energy on a 208 Pb target. The γ rays emitted in-flight were detected with an array of 46 BaF2 crystals. The angles of the deflected nuclei were determined in order to disentangle and extract the Coulomb and nuclear contributions to the excitation of the 2 + states. The measured B(E2; 0 + g.s. → 2 + 1 ) of 1432(124) e 2 fm 4 for 70 Zn falls in the lower part of the published values which clustered either around 1600 or above 2000 e 2 fm 4 , while the B(E2; 0 + g.s. → 2 + 2 ) of 53(7) e 2 fm 4 agrees very well with the two published values. The relatively low B(E2; 0 + g.s. → 2 + 1 ) of 301(38) e 2 fm 4 for 68 Ni agrees with previous studies and confirms a local magicity at Z = 28, N = 40. Combining the results of the low-energy spectra of 68 Ni and 70 Zn and their shell-model interpretations, it is interesting to notice that four different shapes (spherical, oblate, prolate and triaxial) are present. Finally, a summed E2 strength of only about 150 e 2 fm 4 has been found experimentally at high excitation energy, likely due to proton excitations across the Z = 28 gap. The experimental distribution of this high-energy E2 excitation agrees with SM calculations, but its strength is about two times weaker.

Nuclear Structure with Discrete Non-Orthogonal Shell-Model : new frontiers

“…For the first time, we applied the DNO-SM method to a superheavy system 254 No which is obviously far beyond the capabilities of actual diagonalisations codes. The DNO-SM formalism has also recently been very useful in the interpretation of several experimental studies [57][58][59][60] and has been to be extremely promising both for instrinsic interpretation of shell-model diagonalisations, and setting new frontiers for nuclear structure studies within the shell-model framework. where we denote ∆K = K − A λ=1 m 1 (λ) and ∆K = K − A λ=1 m 2 (λ).…”

First Evidence of Axial Shape Asymmetry and Configuration Coexistence in Zn74 : Suggestion for a Northern Extension of the N=40Rocchini1, Garrett2, Zielińska3 et al. 2023Phys. Rev. Lett.Self Cite8000View full textAdd to dashboardCite

“…The experimental information on the development of deformation and shape coexistence in the Zn nuclei (Z ¼ 30) is more limited. Recently, on the basis of Coulomb-excitation measurements combined with largescale shell-model (LSSM) and beyond-mean-field calculations, triaxiality of the ground states in 66;70 Zn was proposed [27,28]. The large quadrupole moment of the 5=2 þ isomer in 73 Zn [29] was also linked to triaxiality following guidance from Monte-Carlo shell-model (MCSM) calculations that furthermore predicted considerable β and γ softness of the ground-state bands in 72;74 Zn [30].…”