Population of a low-spin positive-parity band from high-spin intruder states in 177Au: The two-state mixing effect

New collective structures in Au179 and their implications for the triaxial deformation of the Pt178 core

“…The odd-mass Au isotopes offer a broad systematic view of nuclear structure in a region of near-degenerate, multiple coexisting shapes [1]. The most neutron-deficient Au isotopes have been the subject of an extensive program of investigation using γ -ray and conversion-electron studies following β decay [2][3][4][5][6][7][8], in-beam reaction γ -ray spectroscopy [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], spectroscopy of directly produced isomeric states [25,26], in-beam isomer-tagged studies [27], laser-induced hyperfine spectroscopy [28][29][30], and α-decay studies of odd-mass Tl isotopes [25,[31][32][33]. Nevertheless, in comparison to the heavier Tl and Au isotopes, where multiple shape coexistence has been established [1,4,34,35], a rich variety of structures remain to be discovered.…”

“…This isomer played a major role in advancing the understanding of nuclear structure of odd-mass Au isotopes. Its discovery initiated a focused research program, which resulted in a significant extension of the systematics of the excited states of odd-mass Au isotopes beyond the N = 104 midshell point [2,3,20,27]. The isomer has two parallel decay branches, feeding the 1/2 + ground state: the 62.4-27.1 keV cascade and the 89.5 keV crossover transition.…”

“…Both the 62.4 and 89.5 keV transitions were unambiguously shown to have a retarded E1 nature [25] and therefore they are only weakly converted. Another in-beam study [27] suggested modifications to the level scheme proposed in [15]. Very recently a comprehensive study of decay modes of 183 Tl m was performed at ISOLDE, which extended the decay scheme given in [25].…”

Identification of sub- μs isomeric states in the odd-odd nucleus Au178

“…The region surrounding the Z = 82 shell closure is well known for its exhibition of shape coexistence [1]. The neutron-deficient gold (Z = 79) isotopes are one of the earliest examples of this phenomenon, and have been studied by a variety of decay and in-beam nuclear spectroscopy techniques [2][3][4][5][6][7][8][9][10]; see also the recent review [11] and references therein. The ground state of gold nuclei displays a large increase in the mean-squared charge radius when approaching the N = 104 midshell [12,13].…”

“…While the gold isotopes with A > 186 possess weakly oblate ground states, [183][184][185][186] Au are seen to have strong, prolate shapes. This sudden change in ground-state deformation has been related to the presence of π i 13/2 , π h 9/2 , and π f 7/2 intruder states at low energies, alongside spherical π s 1/2 , π d 3/2 , and π h 11/2 configurations [5,7,8]. Rotational bands built on top of these intruder states have been identified in several odd-A isotopes [2,[14][15][16], with an observed parabolic trend in the bandhead energies as a function of neutron number (see for example, Fig.…”