Figure 1

Levels and transitions associated with the weakly deformed intruder structure in ${}^{154}\mathrm{G}\mathrm{d}$. Relative $B(E2)$ values (in brackets) show that the strongest collective transitions are the in-band 236 and 283 keV $\gamma$ rays.Reuse & Permissions

Figure 2

The 485 keV $\gamma$-gated $\gamma$-ray spectrum from the ${}^{154}\mathrm{T}\mathrm{b}$ decay showing transitions from the $4^{+}$ level at 1701.3 keV identified in Fig. 1. The intensity of the 485 keV $\gamma$ ray in the ${}^{154}\mathrm{T}\mathrm{b}$ ($J=3$) decay is $0.5\%$ relative to the 123 keV $\gamma$ ray.Reuse & Permissions

Figure 3

The ${}^{154}\mathrm{E}\mathrm{u}$ decay 188 keV $\gamma$-gated $\gamma$-ray spectrum. Boxes indicate the energy and measured $I_{\gamma }$ (per 100 $\beta$ decays) for coincident transitions out of the level at $1531.3\mathrm{k}\mathrm{e}\mathrm{V}$ (cf. reported [4] intensity in italics). The 238 keV transition feeding the reported $(2{)}^{+}$ level at $1293.6\mathrm{k}\mathrm{e}\mathrm{V}$ is missing (dotted line shape indicates the expected intensity). Doublets at $267.7$ ($1264\to 996$, $I_{\gamma }=0.012$) and $290.0\mathrm{k}\mathrm{e}\mathrm{V}$ ($1418\to 1128$, $I_{\gamma }=0.0016$) were previously unresolved. A new transition observed at 349 keV feeds the $0^{+}$ level at $1182.0\mathrm{k}\mathrm{e}\mathrm{V}$.Reuse & Permissions

Figure 4

A schematic depiction of the role of the ${\frac{11}{2}}^{-}$ $[505]$ orbital in the proposed structure. (a) The $\nu [505]\uparrow$ orbital is an isolated up-sloping orbital in this region. (b) In the ground state of ${}^{154}\mathrm{G}\mathrm{d}$, the reduced pairing gap of the pairing isomer results in an increased occupation, $V^2$, of the $\nu [505]\uparrow$ orbital. (c) When the $\nu [505]\uparrow$ orbital is occupied ($V^2=0.5$) by the unpaired neutron in odd-$N$ Gd isotopes (and occupancy is increased in the down-sloping orbitals) deformation is increased. (d) As population of this up-sloping orbital is further increased (at the expense of the neighboring down-sloping orbitals), deformation decreases.Reuse & Permissions