Shape coexistence and multiparticle-multihole structures in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Cd</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>110</mml:mn><mml:mo>,</mml:mo><mml:mn>112</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>
P. E. Garrett, T. Rodrı́guez, A. Diaz Varela, K. L. Green, J. Bangay, A. Finlay, R. A. E. Austin, G. C. Ball, D. Bandyopadhyay, V. Bildstein, S. Colosimo, D. S. Cross, G. A. Demand, P. Finlay, A. B. Garnsworthy, G. F. Grinyer, G. Hackman, B. Jigmeddorj, J. Jolie, W. D. Kulp, K. G. Leach, A. C. Morton, J. N. Orce, C. J. Pearson, A. A. Phillips, A. J. Radich, E. T. Rand, M. A. Schumaker, C. E. Svensson, C. S. Sumithrarachchi, S. Triambak, N. Warr, J. Wong, John L. Wood, S. W. Yates
Abstract
From detailed spectroscopy of $^{110}\mathrm{Cd}$ and $^{112}\mathrm{Cd}$ following the ${\ensuremath{\beta}}^{+}/\mathrm{EC}$ decay of $^{110,112}\mathrm{In}$ and the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{112}\mathrm{Ag}$, the presence of very weak decay branches from nonyrast states is revealed. In $^{112}\mathrm{Cd}$, ${2}_{5}^{+}\ensuremath{\rightarrow}{0}_{4}^{+}$ and ${4}_{6}^{+}\ensuremath{\rightarrow}{2}_{5}^{+}$ transitions are observed that yield $B(E2;{2}_{5}^{+}\ensuremath{\rightarrow}{0}_{4}^{+})=34\ifmmode\pm\else\textpm\fi{}15$ W.u. and $B(E2;{4}_{6}^{+}\ensuremath{\rightarrow}{2}_{5}^{+})=77\ifmmode\pm\else\textpm\fi{}30$ W.u., respectively, clearly indicating a collective structure. In $^{110}\mathrm{Cd}$, a weak decay branch from the ${4}_{6}^{+}$ level to the ${2}_{5}^{+}$ level is observed, and from a lifetime measurement following the $(n,{n}^{\ensuremath{'}}\ensuremath{\gamma})$ reaction, $B(E2;{4}_{6}^{+}\ensuremath{\rightarrow}{2}_{5}^{+})=55\ifmmode\pm\else\textpm\fi{}14$ W.u. is determined. A new branch is also observed for the decay of the ${6}_{4}^{+}$ level to the ${4}_{6}^{+}$ state, indicating that the sequence ${2}_{5}^{+}$, ${4}_{6}^{+}$, and ${6}_{4}^{+}$ forms part of a collective structure. The presence of ${3}_{3}^{+}$ and ${5}_{2}^{+}$ levels spaced between the previous sequence is highly suggestive of a $\ensuremath{\gamma}$ band built on the ${0}_{2}^{+}$ shape-coexisting intruder state. The ${0}_{4}^{+}$ levels in $^{110,112,114}\mathrm{Cd}$ have preferred decays to the lowest ${2}^{+}$ members of the intruder bands, and for $^{114}\mathrm{Cd}$ a previous measurement had established an enhanced $B(E2;{0}_{4}^{+}\ensuremath{\rightarrow}{2}_{3}^{+})$. The energy systematics of the ${0}_{2}^{+}$, ${0}_{3}^{+}$, and ${0}_{4}^{+}$ levels all display the characteristic parabolic-shaped pattern, suggesting that they are built on multiparticle-multihole proton excitations. The results are compared with beyond-mean-field calculations that reproduce qualitatively the observed levels and their decays and suggest that the ${0}_{1}^{+}$, ${0}_{2}^{+}$, ${0}_{3}^{+}$, and ${0}_{4}^{+}$ levels and the excited states built on them possess different deformations.