Shape Coexistence and Mixing of Low-Lying $0^{+}$ States in ${}^{96}$Sr

Abstract

The low energy excited $0_{2,3}^{+}$ states in ${}^{96}$Sr are amongst the most prominent examples of shape coexistence across the nuclear landscape. In this work, the neutron $[2s_{1/2}{]}^2$ content of the $0_{1,2,3}^{+}$ states in ${}^{96}$Sr was determined by means of the d(${}^{95}$Sr,p) transfer reaction at the TRIUMF-ISAC2 facility using the SHARC and TIGRESS arrays. Spectroscopic factors of 0.19(3) and 0.22(3) were extracted for the ${}^{96}$Sr ground and 1229~keV $0^{+}$ states, respectively, by fitting the experimental angular distributions to DWBA reaction model calculations. A detailed analysis of the ${\hat{I}}^3$-decay of the isomeric $0_3^{+}$ state was used to determine a spectroscopic factor of 0.33(13). The experimental results are compared to shell model calculations, which predict negligible spectroscopic strength for the excited $0^{+}$ states in ${}^{96}$Sr. The strengths of the excited $0_{2,3}^{+}$ states were also analyzed within a two-level mixing model and are consistent with a mixing strength of $a^2$=0.40(14) and a difference in intrinsic deformations of $|\hat{I}”{\hat{I}}^2|=0.31(3)$. These results suggest coexistence of three different configurations in ${}^{96}$Sr and strong shape mixing of the two excited $0^{+}$ states.

Phys Lett B accepted