Isolated one-phonon mixed-symmetry 2+ state of the radioactive neutron-rich nuclide 132Te
T. Stetz, H. Mayr, V. Werner, N. Pietralla, Y. Tsunoda, T. Otsuka, G. Rainovski, T. Beck, R. Borcea, S. Calinescu, C. Costache, I. E. Dinescu, K. E. Ide, A. N. Ionescu, P. Koseoglou, R. Lica, N. Mărginean, R. E. Mihai, C. M. Nickel, C. R. Nita, L. Stan, S. Toma, R. Zidarova
Published: 2024/12/20
Abstract
The $M1$ transition strengths between excited $2^+$ states of the neutron-rich, radioactive nuclide $^{132}$Te have been studied through direct lifetime measurements using the Doppler-shift attenuation method in a two-neutron transfer reaction on a $^{130}$Te target. An unambiguous identification of the lowest-lying mixed-symmetry $2^+$ state has been achieved on the basis of the large $B(M1;2^+_2\rightarrow2^+_1$)=0.18(2) $\mu_\mathrm{N}^2$ transition strength, in agreement with shell-model calculations. Results are compared to the shell model, and the analysis of both, data and calculations, unambiguously identifies the second-excited $2^+$ state of $^{132}$Te as the one-quadrupole phonon mixed-symmetry state of this isotope. A lowering of the energy and $B(M1;2^+_\mathrm{ms}\rightarrow 2^+_1)$ strength within the $N$=80 isotones toward the $Z$=50 shell closure is observed, which goes alongside with the lowering of the $E2$ collectivity approaching the magic proton shell.