1. Revealing the nature of yrast states in neutron-rich polonium isotopes
- Author
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Lică, R., Andreyev, A. N., Naïdja, H., Blazhev, A., Van Duppen, P., Andel, B., Algora, A., Antalic, S., Benito, J., Benzoni, G., Berry, T., Borge, M. J. G., Costache, C., Cubiss, J. G., De Witte, H., Fraile, L. M., Fynbo, H. O. U., Greenlees, P. T., Harkness-Brennan, L. J., Huyse, M., Illana, A., Jolie, J., Judson, D. S., Konki, J., Lazarus, I., Madurga, M., Marginean, N., Marginean, R., Mihai, C., Mihai, R. E., Mosat, P., Murias, J. R., Nacher, E., Negret, A., Page, R. D., Perea, A., Pucknell, V., Rahkila, P., Rezynkina, K., Sánchez-Tembleque, V., Schomacker, K., Stryjczyk, M., Sürder, C., Tengblad, O., Vedia, V., and Warr, N.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
Polonium isotopes having two protons above the shell closure at $Z=82$ show a wide variety of low-lying high-spin isomeric states across the whole chain. The structure of neutron-deficient isotopes up to $^{210}$Po ($N=126$) is well established as they are easily produced through various methods. However, there is not much information available for the neutron-rich counterparts for which only selective techniques can be used for their production. We report on the first fast-timing measurements of yrast states up to the 8$^+$ level in $^{214,216,218}$Po isotopes produced in the $\beta^-$ decay of $^{214,216,218}$Bi at ISOLDE, CERN. In particular, our new half-life value of 607(14) ps for the 8$_1^+$ state in $^{214}$Po is nearly 20 times shorter than the one available in literature and comparable with the newly measured half-lives of 409(16) and 628(25) ps for the corresponding 8$_1^+$ states in $^{216,218}$Po, respectively. The measured $B(E2;8_1^+ \to 6_1^+)$ transition probability values follow an increasing trend relative to isotope mass, reaching a maximum for $^{216}$Po. The increase contradicts the previous claims of isomerism for the $8^+$ yrast states in neutron-rich $^{214}$Po and beyond. Together with the other measured yrast transitions, the $B(E2)$ values provide a crucial test of the different theoretical approaches describing the underlying configurations of the yrast band. The new experimental results are compared to shell-model calculations using the KHPE and H208 effective interactions and their pairing modified versions, showing an increase in configuration mixing when moving towards the heavier isotopes., Comment: 6 pages, 5 figures (main manuscript), 2 pages (supplemental material)
- Published
- 2024