Speaker
Description
Polonium isotopes having two protons above the shell closure at $Z = 82$ demonstrate a wide variety of high-spin isomeric states across the whole chain.
The structure of neutron-deficient isotopes up to $^{210}$Po ($N = 126$) is well established thanks to being easily produced through different methods, as opposed to their neutron-rich counterparts for which not much information is currently available and only selective techniques can be used for production.
The presentation will focus on first fast-timing measurements of yrast states up to $8^+$ in $^{214,216,218}$Po isotopes produced in the β-decay of $^{214,216,218}$Bi at the ISOLDE Decay Station of ISOLDE-CERN. The only half-life value previously available in literature corresponding to the $8^+$ state in $^{214}$Po was 20 times larger than the presently reported one. The extracted transition probabilities $B(E2)$ values provide a crucial test of the different theoretical approaches describing the underlying configurations of the yrast band.
The new experimental results are described by shell-model calculations using the KHPE and H208 effective interactions and their pairing modified versions. These results contradict the previous expectations of isomerism for the $8^+$ yrast states in neutron-rich polonium isotopes, showing an increase in configuration mixing as opposed to the simple seniority scheme applicable in the neutron-deficient cases.
