Speaker
Description
The odd-odd bismuth isotopes ($Z$ = 83) and their $\beta$-decay polonium daughters $(Z\,=\,84)$ are excellent subjects for nuclear structure studies. With only one and two protons, respectively, above the closed shell $Z$ = 82, they provide an outstanding testing ground for shell-model calculations, and in the case of polonium isotopes, also for the seniority scheme. Moreover, both isotopic chains exhibit a wide variety of low-lying isomers. While the neutron-deficient bismuth and polonium isotopes are rather well explored, the information on the neutron-rich side is often scarce because of limitations in available experimental techniques.
In this contribution, results of a high-statistics $\beta$-decay experiment aimed at neutron-rich $^{214,216,218}$Bi isotopes carried out at ISOLDE Decay Station (IDS) [1] are discussed. The levels populated in daughter nuclei were investigated employing an array of HPGe clover and fast-timing LaBr detectors. A new isomer was identified in $^{214}$Bi [2] and complex decay schemes of $^{216g,m}$Bi were established [3]. Lifetimes of yrast levels in $^{214,216,218}$Po were measured and the deduced transition probabilities $B(E2)$ were confronted with theoretical models [4]. Shell-model calculations based on two different effective interactions, the H208 [5] and the modified Kuo-Herling particle interaction [6], were performed and compared with experimental results. Preferred spin and parity assignments for $^{214m}$Bi and $^{216g,m}$Bi based on the calculations and observed $\beta$-decay feeding intensities will be discussed.
References
[1] https://isolde-ids.web.cern.ch/
[2] B. Andel et al., Phys. Rev. C 104, 054301 (2021).
[3] B. Andel et al., Phys. Rev. C 109, 064321 (2024).
[4] R. Lica et al., submitted to Phys. Rev. Lett.
[5] H. Naïdja, Phys. Scr. 94, 014005 (2019).
[6] E. K. Warburton and B. A. Brown, Phys. Rev. C 43, 602 (1991).
