Speaker
Description
Single-particle motion and nuclear collectivity are the two extremes which have shaped our understanding of the dynamics for the nuclear many-body system. A suitable region for studying the evolution of the nuclear states with the number of valence nucleons from single-particle configurations towards multiconfigurational mixture are the neutron-deficient Po isotopes in the vicinity of the doubly-magic nucleus $^{208}$Pb. To fill the gap in the evolution between the states of seniority-type character in $^{210}$Po [1] and those of collective nature in $^{204}$Po [2], we have studied the low-lying states of the even-even $^{206,208}$Po isotopes as well as the low-lying negative-parity states of $^{209}$Po. The results for the low-lying negative-parity states of $^{209}$Po show that the removal of one neutron from $^{210}$Po does not induce any additional quadrupole collectivity. If we remove further neutrons from the closed shell, the experimental results indicate that in Po isotopes the transition from single-particle to collective excitations has a pronounced spin-dependent behaviour. The nature of the $6^+_1$ and $8^+_1$ states remains of the seniority-type regime and the transition to collectivity occurs at N$\leq$120 since the structures of the $4^+_1$ and $2^+_1$ states of Po isotopes have already collective nature below N=124. In the present study will be summarized results from our previous studies for $^{208}$Po [3] and $^{209}$Po [4] as well as new results for the $B(E2;2^+_1 \to 0^+_1$) of $^{206}$Po will be presented.
- D. Kocheva et. al., Eur. Phys. J. A 53, 175 (2017).
- M. Stoyanova, et. al., Phys. Rev. C 10, 064304 (2019).
- D. Kalaydjieva et. al., Phys. Rev. C 104, 024311 (2021).
- V. Karayonchev et. al., Phys. Rev. C 103, 044309 (2021).
