New evidence for alpha clustering structure in the ground state band of ²¹²Po

Half-lives of the low-lying yrast states of ²¹²Po have been measured using the delayed coincidence fast-timing method. We report on the first measurement of the 4₁⁺ half-life, as well as a new measurement of the 6₁⁺ half-life with improved accuracy compared to previous studies. The extracted lifetime of the 4₁⁺ and 6₁⁺ state have been determined to be 100(14) ps and 1.66(28) ns respectively. With these measurements, precise values are now available for the reduced transition strengths B(E2) of all ground state band levels in ²¹²Po up to the first 8⁺ state, in particular B(E2; 4₁⁺→2₁⁺) = 9.4(13) W.u. and B(E2;6₁⁺→4₁⁺) = 8.7(15) W.u. Comparison of the new available data with an α-clustering model calculation provides evidence that the inclusion of the α-cluster degree of freedom significantly improves agreement with experimental data compared to earlier shell model calculations.