A revised B(E2; 2$^{+}_{1} \to 0^{+}_{1}$) value in the semi-magic nucleus $^{210}$Po
Résumé
The lifetimes of the $ 2^+_1$ , the $ 2^+_2$ and the $ 3^-_1$ states of$^{210}$Po have been measured in the$^{208}$Pb($^{12}$C,$^{10}$Be)$^{210}$Po transfer reaction by the Doppler-shift attenuation method. The result for the lifetime of the $ 2^+_1$ state is about three times shorter than the adopted value. However, the new value still does not allow for a consistent description of the properties of the yrast $ 2^+_1$ , $ 4^+_1$ , $ 6^+_1$ , and $ 8^+_1$ states of$^{210}$Po in the framework of nuclear shell models. Quasi-particle Phonon Model (QPM) calculations also cannot overcome this problem thus indicating the existence of a peculiarity which is neglected in both theoretical approaches.