Search

The lifetimes of the $ 2^+_1$ , the $ 2^+_2$ and the $ 3^-_1$ states of Po have been measured in the Pb(C,Be)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 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. [ABSTRACT FROM AUTHOR]

We present the results from an experiment dedicated to search for quadrupole-collective isovector valence-shell excitations, states with so-called mixed proton-neutron symmetry (MSS), of 212Po. This nucleus was studied in an α-transfer reaction. The lifetimes of two short-lived excited states, candidates for the one-phonon MSS, were determined by utilizing the Doppler shift attenuation method. The experimental results are in qualitative agreement with a simple single-j shell model calculation, which, together with the observed lack of quadrupole collectivity, indicates that the isovector nature of low-lying states is a property of the leading single-particle valence shell configuration. [ABSTRACT FROM AUTHOR]