Coexistence of 'alpha+ 208Pb' cluster structures and single-particle excitations in 212Po

TL;DR

This study investigates the excited states of 212Po, revealing coexistence of alpha+208Pb cluster structures and single-particle excitations through gamma-ray spectroscopy and lifetime measurements.

Contribution

It extends the level scheme of 212Po and provides evidence for the coexistence of cluster and shell-model configurations in its excited states.

Findings

Extended the level scheme up to 3.2 MeV.

Identified enhanced E1 transitions with lifetimes 0.1-0.6 ps.

Observed states with non-natural parity linked to alpha-208Pb structures.

Abstract

Excited states in 212Po have been populated by alpha transfer using the 208Pb(18O,14C) reaction at 85MeV beam energy and studied with the EUROBALL IV gamma multidetector array. The level scheme has been extended up to ~ 3.2 MeV excitation energy from the triple gamma coincidence data. Spin and parity values of most of the observed states have been assigned from the gamma angular distributions and gamma -gamma angular correlations. Several gamma lines with E(gamma) < 1 MeV have been found to be shifted by the Doppler effect, allowing for the measurements of the associated lifetimes by the DSAM method. The values, found in the range [0.1-0.6] ps, lead to very enhanced E1 transitions. All the emitting states, which have non-natural parity values, are discussed in terms of alpha-208Pb structure. They are in the same excitation-energy range as the states issued from shell-model configurations.