Shape evolution in even-even N≤126, Z≥82 nuclei

Abstract

The shape evolution in the neutron-de cient lead, polonium and radium nuclei has been investigated via in-beam and delayed y-ray and conversion electron spectroscopy. The lead isotope 180Pb is found to still exhibit prolate excited structure, related to the known intruder structures in the heavier isotopes. The production cross-section of 180Pb was only 10 nb, one of the lowest ever employed in an in-beam experiment. A candidate for an excited prolate band was found in 192Po, making it the rst polonium isotope for which both oblate and prolate rotational bands have been established. Contrary to the previous results, the current experiments indicate that the onset of deformation in the radium isotopic chain seems not to take place yet in 206Ra. Based on the very similar decay patterns obtained in several in-beam experiments on the neutronde cient nuclei in the region and on the statistical limits of detection, three possible further cases for experiments are proposed. Methods developed for the data analysis, specially aimed at the studies of exotic nuclei, are presented.