SPECTROSCOPY OF PB-186 WITH MASS IDENTIFICATION

Transitions in the very neutron-deficient isotope 186Pb have been iden tified in mass-gated, recoil-gamma, and recoil-gamma-gamma coincidence data obtained with a fragment mass analyzer and Compton-suppressed Ge -detector array. The results of the present work confirm and extend a band of levels tentatively proposed in earlier work done elsewhere, an d provide a definitive mass assignment of the observed transitions. Th e band observed in 186Pb bears a very close resemblance to the yrast b and in the isotone 184Hg, supporting the view that the 186Pb band is b uilt upon a prolate structure.