Octupole transitions in the 208Pb region

Abstract

The 208Pb region is characterised by the existence of collective octupole states. Here we populated such states in 208Pb + 208Pb deep-inelastic reactions. γ-ray angular distribution measurements were used to infer the octupole character of several E3 transitions. The octupole character of the 2318 keV 17- 14+ in 208Pb, 2485 keV 19/2- 13/2+ in 207Pb, 2419 keV 15/2- 9/2+ in 209Pb and 2465 keV 17/2+ 11/2- in 207Tl transitions was demonstrated for the first time. In addition, shell model calculations were performed using two different sets of two-body matrix elements. Their predictions were compared with emphasis on collective octupole states.