Structure of N ≥ 126 nuclei produced in fragmentation of 238U

The nuclear structure of neutron-rich N≥126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV 238U beam on a Be target. The cocktail of secondary beam products was separated and identified using the GSI FRagment Separator (FRS) [1]. The nuclei of interest were implanted in a high-granularity active stopper detector set-up consisting of 6 double sided silicon strip detectors [2]. The associated gamma-ray transitions were detected with the RISING array, consisting of 15 Euroball cluster Ge-detectors. Time-correlated gamma decays from individually identified nuclear species have been recorded, allowing the clean identification of isomeric decays. The initial results of these investigations are compared with previous studies in nearby N=126 nuclei [3]. The preliminary analysis of the current data indicates the presence of previously unreported isomeric states in the N=128 isotones 208Hg and 209Tl.(author)