Abstract
The half-lives of excited isomeric states observed in Au-195, Tl-201 and Rn-215 are reported for the first time. Delayed gamma-rays were correlated with nuclei produced in the projectile fragmentation of relativistic U-238 ions, unambiguously identified in terms of their atomic number (Z) and mass-to-charge ratio (A/Q) after traversing an in-flight separator. The observation of a long-lived isomeric state in Au-195 with t(1/2) = 16(-4)(+8) mu s is presented. Two shorter-lived isomeric states were detected in Tl-201 and Rn-215 with t(1/2) = 95(-21)(+39) and 57(-12)(+21) ns respectively. In total 24 isomeric states were identified in different nuclei from Pt to Rn (A similar to 200) during the current study, the majority of which were previously reported. The wealth of spectroscopic data provides the opportunity to determine the isomeric ratios over a wide range of Z, A and angular momentum (I (h) over bar) of the reaction products. In particular, high-spin states with I greater than or similar to 18 (h) over bar provide a robust test of theoretical models of fragmentation.