Isomeric ratios for nuclei with Z=62-67 and A=142-152 produced in the relativistic fragmentation of 208Pb

We have investigated isomeric states in a number of nuclei with Z=62-67 and A=142-152, produced by the fragmentation of the relativistic(1 GeV/u) 208Pb beam from the SIS-18 synchrotron of the GSI facility on a 9Be target, and selected by the FRagment Separator(FRS). The selected nuclei of interest were implanted into the stopper, a block of plastic 7mm thick. The gamma-rays from the decay of isomeric states in the implanted nuclei were measured by the high purity germanium array, RISING. In total 22 nuclides were detected, isomeric states were observed in 9 of them:19- in 152Ho, 31/2+ in 153Ho, 27+ in 148Tb, 10+in 144Gd, 49/2+in 147Gd, 11/2- in 143Eu, 8- in 144Eu, 11/2- in 145Eu, 10+ in 142Sm and 7- in 142Sm. Of special interest is the 27+ state in 148Tb, the highest spin populated through the fragmentation reaction until present day. The aim of this work was the extraction of isomeric ratios(R) for these isomeric states. The R is the number of ions populated in a given isomeric state compared to the total number of ions populated for the selected nuclide. The R can provide information about the production reaction and nuclear structure. It was evaluated based on flight time, half-life, in-flight losses and by considering the finite measurement time. Results were compared with theoretical predictions, calculated using an abrasion-ablation approach.