Speaker
Description
The isomeric decay of $^{157}_{\,\,62}$Sm was observed for the first time during experiment G-22-00100-1.1-S (S100), conducted at GSI in the spring of 2024. A novel $^{170}$Er beam was fragmented at 1.08 GeV/u on a 6 gm/cm$^{2}$ $^9$Be target. The fragmentation products were separated and identified using the FRagment Separator (FRS) and implanted in the Advanced Implantation Detector Array of the Decay Spectroscopy setup at the S4 focal plane of the FRS. A suite of 12 triple-cluster germanium detectors and 36 fast-timing LaBr$_3$ detectors were employed to study the γ-decay of the stopped fragments. Here, we present the preliminary results for the level scheme and lifetime of the isomeric decay of $^{157}$Sm. The measured level scheme is incorporated with those of recent studies where excited states of $^{157}$Sm were populated via $\beta$-decay [2] and proton induced fission [3].
[1] Li, G. S. et al., Nucl. Instrum. and Methods Phys. Res. A 987, 164806 (2021)
[2] Hartley, D.J. et al., Phys. Rev. C 110, 044319 (2024)
[3] Zachary, C.J., 2019. New Insights into the Structure of Neutron-rich Nuclei $^{157}$Sm, $^{163}$Gd, and $^{163}$Tb (Ph.D.).
keywords: isomeric decay, fragmentation, high-resolution spectroscopy, FAIR Phase-0
