Observation of a $\gamma$-decaying millisecond isomeric state in $^{128}$Cd$_{80}$

A. Jungclaus et al. -- 6 pags., 5 figs., 2 tabs. -- Open Access funded by Creative Commons Atribution Licence 4.0
A new high-spin isomer in the neutron-rich nucleus Cd was populated in the projectile fission of a U beam at the Radioactive Isotope Beam Factory at RIKEN. A half-life of T=6.3(8) ms was measured for the new state which was tentatively assigned a spin/parity of (15). The experimental results are compared to shell model calculations performed using state-of-the-art realistic effective interactions and to the neighbouring nucleus Cd. In the present experiment no evidence was found for the decay of a 18 E6 spin-trap isomer, based on the complete alignment of the two-neutron and two-proton holes in the 0h and the 0g orbit, respectively, which is predicted to exist by the shell model.
We thank the staff of the RIKEN Nishina Center accelerator complex for providing stable beams with high intensities to the experiment. We acknowledge the EUROBALL Owners Committee for the loan of germanium detectors and the PreSpec Collaboration for the readout electronics of the cluster detectors. This work was supported by the Spanish Ministerio de Ciencia e Innovación under contract FPA2011-29854-C04 and the Spanish Ministerio de Economía y Competitividad under contract FPA2014-57196-C5-4-P, the Generalitat Valenciana (Spain) under grant PROMETEO/2010/101, the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (NRF-2014S1A2A2028636, 2016K1A3A7A09005579, 2016R1A5A1013277), the Priority Centers Research Program in Korea (2009-0093817), OTKA contract number K-100835, JSPS KAKENHI (Grant No. 25247045), the European Commission through the Marie Curie Actions call FP7-PEOPLE-2011-IEF under Contract No. 300096, the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357, the STFC (UK), the “RIKEN foreign research program”, the German BMBF (No. 05P12RDCIA, 05P12RDNUP and 05P12PKFNE), HIC for FAIR, the DFG cluster of excellence “Origin and Structure of the Universe” and DFG (Contract No. KR2326/2-1).