Two-hole structure outside Ni 78 : Existence of a μ s isomer of Co 76 and β decay into Ni 76

This work was carried out at the RIBF operated by RIKEN Nishina Center, RIKEN, and CNS, University of Tokyo. We acknowledge the EUROBALL Owners Committee for the loan of germanium detectors and the PreSpec Collaboration for the readout electronics of the cluster detectors. Part of the WAS3ABi was supported by the Rare Isotope Science Project which is funded by the Ministry of Education, Science and Technology (MEST) and National Research Foundation (NRF) of Korea. Parts of this work were supported by Kakenhi Grant No. 25247045 and Spanish Ministerio de Ciencia e Innovacion under Contracts No. FPA2009-13377-C02 and No. FPA2011-29854-C04 and OTKA Contracts No. K100835 and No. K106035. PAS was financed by the Japan Society for Promotion of Sciences (JSPS) Kakenhi Grant No. 23.01752 and the RIKEN Foreign Postdoctoral Researcher Program. V.W. was supported by U.S. DOE Grant No. DE-FG02-91ER-40609 and the German BMBF under Grant No. 05P12RDFN8.