Search for proton emission of the isomeric 10+ state in 54 Ni

Abstract

Several experiments were conducted at the 10 MV Van-de-Graaff tandem accelerator at the Institute of Nuclear Physics, Cologne, to detect proton emission from the isomeric 6457-keV 10 + state in 54Ni. Excitation functions for two fusion–evaporation reactions were measured to maximise the population of the rare two-neutron evaporation channel from a 56Ni compound nucleus. The search for delayed proton emission was based on the 28Si (28Si , 2 n)54Ni reaction at a beam energy of 70 MeV. For this reaction, a cross-section limit for the population of the 10 + state in 54Ni and its proton-decay branch was determined to be σ< 22 nb.