Cold multiproton-transfer reactions in the system 86Kr+54Fe below the Coulomb barrier

Angular distributions of the one- up to four-proton transfer have been measured in the system 86Kr+54Fe at an energy of Elab=291 MeV. The one- and two-proton-transfer angular distributions are well described by the distorted-wave Born approximation. The three- and four-proton transfers show strong deviations from this approach with contributions which are isotropic. The isotropic component is attributed to reaction processes with a longer time scale. This conjecture is supported by the observed total energy loss of 15--20 MeV, consistent with fission systematics, where strongly deformed and cold fragments are produced. These results are interpreted as the decay of a long-lived two-center system which is stabilized by shell effects