Probing particle-phonon-coupled states in the neutron-rich nucleus Cu 65 by lifetime measurements with fast-timing techniques

Abstract

The Cu65 nucleus was populated by the Ni64(Li7,α2n)Cu65 reaction and the lifetime of the 9/2+ state at 2.5 MeV was measured by electronic fast-timing technique, providing the value τ= 37(3) ps. The reduced transition probability B(E3)=8.82(165) W.u. is deduced and compared to theoretical predictions in the framework of a particle-vibration (weak) coupling model. The results indicate that the 9/2+ state is a member of the 3- - πp3/2 multiplet, built by coupling the octupole 3- phonon of Ni64 to an unpaired proton in the p3/2 level, confirming the robustness of core excitations in the medium mass nucleus Ni64. © 2014 American Physical Society.