Gamma spectroscopy as a tool to search for particle–phonon coupled states: status and perspectives

The coupling mechanism between a particle and a phonon is a basic phenomenon in fermonic many-body interacting systems, which is here experimentally investigated in neutron-rich nuclei by in-beam γ-spectroscopy. In particular, nuclei around doubly magic 48Ca are studied by the heavy-ion transfer reaction 48Ca on 64Ni at 282 MeV, with the PRISMA-CLARA setup at Legnaro Laboratory of INFN. Angular distributions, polarizations and lifetimes analyses are used to probe spin and parities of several excited states, shading lights on their configuration. In the one-neutron transfer channels (49Ca and 47Ca), states arising from coupling of a single particle to the 3− phonon of 48Ca are identified, showing the robustness of nuclear collectivity in rather light systems. Preliminary results on 65Cu are also discussed with regard to the coupling of the p3/2 unpaired proton to the 3− phonon of 64Ni. Experimental results are interpreted using a phenomenological weak-coupling model, which is also used to provide predictions on exotic systems around the doubly magic 132Sn core.