Multiphonon excitations in 62Zn

We studied excited states in 62Zn up to an excitation energy of 5.5 MeV via the 61Ni(3He, 2nγ) reaction at the Cologne Tandem accelerator with the high-efficiency HORUS cube spectrometer. We identified several multi-phonon excitations, especially two fragments of the one-phonon mixed-symmetry state image based on effective M1 and E2 transition strengths. The quantities were obtained from γγ angular correlation and Doppler-shift measurements. Shell-model calculations performed for 62Zn give clear support for the fragmentation of the one-phonon mixed-symmetry image state. The assumption of 62Zn being a vibrator-like nucleus is supported by calculations of excitation energies and E2 and M1 transition strengths within the U(5) limit of the neutron–proton Interacting Boson Model.