Structure of Fe 70: Single-particle and collective degrees of freedom

Abstract

Excited states in the neutron-rich Fe70 nucleus were populated in a one-proton removal reaction from Co71 projectiles at 87 MeV/nucleon. A new transition was observed with the γ-ray tracking array GRETINA and shown to feed the previously assigned 41+ state. In comparison to reaction theory calculations with shell-model spectroscopic factors, it is argued that the new γ ray possibly originates from the 61+ state. It is further shown that the Doppler-reconstructed γ-ray spectra are sensitive to the very different lifetimes of the 2+ and 4+ states, enabling their approximate measurement. The emerging structure of Fe70 is discussed in comparison to LNPS-new large-scale shell-model calculations.