Résumé du preprint Irfu-10-70

Irfu-10-70
Onset of collectivity in neutron-rich Fe isotopes: Toward a new island of inversion?
J.Ljungvall, A.Görgen, A.Obertelli, W.Korten, E.Clement, G.de France, A.Bürger, J.P.Delaroche, A.Dewald, A.Gadea, L.Gaudefroy, M.Girod, M.Hackstein, J.Libert, D.Mengoni, F.Nowacki, T.Pissulla, A.Poves, F.Recchia, M.Rejmiund, W.Rother, E.Sahin, C.Schmitt, A.Shrivastava, K.Sieja, J.J.Valiente-Dobon, K.O.Zell, M.Zielinska
The lifetimes of the first excited 2+ states in 62Fe and 64Fe have been measured for the first time using the recoil-distance Doppler shift method after multi-nucleon transfer reactions in inverse kinematics. A sudden increase of collectivity from 62Fe to 64Fe is observed. The experimental results are compared with new large-scale shell model calculations and Hartree-Fock-Bogolyubov-based configuration-mixing calculations using the Gogny D1S interaction. The results give a deeper understanding of the mechanism leading to an onset of collectivity near 68Ni, which is compared with the situation in the so-called island of inversion around 32Mg.