Decay properties of 68,69,70 Mn: Probing collectivity up to N = 44 in Fe isotopic chain

The β decays Mn68→Fe68 , Mn69→Fe69 and Mn70→Fe70 have been measured at the RIBF facility at RIKEN using the EURICA γ spectrometer combined with an active stopper consisting of a stack of Si detectors. The nuclei were produced as fission fragments from a beam of 238 U at a bombarding energy of 345 MeV/nucleon impinging on a Be target and selected using the BigRIPS separator. Half-lives and β -delayed neutron emission probabilities have been extracted for these decays, together with first experimental information on excited states populated in 69,70 Fe. The data indicate a continuously increasing deformation for Fe isotopes up to A=70 . This is interpreted, as for Cr isotopes, in terms of the interplay between the quadrupole correlations of the ν1d5/2 and ν0g9/2 orbitals and the monopole component of the π0f7/2–ν0f5/2 interaction.