The region south of 68Ni (Z=28, N=40) is of particular interest due to an observed onset of deformation in the cobalt [1], iron [2] and chromium [3,4] isotopes. The shape-driving orbitals in this region are believed to be 1g9/2 and 2d5/2. The tensor interaction [5] between neutrons in the latter orbitals and protons in the 1f7/2 orbital further enhances collectivity with decreasing proton number. Shell-model calculations in the proton(f7/2, p3/2, f5/2, p1/2) and neutron(p3/2, f5/2, p1/2, g9/2) model space are on the verge of explaining the observed nuclear structure.

This work will report on a beta-decay study of the neutron-rich 58,60-68Mn isotopes. The isotopes were produced at the ISOLDE facility (CERN, Geneva, Switzerland) in a proton-induced fission of 238U and selected using resonant laser ionization combined with mass separation.

Spectra and decay schemes will be shown and the latest results will be presented. The detailed level schemes of both the Fe daughter and Co grand-daughter isotopes will constitute an important benchmark for establishing proper effective interactions in the 68Ni region.

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[2] M. Hannawald et al., Phys. Rev. Lett. 82 (1999) 1391
[3] O. Sorlin et al., Eur. Phys. J A 16 (2003) 55-61
[4] P. Adrich et al., Phys. Rev. C 77 (2008) 054306
[5] T. Otsuka et al., Phys. Rev. Lett. 95 (2005) 232502