We calculate the B(E2) strength in 68Ni and other nickel isotopes using several theoretical approaches. We find that in 68Ni the gamma transition to the first 2+ state exhausts only a fraction of the total B(E2) strength, which is mainly collected in excited states around 5 MeV. This effect is sensitive to the energy splitting between the fp shell and the g_{9/2}orbital. We argue that the small experimental B(E2) value is not strong evidence for the double-magic character of 68Ni.
@article{arxiv.nucl-th/0210089,
title = {How magic is the magic 68Ni nucleus?},
author = {K. Langanke and J. Terasaki and F. Nowacki and D. J. Dean and W. Nazarewicz},
journal= {arXiv preprint arXiv:nucl-th/0210089},
year = {2009}
}