Intermediate-energy Coulomb excitation measurements wereperformed on the neutron-rich isotopes 58,60,62Crand the electric quadrupole transition probabilities, or B(E2;0+1&rightarrow 2+1) values, of 60,62Cr were determined forthe first time. The results quantify the trend of increasingcollectivity in the chromium isotopic chain approaching the neutron sub-shell gap N=40.For 60,62Cr, the ratios ofneutron to proton transition matrix elements, |Mn/Mp|, were determined by combining theCoulomb excitation data with results from inelastic proton scattering measurements.&gamma-ray spectroscopy was performed on 63Mn and a new transition was added to the level scheme. Excited-state lifetimeswere determined for levels in 62Cr and 63Mn using simulationsof the &gamma-ray detection systems. The results are compared with state-of-the-art large-scaleshell-model calculations using the LNPS effective interaction, which wasdeveloped forthis region. Different formulations of the E2 effective charge were used to calculate the theoretical B(2) and |Mn/Mp| values, which are compared to the experimental values.The results emphasize the importance of the 0g9/2 and 1d5/2 neutronorbitals, which lie beyond the N=40 sub-shell gap,for describing nuclear structurein this region.
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