Identification of significant E 0 strength in the 22+→21+ transitions of 58,60,62 Ni

The E 0 transition strength in the 22+→21+ transitions of 58,60,62 Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the δ(E2/M1) mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, δ(E2/M1) mixing ratios and γ -ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the E 0 strengths. These are the first 2+→2+ E 0 transition strengths measured in nuclei with spherical ground states and the E 0 component is found to be unexpectedly large; in fact, these are amongst the largest E 0 transition strengths in medium and heavy nuclei reported to date.