The isotopes ${}^{54}\mathrm{Ni}$, ${}^{56}\mathrm{Ni}$, and ${}^{58}\mathrm{Ni}$ have been studied via intermediate-energy Coulomb excitation at the National Superconducting Cyclotron Laboratory. Absolute $B(E2;0_1^{+}\to 2_1^{+})$ excitation strengths have been determined for all three nuclei using a consistent experimental approach, and a measure of quadrupole collectivity has been established in the vicinity of the much discussed doubly magic shell closure at $N=Z=28$. The energy of and excitation strength to the first $2^{+}$ state of ${}^{54}\mathrm{Ni}$ have been observed for the first time. The results are compared to large-scale shell-model calculations that predict that the $E2$ strength in ${}^{54}\mathrm{Ni}$ should be divided between the first and second $2^{+}$ states.

• Received 13 March 2004

DOI:https://doi.org/10.1103/PhysRevC.70.054319