Data on single-nucleon transfer, ($t,p$) cross sections, and static and dynamic electromagnetic properties place severe limitations on the structure of the low-lying positive-parity states of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$. We deduce wave functions that best reproduce these data by use of a model space that includes one collective state each of spin $0^{+}$, $2^{+}$, and $4^{+}$ together with all basis states formed from a closed ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ core plus two $d_{\frac{5}{2}}$, $s_{\frac{1}{2}}$ neutrons and up to one $d_{\frac{3}{2}}$ neutron. There is need for only a small $d_{\frac{3}{2}}$ admixture. The $0^{+}$ collective configuration is the dominant constituent of the $0_2^{+}$ state at 3.63 MeV, and the $2^{+}$ collective configuration dominates the $2_3^{+}$ state at 5.25 MeV. Overall, the data favor a small negative value ($\frac{Q}{e}\simeq -5\mathrm{}$ ${\mathrm{fm}}^2$) for the quadrupole moment of the first $2^{+}$ level. The matrix elements of the Hamiltonian that reproduce both the observed energies and transition rates are constructed. Several experiments are suggested to further probe the structure of this nucleus.

NUCLEAR STRUCTURE Deduce wave functions of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ low-lying states that best fit single-nucleon transfer, ($t,p$) data, and static and dynamic electromagnetic properties. Construct Hamiltonian that leads to these eigenfunctions.

• Received 29 March 1976

DOI:https://doi.org/10.1103/PhysRevC.14.1245