Structure of low-lying positive-parity states of ¹⁸O

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 ¹⁸O. 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 ¹⁶O core plus two d_5/2, s_1/2 neutrons and up to one d_3/2 neutron. There is need for only a small d_3/2 admixture. The 0⁺ collective configuration is the dominant constituent of the 0₂⁺ state at 3.63 MeV, and the 2⁺ collective configuration dominates the 2₃⁺ state at 5.25 MeV. Overall, the data favor a small negative value (Q/e≃-5 fm²) 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 ¹⁸O 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.