Admixtures of shell and cluster states in 18O

The energy spectra, electric-transitions and reduced α-widths of the low-lying positive-parity levels of 18O are shown to be well understood by considering admixtures of 2p shell and ''4p-2h'' cluster states. The weak coupling feature of ''4p-2h'' cluster states is well realized in the lowest [lambda x 14C sub(gr)] band. It is discussed that couplings between the shell and the cluster states are rather small in comparison with those in 18F(T=0). In order to reproduce the observed E2-transitions, the additional polarization charges delta e sub(n)sup(2p)=0.5e and delta e sup(4p-2h)=0.2e are required. (auth.)