Low - lying E 1 strength in 20

Intermediate energy Coulomb excitation at 100 MeV/nucleon was used to probe the low-lying level structure of both O and O in the region between 1 and 8 MeV. Discrete 1 states with energies of 5.35~10! and 6.85~5! MeV were observed in O. The strong direct excitation and subsequent g-ray decay of these states, along with B(El) predictions for O levels in this energy region, established their dipole character. The extracted B(E1)↑ values of 0.062(16)e fm and 0.035(9)e fm for the 5.35and 6.85-MeV states, respectively, are significantly larger than shell model calculations, though modification of the single-particle energies, in particular, the p-sd shell gap, improves the agreement. The summed B(E1)↑ value for these levels ~in Weisskopf units! is consistent with that for other nuclei that have been discussed recently in the literature as potential Pygmy dipole resonance hosts.