Possible evidence for nuclear E1 overtones in O 16

Abstract

The inelastic cross section for electron scattering by O/sup 16/ was observed to concentrate into two peaks at excitation energies of 44.5 and 49 Mev with widths of 2-3 Mev. These data are analyzed by comparison with the form factors expected for E0, E1, and E2 transitions, and E1 and E2 transition probabilities are calculated. It is concluded that the observed inelastic scattering is compatible with an E1 transition since the excitation energy corresponds to the expected value and the integrated cross section does not violate the El sum rule. (H.D.R.)