The longitudinal and transverse form factors were determined separately as functions of the excitation energy from 15 to 40 MeV in the momentum-transfer range 0.75-1.56 ${\mathrm{F}}^{-1\mathrm{}}$. For some of the form-factor spectra the measurements were extended up to an excitation energy of 100 MeV and the results were compared with the quasielastic model presented by de Forest. The $q$ dependence of the experimental form factors for levels were compared with the predictions of the particle-hole model and with the intermediate-coupling model. We have then found the levels with the following excitation energies (MeV), spins, and parities: 18.1 ($1^{-}$), 18.6 ($3^{-}$), 19.6 ($4^{-}$), 20.0 ($2^{+}$), 20.6 ($3^{+}$), 21.6 ($3^{-}$), 22.0 ($1^{-}$), 22.7 ($1^{-}$), and 23.8 ($1^{-}$). We have also found new evidence of the possibility of the spin-isospin mode for the 22.7-MeV ($1^{-}$) excitation.

• Received 8 October 1970

DOI:https://doi.org/10.1103/PhysRevC.3.1750