Electroexcitation of giant resonances in 15N

The giant resonance region of 15N has been investigated by means of inelastic electron scattering in a momentum transfer range 0.36--1.25 fm-1. The data show a splitting of the dipole resonance into two main peaks at 22 and 25.5 MeV, with some structure around 20 MeV and strength extending down to 13 MeV. The structure from 19 to 30 MeV correlates well with radiative capture and photoprodisintegration data and is in qualitative agreement with shell model predictions of the isospin splitting of the giant dipole resonance. The data show considerable spin-flip E1 strength, which agrees well with the predictions of the generalized Goldhaber-Teller model. Additional structure found in the energy region from approx. 14 to approx. 19 MeV has been analyzed as a C2-C1 superposition. The C2 strength in the 14--18.5 MeV region exhausts up to 22% of the isoscalar energy-weighted sum rule (Helm model, J = 3/2 assumed). The amount of C2 strength in the region from 18.5 to 30 MeV is negligible