Measurement of the dipole and electric quadrupole strength distributions up to 10 MeV in the doubly magic nuclei 40Ca and 48Ca

The doubly magic nuclei ${}^{40}\\mathrm{Ca}$ and ${}^{48}\\mathrm{Ca}$ have been studied in high resolution photon scattering experiments. We have derived absolute dipole and quadrupole excitation strengths up to 10 MeV. Evidence was found for a two-phonon quadrupole-octupole state in ${}^{48}\\mathrm{Ca}$. At higher energies in contrast to ${}^{40}\\mathrm{Ca}$, a concentration of dipole strength is observed in ${}^{48}\\mathrm{Ca}$ which is discussed in terms of a pygmy resonance originating from the large neutron excess.