Abstract
The pygmy dipole resonance has been studied in the proton-magic nucleus with the (, ) coincidence method at . The comparison with results of photon-scattering experiments reveals a splitting into two components with different structure: one group of states which is excited in (, ) as well as in (, ) reactions and a group of states at higher energies which is only excited in (, ) reactions. Calculations with the self-consistent relativistic quasiparticle time-blocking approximation and the quasiparticle phonon model are in qualitative agreement with the experimental results and predict a low-lying isoscalar component dominated by neutron-skin oscillations and a higher-lying more isovector component on the tail of the giant dipole resonance.
- Received 1 July 2010
DOI:https://doi.org/10.1103/PhysRevLett.105.212503
© 2010 The American Physical Society