Vy. Ponomarev et al., MULTIPLE EXCITATION OF GIANT-DIPOLE RESONANCES IN RELATIVISTIC HEAVY-ION COLLISIONS, Physical review letters, 72(8), 1994, pp. 1168-1171
The relativistic excitation of the double giant dipole resonance in Xe
-136 has been calculated, describing the resonance as a harmonic vibra
tion of the mean held, damped through its coupling to doorway states.
While the predictions associated with the one-phonon states provide an
overall account of the experimental findings, the calculated cross se
ction for the two-phonon states is much smaller than that extracted fr
om the involved analysis of the data. The experimental elucidation of
this discrepancy seems essential for assessing the validity of the sta
ndard picture of giant resonances.