  Multi-electron giant dipole resonances of atoms in crossed electric and
magnetic fields are investigated. Stationary configurations corresponding to a
highly symmetric arrangement of the electrons on a decentered circle are
derived, and a normal-mode and stability analysis are performed. A
classification of the various modes, which are dominated by the magnetic field
or the Coulomb interactions, is provided. Based on the MCTDH approach, we carry
out a six-dimensional wave-packet dynamical study for the two-electron
resonances, yielding in particular lifetimes of more than 0.1 $\mu$s for strong
electric fields.
