Electromagnetic dissociation of Au targets by relativistic Pb projectiles

Electromagnetic dissociation (ED) occurs in collisions of relativistic heavy ions involving impact parameters larger than the nuclear interaction radius. In such collisions strong electromagnetic fields acting at the nucleus can produce, for high charges and ultrarelativistic energies, cross sections much larger than the total nuclear interaction cross section. In ED collisions absorption of a virtual photon generally leads to excitation of a nuclear giant resonance. The NA53 experiment studied ED by bombarding Au targets with 158 GeV/nucleon Pb projectiles from the SPS accelerator. Preliminary values of sigma /sub ED/ for the one- and two-neutron removal processes were determined to be 26.4+or-4.0 and 4.6+or-0.7 barns, respectively. Theoretical predictions for sigma /sub ED/ were calculated including the effects of both the E1 and E2 giant resonances. The calculations are extended to energies planned for heavy ion collisions at the RHIC and LHC colliders. (20 refs).