Simultaneous Projectile-Target Excitation in Heavy Ion Collisions
  We calculate the lowest-order contribution to the cross section for simultaneous excitation of projectile and target nuclei in relativistic heavy ion collisions. This process is, to leading order, non-classical and adds incoherently to the well-studied semi-classical Weizs\"acker-Williams cross section. While the leading contribution to the cross section is down by only $1/Z_P$ from the semiclassical process, and consequently of potential importance for understanding data from light projectiles, we find that phase space considerations render the cross section utterly negligible. 
C. J. Benesh and J.L. Friar