Rapidity dependence of particle production in ultrarelativistic nuclear   collisions
  We compute the rapidity dependence of particle and transverse energy production in ultrarelativistic heavy ion collisions at various beam energies and atomic numbers using the perturbative QCD + saturation model. The distribution is a broad gaussian near $y=0$ but the rapid increase of particle production with the beam energy will via energy conservation strongly constrain the rapidity distribution at large $y$. 
K.J. Eskola, K. Kajantie, P.V. Ruuskanen, K. Tuominen