PHEGAS: a phase-space generator for automatic cross-section computation
  A phase-space generation algorithm, capable to efficiently integrate the squared amplitude of any scattering process, is presented. The algorithm has been implemented in a Monte Carlo program, PHEGAS, which, using HELAC, a helicity amplitude computational package,can be used for automatic cross-section computation and event generation. Results for several scattering processes with four, five and six particles in the final state are briefly presented. 
Costas G. Papadopoulos