CAN ONE EXTRACT SOURCE RADII FROM TRANSPORT THEORIES

To know the space-time evolution of a heavy-ion reaction is of great i nterest, especially in cases where the measured spectra do not allow t o ascertain the underlying reaction mechanism. In recent times it beca me popular to believe that the comparison of Hanbury-Brown-Twiss corre lation functions obtained from classical or semiclassical transport th eories, like Boltzmann-Uhling-Uhlenbeck (BUU), Quantum Molecular Dynam ics (QMD), VENUS, RQMD or ARC, with experiments may provide this insig ht. It is the purpose of this article to show that this conjecture enc ounters serious problems. The models which are suited to be compared w ith the experiments at CERN and Brookhaven are not able to predict a c orrelation function. Any agreement with existing data has to be consid ered as accidental. The models suited for lower energies can in princi ple predict correlation functions. The systematic error may be too lar ge to be of use as far as quantitative conclusions are concerned. (C) 1997 Elsevier Science B.V.