An accurate impact parameter determination in a heavy ion collision is
crucial for almost all further analysis. The capabilities of an artif
icial neural network are investigated in that respect. A novel input g
eneration for the network is proposed, namely, the transverse and long
itudinal momentum distributions of all outgoing (or actually detectabl
e) particles. The neural network approach yields an improvement in per
formance of a factor of 2 as compared to classical techniques. To achi
eve this improvement simple network architectures and a 5X5 input grid
in (p(t),p(z)) space are sufficient.