rest masses. So our most optimistic estimate is that one needs a nucleon-nucleon collision which would have led to 6 pions if it had occurred in free space. One might be less optimistic and require the production of 8 or 10 pions instead.

In Figure 6 we show the total number $N_>$ of nucleon-nucleon collisions which would lead to the production of at least $n_{\rm crit}$ pions. We may view $n_{\rm crit}$ as the minimum number necessary to form a nucleation site or plasma seed. If $n_{\rm crit}$ = 6 is the relevant number then there are on average 7 such nucleon-nucleon collisions per central gold-gold collision. If 8 or 10 are the relevant multiplicities then there is only one such critical star burst every 1 or every 25 central gold-gold collisions, respectively. These numbers vary somewhat with $w$; the numbers quoted are averages. Conservatively, we may conclude that the probability of at least one plasma seed appearing via this mechanism is in the range of 1 to 100% per central gold-gold collision at the highest energy attainable at the AGS. These probabilities are about one to two orders of magnitude greater than those estimated in [@us] on the basis 