Strangeness Production At Mid-Rapidity In S+Pb Collisions At 200 Gev/C Per Nucleon

Experimental evidence is presented for a source of unusually high strangeness content located at mid-rapidity in 200 GeV/c per nucleon collisions of S-32 projectiles with a Pb target. The enhancement is not seen in p + Pb reactions measured in the same apparatus at the same energy. This source becomes dominant for central collisions.