For Publisher's use CENTRALITY DEPENDENCE OF K+ PRODUCED IN PB+PB COLLISIONS AT 158 GEV PER NUCLEON SONJA KABANA FOR THE NA52 COLLABORATION

The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark- gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same p s- in a chemically equilibrated phase.