In the very heavy collision system 197Au+197Au the K+ production process was studied as a function of impact parameter at 1 GeV/nucleon, a beam energy well below the free N-N threshold. The K+ multiplicity increases more than linearly with the number of participant nucleons and the K+/ pi + ratio rises significantly when going from peripheral to central collisions. The measured K+ double differential cross section is enhanced by a factor of 6 compared to microscopic transport calculations if secondary processes ( Delta N-->K Lambda N and Delta Delta -->K Lambda N) are ignored.
weitere Autoren: M. Cieslak, M. Debowski, E. Grosse, W. Henning, P. Koczon, R. Schicker, E. Schwab, and P. Senger , P. Baltes, Ch. Müntz, H. Oeschler, S. Sartorius, Ch. Sturm, and A. Wagner , P. Beckerle, Ch. Bormann, D. Brill, Y. Shin, J. Stein, R. Stock, and H. Ströbele , B. Kohlmeyer, H. Pöppl, F. Pühlhofer, J. Speer, and K. Völkel , W. Walus