Features of particle multiplicities and strangeness production in central heavy ion collisions between 1.7A and 158A GeV/c - art. no. 024901

A systematic study is performed of fully integrated particle multiplicities in central Au-Au and Pb-Pb collisions at beam momenta of 1.7A GeV/c, 11.6A GeV/c (Au-Au), and 158A GeV/c (Pb-Pb) by using a statistical-thermal model . The close similarity of the colliding systems makes it possible to study heavy ion collisions under definite initial conditions over a range of cent er-of-mass energies covering more than 1 order of magnitude. In order to fu rther study the behavior of strangeness production, an updated study of Si- Au collisions at 14.6A GeV is also presented. The data analysis has been pe rformed with two completely independent numerical algorithms giving closely consistent results. We conclude that a thermal model description of partic le multiplicities, with additional strangeness suppression, is possible for each energy. The degree of chemical equilibrium of strange particles and t he relative production of strange quarks with respect to u and d quarks are higher than in e(+)e(-), pp, and p (p) over bar collisions at comparable a nd even at lower energies. The behavior of strangeness production as a func tion of center-of-mass energy and colliding system is presented and discuss ed. The average energy per hadron in the comoving frame is close to 1 GeV p er hadron despite the fact that the energy increases more than tenfold.