The momentum correlation between protons and lambda particles emitted from central Pb+Pb collisions at sqrt(s_{ NN}) = 17.3 GeV was studied by the NA49 experiment at the CERN SPS. A clear enhancement is observed for small relative momenta (q_{ inv} < 0.2 GeV). By fitting a theoretical model, which uses the strong interaction between the proton and the lambda in a given pair, to the measured data a value for the effective source size is deduced. Assuming a static Gaussian source distribution we derive an effective radius parameter of R_G = 3.02 \pm 0.20$(stat.)^{ +0.44}_{ -0.16}(syst.) fm.
Categories: nucl-ex hep-ph