System size dependence of hadron production in A+A collisions at 40 A GeV beam energy

Abstract

Rapidity and transverse mass spectra of charged kaons and negative pions measured in C+C, Si+Si and minimum bias Pb+Pb collisions at 40 A GeV are reported. A monotonous increase of the inverse slope parameter with system size is observed. The ⟨K+⟩/⟨K−⟩ ratio rises with ⟨NW⟩ from the light ion collisions to peripheral Pb+Pb and stays constant from there on. A steep rise of the ⟨K+⟩/⟨π+⟩ ratio is observed for the small systems with the ratio in Si+Si collisions being slightly higher than in peripheral Pb+Pb collisions. The measurement of the ⟨K−⟩/⟨π−⟩ ratio in Si+Si collisions is significantly higher than the ratio in peripheral Pb+Pb collisions; it is rather close to the observed ⟨K−⟩/⟨π−⟩ ratio in central Pb+Pb collisions.