Three-dimensional two-pion source image from Pb+Pb collisions at sNN=17.3 GeV: New constraints for source breakup dynamics

Source imaging methodology is used to provide a three-dimensional two-pion source function for mid-rapidity pion pairs with p T 70 MeV / c in central (0–7%) Pb + Pb collisions at s NN = 17.3 GeV . Prominent non-Gaussian tails are observed in the pion pair transverse momentum (outward) and in the beam (longitudinal) directions. Model calculations reproduce them with the assumption of Bjorken longitudinal boost invariance and transverse flow blast-wave dynamics; they also yield a proper time for breakup and emission duration for the pion source.