Evidence for non-gaussian tail in 3-dimensional pion emission source at SPS

The NA49 experiment at CERN SPS has acquired a huge data set of Pb+Pb events over a broad range of energy and centrality during the last several years. This high statistics data set, coupled with a state-of-the-art analysis technique, allows for the first model-independent extraction and energy scan of 3D emission sources for pion pairs at SPS energies. These 3D pion emission sources provide new insights into the nature of a long-range source previously reported by PHENIX at RHIC. Preliminary results indicate that the pion source function is essentially Gaussian from 20 AGeV to 80 AGeV but it ...