Geometry and Space-Time Extent of Pion Emission Region at FCC Energies

Figure 3

Energy dependence of for secondary charged pions in central heavy ion collisions Au + Au, Au + Pb, and Pb + Pb in midrapidity region and at  GeV/. Error bars are only statistical (for NA44, total uncertainties). Smooth curves are derived from (4) and the fit results for BEC radii [15] without the point of the WA97 experiment [16]. The solid line corresponds to the fits of BEC radii by function (7) and dashed line to the fits by specific case .