Download or read book Centrality Dependence of Pion Freeze-out Radii in Pb-Pb Collisions at [math][mrow][msqrt][msub][mi][/mi][mrow][mi Mathvariant written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, we report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at √sNN = 2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged one-dimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with dNch/d [eta] 1/3. We compare this behavior to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller √sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. Furthermore, these results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider.