# Quark Matter 2014 - XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

19-24 May 2014
Europe/Zurich timezone

## Azimuthally differential pion femtoscopy in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV with ALICE at the LHC

21 May 2014, 13:10
20m

### europium

Contributed Talk Correlations and Fluctuations

### Speaker

Vera Loggins (Wayne State University (US))

### Description

Femtoscopy of non-central heavy-ion collisions provides access to information on the geometry of the effective pion-emitting source. In particular, its shape can be studied by measuring femtoscopic radii as a function of the emission angle relative to the collision plane of symmetry. We present the first measurements of azimuthally differential femtoscopy in Pb-Pb collisions $\sqrt{s_{\rm NN}}$ = 2.76 TeV at the LHC and compare our results to RHIC experiments at lower energies. We measure oscillations of the extracted radii versus the emission angle. We find that $R_{\rm side}$ and $R_{\rm out}$ oscillate out of phase. We show that the relative amplitude of the $R_{\rm side}$ oscillation decreases in more central collisions, but always remains positive. This indicates that the source is out-of-plane extended, which is qualitatively similar to that observations at RHIC energies. We compare our results to existing hydrodynamical and transport model calculations.
On behalf of collaboration: ALICE

### Primary author

Vera Loggins (Wayne State University (US))

 Slides