# Quark Matter 2012

12-18 August 2012
US/Eastern timezone

## Isolated photons in pp and Pb-Pb collisions at the LHC with the ALICE EMCal

16 Aug 2012, 16:00
2h

Poster Electroweak probes

### Speaker

Mauro Rogerio Cosentino (Lawrence Berkeley National Lab. (US))

### Description

Photons are of great interest in relativistic heavy-ion collisions due to the fact that they do not interact strongly, and thus are used to make a tomographic view of those collisions. Of special interest are the directly produced high-transverse momentum photons. The ratio of their yield in Pb-Pb to pp collisions is sensitive to initial state effects. Furthermore, direct photons can be used tag the away-side parton in photon-jet or photon-hadron correlations studies. The application of isolation criteria to the selected photon candidates is an important experimental tool to suppress the contamination from decay photon, but also from fragmentation and Bremstrahlung photons. In this poster, we present isolated photon spectra in transverse momentum ranges between 15 and 50 GeV/c in pp and Pb-Pb collisions at center-of-mass energies of 2.76 and 7 TeV. The isolated photons are reconstructed in datasets triggered by the ALICE Electromagnetic Calorimeter.

### Primary author

Collaboration ALICE (CERN, Geneva, Switzerland)

### Co-author

Mauro Rogerio Cosentino (Lawrence Berkeley National Lab. (US))

 Slides