Speaker
Dr
Alexis Jean-Michel Mas
(Universidade de Sao Paulo (BR))
Description
The ALICE experiment is mainly devoted to the study of quark-gluon plasma (QGP) expected
to be created in heavy ion collisions. Since electromagnetic probes do not interact strongly whith
the QGP, direct photons are reliable witnesses of the energy of the initial hard process. This
property allows one to investigate, e.g., hadrons energy loss mechanisms in the medium via gammajet studies. The measurement of direct photons production is also interesting in p-p collisions, as it
provides a test of the QCD cross section as well as it constrains the proton parton distribution
function (PDF).
The ALICE Electromagnetic Calorimeter (EMCal) efficiently detects photons up to pt=100
GeV/c. To identify direct photons, a combination of techniques including (electromagnetic) shower
shape analysis and isolation cut has been used. These methods are efficient in getting rid of decay
photons background, dominant in p-p collision at the TeV energy scale.
An overview of ALICE prompt photon measurements in pp and Pb-Pb collisions will be
presented. Finally the complementarity of ALICE and the other experiments (CMS and ATLAS) will be highlighted.
Author
Dr
Alexis Jean-Michel Mas
(Universidade de Sao Paulo (BR))
