Heidelberg 2015 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 34: Heavy Ion Collisions and QCD Phases 4

HK 34.4: Vortrag

Dienstag, 24. März 2015, 18:00–18:15, T/HS1

Tagging Neutral Mesons using Photons from Conversions and Calorimeters in ALICE — •Daniel Mühlheim for the ALICE collaboration — Institut für Kernphysik, Wilhelm-Klemm-Str. 9, 48149 Münster

The ALICE experiment is dedicated to the investigation of the so-called Quark-Gluon Plasma (QGP), which is generally believed to be created in highly energetic Pb-Pb collisions. Furthermore, pp and p-Pb collisions are studied in order to identify and understand effects which are not related to the creation of the QGP. Since photons do not directly participate in the strong interaction, they can be regarded as an ideal probe in all three collisions systems.

In general, there are two different principles to measure photons. One way is to make use of electromagnetic calorimeters. The other possibility is to look for photon conversions which happen within the detector material. In this work, photons from both detection principles are combined in order to reconstruct neutral mesons. Since two independent measurements are combined, this method provides an important cross-check for the respective results. Furthermore, the detection efficiency is maximized. By means of tagging neutral pions, the goal of this measurement is to determine the fraction of decay photons from all generated photons, generally referred to as R_γ, in all available collision systems.

In this talk, the measurement principles of the combinational method are introduced and discussed. Moreover, a first look into the analysis will be presented.