Darmstadt 2016 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 18: Heavy Ion Collision and QCD Phases V

HK 18.4: Talk

Tuesday, March 15, 2016, 14:45–15:00, S1/01 A4

Measurement of neutral mesons via combination of calorimeter and conversion photons in pp collisions with ALICE at the LHC — •Daniel Mühlheim for the ALICE collaboration — Institut für Kernphysik, Westfälische-Wilhelms Universität Münster

The ALICE experiment is dedicated to the investigation of the so-called Quark-Gluon Plasma (QGP) which is created in highly energetic Pb-Pb collisions. In order to identify and understand the effects which are not related to the creation of the QGP, the analysis of pp collisions plays an important role. One point of general interest is the measurement of photons. They can be regarded as an ideal probe to study the QGP, since they do not participate in the strong interaction. Hence, they are able to escape the medium unaffected.

There are two different principles to measure photons in ALICE. One way is to make use of electromagnetic calorimeters. The other possibility is to look for photon conversions which occur within the detector material. Both detection principles are combined in order to reconstruct neutral mesons. Since the two detection systems are independent, this method provides an important cross-check for the respective systems. It also profits from the excellent resolution of the conversion method as well as from the high reconstruction efficiency of a calorimeter.

I will introduce this so-called hybrid method in detail and present the current status of neutral meson analysis in pp collisions. Moreover, a first look into the direct photon extraction will be presented.