Münster 2017 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 3: Heavy Ion Collisions and QCD Phases II

HK 3.8: Talk

Monday, March 27, 2017, 18:45–19:00, F 3

Results from a low-field pilot run dedicated for dielectron measurements in pp collisions at 13 TeV with ALICE — •Jerome Jung for the ALICE collaboration — Institut für Kernphysik Frankfurt

Low-mass dielectrons are an important probe for the hot and dense medium which is created in ultrarelativistic heavy-ion collisions. Since leptons do not interact strongly, they carry information from all collision stages with negligible final-state interaction.
The ALICE detector is well-suited to perform this measurement due to its excellent tracking and particle identification capabilities at very low momenta. However, Dalitz decays and photon conversions lead to a high combinatorial background. A detector configuration with reduced magnetic field increases their reconstruction probability allowing to exclude them from the analysis. Additionally, it also provides the opportunity to increase the accessible phase space of the dielectron measurement.
Such a configuration is planned for the Pb-Pb data taking in LHC Run  3. A successful pilot run using pp collisions was done and is used to adapt and develop analysis techniques. We will present first results of the dielectron measurement in pp collisions at √s=13 TeV with the low-field configuration and compare it to reference data with the nominal field to show its benefits.