Köln 2025 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 19: Heavy-Ion Collisions and QCD Phases IV
HK 19.6: Vortrag
Dienstag, 11. März 2025, 17:00–17:15, HS 3 Chemie
Performance of the dielectron analysis in Pb-Pb collisions in Run 3 with ALICE — •Emma Ege for the ALICE Germany collaboration — Goethe University Frankfurt, Frankfurt, Germany
Correlated electron-positron pairs (dielectrons) are a unique probe to study the properties of the medium created in relativistic heavy-ion collisions. They are produced in all stages of the collision and leave the system without loss of information as they do not interact strongly with the medium. However, at LHC energies, the thermal dielectrons emitted in the early stages of the collision from the quark-gluon-plasma are outnumbered by a large contribution of correlated e+e−-pairs from semi-leptonic decays of heavy-flavour (HF) hadrons.
The upgrade of the ALICE detector installed during the Long Shutdown 2 is crucial to boost the precision of thermal radiation measurement. The continuous readout of the TPC allows for higher data acquisition rate of up to 50 kHz in Pb–Pb collisions. Moreover, the new ITS with its higher granularity and closer location to the interaction point improves the pointing resolution by a factor of 2 compared to that in Run 2, leading to a better topological separation of prompt thermal radiation and e+e−-pairs from HF hadron decays, and to smaller background from photon conversions in the detector material.
In this talk, the status of the dielectron analysis of a large data set of Pb–Pb collisions at √sNN=5.36 TeV, recorded with the upgraded ALICE detector in Run 3, is presented. Topological separation capabilities based on distance-of-closest approach (DCA) and the impact of the detector upgrades on the dielectron analysis will be shown.
Keywords: ALICE; Run 3; Pb–Pb collisions; Dielectrons; QGP