Köln 2025 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 20: Instrumentation V

HK 20.5: Vortrag

Dienstag, 11. März 2025, 16:45–17:00, SR Exp1A Chemie

Drift-field distortion corrections of the ALICE TPC in LHC Run 3 — •Matthias Kleiner for the ALICE Germany collaboration — Institut für Kernphysik, Goethe-Universität Frankfurt

The Time Projection Chamber (TPC) in the ALICE experiment at the CERN LHC provides excellent tracking and particle identification capabilities. In order to cope with the high interaction rates of up to 50 kHz in Pb--Pb collisions during Run 3, the Multi-Wire Proportional Chambers (MWPCs) in the TPC were replaced by stacks of four Gas Electron Multiplier (GEM) foils to allow for continuous data acquisition. Despite the intrinsic ion-blocking properties of the 4-GEM system, a residual amount of ions produced during the electron amplification drifts into the active volume of the TPC, leading to space-charge distortions of the nominal drift field. Various further effects, such as fluctuations in the interaction rate or the decay of the LHC beam, cause time dependent variations of the distortions due to space-charge. Additional detector effects cause significant static and time dependent drift-field distortions. These drift-field distortions have to be corrected to preserve the intrinsic tracking precision of the TPC.

In this talk, an overview of drift-field distortions in the ALICE TPC in Run 3 will be presented, along with the precision of the correction procedures.

Supported by BMBF and the Helmholtz Association

Keywords: TPC; calibration; Run 3; LHC