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David Silvermyr

David Silvermyr

Senior lecturer

David Silvermyr

Signal shapes in multiwire proportional chamber-based TPCs

Author

  • J. Alme
  • P. Christiansen
  • D. Silvermyr
  • V. Vislavicius
  • B. Windelband

Summary, in English

A large-volume Time Projection Chamber (TPC) is the main tracking and particle identification (PID) detector of the ALICE experiment at the CERN LHC. PID in the TPC is performed via specific energy-loss measurements (dE/dx), which are derived from the average pulse-height distribution of ionization generated by charged-particle tracks traversing the TPC volume. During Runs 1 and 2, until 2018, the gas amplification stage was based on multiwire proportional chambers (MWPC). Signals from the MWPC show characteristic long negative tails after an initial positive peak due to the long ion drift times in the MWPC amplification region. This so-called ion tail can lead to a significant amplitude loss in subsequently measured signals, especially in the high-multiplicity environment of high-energy Pb-Pb collisions, which results in a degradation of the dE/dx resolution. A detailed study of the signal shapes measured with the ALICE TPC with the Ne-CO2 (90-10) and Ar-CO2 (90-10) gas mixtures is presented, and the results are compared with three-dimensional Garfield simulations. The impact of the ion tail on the PID performance is studied employing the ALICE simulation framework and the feasibility of an offline correction procedure to account for the ion tail is demonstrated. © 2024 The Author(s)

Department/s

  • eSSENCE: The e-Science Collaboration
  • Particle and nuclear physics

Publishing year

2024

Language

English

Publication/Series

Journal of Instrumentation

Volume

19

Issue

2

Document type

Journal article

Publisher

IOP Publishing

Topic

  • Subatomic Physics

Keywords

  • dE/dx detectors
  • Gaseous detectors
  • Heavy-ion detectors
  • Time projection chambers
  • Binary alloys
  • Colliding beam accelerators
  • Energy dissipation
  • Heavy ions
  • Ionization of gases
  • Lead alloys
  • De/dx detector
  • Large volumes
  • Loss measurement
  • Multiwire proportional chamber
  • Particle- identification
  • Signal shapes
  • Specific energy
  • Carbon dioxide

Status

Published

ISBN/ISSN/Other

  • ISSN: 1748-0221