Signal shapes in multiwire proportional chamber-based TPCs
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Published:2024-02-01
Issue:02
Volume:19
Page:P02038
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ISSN:1748-0221
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Container-title:Journal of Instrumentation
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language:
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Short-container-title:J. Inst.
Author:
Alme J., Alt T., Appelshäuser H., Arslandok M.ORCID, Averbeck R., Bartsch E., Becht P., Bratrud L., Braun-Munzinger P., Buesching H., Caines H., Christiansen P., Costa F., Frankenfeld U., Gaardhøje J.J., Garabatos C., Glässel P., Gunji T., Hamagaki H., Harris J.W., Hellbär E., Helstrup H., Ivanov M., Jung J., Jung M., Junique A., Kalweit A., Keidel R., Kirsch S., Kleiner M., Kowalski M., Krüger M., Lippmann C., Mager M., Masciocchi S., Matyja A., Miśkowiec D., Munzer R.H., Musa L., Nielsen B.S., Otwinowski J., Pikna M., Rehman A., Renfordt R., Röhrich D., Scheid H.S., Schmidt C., Schmidt H.R., Schweda K., Sekiguchi Y., Silvermyr D., Sitar B., Stachel J., Ullaland K., Veenhof R., Vislavicius V., Wiechula J., Windelband B.,
Abstract
Abstract
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.
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