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The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events

J. Alme, Y. Andres, H. Appelshauser, S. Bablok, N. Bialas, R. Bolgen, U. Bonnes, R. Bramm, P. Braun-Munzinger, R. Campagnolo, P. Christiansen, A. Dobrin, C. Engster, D. Fehlker, P. Foka, U. Frankenfeld, J. J. Gaardhoje, C. Garabatos, P. Glassel, C. Gonzalez Gutierrez, P. Gros, H. -A. Gustafsson, H. Helstrup, M. Hoch, M. Ivanov, R. Janik, A. Junique, A. Kalweit, R. Keidel, S. Kniege, M. Kowalski, D. T. Larsen, Y. Lesenechal, P. Lenoir, N. Lindegaard, C. Lippmann, M. Mager, M. Mast, A. Matyja, M. Munkejord, L. Musa, B. S. Nielsen, V. Nikolic, H. Oeschler, E. K. Olsen, A. Oskarsson, L. Osterman, M. Pikna, A. Rehman, G. Renault, R. Renfordt, S. Rossegger, D. Rohrich, K. Roed, M. Richter, G. Rueshmann, A. Rybicki, H. Sann, H. -R. Schmidt, M. Siska, B. Sitar, C. Soegaard, H. -K. Soltveit, D. Soyk, J. Stachel, H. Stelzer, E. Stenlund, R. Stock, P. Strmen, I. Szarka, K. Ullaland, D. Vranic, R. Veenhof, J. Westergaard, J. Wiechula, B. Windelband

TL;DR

The paper presents the design, construction, and commissioning of the ALICE TPC, a large-volume, fast-readout tracking and identification device tailored for ultra-high multiplicity Pb–Pb events at the LHC. It details the field cage, readout chambers, electronics, gas system, laser calibration, cooling, and detector-control infrastructure, highlighting innovations to manage extreme rates and space-charge effects. Calibration and commissioning results demonstrate performance close to the Technical Design Report, achieving precision in space-point resolution and dE/dx essential for robust tracking and particle ID. The work underscores the integration of cutting-edge hardware, software, and control systems enabling high-rate operation and reliable long-term stability in a demanding collider environment.

Abstract

The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and is operated in a 0.5 T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb--Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report.

The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events

TL;DR

The paper presents the design, construction, and commissioning of the ALICE TPC, a large-volume, fast-readout tracking and identification device tailored for ultra-high multiplicity Pb–Pb events at the LHC. It details the field cage, readout chambers, electronics, gas system, laser calibration, cooling, and detector-control infrastructure, highlighting innovations to manage extreme rates and space-charge effects. Calibration and commissioning results demonstrate performance close to the Technical Design Report, achieving precision in space-point resolution and dE/dx essential for robust tracking and particle ID. The work underscores the integration of cutting-edge hardware, software, and control systems enabling high-rate operation and reliable long-term stability in a demanding collider environment.

Abstract

The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m^3 and is operated in a 0.5 T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb--Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report.

Paper Structure

This paper contains 141 sections, 11 equations, 80 figures, 16 tables.

Table of Contents

  1. Introduction
  2. Field cage
  3. Vessels
  4. Central electrode
  5. Rods
  6. Resistor rods
  7. High-voltage cable rod
  8. Laser rods
  9. Gas rods
  10. Strips
  11. Skirts
  12. Endplates
  13. I-bars
  14. Readout chambers
  15. Design considerations
  16. ...and 126 more sections

Figures (80)

  • Figure 1: ALICE schematic layout ALICEjinst.
  • Figure 2: 3D view of the TPC field cage. The high voltage electrode is located at the center of the drift volume. The endplates with 18 sectors and 36 readout chambers on each end are shown.
  • Figure 3: Detail view of the outer field cage near the central electrode.
  • Figure 4: Cross-sectional side view of the TPC with relevant dimensions (in mm). The service support wheels and one of the I-bars are also shown.
  • Figure 5: Detailed view of the high-voltage end of the resistor rod, showing the cooling pipes, the central PEEK pipe, the heat-dissipating copper plates, the contacts to the strips, and the high-voltage contact, which matches the contact at the housing rod.
  • ...and 75 more figures