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The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events (2010)

Johan Alme Y. Andres Harald Appelshäuser Sebastian Bablok Norbert Bialas Rikard Bolgen Uwe Bonnes Roland Bramm Peter Braun-Munzinger Roberto Campagnolo Peter Christiansen Alexandru Florin Dobrin Claude Engster Dominik Fehlker Yiota Foka Uli Frankenfeld Jens Joergen Gaardhøje Chilo Garabatos Peter Glässel Carmen Gonzalez Gutierrez Philippe Gros Hans-Ake Gustafsson Haavard Helstrup Michael Hoch Marian Ivanov Rudolf Janik Antoine Junique Alexander Kalweit Ralf Keidel Stefan Kniege Marek Kowalski Dag Toppe Larsen Yannick Lesenechal Philippe Lenoir Niels Lindegaard Christian Lippmann Magnus Mager Manfred Mast Adam Matyja Magne Munkejord Luciano Musa Borge S. Nielsen Vedran Nikolic Helmut Oeschler E.K. Olsen Anders Oskarsson Lennart Osterman Miro Pikna Attiq Ur Rehman Gaël Renault Rainer Renfordt Stefan Rossegger Dieter Röhrich Ketil Røed Mattias Richter G. Rueshmann Andrzej Rybicki Hans Sann Hans-Rudolf Schmidt Martin Siska Brano Sitár Carsten Soegaard Hans Kristian Soltveit Daniel Soyk Johanna Stachel Herbert Stelzer Evert Anders Stenlund Reinhard Stock Peter Strmeň Imrich Szarka Kjetil Ullaland Danilo Vranic Rob Veenhof Joern Westergaard Jens Wiechula Bernd Stefan Windelband

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 m3 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.

Hadronization revisited : the dynamics behind hadro-chemical equilibrium (2007)

Reinhard Stock

The multiplicity of hadronic species created in elementary, and in nucleus-nucleus collisions, are known to be well reproduced by the statistical hadronization model, in its canonical and grand-canonical versions.To understand the origin of the implied equilibrium we revisit the hadronization models developed for e+e- annihilation to hadrons which imply spatial color pre-confinement clusters forming at the end of the pQCD evolution, which decays into on-shell hadrons/resonances. The classical ensemble description arises as a consequence of decoherence and phase space dominance during cluster formation, and decay.For A+A collisions we assume that hadronization occurs from similar singlet clusters which will overlap spatially owing to the extreme density. This is imaged in the transition to the grand-canonical ensemble.This transition sets in with increasing A and collision centrality. It can be described by a percolation model.

Azimuthal anisotropy in Au+Au collisions at SNN=200GeV (2005)