Latest documents http://publikationen.ub.uni-frankfurt.de/index/index/ Thu, 14 Jun 2012 08:29:06 +0200 Thu, 14 Jun 2012 08:29:06 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/25198 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. 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 article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/25198 Thu, 14 Jun 2012 08:29:06 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3765 Data on the mean multiplicity of strange hadrons produced in minimum bias proton--proton and central nucleus--nucleus collisions at momenta between 2.8 and 400 GeV/c per nucleon have been compiled. The multiplicities for nucleon--nucleon interactions were constructed. The ratios of strange particle multiplicity to participant nucleon as well as to pion multiplicity are larger for central nucleus--nucleus collisions than for nucleon--nucleon interactions at all studied energies. The data at AGS energies suggest that the latter ratio saturates with increasing masses of the colliding nuclei. The strangeness to pion multiplicity ratio observed in nucleon--nucleon interactions increases with collision energy in the whole energy range studied. A qualitatively different behaviour is observed for central nucleus--nucleus collisions: the ratio rapidly increases when going from Dubna to AGS energies and changes little between AGS and SPS energies. This change in the behaviour can be related to the increase in the entropy production observed in central nucleus-nucleus collisions at the same energy range. The results are interpreted within a statistical approach. They are consistent with the hypothesis that the Quark Gluon Plasma is created at SPS energies, the critical collision energy being between AGS and SPS energies. Marek Gazdzicki; Dieter Röhrich preprint http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3765 Tue, 04 Oct 2005 08:26:39 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3802 A recent paper on energy dependence of strangeness production in A+A and p+p interactions written by Dunlop and Ogilvie (Phys. ReV. C61 031901(R) (2000) indicates that there is a significant misunderstanding about the concept of strangeness enhancement and its role as a signal of Quark Gluon Plasma creation. In this comment we will try to clarify some essential points. 25.75.Dw, 13.85.Ni, 21.65.+f Marek Gazdzicki; Mark I. Gorenstein; Dieter Röhrich preprint http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/3802 Thu, 29 Sep 2005 08:55:54 +0200