JINR-LHE-1010-1 (ALICE Project)
· Date approved: 1999 · Date started: 1995 · Data of completion: 2015
Status: set-up design and prototyping
Accelerator: CERN LHC
Detector: ALICE set-up with Silicon Inner Tracking System, Time Projection Chamber, Transition Radiation Detector, Time-of-Flight System, High Momentum Particle Identification Detector, Photon Spectrometer, Forward Dimuon Spectrometer, Zero Degree Calorimeter
Beams: Colliding beams of Pb-ions at a center-of-mass energy of about 5.5 TeV/nucleon

 

Project ALICE: Participation of the Joint Institute for Nuclear Research in the A L I C E experiment at the CERN LHC

[1] P.G.Akishin, V.A.Arefiev, V.I.Astakhov, A.M.Baldin, A.A.Baldin, V.D.Bartenev, B.V.Batyunya, Y.A.Belikov, I.V.Boguslavsky, V.V.Borisov, Z.V.Borisovskaya, Z.Bunzarov, P.M.Bylinkin, V.I.Danilov, V.I.Datskov, V.K.Dodokhov, L.G.Efimov, A.G.Fedunov, O.A.Golubitsky, B.N.Guskov, V.G.Kadyshevsky, I.E.Karpunina, E.K.Koshurnikov, A.D.Kovalenko, V.V.Kushpil, S.A.Kushpil, V.I.Lobanov, V.L.Lyuboshits, G.I.Lykasov, A.A.Lyubimtsev, E.A.Matyushevsky, D.P.Mikhalev, K.V.Mikhailov, P.V.Nomokonov, A.N.Parfenov, O.N.Piskunov, V.N.Pozdnyakov, I.V.Puzynin, A.B.Sadovsky, S.V.Semashko, A.E.Senner, G.S.Shabratova, A.V.Shabunov, I.A.Shelaev, Y.A.Shishov, A.V.Sidorov, N.V.Slavin, M.Suleimanov, A.A.Kuznetsov, A.V.Taranenko, G.P.Tsvineva, A.S.Vodopianov, M.B.Yuldasheva, O.I.Yuldashev, S.A.Zaporozhets, A.I.Zintchenko
[1] Joint Institute for Nuclear Research, Dubna

[2] N.Grigalashvili, A.Mamulashvili, Z.Menteshashvili, M.Nioradze, Yu.Tevzadze
[2] Institute of High Energy Physics, Tbilisi State University, Georgia.

[3] K.G.Akhobadze, E.S.Ioramashvili, A.K.Javrishvili, A.V.Kharadze, T.V.Khuskivadze, L.V.Shalamberidze, N.Shubitidze
[3] Institute of Physics, Georgian Academy of Sciences, Tbilisi, Georgia.

[4] V.P.Demkin, V.I.Kuznetsov, V.D.Shestakov, A.A.Vasiliev, A.V.Zhakovsky
[4] Research Center for Applied Nuclear Physics, Minatom RF, Dubna, Russia.

[5] T.Baatar, R.Togoo, B.Khurelbaatar
[5] Institute of Physics and Technology MAN, Ulaanbaatar, Mongolia

[6] D.Hasegan, M.Haiduc, D.Felea, A.Gheata, M.Gheata, A.-A.Radu, I.-S.Zgura
[6] Institute for Space Sciences, Bucharest, Romania

Also participating:

[7] Università del Piemonte Orientale, ALESSANDRIA, Italy
[8] Aligarh Muslim University, ALIGARH, India
[9] National Institute for Nuclear Physics and High Energy Physics (NIKHEF), Amsterdam, The Netherlands
[10] National Research Centre for Physical Sciences (NRCPS) ‘Demokritos’, Institute of Nuclear Physics, ATTIKI, Greece
[11] University of Athens, ATHENS HELLAS, Greece
[12] Dipartimento di Elettronica ed Elettrotecnica del Politecnico, BARI, Italy
[13] Università di Bari & INFN, BARI, Italy
[14] China Institute of Atomic Energy, BEIJING, People's Republic of China
[15] University of Bergen, BERGEN, Norway
[16] Institute of Physics, BHUBANESWAR, India
[17] University of Birmingham, BIRMINGHAM, United Kingdom
[18] Università degli Studi di Bologna, INFN Sezione di Bologna, BOLOGNA, Italy
[19] Comenius University, BRATISLAVA, Slovakia
[20] National Institute for Physics and Nuclear Engineering, BUCHAREST MAGURELE, Romania
[21] Hungarian Academy of Sciences, KFKI Research Institute for Physics and Nuclear Physics, BUDAPEST, Hungary
[22] Università di Cagliari, Cittadella Universitaria di Monserrato, Monserrato CAGLIARI, Italy
[23] Saha Institute of Nuclear Physics, CALCUTTA, India
[24] Variable Energy Cyclotron Centre (VECC), CALCUTTA, India
[25] Università di Catania & INFN, CATANIA, Italy
[26] CERN, Geneva, Switzerland.
[27] Panjab University, CHANDIGARH, India
[28] University Blaise Pascal de Clermond-Ferrand II (IN2P3-CNRS), AUBIERE CEDEX, France
[29] LIP Coimbra, Universidade de Coimbra, COIMBRA, Portugal
[30] Ohio State University, COLUMBUS, U.S.A.
]31] University of Copenhagen, Niels Bohr Institute, KOBENHAVN, Denmark
[32] Gesellshaft fur Schwerionenforschung (GSI), Darmstadt, Germany
[33] Johann-Wolfgang-Goethe Universitat Frankfurt, Institut fur Kernphysik, FRANKFURT AM MAIN, Germany
[34] St. Petersburg Nuclear Physics Institute, GATCHINA (ST. PETERSBURG), Russia
[35] Max-Plank-Institut für Kernphysik, HEIDELBERG, Germany
[36] Rupercht-Karls University Heidelberg, HEIDELBERG, Germany
[37] University of Ioannina, IOANNINA, Greece
[38] University of Rajasthan, JAIPUR, India (Rajasthan)
[39] University of Jammu, JAMMU, India
[40] University of Jyvaskyla, JYVASKYLA, Finland
[41] National Scientific Centre Kharkov Institute of Physics and Technology (KhIPT) KHARKOV, Ukraine
[42] Scientific Research Technological Institute of Instrument Making, KHARKOV, Ukraine
[43] National Academy of Sciences, Bogolyubov Institute for Theoretical Physics, KIEV, Ukraine
[44] Slovak Academy of Sciences, Institute of Experimental Physics, KOSICE, Slovakia
[45] P.J. Safarik University, KOSICE, Slovakia
[46] Henryk Niewodniczanski Institute of Nuclear Physics, KRAKOW, Poland
[47] I.V. Kurchatov Institute of Atomic Energy, MOSCOW, Russia
[48] Laboratori Nazionali di Legnaro, LEGNARO, Italy
[49] Centro de Fisica das Int. Fundamentais, Instituto Superior Tecnico, LISBON, Portugal
[50] Department of Physics, Lund University, LUND, Sweden
[51] Université Claude Bernard Lyon-I, Institut de Physique Nucleaire de Lyon (IPNL), VILLEURBANNE, France
[52] Philipps-Universitet Marburg, MARBURG AN DER LAHN, Germany
[53] Centro de Investigacion y de Estudios Avanzados del IPN (CINVESTAV), MEXICO D.F., Mexico
[54] Belorussian Academy of Sciences, Institute of Physics, MINSK, Belarus
[55] Institute of Nuclear Research, Moscow, Russia
[56] Institute of Theoretical and Experimental Physics, Moscow, Russia
[57] Moscow Engineering Physical Institute, Moscow, Russia
[58] Institute fur Kernphysik, Westfalische Wilhelms Universitat, Munster, Germany
[59] SUBATECH, Nantes, France
[60] Budker Institute for Nuclear Physics, Novosibirsk, Russia
[61] ORNL, Oak Ridge, USA
[62] Institut de Physique Nuclear, Orsay, France
[63] University of Oslo, Oslo, Norway
[64] Università di Padua & INFN, Padua, Italy
[65] Institute of Physics, Prague, Czech Republic
[66] Institute for High Energy Physics, Protvino, Russia
[67] Nuclear Physics Institute, Rez u Prahy, Czech Republic
[68] Università “La Sapienza” & INFN, Rome, Italy
[69] Università di Salerno & INFN, Salerno, Italy
[70] Russian Federal Nuclear Center (VNIIEF), Sarov, Russia
[71] St.Petersburg State University, St.Petersburg, Russia
[72] Centre de Recherches Nucleaires, Strasbourg, France
[73] Università di Trieste & INFN, Trieste, Italy
[74] Università di Torino & INFN, Torino, Italy
[75] NIKHEF and Utrecht University, Utrecht, The Netherlands
[76] Soltan Institute for Nuclear Studies, Warsaw, Poland
[77] Institute of Particle Physics, Huazhong Normal University, Wuhan, China
[78] Yerevan Physics Institute, Yerevan, Armenia
[79] Ruder Boskovic Institute, Zagreb, Croatia

 

Spokesman: J.Schukraft

Contactman from JINR: A.S.Vodopianov

 

ALICE (A Large Ion Collider Experiment) [1,2] is a dedicated heavy-ion experiment and its prime goal is the study of Pb-Pb interactions at the LHC at a center-of-mass energy of about 5.5 TeV/nucleon to establish and analyze the existence of QCD bulk matter and the Quark Gluon Plasma (QGP). The aim is to study the physics of strongly interacting matter at extreme energy densities, where the formation of a new phase of matter, the quark-gluon plasma, is expected. The existence of such a phase and its properties are a key issue in QCD for the understanding of confinement and of chiral-symmetry restoration. For this purpose, we intend to carry out a comprehensive study of the hadrons, electrons, muons and photons produced in the collision of heavy nuclei.

The ALICE Collaboration presently consists of about 750 physicists from 79 institutions. The ALICE experiment will be ready to take data at the start up date of the LHC on July 2005. The JINR involvement in the ALICE project is devoted to four major directions:

  • physics study and simulation;

  • design and construction of the large dipole magnet;

  • design and construction of subsystems for the particle identification;

  • development of the software for the simulation of the inner tracking system, for the pattern recognition and track reconstruction.

 

Physics study and simulation

In order to attain the main goal of the ALICE collaboration a number of various observable have to be obtained and learned in the following main directions of physics investigations:

  • global event features (particle and transverse-energy flows, the shape and structure of rapidity distributions)

  • transverse momentum spectra (large event-by-event fluctuations, the spectra peculiarities related to the ‘jet quenching’)

  • flavor composition (strangeness and charm enhancement)

  • vector meson characteristics (mass, width and decay pattern changeable of lighter (r, w, f) ones, suppression of the heavy quarkonia resonances (J/y, y¢, ¡, ¡¢, ¡¢ ¢) production)

  • correlation and fluctuation (multi particle correlation, CENTAURO events, Bose-Einstein correlation)
  • prompt photons (the thermal radiation from QGP and mixed phase)

The Dubna group main activity relates to the vector meson physics and Bose-Einstein correlation. In order to check the possibility to observe r, w, f decays to e+e- -pairs and K+K- decays the simulation has been done for the Pb-Pb central events taking into account the detectors resolution and tracking and particle identification efficiencies. It has been shown that it will be possible to determine the signals over the background for all considered resonance decay modes. Accuracies of the determination of the resonance mass positions are of the order of a few percent. Besides, in case of K+K- decay the resonance can be width extracted from a fit procedure of the signal shape with the accuracy of the order of a few percents also.

The simulation of Pb-Pb VENUS events with Bose-Einstein correlation including has shown that the corresponding interferometric radii at LHC energy would be rather large - about 15 - 20 fm. Besides, it was shown from nonidentical particles correlation analysis a new possibility to determine a time order of different particles (K+, K- , p+, p- , p) emission at very short time scale of several fm/c. In particular, this effect could be useful to indicate the formation of QGP.

 

Warm Dipole Magnet for the Muon Arm Spectrometer [3]

The large conventional dipole magnet is a major part of the ALICE forward muon spectrometer. The magnet will be designed and constructed at JINR as a join effort of JINR and CERN. The proposed dipole magnet has the central field of 0.7 T, the field integral of 3.0 T×m and the aperture of 9°. The magnet has the length of 5 m and the largest inner diameter of 4.1 m. The coil is made from a hollow aluminium conductor of 50´50 mm2. Its weight is about 30 ton. The weight of the iron yoke is about 800 ton. The coil will be flat wounded and than bent to quasi-cylindrical shape.

 

Particle Identification System

JINR team involved into the particle identification in the ALICE detector via the Transition Radiation Detector for electron identification and Time-of-Flight array based on the Resistive Plate Chambers for hadron identification. Main tasks are development of the prototypes and the production of the detectors.

 

Software development

To simulate the silicon Inner Tracking System (vertex detector) a GEANT-based program for a "realistic" simulation of different types (pixel, drift, double-sided microstrip) silicon detectors was created in Dubna [4]. Such detail as electron and hole drift and diffusion, electronics response and noise influence and also the real detector geometry was taken into account. The main results are the following:

  • the created charge is distributed through one or several cells in dependence of the detector type and direction (cluster creation);

  • the spatial precision’s for the pixel, drift, strip detector obtained;

  • the particle identification power is shown;

  • all parameters are adequate to the detector performance.

Two different tracking programs were created in Dubna based in Kalman filtering and Neural Networks algorithms respectively. The following main results have been obtained for the ITS+TPC detectors:

  • the tracking efficiency is varying from 90% to 50% versus Pt;

  • the mean angular resolutions are 1.5-2.0 mrad, the mean momentum resolution is less than 2% and correspondent resolutions for impact parameters in transverse and longitudinal directions equalled to 40 microns and 90 microns;

  • the tracking efficiency and the resolutions are adequate to physics performances in ALICE.

The project on the participation of the JINR group in ALICE experiment was approved April 1999 by PAC.

 

References:

[1] ALICE. Technical Proposal for A Large Ion Collider Experiment at the CERN LHC. CERN/LHCC/95-71, 1995.

[2] The Forward Muon Spectrometer of ALICE. Addendum to the Technical Proposal. CERN/LHCC/96-32, 1996.

[3] ALICE Technical Design Report of the Dimuon Forward Spectrometer, CERN/LHCC 99-22, 1999.

[4] ALICE Technical Design Report of the Inner Tracking System, CERN/LHCC 99-12, 1999.

 

E-mail contact: vodopian@sunhe.jinr.ru


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