The international collaboration ALICE (“A Large Ion Collider Experiment”), of which the eponymous research group of the IP2I in Lyon is a member, aims to study nuclear matter in a state of extremely high temperature, where the deconfinement of hadrons (including protons and neutrons) into plasma of quarks and gluons takes place.
Matter is made up of atoms, themselves made up of electrons surrounding a nucleus of protons and neutrons, the latter being formed of quarks, linked by gluons. No quark or gluon has ever been observed in isolation: they appear to be permanently bonded together and confined in composite particles. At temperatures 100,000 times higher than those at the centre of the Sun, they deconform to form a plasma, which would have existed a few microseconds after the Big Bang. This plasma is predicted by the fundamental theory of strong interaction, Quantum Chromodynamics (QCD), and its study allows us to understand the ultimate organization of matter subject to strong interaction and the very first moments of the universe.
The LHC collides lead ions to recreate conditions similar to those immediately after the Big Bang and form this quark and gluon plasma. For this infinitely small study, a huge detector has been built at the LHC. It is capable of measuring the particles emitted by the plasma as it expands and cools.
Our group has been involved in this construction and in obtaining major results in this field of physics.
The activities of the ALICE group of the IP2I of Lyon are twofold:
- the analysis of data collected in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN LHC
- participation in the construction and operation of the forward vertex trajectograph, the Muon Forward Tracker
Analysis of data collected in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN LHC
The physics analyses of the ALICE experiment carried out in the Lyon groups cover a wide range of subjects, from the light quark sector u, d, s with the study of the forward production of low mass vector mesons 
and 
in the dimuonic decay channel, to the heavy quarks sector c and b, with the study of the production of the quarkonium states of the 
and 
families. This analytical work has already led to a number of remarkable results, notably through the study of collective phenomena characterizing the evolution of the and mesons, namely the appearance of kinematic correlations between the meson and light hadrons in high multiplicity proton-Pb collisions, and the observation of elliptical flow of the 
meson compatible with zero in Pb-Pb collisions (behavior different from all the other particles studied).
Participation in the construction and operation of the forward vertex trajectograph, the Muon Forward Tracker
The group is also responsible for the construction and operation of the vertex forward trajectograph, the Muon Forward Tracker (MFT), one of the first applications in high energy physics of CMOS silicon pixel sensor technology. The MFT, which will be integrated into the ALICE detector starting with Run3 of the LHC (2021), is designed to enable precise measurement of the details of the vertex region for forward-produced particles, especially muons, whose different topologies and production processes can be studied.
NON-PERMANENTS:
- DOCTORANTS / DOCTORAL STUDENTS:
- M C. Abreu, B. Alessandro, C. Alexa, R. Arnaldi, J. Astruc, et al.. Recent results on anomalous suppression in PbPb collisions at 158 GeV/c. International Workshop on Progress in Heavy Quark Physics 4, Sep 1997, Rostock, Germany. pp.1-32. ⟨in2p3-00000265⟩
- X. Artru. Resolution power of optical transition radiation theoretical considerations. Conference RREPS (Radiation Relativistic Electrons in Periodical Structures) 3, Sep 1997, Tomsk, Russia. ⟨in2p3-00022850⟩
- P. Giubellino, M C. Abreu, B. Alessandro, C. Alexa, R. Arnaldi, et al.. suppression. International symposium on multiparticle dynamics 27, Sep 1997, Frascati, Italy. pp.279-286. ⟨in2p3-00003492⟩
- M. Ericson. Symetrie chirale dans la matiere dense et chaude. Journees d'Etudes sur la Production de Dileptons dans les Collisions Hadroniques et Collisions d'Ions Lourds, Sep 1997, Orsay, France. ⟨in2p3-00022851⟩
- M. Bedjidian, F. Bellaiche, B. Cheynis, O. Drapier, J.-Y. Grossiord, et al.. A new measurement of the J/
production rate in lead-lead interactions at 158 GeV/c per nucleon. International Europhysics Conference on High Energy Physics, Aug 1997, Jerusalem, Israel. pp.1-8. ⟨in2p3-00005050⟩ - M C. Abreu, B. Alessandro, C. Alexa, J. Astruc, C. Baglin, et al.. and
production in lead-lead collisions at 158 A GeV/c. International Conference on Nuclear Reaction Mechanisms 8, Jun 1997, Varenna, Italy. pp.513-522. ⟨in2p3-00000046⟩ - M. Gonin, M.C. Abreu, C. Alexa, B. Alessandro, J. Astruc, et al.. Anomaly in charmonium suppression in Pb + Pb collisions : final results. International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPA-QGP) 3, Mar 1997, Jaipur, India. ⟨in2p3-00007767⟩
- F. Fleuret, M.C. Abreu, B. Alessandro, C. Alexa, J. Astruc, et al.. Charmonium suppression in Pb-Pb collisions. Rencontres de Moriond 32, Mar 1997, Les Arcs, France. ⟨in2p3-00012124⟩
- M.C. Abreu, B. Alessandro, C. Alexa, J. Astruc, C. Baglin, et al.. anomalous suppression in Pb-Pb collisions at 158 AGeV. International Winter Meeting on Nuclear Physics 35, Feb 1997, Bormio, Italy. pp.12-22. ⟨in2p3-00002390⟩
- M. Gonin, M C. Abreu, C. Alexa, B. Alessandro, J. Astruc, et al.. Anomaly in charmonium suppression in Pb+Pb collisions. International Workshop on Gross Properties of Nuclei and Nuclear Excitations 25, Jan 1997, Hirschegg, Austria. pp.254-268. ⟨in2p3-00007651⟩
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