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. Ericson, S. Kulagin, M. Rosa-Clot. Pion and the enhancement factor in the photoabsorption sum rule. Il Nuovo Cimento A, 1998, 111, pp.75. ⟨in2p3-00003786⟩
- G. Chanfray, J. Delorme, M. Ericson. Chiral Symmetry Restoration in nuclei and Parity Mixing. Nuclear Physics A, 1998, 637, pp.421-432. ⟨10.1016/S0375-9474(98)00237-1⟩. ⟨in2p3-00003398⟩
- X. Artru. Comparison of parametric X rays and diffracted transition radiation in perfect and mosaic crystals. International Workshop on Radiation Physics with Relativistic Electron, 1998, Tabarz, Germany. ⟨in2p3-00003857⟩
- M. Acciarri, O. Adriani, M. Aguilar-Benitez, S. Ahlen, J. Alcaraz, et al.. Production of Single W Bosons in
Interactions at 130 
183 GeV and Limits on Anomalous WW
Couplings. Physics Letters B, 1998, 436, pp.417-427. ⟨in2p3-00023168⟩ - L. Ramello, M.C. Abreu, B. Alessandro, C. Alexa, R. Arnaldi, et al.. New results on intermediate mass dileptons. Workshop on Quarkonium Production in Relativistic Nuclear Collisions, 1998, Brookhaven, United States. ⟨in2p3-00023005⟩
- V.N. Baier, T.V. Dimova, V.P. Druzhinin, M.S. Dubrovin, V.B. Golubev, et al.. Set-up optimization for an experimental test of a positron source using channeling. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1998, 145, pp.221-229. ⟨in2p3-00003426⟩
- M C. Abreu, J. Astruc, C. Baglin, A. Baldit, M. Bedjidian, et al.. Transverse momentum of J/
and mass continuum muon pairs produced in 
S-U collisions at 200 GeV/c per nucleon. Physics Letters B, 1998, 423, pp.207-212. ⟨10.1016/S0370-2693(98)00088-4⟩. ⟨in2p3-00005042⟩ - E. Auffray, P. Baillon, D. Barney, G. Bassompierre, Y. Benhammou, et al.. Beam tests of lead tungstate crystal matrices and a silicon strip preshower detector for the CMS electromagnetic calorimeter. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1998, 412, pp.223-237. ⟨in2p3-00002398⟩
- M. Acciarri, O. Adriani, M. Aguilar-Benitez, S. Ahlen, J. Alcaraz, et al.. Study of the Hadronic Photon Structure Function
at LEP. Physics Letters B, 1998, 436, pp.403-416. ⟨10.1016/S0370-2693(98)01025-9⟩. ⟨in2p3-00000021⟩ - M. Acciarri, O. Adriani, M. Aguilar-Benitez, S. Ahlen, J. Alcaraz, et al.. Measurement of the Average Lifetime of b-Hadrons in Z Decays. Physics Letters B, 1998, 416, pp.220-232. ⟨10.1016/S0370-2693(97)01379-8⟩. ⟨in2p3-00000012⟩
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