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:
- CHERCHEURS NON-PERMANENTS / NON-PERMANENT RESEARCHERS:
- P. Cortese, G. Dellacasa, L. Ramello, M. Sitta, N. Ahmad, et al.. ALICE Technical Design Report of the Computing. [Research Report] ALICE collaboration. 2005, pp.1-106. ⟨in2p3-00024494⟩
- P. Cortese, G. Dellacasa, L. Ramello, M. Sitta, N. Ahmad, et al.. ALICE Technical Design Report on Forward Detectors : FMD, T0 and V0. 2005, pp.1-76. ⟨in2p3-00024755⟩
- H.K. Wöhri, R. Arnaldi, K. Banicz, J. Buytaert, J. Castor, et al.. Low mass dimuon production in proton-nucleus collisions with the NA60 apparatus. International Conference on Hard and Electromagnetic Probes of High Energy Nuclear Collisions - Hard Probes 2004, Nov 2004, Ericeira, Portugal. pp.407-413, ⟨10.1140/epjc/s2005-02206-1⟩. ⟨in2p3-00024262⟩
- K. Borer, W. M. Chen, Z. Li, C. Cicalo, A. de Falco, et al.. First results of the NA60 experiment at the CERN SPS. 18th Nuclear Physics Division Conference of the EPS. Phase Transitions in Strongly Interacting Matter., Aug 2004, Prague, Czech Republic. pp.251-256, ⟨10.1016/j.nuclphysa.2004.12.047⟩. ⟨in2p3-00024626⟩
- B. Alessandro, C. Alexa, R. Arnaldi, M. Atayan, C. Baglin, et al.. Charged particle multiplicity in Pb-Pb collisions from the NA50 experiment. Focus On Multiplicity: International Workshop On Particle Multiplicity In Relativistic Heavy Ion Collisions, Jun 2004, Bari, Italy. pp.86-96, ⟨10.1088/1742-6596/5/1/008⟩. ⟨in2p3-00024210⟩
- M. Floris, K. Borer, W. M. Chen, Z. Li, C. Cicalo, et al.. Charged particle multiplicity measurements in NA60. International Workshop on Particle Multiplicity In Relativistic Heavy Ion Collisions Focus on Multiplicity, Jun 2004, Bari, Italy. pp.55-63, ⟨10.1088/1742-6596/5/1/005⟩. ⟨in2p3-00024196⟩
- P. Sonderegger, R. Arnaldi, R. Averbeck, K. Banicz, K. Borer, et al.. Accurate measurements of dimuon production in the NA60 experiment. Quark Matter 2004 - 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Jan 2004, Oakland, California, United States. pp.S1027-S1030, ⟨10.1088/0954-3899/30/8/052⟩. ⟨in2p3-00024596⟩
- B. Alessandro, C. Alexa, R. Arnaldi, M. Atayan, C. Baglin, et al.. Charmonium production and nuclear absorption in p-A interactions at 450 GeV. European Physical Journal C: Particles and Fields, 2004, 33, pp.31-40. ⟨10.1140/epjc/s2003-01539-y⟩. ⟨in2p3-00020479⟩
- R. Arnaldi, B. Alessandro, C. Alexa, M. Atayan, C. Baglin, et al.. Charmonia Suppression in Nucleus–Nucleus Interactions at CERN SPS. Acta Physica Hungarica, 2004, 19, pp.337-341. ⟨10.1556/APH.19.2004.3-4.33⟩. ⟨in2p3-00112324⟩
- B. Alessandro, C. Alexa, R. Arnaldi, M. Atayan, C. Baglin, et al.. Fission cross sections of lead projectiles in Pb-nucleus interactions at 40 and 158 GeV/c per nucleon. Physical Review C, 2004, 69, pp.034904-. ⟨10.1103/PhysRevC.69.034904⟩. ⟨in2p3-00021733⟩
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