Particle Physics Division

With more than 5,000 scientists, engineers, technicians, administrators and students, CMS is one of the largest scientific collaborations in the world. With members from more than 240 institutes and universities in nearly 50 countries around the world, the collaboration exploits the data provided by the CMS experiment, one of the two giant general-purpose detectors installed along the circumference of the LHC, CERN's Large Hadron Collider.

Gautier Hamel de Monchenault, a physicist in the particle physics department at CEA-IRFU, was elected on Monday 12 February 2024 as the spokesperson for the CMS collaboration at CERN. He will hold this prestigious position from 1 September 2024 to 31 August 2026. He will be the 10th spokesperson for the CMS collaboration and the second French spokesperson to lead one of the four LHC experiments.

These intense years will see the end of the third data-taking period of the LHC as we know it, and the start of the installation of detector upgrades in preparation for the high-luminosity HL-LHC data, as well as the update of the European particle physics strategy.

On January 17, the T2K collaboration announced the launch of the second phase of its experiment, as stated in a press release. This phase will exploit an upgrade of the beam, whose nominal power has been increased from 450 kW to 710 kW, with the aim of reaching 1.2 MW by 2027. An improved version of the experiment's near detector ND280 is also being implemented, incorporating new time-projection chambers using resistive-Micromegas technology designed and developed by the IRFU teams. The aim of this second phase is to collect more than twice the neutrino statistics recorded during the previous phase by 2027, and to reduce the uncertainty in the measured neutrino  interaction rate by a factor of two. The aim is to achieve a statistical significance of 3σ on the violation of Charge-Parity (CP) symmetry, in the event of maximum CP violation, as suggested by the results of the first phase of T2K. The discovery of CP symmetry violation in the lepton sector could explain one of the most fundamental mysteries of modern physics: the matter-antimatter asymmetry observed in the Universe.