Département de Physique des Particules

CMS is the detector of one of the 2 multi-purpose experiments out of the 4 experiments located at the LHC at CERN near Geneva. CMS is installed at point 5 in Cessy.

Main goals :

During the last decades, research in particle physics has made tremendous progress and succeeded in validating the theoretical framework called “Standard Model”. Nevertheless, lot of questions remain opened: Why matter is in excess in our universe while it was produced the same amount of matter and antimatter at the Big Bang ? How elementary particles acquire their mass? Would we have to modify our understanding of matter and energy if we observe new processes or new particles? In particular, the field associated to the “Higgs boson” could have generated the mass of all other particles. Other new particles are expected in the framework of Standard Model extensions such as a particle to explain the Dark Matter component of the universe as suggested by measurements from astrophysics and cosmology, or particles from supersymmetry, extra-dimensions or mini black holes ?

The past and present analysis activities of the CMS-Saclay group covers several domains with a predominance for the physics of the Higgs boson. Precision measurements in the context of the standard model and the search for new particles constitute the other components of the analysis activities of the CMS-Saclay group.

For the CMS detector, the Saclay group is responsible for the design, manufacture and commissioning of the calibration system, by laser light injection, of the electromagnetic calorimeter (ECAL) with lead tungstate crystals and its permanent online monitoring. The group is also responsible for the development, commissioning and maintenance of the off-detector electronic system called the Selective Read-out Processor (SRP). For each event accepted by the first level of the experiment triggering system, the SRP makes it possible to alleviate in real time the quantity of calorimeter raw data before being sent to the acquisition system.

Concerning the upgrades of the CMS detector for the high-luminosity phase of the LHC i.e. the phase 2 upgrades for  HL-LHC, the CMS-Saclay group is involved in the design, development and manufacture of the front-end electronics of the barrel electromagnetic calorimeter. In addition, CMS endcap calorimeters will be replaced for this HL-LHC phase. In May 2015 CMS opted for a radiation hard high granularity and dense silicon / tungsten calorimeter called HGCAL. The CMS-Saclay group in Saclay is involved in this project by taking the responsibility for the design and development of the precise LHC clock distribution system, including the TDC part of the HGCAL front end electronics, in order to ensure the synchronization of the HGCAL electronic channels and the precise determination of particles time of the flight. The development of the clock distribution system may go beyond the HGCAL framework and become generalized to other CMS detectors. The CMS-Saclay group is also involved in the study of jets trigger primitives algorithms for HGCAL and their implementation in firmwares (FPGA).