CMS (Compact Muon Solenoid) is a particle physics experiment that studies frontal collisions of protons and operates at the high energy frontier. The experiment is located in an underground cavern about a hundred meters deep in Cessy, in France, not far from the city of Geneva in Switzerland, in one of the four interaction points of the two proton beams accelerated by the Large Hadron Collider (LHC, CERN).
LHC is the most powerful accelerator machine built up to today, it develops along a circular tunnel of 27 km and reaches a maximum energy of 14 TeV in the impact of two protons, allowing a remarkable step forward in the ability to discover new particles and explore possible new particle structures that we now consider elementary. In fact part of the collision energy is transformed into mass, creating new particles. CMS is a large-scale apparatus (15 meters high, like a 5-storey building, for about 14,000 tons of weight) and extremely complex, where the most modern technologies in the field of detectors, electronics, data acquisition systems and computing are applied. CMS has been explicitly designed to discover new phenomena and new particles.
CMS consists of several sub-detectors arranged according to concentric shells around the crossing point of the beams. From the interaction point to the outside, the CMS sub-detectors are:
- the tracker, based on silicon detectors, which accurately measures the track properties of the charged particles;
- the electromagnetic calorimeter (ECAL), composed of sparkling crystals, detecting and measuring the energy of electrons and photons;
- the system of hadron calorimeters (HCAL and HF), for the measurement of hadron jets;
- the muon chambers system (MUON), for the identification and measurement of muons
The CMS group of Padova-Legnaro-Trento participated in the design, testing, construction and installation of the muon chambers of the inner barrel tracker (TIB), and contributed to the definition of the trigger and the data acquisition system of the experiment.