CMS is one of the four large experiments around the LHC that are built in large underground halls.
At these locations, the proton beams of the LHC are brought together into one beampipe, focused and collided in the center of the detector.
CMS can be seen as a large onion built around the collision point, with layers of detectors each with their own specific task. Closest to the collisions is the track detector to measure momenta of charged particles, then comes the electromagnetic and hadronic calorimeter that measure energies of particles that interact respectively via the electromagnetic (photons, electrons) or hadronic (mesons and baryons, mostly charged pions, protons and neutrons) interaction, and in the outer layers are muon chambers that allow us to track the few muons that are being produced, heavy siblings of the electron that travel all the way through as they do not leave much energy in the detector. A central piece is the very strong magnet that bends the charged particles, and makes it possible to estimate their momenta very accurately.
You may find a general introduction to these components (but also other items like the detector construction of the data handling) here:
On the right side you see a menu with details on the detector. Clicking on these items opens new pages, but also sometimes further subitems with even more information.
The VUB takes part in CMS since almost 30 years already, and in particular played a large role in the construction and operation of the inner silicon strip tracker. We also host one of the large so-called “Tier-2” computing centres for the experiment. At this moment, in the labs on the ground floor of VUB's building G, advanced equipment is being prepared to build again a large tracking detector as an upgrade for the current tracker, that will come to the end of its lifetime in 2025.