Compact Muon Solenoid

Compact Muon Solenoid
source
Name	Compact Muon Solenoid
Caption	The CMS detector at the Large Hadron Collider.
Experiment	LHC experiment
Institution	CERN
Location	Cesson
Date	1998–present

Compact Muon Solenoid. The Compact Muon Solenoid is one of two large, general-purpose particle physics detectors built on the Large Hadron Collider at CERN. It is designed to investigate a wide range of physics, including the properties of the Higgs boson, extra dimensions, and particles that could make up dark matter. The international collaboration behind it involves thousands of scientists and engineers from hundreds of institutes worldwide.

Overview

The detector is a key component of the LHC experiments, situated in an underground cavern near the French village of Cesson. Its primary purpose is to explore physics at the TeV scale, probing fundamental questions left unanswered by the Standard Model. The project was formally approved in the late 1990s, with construction completed in time for the first LHC collisions in 2009. Alongside its counterpart ATLAS, it forms the cornerstone of the LHC's experimental program.

Design and components

The detector employs a cylindrical design, approximately 21 meters long and 15 meters in diameter, with a weight of around 14,000 tonnes. Its central feature is a powerful 3.8 Tesla superconducting solenoid magnet, which bends the paths of charged particles for momentum measurement. Surrounding the magnet are several layered sub-detectors: an inner silicon tracker, an electromagnetic calorimeter made of lead tungstate crystals, a hadron calorimeter using brass and plastic scintillator, and an extensive muon spectrometer embedded in the iron return yoke. This onion-like structure allows for the precise reconstruction of collision events from the proton–proton collisions produced by the LHC.

Physics goals and discoveries

A central goal was the search for and characterization of the Higgs boson, the particle associated with the Brout–Englert–Higgs mechanism. In July 2012, the collaboration, together with the ATLAS experiment, announced the discovery of a new particle consistent with the Higgs boson, a milestone later recognized by the Nobel Prize in Physics awarded to François Englert and Peter Higgs. Other major physics programs include searches for supersymmetry, evidence of dark matter candidates, studies of quark–gluon plasma, and precision measurements of top quark properties and quantum chromodynamics processes.

Operation and performance

The detector began recording data from the first LHC runs in 2010 and has operated through several extended periods, including Long Shutdown 1 and Long Shutdown 2, for upgrades and maintenance. It has consistently performed with high efficiency, recording billions of collision events. Its sophisticated trigger system and data acquisition system filter and store petabytes of data for analysis by the global collaboration. The detector underwent significant upgrades during the High-Luminosity LHC preparation phase to withstand the increased collision rates and radiation.

Collaboration and institutions

The collaboration is a vast international scientific endeavor, uniting over 200 institutions from more than 40 countries, including major contributions from Fermilab in the United States, the Institute for High Energy Physics in Russia, and the Tata Institute of Fundamental Research in India. Key funding and coordinating roles are held by agencies like the United States Department of Energy, the National Science Foundation, and various national bodies within the European Union. The management structure is led by a collaboration board and spokespersons, with technical work distributed across numerous specialized groups and committees. Category:Particle detectors Category:CERN Category:Experiments in particle physics