page_title: Hermetic detector
section_title: Components
hierarchical_section_title: Hermetic detector / Components
caption_attribution_description: Rough schematic of a hermetic particle physics detector.
context_page_description: In particle physics, a hermetic detector is a particle detector designed to observe all possible decay products of an interaction between subatomic particles in a collider by covering as large an area around the interaction point as possible and incorporating multiple types of sub-detectors. They are typically roughly cylindrical, with different types of detectors wrapped around each other in concentric layers; each detector type specializes in particular particles so that almost any particle will be detected and identified. Such detectors are called "hermetic" because they are constructed so as the motion of particles are ceased at the boundaries of the chamber without any moving beyond due to the seals; the name "4π detector" comes from the fact that such detectors are designed to cover nearly all of the 4π steradians of solid angle around the interaction point; in terms of the standard coordinate system used in collider physics, this is equivalent to coverage of the entire range of azimuthal angle and pseudorapidity.
context_section_description: There are three main components of a hermetic detector.  From the inside out, the first is a tracker, which measures the momentum of charged particles as they curve in a magnetic field.  Next there are one or more calorimeters, which measure the energy of most charged and neutral particles by absorbing them in dense material, and a muon system which measures the one type of particle that is not stopped through the calorimeters and can still be detected.  Each component may have several different specialized sub-components.
caption: A schematic of the basic components of a hermetic detector; I.P. refers to the region containing the interaction point for the colliding particles.  This is a cross section of the typical cylindrical design.
exif: {}