In
particle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
, an interaction point (IP) is the place where particles collide in an
accelerator experiment. The ''nominal'' interaction point is the design position, which may differ from the ''real'' or ''physics'' interaction point, where the particles actually collide. A related, but distinct, concept is the ''primary vertex'': the reconstructed location of an individual particle collision.
For
fixed target experiments, the interaction point is the point where beam and target interact. For
collider
A collider is a type of particle accelerator which brings two opposing particle beams together such that the particles collide. Colliders may either be ring accelerators or linear accelerators.
Colliders are used as a research tool in particl ...
s, it is the place where the beams interact.
Experiments (
detector
A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon.
In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
s) at particle accelerators are built around the nominal interaction points of the accelerators. The whole region around the interaction point (the experimental hall) is called an interaction region.
Particle colliders such as
LEP,
HERA,
RHIC,
Tevatron
The Tevatron was a circular particle accelerator (active until 2011) in the United States, at the Fermi National Accelerator Laboratory (also known as ''Fermilab''), east of Batavia, Illinois, and is the second highest energy particle collider ...
and
LHC can host several interaction regions and therefore several experiments taking advantage of the same beam.
Accelerator physics
Experimental particle physics
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