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) and ...
, 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 particle ...
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
In ancient Greek religion, Hera (; grc-gre, Ἥρα, Hḗrā; grc, Ἥρη, Hḗrē, label=none in Ionic and Homeric Greek) is the goddess of marriage, women and family, and the protector of women during childbirth. In Greek mythology, she ...
,
RHIC
The Relativistic Heavy Ion Collider (RHIC ) is the first and one of only two operating heavy-ion colliders, and the only spin-polarized proton collider ever built. Located at Brookhaven National Laboratory (BNL) in Upton, New York, and used by a ...
,
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
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundr ...
can host several interaction regions and therefore several experiments taking advantage of the same beam.
Accelerator physics
Experimental particle physics
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