FixedTargetExperimente

FixedTargetExperimente refer to a class of experiments in high-energy and nuclear physics in which a high-energy particle beam is directed at a stationary target. This configuration contrasts with collider experiments, where two beams collide head-on. Fixed-target setups are used to study fundamental interactions, hadron structure, and the behavior of nuclear matter under extreme conditions.

Key elements of fixed-target experiments include a well-collimated primary beam, a solid or liquid target composed of protons or nuclei, and a complex array of detectors arranged to capture charged particles, photons, and neutrons produced in the interaction. Detectors typically provide precise tracking, momentum measurement, energy determination, and particle identification. Because the target is at rest, the center-of-mass energy is determined primarily by the beam energy, allowing very high luminosities in some regimes and enabling detailed mapping of reaction channels and cross sections.

Physically, fixed-target programs address a range of topics: the internal structure of hadrons through parton distribution functions and form factors, the production mechanisms of strange and heavy quarks, and the properties of nuclear matter under extreme temperature and density, including signatures of the quark-gluon plasma in heavy-ion fixed-target collisions. The approach has been central to facilities like SLAC, CERN's SPS program, Fermilab's fixed-target experiments, and Jefferson Lab, with ongoing discussions of fixed-target extensions at modern accelerators such as proposed AFTER/AFTER@LHC projects. The method remains complementary to collider experiments, offering unique kinematic access and high interaction rates.