Jump to content

Fixed-target experiment

Add links
From Wikipedia, the free encyclopedia
This is an old revision of this page, as edited by Betelgeuse496 (talk | contribs) at 09:33, 24 July 2021 (added more information). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.


A fixed-target experiment in particle physics is an experiment in which a beam of accelerated particles is collided with a stationary target. The moving beam (also known as a projectiles) consists of charged particles such as electrons or protons and is accelerated to relativistic speed. The fixed target can be a solid block or a liquid or a gaseous medium.[1][2] These experiments are distinct from the collider-type experiments in which two moving particle beams are accelerated and collided. The famous Rutherford gold foil experiment, performed between 1908 and 1913, was one of the first fixed-target experiments, in which the alpha particles were targeted at a thin gold foil.[1][3][4]

Explanation

The energy involved in a fixed target experiment is 4 times smaller compared to that in collider with the dual beams of same energy.[5][6] More over in collider experiments energy of two beams is available to produce new particles, while in fixed target case a lot of energy is just expended in giving velocities to the newly created particles. This clearly implies that fixed target experiments are not helpful when it comes to increasing the energy scales of experiments.[3][7] The targeted source also wears down with number of strikes and usually require a regular replacement. Current day fixed-target experiments try to use highly resistant materials but the damage cannot be avoided entirely.[8]

The fixed target experiments have a significant advantage for experiments that require higher luminosity (rate of interaction).[5][9] The High Luminosity LHC, which is an upcoming upgraded version of the Large Hadron Collider at CERN, will attain total integrated luminosity of around in its run.[10] While luminosity scale of about have already been approached by older fixed target experiments such at the E288 lead by Leon Lederman at Fermilab.[3][11]Another advantage for fixed-target experiments is that they are easier and cheaper to built compared to the collider accelerators.[5]

Experimental facilities

Rutherford's gold foil experiment that led to the discovery that mass and positive charge of an atom was concentrated in a small nucleus was probably the first fixed-target experiment. Later half of the 20th century saw the rise of particle and nuclear physics facilities such as CERN's Super Proton Synchrotron (SPS) and Fermilab's Tevatron where number of fixed-target experiments led to new discoveries. Tevatron conducted 43 fixed-target experiments during its run period from 1983 to 2000.[12] While proton and other beams from SPS are still used by fixed target experiments such as NA61/SHINE and COMPASS collaboration. Fixed-target facility at the Large Hadron Collider (LHC) termed at AFTER@LHC is also being planned.[13]

Physics Goals

The fixed-target experiments are mainly implemented for the intensive studies of the rare processes, dynamics at high Bjorken x, diffractive physics, spin-correlations, and numerous nuclear phenomena.[13]

References

  1. ^ a b "The Particle Adventure | How do we experiment with tiny particles? | Fixed-target experiments". particleadventure.org. Retrieved 2021-07-16.
  2. ^ "Detectors, Fixed-Target | Encyclopedia.com". encyclopedia.com. Retrieved 2021-07-16.
  3. ^ a b c "Fixed-target physics". ed.fnal.gov. Retrieved 2021-07-16.
  4. ^ "Fixed target, striking physics". CERN Courier. 2019-03-11. Retrieved 2021-07-21.
  5. ^ a b c "Fixed Target vs Collider Experiments (with discussion) | Matt Evans". mtdevans.com. Retrieved 2021-07-22.
  6. ^ Lincoln, Don (2013-08-02). "Fixed-target vs. collider". News. Retrieved 2021-07-20.
  7. ^ "Fixed Target and Colliding Beam Accelerators". www.hep.ucl.ac.uk. Retrieved 2021-07-22.
  8. ^ Lawhun, Sarah. "Right on target". symmetry magazine. Retrieved 2021-07-22.
  9. ^ https://edu.itp.phys.ethz.ch/hs10/ppp1/PPP1_4.pdf
  10. ^ "Physics opportunities of a fixed-target experiment using LHC beams". Physics Reports. 522 (4): 239–255. 2013-01-01. doi:10.1016/j.physrep.2012.10.001. ISSN 0370-1573.
  11. ^ Topilskaya, Nataliya; Kurepin, Alexey (2019). Bondarenko, S.; Burov, V.; Malakhov, A. (eds.). "Some proposed fixed target experiments with the LHC beams". EPJ Web of Conferences. 204: 03002. doi:10.1051/epjconf/201920403002. ISSN 2100-014X.
  12. ^ "INSPIRE". inspirehep.net. Retrieved 2021-07-24.
  13. ^ a b "Physics at a Fixed-Target Experiment Using the LHC Beams". Hindawi. Retrieved 2021-07-24.

See also


Retrieved from "https://en.wikipedia.org/w/index.php?title=Fixed-target_experiment&oldid=1035207349"