Low Energy Antiproton Ring
| Low Energy Antiproton Ring (1982–1996) | |
|---|---|
Extra Low Energy Antiproton ring (ELENA) | Decelerates antiprotons received from AD |
The Low Energy Anti-Proton Ring (LEAR) was a particle accelerator at CERN which operated from 1982 until 1996.[1] The ring was designed to decelerate and store antiprotons, to study the properties of antimatter and to create atoms of antihydrogen.[2] Antiprotons for the ring were created by the CERN Proton Synchrotron via the Antiproton Collector and the Antiproton Accumulator (AA). The creation of at least nine atoms of antihydrogen were confirmed by the PS210 experiment in 1995.
Experimental setup
LEAR is a multipurpose
Bunches of usually a few 109 antiprotons are skimmed off the AA and then decelerated by the PS from 3.5 GeV/c to 0.6 GeV/c.[5][6] The bunch was transferred to LEAR where it could be decelerated to a minimum 100 MeV/c or accelerated to generally 1000 MeV/c.[5] For most experiments, a "beam stretcher mode" was used, where an ultra-slow extraction provided a high-duty (continuous) amount of antiprotons.[5] Another mode, "internal target", kept a beam circulating for hours, or even days, until most particles were consumed by a gas jet target.[7][5]
Stochastic cooling is implemented at several stages of the LEAR experimental setup, at different momenta.[5] The focus of stochastic cooling is to restrict the motion of particles in the beam and control their energies close to a certain value. From 1987, the setup included electron cooling, using the electron cooler from the Initial Cooling Experiment (ICE) to complement the stochastic cooling.[8][9] Using cooling, high quality beams at low energies and low emittances could be produced.[5]
Results
There was a total of 27 experiments performed during LEAR's 14 years of running.[10] Several meson spectroscopy experiments were setup at LEAR to analyse the rare meson resonances produced in nucleon-antiproton annilhilation.[11] These included the Crystal Barrel, OBELIX and JETSET experiments.[10] Furthermore, matter-antimatter symmetry was investigated by studying specific proton-antiproton interactions, resulting in detailed measurements of CP violation.[12] The mass difference between the proton and antiproton was also studied at LEAR with an accuracy in 1 part in 1010.[13][10]
Conversion to LEIR
In 1996, LEAR was converted into the Low Energy Ion Ring, which has since been used in the lead ion injection process for the Large Hadron Collider.[1][14] Low energy antiproton research continues at CERN using the Antiproton Decelerator. It was built as a successor for LEAR and started operation in 2000.[15]
References
- ^ a b "The Low Energy Antiproton Ring". CERN. Retrieved 2021-08-17.
- ^ "The History of Antimatter - The Accelerator Era". 2001-02-22. Archived from the original on 2001-02-22. Retrieved 2021-08-17.
- ^ a b Plass, Gunther (16 May 1980). "Design study of a facility for experiments with low energy antiprotons (LEAR)" (PDF). Cern/Ps/Dl 80-7.
- ^ ISBN 978-3-0348-5540-2, retrieved 2023-08-07
- ^ ISSN 0370-1573.
- S2CID 250785310.
- ISBN 978-1-4684-8727-5, retrieved 2023-08-07
- ISSN 0168-9002.
- ISBN 978-3-0348-5540-2, retrieved 2023-08-07
- ^ a b c Bloch, Philippe (11 Jun 2012). "LEAR'S PHYSICS LEGACY". CERN Bulletin.
- .
- ISSN 0370-2693.
- PMID 10042233.
- ^ Katarina Anthony (2012). "LEAR: a machine ahead of its time". CERN Bulletin.
- ^ "The Antiproton Decelerator". CERN. Retrieved 2021-08-17.
| Large Hadron Collider (LHC) | |
|---|---|
| Large Electron–Positron Collider (LEP) | |
| Super Proton Synchrotron (SPS) |
|
| Proton Synchrotron (PS) | |
| Linear accelerators | |
| Other accelerators | |
ISOLDE facility | |
| Non-accelerator experiments | |
| Future projects | |
| Related articles | |
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