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Extra Low Energy Antiproton ring

(Redirected from ELENA)
"ELENA" redirects here. For other uses, see Elena (disambiguation).

Extra Low ENergy Antiproton ring (ELENA) is a 30 m hexagonal storage ring that decelerates antiproton beams and delivers it to different AD experiments. It is situated inside the Antiproton Decelerator (AD) complex at CERN, Geneva.[1][2] It is designed to further decelerate the antiproton beam coming from the Antiproton decelerator to an energy of 0.1 MeV for more precise measurements.[3][4] The first beam circulated ELENA on 18 November 2016.[5] The ring is expected to be fully operational by the end of the Long Shutdown 2 (LS2) in 2021.

Antiproton decelerator
(AD)
ELENAExtra low energy antiproton ring – further decelerates antiprotons coming from AD
AD experiments
ATHENAAD-1 Antihydrogen production and precision experiments
ATRAPAD-2 Cold antihydrogen for precise laser spectroscopy
ASACUSAAD-3 Atomic spectroscopy and collisions with antiprotons
ACEAD-4 Antiproton cell experiment
ALPHAAD-5 Antihydrogen laser physics apparatus
AEgISAD-6 Antihydrogen experiment gravity interferometry spectroscopy
GBARAD-7 Gravitational behaviour of anti-hydrogen at rest
BASEAD-8 Baryon antibaryon symmetry experiment
PUMAAD-9 Antiproton unstable matter annihilation

GBAR experiment (AD-7) was the first experiment to use a beam from ELENA, with the rest of the AD experiments following suit after LS2 when beam transfer lines from ELENA will have been laid to all the experiments using the facility.[6] Long Shutdown 2 (LS2) officially ended on July 5, 2022 with the beginning of LHC Run 3.[7] Antiprotons from ELENA have been available to the MUSASHI trap of the ASACUSA CUSP experiment from August 2021.[8]

ELENA decelerator

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The AD and ELENA experiments require antiprotons of about 3 to 5 keV energy, suitable for trapping them in the Penning traps and carrying out further measurements. The AD outputs 5.3 MeV energy antiprotons which are then decelerated to ~5keV using the degrader foils by each of the experimental setups.

This results in a loss of about 99.9% of antiprotons. The ELENA ring with its efficient beam cooling and deceleration method is meant to increase the effective number of antiprotons that could be made available to the antimatter experiments by reducing the usage of the degrader foils.[1][9]

 
CERN Antimatter Factory – antiproton decelerator

Efficiency of ELENA

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Antimatter facilities
Low Energy Antiproton Ring (1982–1996)
Antiproton AccumulatorAntiproton production
Antiproton CollectorDecelerated and stored antiprotons
Antimatter Factory (2000–present)
Antiproton Decelerator (AD)Decelerates antiprotons
Extra Low Energy Antiproton ring (ELENA)Decelerates antiprotons received from AD

ELENA will deliver antiprotons at 100 keV energy (compared to AD's 5.3 MeV beam energy). Beam cycle through ELENA ring is ~20 seconds long, while it decelerates antiprotons from 5.3 MeV to 100 keV. These antiprotons still require some further deceleration by the experiments themselves using the degrader foil. But a lesser amount of deceleration through degrading foils would ultimately increase the efficiency. Through ELENA, the ATRAP, ALPHA, and AEgIS experiments will get a two-fold increase in the number of antiprotons.[1][10] While the ASACUSA experiment, which uses radiofrequency quadrupole (RFQD), and an ultra-degrader foil for deceleration will receive a ten-fold increase in the number of its antiprotons.[1]

Unlike AD, which can deliver antiprotons to only one experiment at a time, ELENA is capable of delivering it to up to four experiments simultaneously. New experiments such as ReMi (Reaction Microscope) are therefore under the proposal.

 
ELENA ring

Process of deceleration

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The first step of deceleration in ELENA uses a radiofrequency cavity and brings down the energy of antiprotons from 5.3 MeV to ~0.65 MeV. During this step the beam is de-bunched and the electron-cooling method is used to decreases the beam emittance, allowing beam intensity preservation. At the end of this procedure, 0.65 MeV beam is re-bunched and further decelerated to 0.1 MeV by debunching it and by applying electron cooling.[2][11]

During the commissioning time period, AD being actively used by its experiments, its beams were not regularly available for ELENA's testing. Therefore, an ion source developed at Julich Forschungszentrum in Germany for producing  and   ions was used.[12]

See also

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References

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  1. ^ a b c d "ELENA – Home". Archived from the original on 2013-11-03. Retrieved 2021-08-17.
  2. ^ a b Oelert, W. (2015). "The ELENA Project at CERN". Acta Physica Polonica B. 46 (1): 181. arXiv:1501.05728. Bibcode:2015AcPPB..46..181O. doi:10.5506/APhysPolB.46.181. S2CID 119270123.
  3. ^ Jorgensen, L V; Nosych, A; Sanchez-Quesada, J; Harasimowicz, J; LeGodec, G; Angoletta, M E; Kuchler, D; Zickler, T; Eriksson, T; Capatina, O; Dobers, T (2014). "Extra Low ENergy Antiproton (ELENA) ring and its Transfer Lines: Design Report". doi:10.5170/CERN-2014-002. {{cite journal}}: Cite journal requires |journal= (help)
  4. ^ Madsen, N. (2018). "Antiproton physics in the ELENA era". Phil. Trans. R. Soc. A. 376 (2116): 20170278. Bibcode:2018RSPTA.37670278M. doi:10.1098/rsta.2017.0278. PMC 5829179. PMID 29459419.
  5. ^ "A new ring to slow down antimatter – CERN". Retrieved 21 December 2016.
  6. ^ "Exceptionally slow antiprotons". CERN. Retrieved 2020-02-28.
  7. ^ "LHC Run 3 Begins!". Facebook. Retrieved 30 July 2022.
  8. ^ "PROGRESS REPORT OF THE ASACUSA AD-3 COLLABORATION" (PDF). Archived (PDF) from the original on 7 July 2022. Retrieved 30 July 2022.
  9. ^ Bartmann, Wolfgang; Belochitskii, Pavel; Breuker, Horst; Butin, Francois; Carli, Christian; Eriksson, Tommy; Oelert, Walter; Ostojic, Ranko; Pasinelli, Sergio; Tranquille, Gerard (2018-02-19). "The ELENA facility". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 376 (2116): 20170266. Bibcode:2018RSPTA.37670266B. doi:10.1098/rsta.2017.0266. ISSN 1364-503X. PMC 5829171. PMID 29459416.
  10. ^ Gamba, Davide; Carli, Christian; Eriksson, Tommy; Ponce, Laurette; Tranquille, Gerard (2019). "ELENA Commissioning". Proceedings of the 12th Workshop on Beam Cooling and Related Topics. COOL2019. Kuzin, Maksim V. (Ed.), Schaa, Volker RW (Ed.): 3 pages, 8.376 MB. doi:10.18429/JACOW-COOL2019-WEX03. ISSN 2226-0374.
  11. ^ Tranquille, Gerard; Cenede, Jean; Frassier, Alexandre; Jørgensen, Lars; Kolehmainen, Antti; Moles, Benjamin; Timmins, Marc (2016). "The ELENA Electron Cooler". Proceedings of the 7th Int. Particle Accelerator Conf. IPAC2016. Petit-Jean-Genaz Christine (Ed.), Kim, Dong Eon (Ed.), Kim, Kyung Sook (Ed.), Ko, In Soo (Ed.), Schaa, Volker RW (Ed.): 3 pages, 0.990 MB. doi:10.18429/JACOW-IPAC2016-TUPMR006.
  12. ^ Megía-Macías, A.; Gebel, R.; Lefort, B. (2018-09-21). "The ion source for the commissioning of ELENA ring". AIP Conference Proceedings. 2011 (1): 090014. Bibcode:2018AIPC.2011i0014M. doi:10.1063/1.5053395. ISSN 0094-243X.
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