ASACUSA experiment

Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA), AD-3, is an experiment at the Antiproton Decelerator (AD) at CERN. The experiment was proposed in 1997, started collecting data in 2002 by using the antiprotons beams from the AD, and will continue in future under the AD and ELENA decelerator facility.

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

ASACUSA physics

ASACUSA collaboration is testing for CPT-symmetry by laser spectroscopy of antiprotonic helium and microwave spectroscopy of the hyperfine structure of antihydrogen. It compares the matter and antimatter using antihydrogen and antiprotonic helium and looks into the matter-antimatter collisions.[1][2][3] It also measures atomic and nuclear cross-sections of antiprotons on various targets at extremely low energies.[4]

In 2020 ASACUSA in collaboration with the Paul Scherrer Institut (PSI) reported the experimental verification with spectral measurements of long lived pionic helium.[5][6][7]

In 2022 ASACUSA reported the unexpected narrowing of antiprotonic helium spectral lines instead of broadening and an abrupt further narrowing close to the temperature at which Helium becomes superfluid, it is hypothesized to be related to the little change of the orbital radius when shone by laser light in contrast with normal atoms.[8][9][10]

Experimental setup

ASACUSA receives antiproton beams from the AD and ELENA decelerator. These beams are decelerated to 0.01 MeV energy using a radiofrequency decelerator and the antiprotons are stored in the MUSASHI traps. The positrons to form antihydrogen atoms are obtained from radioactive source and stored in a positron accumulator. The mixing of antiprotons and positrons forms polarised and cold antihydrogen inside a double-Cusp trap. The polarised antihydrogen atoms from this system then enter the spectrometer where the measurements are done.[11]

ASACUSA team at beam setup preparation in September 2018

ASACUSA collaboration
ASACUSA team preparing beam setup for the ELENA beams in September 2018.

See also

References
  1. "ASACUSA – General". Retrieved 21 December 2016.
  2. "Archived copy" (PDF). Archived from the original (PDF) on 13 December 2013. Retrieved 9 February 2011.{{cite web}}: CS1 maint: archived copy as title (link)
  3. "CERN experiment improves precision of antiproton mass measurement with new innovative cooling technique". phys.org.
  4. "Archived copy". Archived from the original on 15 April 2013. Retrieved 17 February 2010.{{cite web}}: CS1 maint: archived copy as title (link)
  5. Hori, Masaki; Aghai-Khozani, Hossein; Sótér, Anna; Dax, Andreas; Barna, Daniel (6 May 2020). "Laser spectroscopy of pionic helium atoms". Nature. 581 (7806): 37–41. doi:10.1038/s41586-020-2240-x. ISSN 1476-4687.
  6. "ASACUSA sees surprising behaviour of hybrid matter–antimatter atoms in superfluid helium". CERN. Retrieved 2022-03-16.
  7. "Pionic helium". www.mpq.mpg.de. Retrieved 2022-03-16.
  8. Sótér, Anna; Aghai-Khozani, Hossein; Barna, Dániel; Dax, Andreas; Venturelli, Luca; Hori, Masaki (2022-03-16). "High-resolution laser resonances of antiprotonic helium in superfluid 4He". Nature: 1–5. doi:10.1038/s41586-022-04440-7. ISSN 1476-4687.
  9. "ASACUSA sees surprising behaviour of hybrid matter–antimatter atoms in superfluid helium". CERN. Retrieved 2022-03-17.
  10. "Icy Antimatter Experiment Surprises Physicists". Quanta Magazine. 2022-03-16. Retrieved 2022-03-17.
  11. Amsler, C.; Barna, D.; Breuker, H.; Chesnevskaya, S.; Costantini, G.; Ferragut, R.; Giammarchi, M.; Gligorova, A.; Higaki, H. (2021). Status report of the ASACUSA experiment - progress in 2020 and plans for 2021. Status Report. CERN. Geneva. SPS and PS Experiments Committee, SPSC.

Record for ASACUSA experiment on INSPIRE-HEP

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