AEgIS experiment

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Antiproton decelerator
(AD)
ELENA Extra low energy antiproton ring – further decelerates antiprotons coming from AD
AD experiments
ATHENA AD-1 Antihydrogen production and precision experiments
ATRAP AD-2 Cold antihydrogen for precise laser spectroscopy
ASACUSA AD-3 Atomic spectroscopy and collisions with antiprotons
ACE AD-4 Antiproton cell experiment
ALPHA AD-5 Antihydrogen laser physics apparatus
AEgIS AD-6 Antihydrogen experiment gravity interferometry spectroscopy
GBAR AD-7 Gravitational behaviour of anti-hydrogen at rest
BASE AD-8 Baryon antibaryon symmetry experiment
PUMA AD-9 Antiproton unstable matter annihilation

AEgIS (Antimatter Experiment: gravity, Interferometry, Spectroscopy), AD-6, is an experiment at the Antiproton Decelerator facility at CERN. Its primary goal is to measure directly the effect of Earth's gravitational field on antihydrogen atoms with significant precision. [1] Indirect bounds that assume the validity of, for example, the universality of free fall, the Weak Equivalence Principle or CPT symmetry also in the case of antimatter constrain an anomalous gravitational behavior to a level where only precision measurements can provide answers. Vice versa, antimatter experiments with sufficient precision are essential to validate these fundamental assumptions. AEgIS was originally proposed in 2007. [2] Construction of the main apparatus was completed in 2012. Since 2014, two laser systems with tunable wavelengths (few picometer precision) and synchronized to the nanosecond for specific atomic excitation have been successfully commissioned. [3]

Contents

AEgIS experimental setup and physics

Simplified model of an antihydrogen atom in ground state Antihydrogen.gif
Simplified model of an antihydrogen atom in ground state

AEgIS will attempt to determine if gravity affects antimatter in the same way it affects normal matter by testing its effect on an antihydrogen beam. The aspired experimental setup uses the Moiré deflectometer to measure the vertical displacement of a beam of cold antihydrogen atoms traveling in Earth's gravitational field. [4]


In the first phase of the experiment (running until 2018), antiprotons from the Antiproton Decelerator (AD) with a kinetic energy of 5.3MeV had to pass through a series of aluminum foils which acted as so-called degraders, slowing down a fraction of the fast antiprotons to few keV. The slow antiprotons were then further cooled by merging them with extra cold trapped electrons (electron cooling) and finally trapped inside a Malmberg–Penning trap. [5] An intense radioactive β+ source (22Na) was used to produce positrons, which were accumulated in a Surko-type storage trap at low pressure (3e-8 mbar). These positrons were implanted into a nano-structured porous silicon target in order to efficiently form positronium (Ps) - even at cryogenic temperatures in Ultra-high vacuum (UHV). [6] A cloud of positronium emerging from the target was then excited to a Rydberg level of n=16/17 by using laser-induced two-step optical transitions. [3] Inside the Malmberg–Penning trap, the charge exchange reaction between cold antiprotons and Rydberg-Ps took place, leading to the formation of Rydberg-antihydrogen with high efficiency in the form of a 4π pulse. [7] [8]

(Charge exchange reaction)

The following paragraph is out of date. It appears to have been written in 2014, nine years ago. In the 27 October 2023 issue of Nature, the ALPHA experiment published the result that antihydrogen falls. [9]

In the second phase of the AEGIS experiment, starting from 2021 after AEgIS has been successfully connected to the new antiproton deceleration and storage ring ELENA, the Rydberg antihydrogen atoms will be channeled into a beam, which then will pass through a series of matter gratings, the central piece of a Moiré-deflectometer. The antihydrogen atoms will ultimately hit onto the surface of a position and time-resolving detector, where they will annihilate. Areas behind the gratings are shadowed, while those behind the slits are not. The annihilation locations reproduce a periodic pattern of light and shadowed areas. This pattern is highly sensitive to small vertical displacements of the anti-atoms during their horizontal flight - the Earth's gravitational force on antihydrogen can thus be determined. [4]

AEgIS collaboration

Laser experimental setup at AEgIS Aegis2.jpg
Laser experimental setup at AEgIS
AEgIS technical coordinator Stefan Haider in front of the main apparatus. The part removed is amongst colleagues called the "Sun" as it has several instruments sticking out from the central circular flange. Aegis1.jpg
AEgIS technical coordinator Stefan Haider in front of the main apparatus. The part removed is amongst colleagues called the “Sun” as it has several instruments sticking out from the central circular flange.

The AEgIS collaboration comprises the following institutions:

See also

  1. Antiproton Decelerator
  2. GBAR experiment
  3. ALPHA experiment

Related Research Articles

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The PS210 experiment was the first experiment that led to the observation of antihydrogen atoms produced at the Low Energy Antiproton Ring (LEAR) at CERN in 1995. The antihydrogen atoms were produced in flight and moved at nearly the speed of light. They made unique electrical signals in detectors that destroyed them almost immediately after they formed by matter–antimatter annihilation.

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<span class="mw-page-title-main">Antiproton Decelerator</span> Particle storage ring at CERN, Switzerland

The Antiproton Decelerator (AD) is a storage ring at the CERN laboratory near Geneva. It was built from the Antiproton Collector (AC) to be a successor to the Low Energy Antiproton Ring (LEAR) and started operation in the year 2000. Antiprotons are created by impinging a proton beam from the Proton Synchrotron on a metal target. The AD decelerates the resultant antiprotons to an energy of 5.3 MeV, which are then ejected to one of several connected experiments.

<span class="mw-page-title-main">Low Energy Antiproton Ring</span> Former CERN infrastructure

The Low Energy Anti-Proton Ring (LEAR) was a particle accelerator at CERN which operated from 1982 until 1996. The ring was designed to decelerate and store antiprotons, to study the properties of antimatter and to create atoms of antihydrogen. 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.

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<span class="mw-page-title-main">Jeffrey Hangst</span> Experimental particle physicist

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References

[1] [2] [5] [4] [3] [8] [6] [7] [10]

  1. 1 2 Doser, M. (2022). Status report for the AEgIS experiment for 2021 (PDF). CERN. Geneva. SPS and PS Experiments Committee, SPSC.
  2. 1 2 Drobychev, G.Yu; Doser, M.; et, al. (2007). Proposal for the AEGIS experiment at the CERN antiproton decelerator (Antimatter Experiment: Gravity, Interferometry, Spectroscopy). CERN. Geneva. SPS Experiments Committee, SPSC.
  3. 1 2 3 Aghion, S.; et, al. (AEgIS Collaboration) (July 2016). "Laser excitation of the n=3 level of positronium for antihydrogen production". Physical Review A. 94 (1): 012507. Bibcode:2016PhRvA..94a2507A. doi: 10.1103/PhysRevA.94.012507 . hdl: 11311/1007035 .
  4. 1 2 3 Aghion, S.; Ahlén, O.; Amsler, C.; et, al.(AEgIS Collaboration) (July 2014). "A moiré deflectometer for antimatter". Nature Communications. 5: 4538. Bibcode:2014NatCo...5.4538A. doi:10.1038/ncomms5538. PMC   4124857 . PMID   25066810.
  5. 1 2 Tietje, I.C.; et, al. (August 2020). "Protocol for pulsed antihydrogen production in the AEgIS apparatus". Journal of Physics: Conference Series. 1612 (1): 012025. Bibcode:2020JPhCS1612a2025T. doi: 10.1088/1742-6596/1612/1/012025 . hdl: 11572/297549 . S2CID   225388648.
  6. 1 2 Mariazzi, S.; et, al. (AEgIS Collaboration) (May 2021). "High-yield thermalized positronium at room temperature emitted by morphologically tuned nanochanneled silicon targets". Journal of Physics B: Atomic, Molecular and Optical Physics. 54 (8): 085004. Bibcode:2021JPhB...54h5004M. doi: 10.1088/1361-6455/abf6b6 . hdl: 10852/92391 . S2CID   234865124.
  7. 1 2 Antonello, M.; et, al. (AEgIS Collaboration) (July 2020). "Rydberg-positronium velocity and self-ionization studies in a 1T magnetic field and cryogenic environment". Physical Review A. 102 (1): 013101. arXiv: 1911.04342 . Bibcode:2020PhRvA.102a3101A. doi: 10.1103/PhysRevA.102.013101 . S2CID   207853146.
  8. 1 2 Amsler, C.; Antonello, M.; Belov, A.; et, al. (AEgIS Collaboration) (February 2021). "Pulsed production of antihydrogen". Communications Physics. 4 (1): 19. Bibcode:2021CmPhy...4...19A. doi: 10.1038/s42005-020-00494-z . hdl: 10852/92284 . S2CID   231858825.
  9. ↑ Anderson, E. K.; Baker, C. J.; Bertsche, W.; Bhatt, N. M.; Bonomi, G.; Capra, A.; Carli, I.; Cesar, C. L.; Charlton, M.; Christensen, A.; Collister, R.; Cridland Mathad, A.; Duque Quiceno, D.; Eriksson, S.; Evans, A.; Evetts, N.; Fabbri, S.; Fajans, J.; Ferwerda, A.; Friesen, T.; Fujiwara, M. C.; Gill, D. R.; Golino, L. M.; Gomes Gonçalves, M. B.; Grandemange, P.; Granum, P.; Hangst, J. S.; Hayden, M. E.; Hodgkinson, D.; Hunter, E. D.; Isaac, C. A.; Jimenez, A. J. U.; Johnson, M. A.; Jones, J. M.; Jones, S. A.; Jonsell, S.; Khramov, A.; Madsen, N.; Martin, L.; Massacret, N.; Maxwell, D.; McKenna, J. T. K.; Menary, S.; Momose, T.; Mostamand, M.; Mullan, P. S.; Nauta, J.; Olchanski, K.; Oliveira, A. N.; Peszka, J.; Powell, A.; Rasmussen, C. Ø; Robicheaux, F.; Sacramento, R. L.; Sameed, M.; Sarid, E.; Schoonwater, J.; Silveira, D. M.; Singh, J.; Smith, G.; So, C.; Stracka, S.; Stutter, G.; Tharp, T. D.; Thompson, K. A.; Thompson, R. I.; Thorpe-Woods, E.; Torkzaban, C.; Urioni, M.; Woosaree, P.; Wurtele, J. S. (September 2023). "Observation of the effect of gravity on the motion of antimatter". Nature. 621 (7980): 716–722. Bibcode:2023Natur.621..716A. doi:10.1038/s41586-023-06527-1. PMC   10533407 . PMID   37758891.
  10. ↑ Glöggler, L. T. (2024). "Positronium Laser Cooling via the 13S−23P Transition with a Broadband Laser Pulse". Physical Review Letters . 132 (8): 083402. doi: 10.1103/PhysRevLett.132.083402 . hdl: 11311/1261341 . PMID   38457696.
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