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)

This paragraph is woefully out of date. It appears to have been written in 2014, nine year ago. In the 27 October 2023 issue of Nature they published the result that antihydrogen falls. Gravity attracts it in the same way it attracts hydrogen. What follows needs to be updated. In the second phase of the 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-g experiment

Related Research Articles

<span class="mw-page-title-main">Antimatter</span> Material composed of antiparticles of the corresponding particles of ordinary matter

In modern physics, antimatter is defined as matter composed of the antiparticles of the corresponding particles in "ordinary" matter, and can be thought of as matter with reversed charge, parity, and time, known as CPT reversal. Antimatter occurs in natural processes like cosmic ray collisions and some types of radioactive decay, but only a tiny fraction of these have successfully been bound together in experiments to form antiatoms. Minuscule numbers of antiparticles can be generated at particle accelerators; however, total artificial production has been only a few nanograms. No macroscopic amount of antimatter has ever been assembled due to the extreme cost and difficulty of production and handling. Nonetheless, antimatter is an essential component of widely available applications related to beta decay, such as positron emission tomography, radiation therapy, and industrial imaging.

<span class="mw-page-title-main">Positron</span> Anti-particle to the electron

The positron or antielectron is the particle with an electric charge of +1e, a spin of 1/2, and the same mass as an electron. It is the antiparticle of the electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons.

<span class="mw-page-title-main">Antihydrogen</span> Exotic particle made of an antiproton and positron

Antihydrogen is the antimatter counterpart of hydrogen. Whereas the common hydrogen atom is composed of an electron and proton, the antihydrogen atom is made up of a positron and antiproton. Scientists hope that studying antihydrogen may shed light on the question of why there is more matter than antimatter in the observable universe, known as the baryon asymmetry problem. Antihydrogen is produced artificially in particle accelerators.

<span class="mw-page-title-main">Antiproton</span> Subatomic particle

The antiproton,
p
, is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy.

ATHENA, also known as the AD-1 experiment, was an antimatter research project at the Antiproton Decelerator at CERN, Geneva. In August 2002, it was the first experiment to produce 50,000 low-energy antihydrogen atoms, as reported in Nature. In 2005, ATHENA was disbanded and many of the former members of the research team worked on the subsequent ALPHA experiment and AEgIS experiment.

<span class="mw-page-title-main">Protonium</span> Bound state of a proton and antiprotron

Protonium, also known as antiprotonic hydrogen, is a type of exotic atom in which a proton and an antiproton are bound to each other.

The Antihydrogen Trap (ATRAP) collaboration at the Antiproton Decelerator facility at CERN, Geneva, is responsible for the AD-2 experiment. It is a continuation of the TRAP collaboration, which started taking data for the TRAP experiment in 1985. The TRAP experiment pioneered cold antiprotons, cold positrons, and first made the ingredients of cold antihydrogen to interact. Later ATRAP members pioneered accurate hydrogen spectroscopy and observed the first hot antihydrogen atoms.

<span class="mw-page-title-main">Antiprotonic helium</span> Exotic matter with an antiproton in place of an electron

Antiprotonic helium is a three-body atom composed of an antiproton and an electron orbiting around a helium nucleus. It is thus made partly of matter, and partly of antimatter. The atom is electrically neutral, since both electrons and antiprotons each have a charge of −1, whereas helium nuclei have a charge of +2. It has the longest lifetime of any experimentally producible matter-antimatter bound state.

<span class="mw-page-title-main">Gravitational interaction of antimatter</span> Theory of gravity on antimatter

The gravitational interaction of antimatter with matter or antimatter has been observed by physicists. As was the consensus among physicists previously, it was experimentally confirmed that gravity attracts both matter and antimatter at the same rate within experimental error.

<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.

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.

High-precision experiments could reveal small previously unseen differences between the behavior of matter and antimatter. This prospect is appealing to physicists because it may show that nature is not Lorentz symmetric.

<span class="mw-page-title-main">Antiproton Collector</span> CERN infrastructure

The Antiproton Collector (AC) was part of the antiparticle factory at CERN designed to decelerate and store antimatter, to study the properties of antimatter and to create atoms of antihydrogen. It was built in 1986 around the existing Antiproton Accumulator (AA) to improve the antiproton production by a factor of 10. Together, the Antiproton Collector and the Antiproton Accumulator formed the so-called Antiproton Accumulator Complex (AAC).

<span class="mw-page-title-main">ALPHA experiment</span> Antimatter gravitation experiment

The Antihydrogen Laser Physics Apparatus (ALPHA), also known as AD-5, is an experiment at CERN's Antiproton Decelerator, designed to trap antihydrogen in a magnetic trap in order to study its atomic spectra. The ultimate goal of the experiment is to test CPT symmetry through comparing the respective spectra of hydrogen and antihydrogen. Scientists taking part in ALPHA include former members of the ATHENA experiment (AD-1), the first to produce cold antihydrogen in 2002.

<span class="mw-page-title-main">GBAR experiment</span> Experiment at the Antiproton Decelerator

GBAR, AD-7 experiment, is a multinational collaboration at the Antiproton Decelerator of CERN.

The rotating wall technique is a method used to compress a single-component plasma confined in an electromagnetic trap. It is one of many scientific and technological applications that rely on storing charged particles in vacuum. This technique has found extensive use in improving the quality of these traps and in tailoring of both positron and antiproton plasmas for a variety of end uses.

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

Jeffrey Scott Hangst is an experimental particle physicist at Aarhus University, Denmark, and founder and spokesperson of the ALPHA collaboration at the Antiproton Decelerator (AD) at CERN, Geneva. He was also one of the founding members and the Physics Coordinator of the ATHENA collaboration at the AD facility.

<span class="mw-page-title-main">Stefan Ulmer (physicist)</span> Particle physicist

Stefan Ulmer is a particle physicist, professor of Physics at Heinrich Heine University Düsseldorf and chief scientist at the Ulmer Fundamental Symmetries Laboratory, RIKEN, Tokyo. He is the founder and the spokesperson of the BASE experiment (AD-8) at the Antiproton Decelerator facility at CERN, Geneva. Stefan Ulmer is well known for his contributions to improving Penning trap techniques and precision measurements on antimatter. He is the first person to observe spin transitions with a single trapped proton as well as single spin transitions with a single trapped antiproton, a significant achievement towards a precision measurement of the antiproton magnetic moment.

<span class="mw-page-title-main">PUMA experiment</span> Particle physics experiment at CERN

The PUMA AD-9 experiment, at the Antiproton decelerator (AD) facility at CERN, Geneva, aims to look into the quantum interactions and annihilation processes between the antiprotons and the exotic slow-moving nuclei. PUMA's experimental goals require about one billion trapped antiprotons made by AD and ELENA to be transported to the ISOLDE-nuclear physics facility at CERN, which will supply the exotic nuclei. Antimatter has never been transported out of the AD facility before. Designing and building a trap for this transportation is the most challenging aspect for the PUMA collaboration.

References

[1] [2] [5] [4] [3] [8] [6] [7] [9]

  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: 012507. 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. 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: 012025. 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. 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: 013101. arXiv: 1911.04342 . 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: 19. doi: 10.1038/s42005-020-00494-z . hdl: 10852/92284 . S2CID   231858825.
  9. ↑ 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 .
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