New Insights Into Antimatter, 20 Years In the Making

By Alison Klesman | December 20, 2016 2:58 pm
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Anti-hydrogen particles react with the walls of the experimental chamber, producing the flashes of light seen here. (Credit: CERN)

Antimatter is more than a science fiction concept that allows engineers to power the Enterprise. It’s an actual — albeit small — constituent of our universe. While antimatter is rare, it can exist under the right conditions. Information about the way antimatter behaves provides a powerful tool for testing the Standard Model of particle physics we currently use to understand the forces that govern the way particles behave.

For Every Particle, An Anti-

Antimatter was first predicted by British physicist Paul Dirac in 1928. He proposed that every particle of matter should have a corresponding antiparticle. These antiparticles are identical to their particle counterparts in every way except for charge. For example, the antimatter counterpart to the negatively-charged electron is the positively-charged antielectron, also called the positron.

When matter and antimatter meet, they annihilate each other and leave only energy behind. The Big Bang should have created matter and antimatter in equal amounts, but today, our universe is dominated by matter, with very little antimatter present. Understanding why this asymmetry exists would be a significant step towards understanding the origin and evolution of our universe.

However, naturally-occurring antimatter is often immediately destroyed when it encounters the universe’s abundant matter. Today, particle physicists can routinely create antimatter for study at the CERN Antiproton Decelerator facility, which has led to several new breakthroughs in the characterization of antimatter.

Identical Lines

In a recently-published Nature article, CERN’s ALPHA collaboration has announced the very first measurement of a spectral line in an antihydrogen atom. This result, which was over 20 years in the making, was achieved using a laser to observe the 1S-2S transition in antihydrogen. To within experimental limits, the ALPHA collaboration’s results show that this transition is identical in both hydrogen and antihydrogen atoms — a condition required by the Standard Model. If these transitions were different, it would essentially break our current understanding of physics.

The 1S-2S transition is one of many that contribute to hydrogen’s spectrum. A spectrum is created when electrons that have been excited by radiation “fall” from a higher energy level inside an atom to a lower one. This process releases energy at precise wavelengths. Each element produces a unique spectrum, like a fingerprint. Astronomers often use spectra to determine an object’s composition based on the light it produces.

Making Antimatter

To observe the 1S-2S transition in antihydrogen, the ALPHA collaboration first had to create antiatoms and keep them stable — no easy task. ALPHA’s recipe for antihydrogen consisted of mixing plasmas containing antiprotons and positrons together to produce antihydrogen atoms. The resulting antiatoms were then magnetically trapped to hold them for experimentation.

From an original batch of 90,000 antiprotons, researchers could create 25,000 antihydrogen atoms; of these, the ALPHA collaboration managed to trap and study an average of 14 antiatoms per trial. By illuminating the antihydrogen atoms with a laser tuned to provide exactly the energy needed to achieve the proposed transition, researchers were then able to observe the resulting emission to look for deviations from the spectrum of normal hydrogen.

The ALPHA collaboration’s result, along with the results from other antimatter experiments performed by the ASACUSA and BASE collaborations, shows just how far antimatter research has come at CERN. The ALPHA collaboration plans to further refine the precision of their results in the future for even more robust testing of the Standard Model. Such high-precision antimatter testing may also be able to shed light on the matter-antimatter asymmetry we observe in our universe.

[This article originally appeared on Astronomy.com.]

CATEGORIZED UNDER: Space & Physics, top posts
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  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    our universe is dominated by matter, with very little antimatter present. Understanding why this asymmetry exists would be a significant step towards understanding the origin and evolution of our universe.” (matter – antimatter)/(photons) ≈ 6.1×10^(-10) A shotgun will fire anything that fits (Youtube, Taofledermaus). Make the projectile clever.

    1) Sakharov conditions
    2) Einstein-Cartan-Kibble-Sciama gravitation taking achiral isotropic space-time curvature plus tracechiral anisiotropic space-time torsion (re Lorentz force). Matter will be universally in trace excess.
    3) It’s testable in existing apparatus, arXiv:1207.2442, below, plus deeply supportive footnotes re quantum gravitation.
    4) Trace chiral anisotropic space-time compromises Noether’s theorems re conservation of angular momentum, then
    5) The Tully-Fisher relation is Milgrom acceleration Neotherean leakage of consistent magnitude, 1.2×10^(-10) m/s², not dark matter.
    6) PERFORM AN EÖTV‎ÖS EXPERIMENT TESTING SPACE-TIME GEOMETRY WITH TEST MASS GEOMETRY. Composition and field tests using classical, quantum mechanical, relativistic, and gravitational (strong Equivalence Principle) divergences are excluded by observation plus Einstein’s inertial gedanken-elevator.

    doi:10.1088/0264-9381/29/18/184002, arXiv:1207.2442, pp. 6-7. In Fig 3, one vertical plane of four test masses would be single crystals of space group P3(1)21 alpha-quartz (all atoms in self-similar right-handed helices, 9 atoms/0.113 nm³ chiral unit cell). The opposite vertical plane of four test masses would be single crystals of space group P3(2)21 alpha-quartz (all atoms in self-similar left-handed helices, ditto).

    doi:10.1107/S0108767303004161, Section 3ff. Enantiomorphic space groups.

    doi:10.1016/0550-3213(81)90361-8, Erratum, ibid. 195(3), 541 (1982), doi:10.1016/0550-3213(82)90011-6; doi:10.1016/j.disc.2013.02.010, arXiv:1109.1963;

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    Sourcing baryogenesis, matter in excess of antimatter, is the fundamental boundary condition of all exact physical theory.

    time-symmetry in quantum mechanics implies retro-causality, arXiv:002.0906. Breaking time reversal symmetry creates chirality, arXiv:1006.0762(p. 3 last paragraph), doi:10.1103/PhysRevA.82.043811. Chirality is the strong arrow of time. The Second Law is statistical. Chirality sources baryogenesis (Sakharov conditions). If matter exists in excess of antimatter, QM is faulty, SUSY is wrong, M-theory gets a haircut. Big stuff.

  • OWilson

    It is established that the properties of anti-matter are the mirror image of matter.

    What is so noteworthy to find the anti-matter spectral lines where they should be?

    Why spend all that money, and where the “new insight” to see if you unbutton your shirt in front of a mirror and reveal a tattoo of Mary on your chest, your doppleganger reveals one. too?

    Uncle Al?

    • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

      Mirror symmetry has clean matrices and tight equations. It also prohibits the universe. Paired shoes test for a left foot. Management decrees a large right shoe on a small left foot, simultaneously true and untrue – and everybody publishes.

      Chemistry offers chiral geometric observation with the tight shoes: Eötvös experiment, calorimetry; racemate microwave or Raman rotational spectra; pawnbroker experiment, literal Galilean vacuum free fall in a sounding rocket. Test masses are macroscopically and compositionally identical, cancelling all conventional physics. Atom-scale geometry is enantiomorphic.

      Green’s function removes geometric chirality from physics. There is no need to look (other than to understand why the universe exists).

      • OWilson

        Thanks!

        I understood some of that.

        Actually I always understand and appreciate the satirical bent of your responses, but I’m afraid I don’t always have the background to follow you into the chemistry.

        Wish I did!

        • reed1v

          If a duck quacks, is it a duck.

  • antonio carlos motta

    cannot exist asymmetry between matter and antimatter,because antimatter does not exist in the universe,same in earliest equal amounts.the universe appear as asymmetrical,so as the antiparticles is the symmetry spacetime .there appear the violation of cp for particles and antiparticles.the transformations of energy into mass and viceversa in relativistic speeds near the speed of light is not uniform,as so the space and time are asymmetrical doing appear the breaks of cp,to measure the contraction of space and time dilatation

    • OWilson

      Antimatter does not exist.

      I like that!

      But it can be created by humans in the laboratory.

      Sounds a lot like Global Warming!

  • antonio carlos motta

    the direct violation of cp show that antimatter does not exist in the universe.the asymmetry between neutrinos and anti neutrinos show that the anomalies between theirs are different quantic states that does violate the symmetry T.Only exist antiparticles as sub product of the matter.

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