substance

antihydrogen

The antimatter counterpart of hydrogen, composed of an antiproton and a positron, which annihilates on contact with hydrogen.
20 related articles

Description

Antihydrogen is the antimatter counterpart of hydrogen: instead of a proton and an electron, it consists of an antiproton and a positron. It is electrically neutral, like ordinary hydrogen, and is expected to have nearly identical spectral properties, but with key symmetries reversed. When antihydrogen meets ordinary matter, both annihilate completely, converting their mass into energy — a process that makes storing and studying it extremely challenging.

History

The first antihydrogen atoms were produced at CERN in 1995, but they were fast-moving and annihilated immediately. In 2010, the ALPHA collaboration succeeded in trapping antihydrogen atoms for the first time, and in 2011 they held them for over 15 minutes.

How it works

Antihydrogen is produced by combining antiprotons and positrons in a low-temperature trap. Because antimatter annihilates on contact with normal matter, the particles must be held in a vacuum and confined using magnetic fields — antihydrogen atoms are neutral, but their magnetic moments allow them to be trapped in an inhomogeneous field. Once formed, the atoms can be held for minutes or hours, long enough to probe their internal structure with lasers or microwaves.

In practice

Antihydrogen is used to test fundamental symmetries of physics, particularly CPT symmetry, by comparing the spectral lines of hydrogen and antihydrogen to extreme precision.

Fun fact

A single gram of antihydrogen annihilating with ordinary matter would release energy equivalent to about 43 kilotons of TNT — roughly the yield of the Hiroshima bomb.

Concept graph →

Related articles · 20

Lensless Camera Counts Antiprotons by Annihilation Sparks
The antiproton beam hits the plate, and each impact bursts into a shower of charged particles. In the GBAR experiment at CERN, this picture is captured not by a sophisticated detector but by an ordinary industrial camera without a lens, pressed against the vacuum window from the outside.
HEP Experiment2026-08-122 minarXiv:2608.11795express
Antiprotons: Bounce or Annihilate?
The antiproton is the mirror twin of the proton: same mass, but negative charge. When it hits matter, it usually annihilates instantly — disappearing in a burst of energy upon colliding with an atomic nucleus.
HEP Phenomenology2026-07-191 minarXiv:2607.17440express
A Trace of a New Force in Electron Waves
In a quiet room, you can hear the faintest whisper. Likewise, in the hydrogen atom, the lightest of all, an uninvited guest is easier to spot. That guest could be the Z' boson, a mediator particle of a new force predicted by many unification theories. The Standard Model already has its own mediator — the Z boson.
Quantum Physics2026-06-161 minarXiv:2606.17620express
Single Photons in High Harmonics
In very dim light, photons arrive one by one, like drops from a leaky faucet — never in pairs. This effect, predicted by Roy Glauber and confirmed by Leonard Mandel, directly proves that light is made of particles.
HEP Phenomenology2026-05-111 minarXiv:2605.11278express
Cosmic Hydrogen Catches Gravitational Waves
Hydrogen is the most common element. Its atoms are like antennas: they emit and absorb light at very specific frequencies. Einstein predicted that spacetime can ripple: these are gravitational waves.
HEP Phenomenology2026-05-072 minarXiv:2605.06777express
Dark Matter Changes the Face of Neutrinos
A translator halfway across the hall suddenly starts rendering the message backwards. That's roughly how a neutrino, a ghost particle that barely notices matter, might behave if it encounters a cloud of ultralight dark matter.
Optics2026-04-251 minarXiv:2604.23186express
Magnetic charge hides in layers of matter
A stack of magnetic plates, each magnetized opposite to its neighbor, is like a layered sandwich where electrons move as a single organism. The whole material starts mimicking an axion — a ghost particle that physicists suspect might be dark matter.
Nuclear Experiment2026-04-161 minarXiv:2604.15546express
Why the Proton 'Lost Weight' and Then 'Gained It Back'
To uncover the proton's true size, physicists swapped the electron in a hydrogen atom for its heavy copy — the muon. Acting like a magnifying glass with thousandfold power, the muon gets right up against the nucleus and 'probes' the proton with unprecedented precision.
HEP Phenomenology2026-03-282 minarXiv:2603.27257express
Quantum Ripples That Gave Rise to Baryonic and Dark Matter
In the first instants after the big bang, the universe was a quantum vacuum where pairs of particles and antiparticles, virtual "guests" from physical nothingness, spontaneously appeared and almost immediately annihilated.
HEP Experiment2026-03-221 minarXiv:2603.21168express
Trapping Antimatter: How to Catch What You Can't Touch
At CERN's antimatter factory, antiprotons are born with the energy of a bullet from a rifle. You can't just put them in a box: they instantly annihilate upon touching ordinary matter. So physicists devised a way to catch them in electromagnetic traps — invisible cages made of fields.
Materials2026-03-142 minarXiv:2603.14139express
Hydrogen Under Control: A Database for New Materials
Hydrogen is a champion in energy per kilogram, but storing it is a hassle. As a gas, it takes up a huge volume, and if you compress it or cool it to a liquid, you need heavy tanks and lots of energy. There's a third way: some solid materials absorb hydrogen like a sponge soaks up water and hold it within. Heat it up, hydrogen comes out; cool it down, it gets absorbed back.
Nuclear Theory2026-02-202 minarXiv:2602.18162express
Antihydrogen in the Light: How an Antiproton Probes the Nucleus
The antiproton is the proton's twin, only with a negative charge. When such a twin approaches a nucleus, it doesn't just bounce off: a whole dance of attraction and repulsion unfolds between them.
Materials2026-02-131 minarXiv:2602.13432express
Supercapacitor from an Old T-Shirt
An old T-shirt was dissolved in alkali to produce a gel, and it became the heart of an energy storage device. The second component was made from chitosan, a substance derived from shrimp shells. No metals: just recycled cotton and seafood. The gel was soaked in ammonium salt, and its conductivity nearly doubled: from 17.1 to 37.8 millisiemens per centimeter.
HEP Experiment2026-02-052 minarXiv:2602.05455express
How Current in a Wire Explains Hydrogen Catalysis
Hydrogen is the lightest fuel, and its conversion into electricity on a metal surface resembles a game of ping-pong: hydrogen atoms alternately attach to and detach from the electrode. But the score in this game depends on solution acidity in ways that were unexpected. Classical formulas predict a smooth change, while experiments show jumps and kinks.
HEP Phenomenology2026-02-021 minarXiv:2602.02694express
A Hydrogen Trap for Dark Matter
Dark matter is invisible, but you can catch it on the rebound. Hydrogen embedded in a carbon film acts like a billiard ball: when a dark matter particle hits it, the proton flies out. That ejection is the signal you're looking for.
Materials2026-01-211 minarXiv:2601.14756express
A Lone Rhodium Atom Snaps Up Hydrogen Like a Trap
Chemistry has two worlds: in one, the catalyst is a solid particle and the reaction happens on its surface; in the other, it's a dissolved molecule where everything occurs around a single metal center. These worlds rarely meet. But in a new study, they collide. The researchers took iron oxide, a black powder used in magnetic tapes, and scattered single rhodium atoms across its surface.
Nuclear Theory2026-01-101 minarXiv:2601.06541express
Antiproton in the Nuclear Halo
The antiproton is a mirror twin of the proton: same mass, but negative charge. When it approaches an atomic nucleus, the particles can annihilate, turning into radiation.
Quantum Physics2025-12-011 minarXiv:2512.02156express
Hidden Wormholes in the Hydrogen Atom
Two water droplets tremble in sync — because they're connected by a straw. So it is with entangled particles: their unity may be held together by a microscopic wormhole.
A Ghost in the Atom: How Vacuum Hides a Pseudoscalar
In 1976, Gerard 't Hooft noticed that the vacuum of a gauge theory is not as simple as it seems: it possesses a topological structure that manifests itself in a nonzero topological susceptibility.
A Time Machine in a Superconducting Circuit
In a dark laboratory where superconducting chips are cooled to thousandths of a kelvin, a qubit spins under the influence of a magnetic field. A regular qubit rotates in one direction. An antiqubit, its mirror twin, rotates in the opposite direction. Together they form a pair that senses the field twice as sharply as any ordinary pair.