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. Its (proposed) chemical symbol is H, that is, H with an overbar (pronounced aytch-bar; IPA representation [eɪtʃ ba:ɹ]). In particle physics, antimatter extends the concept of the antiparticle to matter, wherein if a particle and its antiparticle come into contact with each other, the two annihilate —that is, they may both be converted into other particles with equal energy in accordance with Einsteins equation E = mc2. ... In particle physics, antimatter extends the concept of the antiparticle to matter, wherein if a particle and its antiparticle come into contact with each other, the two annihilate —that is, they may both be converted into other particles with equal energy in accordance with Einsteins equation E = mc2. ... Annihilation is defined as total destruction or complete obliteration of an object; having its root in the Latin nihil (nothing). ... A 1960s single stage 2 MeV linear Van de Graaff accelerator, here opened for maintenance A particle accelerator is a device that uses electric fields to propel electrically charged particles to high speeds and magnetic fields to contain them. ... Penning traps are devices for the storage of charged particles using a constant magnetic field and a constant electric field. ... Please wikify (format) this article as suggested in the Guide to layout and the Manual of Style. ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... The antiproton (aka pbar) is the antiparticle of the proton. ... The antineutron is the antiparticle of the neutron. ... An antimuon is the antiparticle of the muon. ... An antitauon is the antiparticle of the tauon. ... An antineutrino is the antimatter equivalent particle of the neutrino. ... An antineutrino is the antimatter equivalent particle of the neutrino. ... An antineutrino is the antimatter equivalent particle of the neutrino. ... Image of a typical positron emission tomography (PET) facility Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three dimensional image or map of functional processes in the body. ... Antimatter or contra-terrene matter is matter that is composed of the antiparticles of those that constitute normal matter. ... An antimatter weapon is a hypothetical device using antimatter as a power source, a propellant, or an explosive for a weapon. ... The ALPHA collaboration consists of scientists from a number scientific institutions whose goal it is to trap neutral antimatter in the form of antihydrogen in a magnetic trap and consecutively conduct experiments with the trapped antiatoms. ... Helmeted Athena, of the Velletri type. ... The ATRAP collaboration at CERN developed out of TRAP, a collaboration whose members pioneered cold antiprotons, cold positrons, and first made the ingredients of cold antihydrogen to interact. ... CERN logo The Organisation Européenne pour la Recherche Nucléaire (English: European Organization for Nuclear Research), commonly known as CERN, pronounced (or in French), is the worlds largest particle physics laboratory, situated just west of Geneva on the border between France and Switzerland. ... Paul Adrien Maurice Dirac, OM, FRS (IPA: [dɪræk]) (August 8, 1902 – October 20, 1984) was a British theoretical physicist and a founder of the field of quantum physics. ... Carl Anderson at LBNL 1937 Carl David Anderson (3 September 1905 – 11 January 1991) was a U.S. experimental physicist. ... In particle physics, antimatter extends the concept of the antiparticle to matter, wherein if a particle and its antiparticle come into contact with each other, the two annihilate —that is, they may both be converted into other particles with equal energy in accordance with Einsteins equation E = mc2. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Properties For other uses, see Atom (disambiguation). ... Properties The electron is a lightweight fundamental subatomic particle that carries a negative electric charge. ... Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... The antiproton (aka pbar) is the antiparticle of the proton. ... A chemical symbol is an abbreviation or short representation of the name of a chemical element. ... The International Phonetic Alphabet (IPA) is a system of phonetic notation devised by linguists to accurately and uniquely represent each of the wide variety of sounds (phones or phonemes) used in spoken human language. ...

According to the CPT theorem (CPT stands for charge conjugation, parity reversal, and time/motion reversal) of particle physics, antihydrogen atoms should have many of the same characteristics as hydrogen atoms, i.e. they should have the same mass, magnetic moment, and transition frequencies between its atomic quantum states (this means that if we were to excite the antihydrogen atom by shooting a laser or microwave beam onto it for example, it should glow with the exact same color as that of hydrogen). Antihydrogen atoms should be attracted to other matter or antimatter gravitationally with a force of the same magnitude as ordinary hydrogen atoms would experience. This would not be true if antimatter has negative mass, which is considered highly unlikely, though not yet empirically disproven. CPT-symmetry is a fundamental symmetry of physical laws under transformations that involve the inversions of charge, parity and time simultaneously. ... Unsolved problems in physics: What causes anything to have mass? Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... In physics, the magnetic moment or magnetic dipole moment is a measure of the strength of a magnetic source. ... Quite literally, quantum state describes the state of a quantum system. ... // Experiment using a (likely argon) laser. ... Microwaves are electromagnetic waves with wavelengths longer than those of Terahertz (THz) wavelengths, but relatively short for radio waves. ... Exotic matter is a hypothetical concept of particle physics. ...

When antihydrogen atoms come into contact with ordinary matter, they quickly annihilate and produce energy in the form of gamma rays and high-energy particles called pions. These pions in turn quickly decay into other particles called muons, neutrinos, positrons, and electrons, and these particles rapidly dissipate. If antihydrogen atoms were to be suspended in a perfect vacuum, however, they should survive indefinitely. This article is about electromagnetic radiation. ... In particle physics, pion (short for pi meson) is the collective name for three subatomic particles: Ï€0, Ï€+ and π−. Pions are the lightest mesons and play an important role in explaining low-energy properties of the strong nuclear force. ... In the Standard Model of particle physics, a muon (Greek μείον = minus) is a semistable fundamental particle with negative electric charge and a spin of 1/2. ... The neutrino is an elementary particle. ... In physics, free space is a concept of electromagnetic theory, corresponding roughly to the vacuum, the baseline state of the electromagnetic field, or the replacement for the electromagnetic aether. ...

Antihydrogen does not occur naturally, and therefore must be manufactured by bringing together the necessary building blocks. In 1995 at the CERN laboratory in Geneva, Switzerland, it was first produced by shooting antiprotons, which were produced in a particle accelerator, at xenon clusters. When an antiproton gets close to a xenon nucleus, an electron-positron-pair can be produced, and with some probability the positron will be captured by the antiproton to form antihydrogen. The probability for producing antihydrogen from one antiproton was only about 10^-19, so this method is not well suited for the production of substantial amounts of antihydrogen. 1995 (MCMXCV) was a common year starting on Sunday of the Gregorian calendar. ... CERN logo The Organisation Européenne pour la Recherche Nucléaire (English: European Organization for Nuclear Research), commonly known as CERN, pronounced (or in French), is the worlds largest particle physics laboratory, situated just west of Geneva on the border between France and Switzerland. ... Geneva (pronunciation //; French: Genève //, German: //, Italian: Ginevra) is the second most populous city in Switzerland (after Zürich), and is the most populous city of Romandy (the French-speaking part of Switzerland). ... A 1960s single stage 2 MeV linear Van de Graaff accelerator, here opened for maintenance A particle accelerator is a device that uses electric fields to propel electrically charged particles to high speeds and magnetic fields to contain them. ... General Name, Symbol, Number xenon, Xe, 54 Chemical series noble gases Group, Period, Block 18, 5, p Appearance colorless Atomic mass 131. ... In physics, clusters are small groups of atoms or molecules. ...

In recent experiments carried out by the ATRAP and ATHENA collaborations at CERN, positrons from a sodium radioactive source and antiprotons were brought together in a magnetic Penning trap, where synthesis took place at a typical rate of 100 antihydrogen atoms per second. Antihydrogen was first produced by these two collaborations in 2002, and by 2004 perhaps a hundred thousand antihydrogen atoms were produced in this way. The ATRAP collaboration at CERN developed out of TRAP, a collaboration whose members pioneered cold antiprotons, cold positrons, and first made the ingredients of cold antihydrogen to interact. ... Helmeted Athena, of the Velletri type. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... Penning traps are devices for the storage of charged particles using a constant magnetic field and a constant electric field. ... For album titles with the same name, see 2002 (album). ...

The antihydrogen atoms synthesized so far have a very high temperature (perhaps a few thousand kelvins), and so they hit the walls of the experimental apparatus and annihilate. The next goal is to produce antihydrogen having such low temperature (perhaps a fraction of a kelvin) that they can be captured in a magnetic trap. The antihydrogen atoms can then be interrogated by laser beams, so that their atomic transition frequencies can be precisely measured. If any difference between hydrogen and antihydrogen were observed, however small, it would indicate that matter and antimatter do not behave in exactly the same way. This may help explain why the observable Universe appears to be made entirely of matter and not antimatter. The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... Penning traps are devices for the storage of charged particles using a constant magnetic field and a constant electric field. ...

Antimatter atoms such as antideuterium (D), antitritium (T), and antihelium (He) are much more difficult to produce than antihydrogen. Among these, only antideuterium nuclei have been produced so far, and these have such very high velocities that synthesis of antideuterium atoms may still be many decades ahead. Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of one atom in 6400 of hydrogen (see VSMOW; the abundance changes slightly from one kind of natural water to another). ... Antimatter is matter that is composed of the antiparticles of those that constitute normal matter. ... Antimatter is matter that is composed of the antiparticles of those that constitute normal matter. ...

See also

Gravitational interaction of antimatter The factual accuracy of this article is disputed. ...