Antihydrogen

In physics, antihydrogen is the antimatter atom equivalent to ordinary hydrogen. It is made up of an antiproton and a positron, so it has the same properties, but with the electrical charges reversed.

Its chemical symbol is H, that is, an H with a macron.

It annihilates upon contact with a hydrogen atom, so they are unstable between them. Decomposing is where light photons are produced. One of the scientists who outlined it was Robert L. Forward, in the scientific magazine Mirror Matter Newsletter. ^{[citation required]} The best way to understand antimatter is with a number line, where what is below zero is subtle matter (What scientists call antimatter) and what is above zero is Viteria dense (What scientists call matter). In this way, that is, with these new linguistic concepts of technical terms, they allow a better understanding of things, something that current science must correct.^{[citation required]}

Experimental history

In 1995, CERN announced the creation of nine antihydrogen atoms in the PS210 experiment, led by Walter Oelert and Mario Macri. The method used by this experiment was proposed in 1994 by Charles Munger Jr., Stanley J. Brodsky and Ivan Schmidt Andrade.

Experiments carried out at Fermilab confirmed the fact, and shortly after (who?) announced the creation of another 100 atoms of antihydrogen. It was created by combining, in a particle accelerator, an antielectron and an antiproton, cooled to almost absolute zero to slow them down and confine them with magnetic fields so that they would not collide with normal atoms.

Antihydrogen was first produced by ATHENA (also known as the AD-1 experiment, an antimatter research project at CERN's Antiproton Decelerator), in 2002, and then by ATRAP (The Antihydrogen Trap Collaboration)., ATRAP, at the CERN Antiproton Decelerator facility in Geneva, responsible for the AD-2 experiment) and in 2004 millions of antihydrogen atoms had already been manufactured. The synthesized atoms had a relatively high temperature (a few thousand kelvins), so they would collide with the walls of the experimental apparatus and annihilate. Most precision tests require long observation times.

In 2010, CERN scientists led by Jeffrey Hangst carried out the Alpha experiment, through which they achieved the capture and subsequent detection of 38 antihydrogen atoms. To do this, the scientists used ten million antiprotons and even more positrons, and they used a 'trap' magnetic that confines neutral atoms by interacting with their magnetic instants (explain magnetic instants).

In 2011 the Alpha project managed to create more than 300 atoms of antihydrogen and store them for 1000 seconds (16 minutes 40 seconds). This will allow the scientists of this experiment to learn more information about antimatter.

In March 2012, CERN managed to manipulate antihydrogen atoms using microwaves, achieving the first glimpse of an antiatomic fingerprint.

In 2016, the ALPHA project measured the transition between the two lowest energy levels of antihydrogen, 1S–2S. The results, identical to those for hydrogen within the experimental resolution, support the idea of symmetry between matter and antimatter.

Features

The CPT theorem of particle physics predicts that antihydrogen atoms have many of the characteristics that normal hydrogen has; that is, the same mass, magnetic moment, and atomic state transition frequencies (see atomic spectroscopy). For example, excited antihydrogen atoms are expected to glow the same color as normal hydrogen. Antihydrogen atoms should be gravitationally attracted to other matter or antimatter with a force of the same magnitude as that experienced by ordinary hydrogen atoms. This would not be true if antimatter had negative gravitational mass, which is considered highly unlikely, although it has not yet been empirically disproved (see Gravitational interaction of antimatter). A recent theoretical framework has been developed for negative mass and repulsive gravity (antigravity) between matter and antimatter, and the theory It is compatible with the CPT theorem.

When antihydrogen comes into contact with ordinary matter, its constituents are rapidly annihilated. The positron annihilates with an electron to produce gamma rays. The antiproton, for its part, is formed by antiquarks that combine with quarks in neutrons or protons, giving rise to high-energy pions, which quickly decay into muons, neutrinos, positrons and electrons. If antihydrogen atoms were suspended in a perfect vacuum, they would survive indefinitely.

As an antielement, it is expected to have exactly the same properties as hydrogen. For example, antihydrogen would be a gas under standard conditions and would combine with antioxygen to form antiwater,

Production

The first antihydrogen was produced in 1995 by a team led by Walter Oelert at CERN using a method first proposed by Charles Munger Jr, Stanley Brodsky and Ivan Schmidt Andrade.

At LEAR, antiprotons were fired from an accelerator into xenon clusters, producing electron-positron pairs. Antiprotons can capture positrons with a probability of about 10^-19, so this method is not suitable for substantial production, according to calculations. Fermilab measured a somewhat different cross section, in accordance with the predictions of quantum electrodynamics. Both gave rise to very energetic, or hot, anti-atoms, unsuitable for detailed study.

Later, CERN built the Antiproton Decelerator (AD) to support efforts toward low-energy antihydrogen, for testing fundamental symmetries. The AD will supply several groups at CERN. CERN expects its facilities to be capable of producing 10 million antiprotons per minute.

Low energy antihydrogen

The ATRAP and ATHENA collaboration experiments at CERN brought together positrons and antiprotons in Pennings traps, leading to synthesis at a typical rate of 100 antihydrogen atoms per second. Antihydrogen was first produced by ATHENA in 2002, and later by ATRAP, and by 2004 millions of antihydrogen atoms had already been manufactured. The synthesized atoms had a relatively high temperature (a few thousand kelvins), so they would collide with the walls of the experimental apparatus and annihilate. Most precision tests require long observation times.

ALPHA, a successor to the ATHENA collaboration, was formed to stably trap antihydrogen. While electrically neutral, its spin magnetic moment interacts with an inhomogeneous magnetic field; Some atoms will be attracted to a magnetic minimum, created by a combination of mirror and multipolar fields.

In November 2010, the ALPHA collaboration announced that they had trapped 38 atoms of antihydrogen for one-sixth of a second, the first confinement of neutral antimatter. In June 2011, they trapped 309 antihydrogen atoms, up to 3 simultaneously, for up to 1,000 seconds. Next, they studied its hyperfine structure, the effects of gravity, and charge. ALPHA will continue measurements together with the ATRAP, AEGIS and GBAR experiments.