How to trap antimatter

A group of scientists from CERN, including Russian physicists, has developed an effective technique for synthesizing and trapping antimatter particles for a relatively long time. Antimatter particles were atoms of antihydrogen, consisting of antiprotons and positrons instead of protons and electrons, an article in Nature reveals.

The problem of antimatter, or to be more precise, antimatter’s absence in our Universe, has always been one of the major problems for physicists all around the world. The Big Bang should have resulted in generating equal amounts of matter and antimatter, however, due to unknown reasons antimatter had disappeared. Studying atoms of antihydrogen is expected to help scientists understand why antimatter is so mysteriously gone from our Universe.

Physicists, participating in the ALPHA project, which is a magnetic trap for neutral antihydrogen, have developed a technique for producing and conserving “cold” atoms of antihydrogen, which is definitely a breakthrough in studying antimatter and understanding, how it differs from ordinary matter.

Antiparticles, like positrons were discovered in 1930s, and in 1955 an antiproton – proton’s antipode – has been synthesized. However, only in 1995 CERN researchers succeeded in assembling at least nine atoms of antihydrogen by means of an interaction of antiproton and positron beams in LEAR (Low Energy Anti-Proton Ring) accelerator. Well, atoms of antimatter showed a strong tendency to annihilate and disappear after colliding with ordinary matter. LEAR operated until 1996, and is expected to part of the Large Hadron Collider. Trapping neutral atoms of antimatter is much harder, than doing it with individual particles, because these atoms do not have an electric charge and cannot be trapped in a electromagnetic field.

CERN research group has developed an original facility – a trap, which generates extremely powerful magnetic field with complicated configuration, which prevents atoms of antihydrogen from meeting ordinary matter and annihilating. Physicists showed that their trap was able to hold atoms of antihydrogen for about one tenth of a second – time long enough for exploring some properties of antimatter, recording its spectrum, for instance.

Antimatter’s spectrum can tell researchers whether a symmetry between matter and antimatter in charge, spatial coordinates and time (so-called CPT-symmetry) persisted. This CPT-symmetry (CPT comes from “charge, parity, time”) is a fundamental symmetry of physical laws under conditions, when charge, parity and time change simultaneously. This kind of symmetry is one of the base elements of current physical theory, known as the Standard Model. The Standard Model describes nuclear interactions between known subatomic particles.

In case spectra of normal hydrogen and antihydrogen are not identical, it will indicate absence of the symmetry, which can become antimatter’s Achilles' heel.

Anna Kizilova