Antimatter Research

Over the past 20 years scientists at CERN have been using antiparticles in many different ways for their daily work. Antiparticles can be generated by colliding subatomic particles. Such antiparticles must be isolated, collected and stored in order to tune their energy to the appropriate level.

The first Antiproton Decelerator (AD) at CERN is able to carry out all of these tasks. It can produce the low energy antiprotons needed for a variety of studies. It produces, collects, cools, decelerates and eventually extracts antimatter particles to the experiments in which they are needed.

Antiparticles have to be created from energy. This energy is obtained from protons that have been previously accelerated. These protons are smashed into a block of metal. Then, the abrupt stopping of such energetic particles releases a huge amount of energy into a small volume, heating it up to such temperatures that matter-antimatter particles are spontaneously created. In about one collision out of a million, an antiproton-proton pair is formed, but given the fact that about 10 trillion protons hit the target, around 10 million antiprotons are still created.

The newly created antiprotons, however, are produced almost at the speed of light, but do not have exactly the same energy. They also move in random directions, and hence magnets must be used to direct them. When the antiparticles speed is down to about 10% of the speed of light, the antiprotons are ejected as a bunch.

Three experiments are installed in the Antiproton Decelerator's experimental hall: ASACUSA "Atomic Spectroscopy and Collisions using Slow Antiprotons", ATHENA "Antihydrogen Production and Precision Experiments", and ATRAP "Cold Antihydrogen for Precise Laser Spectroscopy".

ATHENA and ATRAP's goal is to produce antihydrogen in traps, by combining antiprotons delivered by the AD with positrons emitted by a radioactive source.

ASACUSA, on the other hand, will synthesize "exotic" atoms, in which an electron is replaced by an antiproton. Precise laser spectroscopy of these exotic atoms is expected to reveal lots of information on the behavior of atomic systems.

Continue to the search for antimatter in space.