Physics of the Relativistic Heavy Ion Collider (RHIC) in New York claim that they created nuclei of antihelium-4 for the first time – the heaviest antimatter element ever seen on Earth.
Antimatter nuclei are made from antiprotons and antineutrons but, with all the types of combinations of two and three quarks that can appear in the particle collisions, it is rare that multiple antiprotons and antineutrons appear close enough to each other to form anti-nuclei. Although the first antiprotons and antineutrons were discovered in 1950s, the construction of heavier nuclei has been very difficult and each additional anti-nucleon makes the anti-nuclei 1000 less probable to appear in a collision of particles. Until now, the heaviest anti-nuclei observed was limited to three anti-nucleons. But with RHIC experiment and the new detectors of STAR was possible to detect such anti-nuclei.
read more in: physicsworld.com