Antimatter matters: physicists created 18 antihelium 4 nuclei at Brookhaven National Laboratory.
Physicists recently banged together 109 gold nuclei at energies of 200 GeV and spotted 18 antinuclei of helium-4 in the ensuing wreckage.
These kinds of impacts create a hot blob of more or less equal numbers of quarks and antiquarks, a so-called quark gluon plasma. This cools down forming various particles and their antiparticles.
Positrons were first observed in 1932, antiprotons and neutrons were not seen until 1955 and it wasn't until 1970 that a Russian team announced the first observation of antihelium-3.
The antimatter helium-4 nucleus, also known as the anti-alpha particle, consists of two antiprotons and two antineutrons (baryon number B = -4).
The yield is consistent with expectations from thermodynamic and coalescent nucleosynthesis models, which has implications beyond nuclear physics.
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