Editing Antimatter (section)

===Antihelium===
Antihelium-3 nuclei ({{SimpleNuclide|anti=yes|helium|3}}) were first observed in the 1970s in proton–nucleus collision experiments at the Institute for High Energy Physics by Y. Prockoshkin's group (Protvino near Moscow, USSR)<ref>
{{cite journal
 |last=Antipov |first=Y. M.
 |display-authors=etal
 |date=1974
 |title=Observation of antihelium3 (in Russian)
 |journal=[[Yadernaya Fizika]]
 |volume=12 |page=311
}}</ref> and later created in nucleus–nucleus collision experiments.<ref>
{{cite journal
 |last=Arsenescu |first=R.
 |display-authors=etal
 |date=2003
 |title=Antihelium-3 production in lead–lead collisions at 158&nbsp;''A''&nbsp;GeV/''c''
 |journal=[[New Journal of Physics]]
 |volume=5 |issue=1 |page=1
 |bibcode=2003NJPh....5....1A
 |doi=10.1088/1367-2630/5/1/301
|doi-access=free
 }}</ref> Nucleus–nucleus collisions produce antinuclei through the coalescence of antiprotons and antineutrons created in these reactions. In 2011, the [[STAR detector]] reported the observation of artificially created antihelium-4 nuclei (anti-alpha particles) ({{SimpleNuclide|anti=yes|helium|4}}) from such collisions.<ref>
{{cite journal
 |last=Agakishiev |first=H.
 |display-authors=etal
 |date=2011
 |title=Observation of the antimatter helium-4 nucleus
 |journal=Nature
 |volume=473 |issue=7347 |pages=353–356
 |arxiv=1103.3312
 |doi=10.1038/nature10079
 |bibcode=2011Natur.473..353S
 |pmid=21516103
|s2cid=118484566
 }}</ref>

The [[Alpha Magnetic Spectrometer]] on the [[International Space Station]] has, as of 2021, recorded eight events that seem to indicate the detection of antihelium-3.<ref>{{cite journal |last1=Leah Crane |title=Antimatter stars may lurk in the solar system's neighbourhood |journal=New Scientist |date=May 1, 2021 |url=https://www.newscientist.com/article/2275563-antimatter-stars-may-lurk-in-the-solar-systems-neighbourhood/ |access-date=1 May 2021 |archive-date=1 May 2021 |archive-url=https://web.archive.org/web/20210501150008/https://www.newscientist.com/article/2275563-antimatter-stars-may-lurk-in-the-solar-systems-neighbourhood/ |url-status=live }}</ref><ref>{{cite journal |last1=Joshua Sokol |title=Giant space magnet may have trapped antihelium, raising idea of lingering pools of antimatter in the cosmos |journal=Science |date=Apr 19, 2017 |doi=10.1126/science.aal1067 |url=https://www.science.org/content/article/giant-space-magnet-may-have-trapped-antihelium-raising-idea-lingering-pools-antimatter |access-date=1 May 2021 |archive-date=1 May 2021 |archive-url=https://web.archive.org/web/20210501145420/https://www.sciencemag.org/news/2017/04/giant-space-magnet-may-have-trapped-antihelium-raising-idea-lingering-pools-antimatter |url-status=live }}</ref>