antihelium

plural antiheliums

1. countableparticleuncountablenatural sciencesThe antiatom form of helium

   In 1970, a more complex antinucleus, antihelium-3 (iHe), was discovered in the USSR.

   1987, K. N. Mukhin, Experimental Nuclear Physics: Elementary particle physics, page 134

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   In principle the energy should have been enough for the production of even heavier antinuclei. However, the probability for production of heavier masses is very tiny, and antihelium-3 is still the heaviest known antielement.

   1994, Sven Kullander, Kullander Sven, Börje Larsson, Out of Sight!: From Quarks to Living Cells, →ISBN, page 218

   After several launches of their balloon, the scientists registered more than 40 million nuclei of helium in the cosmic rays, but not a single nucleon of antihelium.

   2018, Borissov Guennadi, Story Of Antimatter, The: Matter's Vanished Twin, →ISBN, page 91