Physics: Antinuclei travel from far, far away

Light antinuclei, comprised of antiprotons and antineutrons, may travel long distances throughout the Galaxy reports a paper published in Nature Physics. The findings suggest these antinuclei could be used in the search for dark matter.

There are no natural sources of antinuclei on Earth, but they are produced elsewhere in the Galaxy. It has been proposed that antinuclei may be the result of interactions between high-energy cosmic radiation, originating from outside our Solar System, and atoms in the interstellar medium (the space between stars in a galaxy). An alternative scenario is that antinuclei are formed by the annihilation of dark-matter particles that have not yet been discovered.

To explore the interactions of light antinuclei and matter, the ALICE Collaboration analysed the antiparticle of the helium-3 (a stable isotope of helium) nucleus. Anti-helium-3 nuclei were produced in particle collisions at the Large Hadron Collider, and these antinuclei then interacted with matter in the ALICE detector causing them to disappear. The authors determined the disappearance probability of antihelium-3 nuclei, and the impact of this probability on the journey of these antinuclei through our Galaxy. Their findings suggest that antihelium-3 nuclei can travel long distances, making them suitable for searching for dark-matter annihilation.