The ALICE cavern in CERN, Geneva. Credit: Maximilien Brice © 2020 CERN
A study reveals that light antinuclei, composed of antiprotons and antineutrons, may travel long distances in the Milky Way and head towards Earth without being absorbed1. These antinuclei, thought to form through dark matter destruction, could be used to trace such matter.
On Earth, particle accelerators produce light antimatter nuclei, such as antideuteron and antihelium. But similar antimatter nuclei have not been observed to come from outer space. To find out, scientists made lead ions collide with protons at the Large Hadron Collider, which generates temperatures 100,000 times hotter than the centre of the Sun.
The collisions generated large amounts of antihelium-3 nuclei. These antinuclei were then made to interact with normal matter in the ALICE (A Large Ion Collider Experiment) detector causing them to disappear.
The team, which included physicists at the Variable Energy Cyclotron Centre, Homi Bhabha National Institute in Kolkata, determined the disappearance probability of antihelium-3 nuclei and the impact of this probability on the journey of these antinuclei through the Milky Way.
Theoretical models predict that dark matter could be composed of particles which interact weakly with one another. This produces antihelium-3 nuclei. Using the results of the ALICE experiment, the researchers speculated that about half the antihelium-3 nuclei expected to be generated by the interaction of dark matter particles would reach the vicinity of Earth.
They say that these antinuclei could be used to study cosmic-ray interactions and dark matter annihilation.
