Antiprotonic helium

Schematic drawing of an antiprotonic helium atom.
Antimatter
A Feynman diagram showing the annihilation of an electron and a positron (antielectron), creating a photon that later decays into an new electron–positron pair.
Antiparticles

Onia

Concepts and phenomena
Devices
Uses
Scientists

Antiprotonic helium is a three-body atom composed of an antiproton and an electron orbiting around a helium nucleus. It is thus made partly of matter, and partly of antimatter. The atom is electrically neutral, since an electron and an antiproton each have a charge of −1 e, whereas a helium nucleus has a charge of +2 e. It has the longest lifetime of any experimentally produced matter–antimatter bound state.[1]

  1. ^ "PROGRESS REPORT OF THE ASACUSA AD-3 COLLABORATION" (PDF). Archived (PDF) from the original on 7 July 2022. Retrieved 30 July 2022.