Physicists Trap Single Positron for Months, Opening New Tests of Matter-Antimatter Symmetry

Scientists at Northwestern University succeeded in capturing a single positron— the electron’s antimatter counterpart— inside a vacuum chamber, where it remained confined for several months. They achieved this by directing the particle into a magnetic-electric trap that reduced its speed to near-standstill, then used microwaves to promote it to excited orbital states, confirming that its dynamics match those of an electron.

The experiment demonstrates a new capability to hold antimatter long enough for detailed study. The next phase involves detecting the tiny magnetic field generated by the moving positron, aiming to compare its magnetic moment with the precisely known value for electrons. Any difference would indicate physics beyond one outlet Standard Model, which cannot explain why the universe contains more matter than antimatter. The team hopes this approach will help resolve that fundamental mystery.