[Science] Physicists trap a single positron for months to test antimatter symmetry

[Maisie92]

Physicists have held a single particle of antimatter in a trap for months. ScienceAlert's Michelle Starr reports on work by Gerald Gabrielse's group at Northwestern University, with Tom Myers, published in Physical Review Letters

The particle is a positron, the antimatter partner of the electron. The team kept it in a cryogenic superconducting Penning trap cooled to 300 millikelvin, just above absolute zero. Holding antimatter is difficult because it is destroyed the moment it touches ordinary matter

Getting the positron into the trap was clever. Positrons from a radioactive sodium source were slowed by a tungsten crystal, entered through a tiny opening as positronium, and then had their partner electron stripped away by an electric field. Once inside, the team saw single quantum jumps in the positron's motion and detected flips in its spin

The goal is to compare the magnetic moments of the positron and the electron very precisely. That tests a fundamental principle called CPT symmetry, which says matter and antimatter should behave as mirror images. A result is expected in early 2027 or later

Gabrielse's group famously made the most precise measurement of the electron's magnetic moment, so applying the same techniques to antimatter makes sense. Any difference between the two would be a huge discovery. It might even help explain why the universe contains more matter than antimatter

Do you think matter and antimatter will turn out to be perfect mirrors? And what would it mean if they are not?

Physicists Trapped a Particle of Antimatter And Kept It Caged For Months www.sciencealert.com