Isophoric News · Tuesday, October 27, 2026
Northwestern physicists reported holding one positron, the electron's antimatter counterpart, in a trap for a month or more, with the aim of comparing its magnetic moment with the electron's
A team led by Gerald Gabrielse at Northwestern University reported in Physical Review Letters, in a paper published 21 October, that it had suspended a single positron in the magnetic field of a trap, a setup the paper's authors call a one-positron quantum cyclotron. The journal abstract says the positron was held "indefinitely" and that the setup opens the way to measuring its magnetic moment at much higher precision than before. Comparing that with the same measurement on an electron, the abstract says, should give the most stringent test yet of a basic symmetry (CPT invariance) of the Standard Model in the lepton sector. The outlets differ on how long the positron was held. Wired, in a story translated from its Spanish edition, and ScienceAlert said months; Slashdot, summarising a Scientific American report, said a month. ScienceAlert and Slashdot both described the method: positrons from radioactive sodium-22 pass through a tungsten crystal that slows them, then are captured in a vacuum chamber cooled to about three tenths of a degree above absolute zero. Wired said the experiment has so far shown no unexpected difference between the positron and the electron; the stated purpose is to improve the ability to detect one. Gabrielse said in the Slashdot excerpt that the aim is to see whether the two have exactly opposite magnetic moments, as the Standard Model predicts.
