Northwestern Physicists Trap 1 Positron for Months, Advancing CPT Symmetry Tests

Q: What would happen to the isolated antimatter particle if the ultra-cold electromagnetic trap suspending it suddenly lost power?

If the trap suddenly lost confinement, the positron would very quickly hit ordinary matter in the apparatus and annihilate. A positron is the electron’s antimatter counterpart, so once the electric and magnetic fields no longer kept it suspended in the ultrahigh vacuum, it would drift into the trap electrodes or chamber wall. There it would encounter an electron, and the pair would annihilate. For a low-energy positron, that typically produces two gamma rays of about 511 keV each. In practical terms, the particle would not explode or damage the lab. This experiment stores only a single positron, so the released energy is tiny on a human scale. The significance is scientific, not hazardous: the trapped particle would simply be lost, ending that measurement run. In many Penning-trap systems, a total “power loss” does not necessarily mean immediate loss of confinement, because superconducting magnets can hold their magnetic field for some time even without external power, and cryogenic systems can provide a grace period. But if the fields actually decayed below the confinement threshold, the result for the isolated positron would be annihilation on contact with matter.

3 articles · Updated · ScienceAlert · Oct 21

Months-long confinement of a single positron marks a step beyond earlier month-scale trapping, giving Northwestern physicists sustained control of an antimatter particle that normally annihilates on contact with electrons.
546-kiloelectronvolt positrons from radioactive sodium were slowed in a tungsten crystal, briefly formed into positronium, then fed through a 640-micrometer opening into a Penning trap cooled to 300 millikelvins.
Inside the superconducting vacuum trap, the team cooled the positron to its lowest quantum state and detected one-quantum cyclotron jumps and spin flips without disturbing the measurement.
That control is aimed at a high-precision measurement of the positron's magnetic moment, to be compared with the electron's as a stringent test of CPT symmetry under the Standard Model.
Researchers hope to report the measurement early next year; even a perfect match would sharpen the unresolved puzzle of why the universe contains far more matter than antimatter.

Sources

ScienceAlert4h ago

Northwestern Physicists Trap Single Positron for Months to Test CPT Symmetry

The Brighter Side of News8h ago

Quantum first: Physicists contain a single antimatter particle for months - The Brighter Side of News

New Scientist12h ago

A single antimatter particle was held in a trap for months | New Scientist

11 Sources

If this trapped positron perfectly mirrors the electron, where else must physicists look to solve the universe's greatest matter-antimatter mystery?

What would happen to the isolated antimatter particle if the ultra-cold electromagnetic trap suspending it suddenly lost power?

Could a tiny magnetic discrepancy in a trapped antimatter particle finally explain why our universe is made of matter instead of nothing?

Record-Breaking Quantum Isolation of a Single Positron: Precision Tests of CPT Symmetry and the Matter-Antimatter Mystery

Overview

This report highlights a major breakthrough in antimatter research, where scientists isolated a single positron for months by first slowing it down from radioactive sodium-22 decay using a tungsten crystal, forming neutral positronium that could enter a special trap. Inside, advanced cooling and a Penning trap kept the positron stable, while precise detection methods and SQUID technology enabled long-term quantum control. This achievement allows for unprecedented tests of CPT symmetry, addressing why the universe is made of matter and not antimatter, and drives the search for new physics beyond the Standard Model by connecting experimental advances to deep cosmological questions.

...