CERN achieves record precision in antihydrogen measurement

Friday 29 May 2026 - 08:35

By: Dakir Madiha

CERN achieves record precision in antihydrogen measurement

Scientists working on the ALPHA experiment at the European research organization CERN have measured a fundamental property of antihydrogen with a precision of 4 parts per million, improving their previous result by two orders of magnitude. The findings, published on May 27 in the journal Nature, represent a significant step forward in testing whether antimatter follows the same physical laws as ordinary matter.

The experiment focused on the hyperfine structure of ground-state antihydrogen, a subtle splitting of atomic energy levels caused by magnetic interactions between an antiproton and a positron. In ordinary hydrogen, this same effect produces the well-known 21-centimeter spectral line used in radio astronomy. Researchers use this signal to study the structure of the universe and to search for potential signs of extraterrestrial intelligence.

Antihydrogen remains one of the most difficult systems to study in physics because it annihilates instantly upon contact with matter. Scientists must therefore create it in controlled conditions and confine it using magnetic traps inside ultra-high vacuum environments. Earlier measurements in 2017 reached a precision of about 400 parts per million. The latest result reduces that uncertainty to 4 parts per million, enabling more detailed comparisons between matter and antimatter.

The achievement was made possible by advances in particle cooling and trapping techniques. The ALPHA team used laser-cooled beryllium ions to sympathetically cool positrons to around 10 kelvin. This improvement increased the efficiency of antihydrogen production and confinement, allowing the experiment to generate more than 15,000 antihydrogen atoms in under seven hours. Previous methods produced roughly 2,000 atoms over a 24-hour period, highlighting a dramatic improvement in experimental capability.

Researchers say this level of precision confirms consistency with hydrogen measurements and supports the principle of CPT symmetry, a key feature of the Standard Model of particle physics. The results also open new pathways for testing quantum electrodynamics, which describes how light interacts with charged particles at the quantum level.

Further work is underway at the antimatter facility, where another experiment known as ASACUSA is pursuing similar measurements using a beam-based technique. Scientists expect that future approaches could push precision even further, offering deeper insight into the fundamental differences, or potential lack thereof, between matter and antimatter.