KATRIN sets a new record: Neutrino mass to 0.45 eV for the first time!

KATRIN sets a new record: Neutrino mass to 0.45 eV for the first time!

On April 11, 2025, the “Karlsruhe Tritium Neutrino Experiment” (KATRIN) at the Karlsruhe Institute of Technology (KIT) achieved remarkable progress in neutrino research. In an article published in the journalSciencewas published, a new upper limit for the neutrino mass of at most 0.45 electron volts (eV) was determined, which is only 8 x 10^-37corresponds to kilograms. This finding represents a global record and is crucial to shedding light on the physical properties of one of the least understood particles in the universe. The precise measurement of neutrino mass is central to understanding fundamental laws of nature, as the KATRIN collaboration explains.

Neutrinos, which exist in three main types—electron, muon, and tau neutrinos—are electrically neutral and rarely react with matter. The KATRIN experiment uses the beta decay of tritium to precisely measure the neutrino mass. During this process, a neutron transforms into a proton and emits an electron and an electron antineutrino. Analyzing the energy distribution of these particles allows scientists to draw conclusions about the mass of the neutrinos. Information on the estimated neutrino mass in 2025 expects to approach 0.3 eV with 90% confidence.

Technical details of the KATRIN experiment

The KATRIN system is 70 meters long and includes a high-resolution spectrometer with a diameter of ten meters. The neutrino mass measurements were carried out over a total of 259 days in five measurement campaigns, during which around 36 million electrons were analyzed. This amount of data exceeds previous measurements sixfold and enables a much more precise study of neutrino mass. KATRIN's results also confirm the theory that neutrinos are at least a million times lighter than electrons and strengthen evidence that neutrinos have mass - an aspect that contradicts the traditional assumption in the Standard Model.

Researchers have significantly refined the limits of neutrino measurements through improved data collection methods and reduced systematic uncertainties. Christian Weinheimer from the University of Münster, one of the previous speakers for the experiment, and his team played a key role in setting up and operating KATRIN and developed innovative analysis and measurement methods that significantly increase the sensitivity of the experiments.

Outlook and future projects

The neutrino mass measurements as part of KATRIN will run until the end of 2025. From 2026 onwards, a new detector system called TRISTAN will be connected, which will enable the search for hypothetical sterile neutrinos. In addition, a research and development program called KATRIN++ is underway to develop concepts for future experiments on neutrino mass. Scientists from over 20 institutions from seven countries are involved in this international joint project.

In summary, the progress of the KATRIN experiment not only shows how important research into neutrinos is for understanding our universe, but also what innovative approaches are possible in modern particle physics. The findings from KATRIN push the boundaries of knowledge and highlight the enormous challenges facing scientists. The results and techniques of this research have the potential to permanently change the entire field of particle physics.

For further information on the results of the KATRIN experiment, read the reports uni-muenster.de, deinkalert.org and kit.edu.