An Oxford University led research project has made a significant breakthrough observing ‘ghost particles’ for the first time using the SNO+ detector at the SNOLAB in Sudbury.
SNOLAB is an underground science laboratory located two kilometres down which specializes in neutrino and dark matter physics, quantum technology, and life sciences.
In a press release the researchers say this is the “First observation of carbon-neutrino interactions opens new frontiers in nuclear and particle physics.” The researchers say that neutrinos rarely interact with anything else, hence the name ‘ghost particles.’
Neutrinos are produced during nuclear reactions and one location they are found is the Sun’s core and “trillions stream through our bodies every second, yet leave no trace.”
To find the ‘ghost particles’ “the team searched for events where a carbon-13 nuclei is struck by a high-energy neutrino and transformed into radioactive nitrogen-13, which decays about ten minutes later. They used a ‘delayed coincidence’ method, which looks for two linked signals: an initial flash from a neutrino striking a carbon-13 nucleus, followed several minutes later by a second flash from the resulting radioactive decay. This distinctive pattern allows researchers to confidently separate real neutrino interactions from background noise” according to the news release.
What they found was “5.6 observed events over a 231-day period, from 4 May 2022 to 29 June 2023. This is statistically consistent with the 4.7 expected to be generated by neutrinos during this time.”
Gulliver Milton, the lead author, and a PhD student at the University of Oxford’s Department of Physics, said “Capturing this interaction is an extraordinary achievement. Despite the rarity of the carbon isotope, we were able to observe its interaction with neutrinos, which were born in the Sun’s core and travelled vast distances to reach our detector.”
SNOLAB staff scientist Dr Christine Kraus added, “This discovery uses the natural abundance of carbon-13 within the experiment’s liquid scintillator to measure a specific, rare interaction. To our knowledge, these results represent the lowest energy observation of neutrino interactions on carbon-13 nuclei to date and provides the first direct cross-section measurement for this specific nuclear reaction to the ground state of the resulting nitrogen-13 nucleus.”
The results were published under the title “First Evidence of Solar Neutrino Interactions on 13C” in Physical Review Letters, Wednesday 10 December 2025, DOI https://doi.org/10.1103/1frl-95gj.