Ghost particles slip through Earth and spark a hidden atomic reaction

Science News from research organizations Ghost particles slip through Earth and spark a hidden atomic reaction Date: December 12, 2025 Source: University of Oxford Summary: Scientists have managed to observe solar neutrinos carrying out a rare atomic transformation deep underground, converting carbon-13 into nitrogen-13 inside the SNO+ detector. By tracking two faint flashes of light separated by several minutes, researchers confirmed one of the lowest-energy neutrino interactions ever detected. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY The 12-meter-diameter acrylic vessel surrounded by 9,000 photomultiplier tubes at the heart of the Sudbury Neutrino Observatory and SNO+ experiments. The vessel currently holds about 800 tonnes of liquid scintillator for neutrino detection. Credit: SNOLAB Neutrinos are among the most puzzling particles known to science and are often called 'ghost particles' because they so rarely interact with matter. Trillions pass through each person every second without leaving any mark. These particles are created during nuclear reactions, including those inside the Sun's core. Their extremely weak interactions make them exceptionally challenging to study. Only a few materials have ever been shown to respond to solar neutrinos.

Scientists have now added another to that short list by observing neutrinos convert carbon atoms into nitrogen inside a massive underground detector. This achievement came from a project led by Oxford researchers using the SNO+ detector, which sits two kilometers underground at SNOLAB in Sudbury, Canada. SNOLAB operates within an active mine and provides the shielding needed to block cosmic rays and background radiation that would otherwise overwhelm the delicate neutrino measurements. Capturing a Rare Two-Part Flash From Carbon-13 The research team focused on detecting moments when a high-energy neutrino hits a carbon-13 nucleus and converts it into nitrogen-13, a radioactive form of nitrogen that decays roughly ten minutes later. To spot these events, they relied on a 'delayed coincidence' technique that searches for two related bursts of light: the first from the neutrino striking the carbon-13 nucleus and the second from the decay of nitrogen-13 several minutes afterward. This paired signal makes it possible to confidently distinguish true neutrino events from background noise. Over a span of 231 days, from May 4, 2022, to June 29, 2023, the detector recorded 5.6 such events. This matches expectations, which predicted that 4.7 events would occur due to solar neutrinos during this period. A New Window Into How the Universe Works Neutrinos behave in unusual ways and are key to understanding how stars operate, how nuclear fusion unfolds, and how the universe evolves. The researchers say this new measurement opens opportunities for future studies of other low-energy neutrino interactions. Lead author Gulliver Milton, a PhD student in 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 traveled vast distances to reach our detector." Co-author Professor Steven Biller (Department of Physics, University of Oxford) added: "Solar neutrinos themselves have been an intriguing subject of study for many years, and the measurements of these by our predecessor experiment, SNO, led to the 2015 Nobel Prize in physics. It is remarkable that our understanding of neutrinos from the Sun has advanced so much that we can now use them for the first time as a 'test beam' to study other kinds of rare atomic reactions!" Building on the SNO Legacy and Advancing Neutrino Research SNO+ is a successor to the earlier SNO experiment, which demonstrated that neutrinos switch between three forms known as electron, muon, and tau neutrinos as they travel from the Sun to Earth. According to SNOLAB staff scientist Dr. Christine Kraus, SNO's original findings, led by Arthur B. McDonald, resolved the long-standing solar neutrino problem and contributed to the 2015 Nobel Prize in Physics. These results paved the way for deeper investigations into how neutrinos behave and their significance in the universe. "This discovery uses the natural abundance of carbon-13 within the experiment's liquid scintillator to measure a specific, rare interaction," Kraus said. "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." RELATED TOPICS Space & Time Cosmic Rays Stars Dark Matter Sun Matter & Energy Physics Detectors Materials Science Quantum Physics RELATED TERMS Neutrino Solar power Potential energy Renewable energy Solar cell Large-scale structure of the cosmos Light-year Dark energy Story Source: Materials provided by University of Oxford. Note: Content may be edited for style and length. Journal Reference: M. Abreu, A. Allega, M. R. Anderson, S. Andringa, D. M. Asner, D. J. Auty, A. Bacon, T. Baltazar, F. Barão, N. Barros, R. Bayes, E. W. Beier, A. Bialek, S. D. Biller, E. Caden, M. Chen, S. Cheng, B. Cleveland, D. Cookman, J. Corning, S. DeGraw, R. Dehghani, J. Deloye, M. M. Depatie, F. Di Lodovico, C. Dima, J. Dittmer, K. H. Dixon, M. S. Esmaeilian, E. Falk, N. Fatemighomi, R. Ford, S. Gadamsetty, A. Gaur, O. I. González-Reina, D. Gooding, C. Grant, J. Grove, S. Hall, A. L. Hallin, D. Hallman, M. R. Hebert, W. J. Heintzelman, R. L. Helmer, C. Hewitt, B. Hreljac, P. Huang, R. Hunt-Stokes, A. S. Inácio, C. J. Jillings, S. Kaluzienski, T. Kaptanoglu, J. Kladnik, J. R. Klein, L. L. Kormos, B. Krar, C. Kraus, C. B. Krauss, T. Kroupová, C. Lake, L. Lebanowski, C. Lefebvre, V. Lozza, M. Luo, S. Maguire, A. Maio, S. Manecki, J. Maneira, R. D. Martin, N. McCauley, A. B. McDonald, G. Milton, D. Morris, M. Mubasher, S. Naugle, L. J. Nolan, H. M. O’Keeffe, G. D. Orebi Gann, S. Ouyang, J. Page, S. Pal, K. Paleshi, W. Parker, L. J. Pickard, B. Quenallata, P. Ravi, A. Reichold, S. Riccetto, J. Rose, R. Rosero, J. Shen, J. Simms, P. Skensved, M. Smiley, R. Tafirout, B. Tam, J. Tseng, E. Vázquez-Jáuregui, C. J. Virtue, F. Wang, M. Ward, J. D. Wilson, J. R. Wilson, A. Wright, S. Yang, Z. Ye, M. Yeh, S. Yu, Y. Zhang, K. Zuber, A. Zummo. First Evidence of Solar Neutrino Interactions on C13.

Physical Review Letters, 2025; 135 (24) DOI: 10.1103/1frl-95gj Cite This Page: MLA APA Chicago University of Oxford. "Ghost particles slip through Earth and spark a hidden atomic reaction." ScienceDaily. ScienceDaily, 12 December 2025. . University of Oxford. (2025, December 12). Ghost particles slip through Earth and spark a hidden atomic reaction. ScienceDaily. Retrieved December 12, 2025 from www.sciencedaily.com/releases/2025/12/251212022252.htm University of Oxford. "Ghost particles slip through Earth and spark a hidden atomic reaction." ScienceDaily. www.sciencedaily.com/releases/2025/12/251212022252.htm (accessed December 12, 2025). Explore More from ScienceDaily RELATED STORIES After 50 Years, Scientists Finally Catch Elusive Neutrinos Near a Reactor Aug. 1, 2025 — A tiny 3 kg detector has made a huge leap in neutrino science by detecting rare CEvNS interactions at a Swiss reactor. This elusive effect, long predicted and hard to measure, was captured with ... First Measurement of Electron And Muon-Neutrino Interaction Rates at the Highest Energy Ever Detected from an Artificial Source Aug. 5, 2024 — Understanding neutrino interactions is crucial for obtaining a complete picture of particle physics and the universe. To date, neutrino interaction cross sections have not been measured at high ... Imaging the Proton With Neutrinos Mar. 21, 2023 — The interactions of the quarks and gluons that make up protons and neutrons are so strong that the structure of protons and neutrons is difficult to calculate from theory and must be instead measured ...

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