SNO+ Detects First Geoneutrinos in Western Hemisphere, Hinting at Uneven Mantle
In November 2025, the SNO+ experiment located in Sudbury, Canada, achieved its inaugural detection of geoneutrinos, boosting the total count by approximately 50 and representing the first such measurements in the western hemisphere. Utilizing elements from the earlier SNO experiment (1999-2006), SNO+ features an acrylic sphere equipped with nearly 10,000 light detectors, 780 tons of liquid scintillator, and 7,000 tons of ultrapure water. Geoneutrinos arise from the decay of uranium, thorium, and potassium, playing a role in mantle convection and plate tectonics. The first geoneutrinos were identified by Kamland in 2005, followed by Borexino in 2009. Mark Chen, the director of SNO+, indicates the mantle may not be uniform. Additionally, China's JUNO detector, which has been operational since August 2025, is anticipated to announce its first geoneutrino flux later this year.
Key facts
- SNO+ reported its first geoneutrino detection in November 2025, increasing observed geoneutrinos by about 50
- The SNO+ detector sits 2 kilometers underground in the Creighton mine at Snolab in Sudbury, Canada
- SNO+ holds 780 tons of liquid scintillator in an acrylic sphere lined with nearly 10,000 light detectors, surrounded by about 7,000 tons of ultrapure water
- Kamland in Japan made the first geoneutrino detection in 2005; Borexino in Italy reported several dozen more in 2009
- SNO+ results are the first geoneutrinos measured in the western hemisphere
- Mark Chen directs the SNO+ collaboration and is a particle astrophysicist at Queen's University in Ontario
- Large low-shear-velocity provinces lie beneath Africa and the Pacific Ocean
- China's 20-kiloton JUNO detector began operation in August 2025 and is expected to report its first geoneutrino flux later this year
Entities
Artists
- Matt Depatie
- Ryan Bayes
- Mark Chen
- William McDonough
- Virginia Strati
Institutions
- Quanta Magazine
- Simons Foundation
- SNO+
- Snolab
- SNO experiment
- Queen's University
- Kamland
- Borexino
- Gran Sasso National Laboratory
- Chinese Academy of Sciences
- University of Ferrara
- JUNO
- Taishan nuclear power plant
- Yangjiang nuclear power plant
- Wired
Locations
- Sudbury
- Canada
- Ontario
- Japan
- Italy
- China
- Guangzhou
- Africa
- Pacific Ocean