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SNO+ Detects Solar Neutrinos Converting Carbon-13 to Nitrogen-13

An Oxford-led team used a delayed-coincidence technique in the deep SNOLAB detector to make the first direct cross-section measurement of this low-energy reaction.

Overview

  • Peer-reviewed findings appear in Physical Review Letters as “First Evidence of Solar Neutrino Interactions on 13C.”
  • Over 231 days of data taking from May 4, 2022 to June 29, 2023, the analysis identified 5.6 events, consistent with 4.7 expected from solar neutrinos.
  • The SNO+ detector sits two kilometers underground at SNOLAB and uses a 12-meter acrylic vessel with about 800 tonnes of liquid scintillator viewed by roughly 9,000 photomultiplier tubes.
  • Researchers isolated the rare reaction using a distinctive two-flash signal: the initial neutrino interaction followed minutes later by nitrogen-13 decay.
  • The result is reported as the lowest-energy observation on carbon-13 to date and positions solar neutrinos as a practical test beam for studying other rare interactions, extending the SNO legacy that led to a 2015 Nobel Prize.