Speaker
Description
To date, the least energetic neutrinos ever detected belong to the solar pp chain, with energies above 100 keV. Yet, the Sun is expected to produce an even lower-energy population of neutrinos, generated by pair-production processes in the solar plasma. These solar thermal neutrinos populate the eV-keV energy range, well below the energies probed by existing neutrino experiments.
In this contribution, we discuss the feasibility of detecting such low-energy neutrinos via neutrino capture on tritium, the same process proposed for direct detection of the Cosmic Neutrino Background. By modeling the resulting electron spectrum and using the KATRIN 2025 data release, we derive the first experimental constraint on the solar thermal neutrino flux.
Our results demonstrate that tritium-based neutrino detectors can extend neutrino astrophysics well below the detection threshold traditionally limiting existing neutrino experiments, opening a new observational window to low-energy neutrino populations from the Sun and potentially other sources.