Speaker
Description
The Earth Potassium β⁻ decay produces antineutrinos below the 1.8 MeVinverse-beta-decay(IBD) threshold on free protons, rendering $^{40}$K geoneutrinos invisible to every detector that has observed U/Th geoneutrinos to date. Yet $^{40}$K is expected to contribute significantly to Earth’s total radiogenic heat — the largest unmeasured component of the planetary heat budget and a direct probe of the bulk silicate Earth’s volatile inventory. Measuring Potassium is recognised as critical to closing the geoneutrino-based knowledge of the Earth model.
We recently proposed a new detection methodology[1]based on charged-current antineutrino capture on $^{63}$Cu [ν̄ₑ + $^{63}$Cu → $^{63}$Ni$^{*}$ + e⁺] exploiting the event-by-event positron identification capability of aLiquidOusing a heavy-doped opaque-scintillator technology[2]to suppress backgrounds that have historically made sub-IBD-threshold antineutrino detection impractical. The positron’s unique triple-blob annihilation topology, resolved by LiquidO’s stochastic light confinement, provides the discriminating signal against solar-neutrino-induced electron backgrounds.
This talk presentsCLOUD III(first released in Venice in 2023[3]), the experimental programme designed to validate the $^{63}$Cu charged-current channel end-to-end upon the completion of the AntiMatter-OTech project programme[4]. CLOUD III aims to deploy a copper-loaded LiquidO detector at the Chooz nuclear power plant (France), approximately 35 m from a 4.25 GW$_{th}$ reactor core. The reactor’s copious antineutrino flux, which increases in the 1–2 MeV range — overlapping the $^{40}$K geoneutrino window — functions as a controlled, high-statisticstest beamfor the detection channel, enabling the first observation of $^{63}$Cu interaction and the measurement of its cross section relative to IBD on hydrogen (known to 0.2%) in the same detector volume. The talk will conclude with a discussion of the challenging scalability prospects this validated methodology offers for definitive observation of Earth’s missing potassium.
Useful References:
[1]: https://www.nature.com/articles/s42005-026-02518-6
[2]: https://www.nature.com/articles/s42005-021-00763-5
[3]: https://doi.org/10.5281/zenodo.10049845
[4]: https://doi.org/10.5281/zenodo.15198757
