On August 31, during a seminar at the INFN Laboratori Nazionali del Gran Sasso, the XENON Collaboration presented an important new result from the XENONnT experiment: the first measurement of solar neutrinos through elastic neutrino-electron scattering at the keV scale.

Thanks to XENONnT’s extremely low energy threshold and exceptional control of radioactive backgrounds, a signal dominated by pp neutrinos, produced in the fusion reactions that power the Sun, was observed with a statistical significance of 5 sigma. The 1 keV electron recoil energy threshold provides sensitivity to neutrinos with energies as low as approximately 17 keV, the lowest neutrino energy threshold ever achieved.

This result confirms that XENONnT, primarily designed for the direct search for dark matter, is also becoming a powerful observatory for neutrinos and other extremely rare processes.

The XENON group at the INFN Bologna Division plays a leading role in the experiment, particularly in Monte Carlo simulations and background characterization, as well as in the design, construction and operation of the neutron veto system. Understanding and reducing radioactive backgrounds also played a crucial role in making this new measurement possible.

For more information:

News XENON (in English): https://xenonexperiment.org/xenonnt-first-measurement-of-low-energy-solar-neutrinos-scattering-off-electrons/

Preprint: https://arxiv.org/pdf/2608.29450