Limits on the Existence of sub-MeV Sterile Neutrinos from the Decay of 7Be in Superconducting Quantum Sensors

Sterile neutrinos are natural extensions to the standard model of particle physics and provide a possible portal to the dark sector. We report a new search for the existence of sub-MeV sterile neutrinos using the decay-momentum reconstruction technique in the decay of Be-7. The experiment measures the total energy of the Li-7 daughter atom from the electron capture decay of Be-7 implanted into sensitive superconducting tunnel junction (STJ) quantum sensors. This first experiment presents data from a single STJ operated at a low count rate for a net total of 28 days, and provides exclusion limits on sterile neutrinos in the mass range from 100 to 850 keV that improve upon previous work by up to an order of magnitude.

Automated summary

This experiment reports a new search for sub-MeV sterile neutrinos using decay-momentum reconstruction technique in the decay of Be-7 and sensitive superconducting tunnel junction (STJ) quantum sensors. The data from a single STJ operating at a low count rate for 28 days improved exclusion limits on sterile neutrinos in the mass range from 100 to 850 keV.