Constraints on ultra-high-energy neutrino flux from radio observations of the Moon

The NuMoon project aims to study ultra-high-energy neutrinos and cosmic rays by using radio telescopes to search for short pulses from the Moon. These pulses are created when a neutrino or cosmic ray impinges on the Moon and interacts below the lunar surface. Part of the energy is converted into a hadronic shower, which emits radio emission in a process known as the Askaryan effect. In the first phase of the NuMoon project, 46 hrs of data were collected with the Westerbork Synthesis Radio Telescope in a low frequency band: 40–80 MHz. This resulted in an upper limit on the neutrino flux above 1022 eV which is an order of magnitude lower than previous limits. Additionally, an upper limit has been set on the ultra-high-energy cosmic-ray flux. The second phase of NuMoon will consist of observations with LOFAR.