The NuMoon Experiment: Preliminary results and upper limits on UHE particles

The main goal of the NuMoon experiment is study ultra-high energy cosmic rays and neutrinos
interacting with the Moon using ground-based radio telescopes. Ultra-high energy (UHE) particles
interacting with the Moon produce particle showers in the regolith. Due to charge asymmetry
in the shower front, a short broadband coherent burst of radio emission is produced - via a
phenomenon referred to as the Askaryan effect. With ground based radio telescopes, such pulses
can be searched for. The LOw Frequency ARray (LOFAR) - a radio observatory located in the
Netherlands - is currently the largest radio array operating at frequencies between 110 − 190 MHz;
an optimal frequency range for Lunar signal search. A pulse search on the near-surface of the
Moon is carried out. This requires a proper understanding of the background noise and other
factors (like the ionosphere) that could have an adverse effect on the signal. In this contribution,
we discuss results from first Lunar observations with LOFAR and the development of a trigger
algorithm for future observations. Results from a detailed Monte-Carlo (MC) simulation of the
effective lunar aperture for UHE particles and the expected sensitivity to the UHE particle flux are
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shown.