Searching for neutrino radio flashes from the Moon with LOFAR

Abstract

Abstract. Ultra-high-energy neutrinos and cosmic rays produce short radio flashes through the Askaryan effect when they impact on the Moon. Earthbound radio telescopes can search the Lunar surface for these signals. A new generation of lowfrequency, digital radio arrays, spearheaded by LOFAR, will allow for searches with unprecedented sensitivity. In the first stage of the NuMoon project, low-frequency observations were carried out with the Westerbork Synthesis Radio Telescope, leading to the most stringent limit on the cosmic neutrino flux above 10 23 eV. With LOFAR we will be able to reach a sensitivity of over an order of magnitude better and to decrease the threshold energy.

Radio pulses from ultra-high energy atmospheric showers as the superposition of Askaryan and geomagnetic mechanisms

“…The technique is attractive because it requires detectors which are relatively cheap and is not limited by a small duty cycle, unlike the fluorescence technique [2]. Several experimental initiatives such as AERA [3] and EASIER [4] in coincidence with the Pierre Auger Observatory [5], CODALEMA [6], LOPES [7], TREND [8], LOFAR [9] and Tunka-Rex [10], have been exploring emission from air showers mainly in the 30-80 MHz frequency range, studying the relation of the pulses to composition [11,12] and trying to understand the lateral distribution of the emission [13,14,3,9]. In addition the fortuitous detection of pulses from air showers with the ANITA balloon flown detector [15] has revealed that the pulses from these showers extend to the GHz regime, with more experimental evidence also obtained by the CROME experiment [16].…”

Cosmic Ray Mass Measurements with LOFAR

“…By fitting two-dimensional radiation profiles to the data, LOFAR has achieved a e-mail: Stijn.Buitink@vub.ac.be resolution on X max below 20 g/cm 2 [3] which is comparable to the resolution of fluorescence detection. An analysis of the first set of high-quality LOFAR events has yielded mean X max values that are in agreement with existing data based on other techniques and is indicative of a strong contribution of light nuclei in the energy range of 10 17 -10 17.5 eV [10].…”

“…The total systematic uncertainty on X max is +14/-10 g/cm 2 and on the energy is 27%. More details are given in [3] and [10].…”

“…Finally, a two-dimensional map of the pulse power is created by interpolation of the star-shaped pattern. A detailed description of this procedure can be found in [3].…”

“…Radio detection of extended air showers is a powerful and rapidly developing technique [1] that is suitable for measuring the atmospheric depth of the shower maximum X max [2,3]. Arrays with a high density of radio antennas, like LOFAR [4] and the future SKA [5], are capable of accurately measuring the mass composition of cosmic rays below the ankle, where a transition of a Galactic to an extragalactic component is expected to occur [6,7].…”