Senior Research Fellowship: Searching for the origins of cosmic rays with the LOFAR radio telescope - 1st term

Ultra-high energy cosmic rays (UHE CRs) are the most energetic particles known in the Universe but their origin remains a mystery. Cosmic rays of energies around and below 1015 eV, are most likely produced in supernova remnants. At even higher energies there are multiple possible galactic and extragalactic sources.
The LOFAR radio telescope contributes to the search for the origin of cosmic rays on two fronts. Atmospheric air shower initiated by cosmic rays emit a short radio pulse that can be observed with individual antennas of the LOFAR array. The reconstruction of these signals allows for the determination of the mass composition of cosmic rays in the 1016-1018 eV energy range. This information is crucial for our understanding of the transition from Galactic to extragalactic sources. LOFAR can also be used to search for the radio signal from cosmic rays and neutrinos impacting on the Moon. The energy threshold for this technique is high but the Moon offers an enormous detector area of ~107 km2. The technique can therefore be used to study the highest energy cosmic
particles: cosmic rays at the cut-off of the energy spectrum and neutrinos produced in exotic physics scenarios such as super-heavy dark matter or cosmological defects.