Ultra-high energy cosmic rays are the most energetic particles in the Universe but their origin is unknown. On their journey to Earth, cosmic rays are deflected in magnetic fields, and their arrival directions do not point back to the sources. The key to solving this mystery is to measure the mass composition of cosmic rays - are they protons or heavier nuclei? By measuring the ratio of different
chemical elements we learn more about the accelerators that produce cosmic rays.
We have developed a novel method to derive the cosmic-ray mass composition with the LOFAR radio telescope in Netherlands. By measuring the short radio pulses that are created when cosmic rays interact in the atmosphere, we can reconstruct the altitude at which the particles interact.
However, due to limitations in triggering and simulation techniques we are not yet able to use the full potential of the extremely densely populated antenna fields at the core of LOFAR.
We propose the development of a smarter triggering method that lowers the energy threshold and increases the trigger purity, by combining data from antennas and particle detectors in real-time. To handle the increased data rate it is imperative to also develop a simulation approach that runs much faster while maintaining a high accuracy.
These upgrades will shed new light on a poorly understood part of the cosmic-ray spectrum: the transition from Galactic to extragalactic sources.