The COsmic-ray Real Time Observation (CORTO) project aims at developing a real-time cosmic-ray detection system for the LOFAR observatory, so to let it be the first self-standing radio-antenna cosmic-ray detector. That will be the final prove of the feasibility of cosmic-ray detectors based on radio antennas, thus opening a new opportunity window in the detection of cosmic rays.
Cosmic rays are high energy particles which are accelerated in galactic and extra-galactic astrophysical sources, most of them still unknown. Their energy spectrum observed at Earth spans between 108 and 1020 eV, much above the reachable energy of current particle accelerators (LHC can accelerate proton up to 1013 eV, 1 eV = 1.6 10-19 J).
When a cosmic ray interacts with the Earth's atmosphere, a cascade of secondary particles is generated. Associated with the cascade, a radio signal is emitted. The LOw Frequency ARray (LOFAR) radio-antenna observatory has proven in the recent past that the radio signal can be used for reconstructing the properties of the primary particle (i.e. energy, direction, and mass composition), which are crucial for the understanding of cosmic-ray acceleration and propagation mechanisms.
Radio antenna experiments can cover a larger area (because of their reduced cost) compared to currently-running detectors and can reach a 100% duty-cycle (i.e. the fraction of time in which the detecting system is active), making them the best-suited way for detecting cosmic rays. On the other hand, the real-time recognition system of the very short radio pulses induced by the secondary particles cascades has always been problematic, because of the overwhelming background noise. As consequence, all current radio-antenna detectors rely on external particle detectors for starting the data acquisition, which sets a huge constraint in the exploitation of radio antennas for large detectors.