GRAND will use 200,000 radio antennas (one per square kilometre) to detect air shower signals in the 50 to 200 MHz domain as local transient signals measured at several neighbouring antennas. The collaboration will reconstruct these events to extract information on the nature, energy and direction of the cosmic particles that initiated the air shower. To fully understand the signals from the antennas, the atmospheric conditions need to be measured accurately as well. In addition to transient radio frequency information in the time domain, frequency information will be recorded in coarser time bins to monitor the continuous radio background, but also to find dispersed transient signals, e.g. from fast radio bursts and giant radio pulses. At the first hotspot in the desert about 80 kilometres from LengHu the Chinese authorities ensure radio quietness and provide the required infrastructure to move the data to datacentres in Beijing and Europe. Besides astrophysics research with ultra-high-energy particles, the particle physics of neutrino properties and searches for dark matter and other physics beyond the Standard Model at extreme energies will be pursued.
GRANDGiant Radio Array for Neutrino Detection
GRAND will be a distributed observatory detecting the highest energy particles (neutrinos, cosmic rays and photons) from the Universe. Using radio-antennas, GRAND will measure radiation created by air showers initiated from the interactions of cosmic rays and photons in the atmosphere. Cosmic neutrinos will first interact in nearby rock, and the decay of the produced tau-particle creates the detectable air shower. GRAND will be the prime facility to pursue multi-messenger studies of astronomical objects, as well as studying particle interactions at the highest energies available. Its envisioned size of 200,000 square kilometers (or 5 times the Netherlands) is required to open the field of neutrino astronomy. In order to achieve this goal GRAND will be distributed over several locations in the world. The location of its first hotspot, with an area of 10,000 square kilometers, is located near the town of LengHu in the QingHai province in western China.