Grand, A Giant Radio Array For Neutrino Detection: Objectives, Design And Current Status

Abstract

The Giant Radio Array for Neutrino Detection (GRAND) aims to answer one of the most pressing open questions in astrophysics: what is the origin of ultra-highenergy cosmic rays (UHECRs)?. It will do so indirectly: UHECRs make secondary UHE neutrinos which encode information about the properties of UHECRs and their sources. GRAND is designed to discover UHE neutrinos even under pessimistic predictions of their flux, reaching a sensitivity of 6x10−9GeV.cm−2.s−1.sr−1 around 109GeV. It will do so by using 20 sub-arrays of 10 000 radio antennas forming a total detector area of 200 000 km2, making it the largest air-shower detector ever built. With this sensitivity, GRAND will discover cosmogenic neutrinos in 3 years of operation, even in disfavorable scenarios. Because of its subdegree angular resolution, GRAND will also search for point sources of UHE neutrinos, both steady and transient. Moreover, GRAND will be a valuable instrument for astronomy and cosmology, allowing for the discovery and followup of large numbers of radio transients - fast radio bursts, giant radio pulses - and studies of the epoch of reionization. In this contribution we will present briefly some of the science goals, detection strategy, construction plans and current status of the GRAND project.