Exploring the Frontiers of Cosmic Ray Physics: Perspectives on GRANDProto300 and the GRAND Project

TL;DR

The paper discusses the GRAND project and its pathfinder array GRANDProto300, highlighting its potential to advance ultra-high-energy cosmic ray and neutrino detection through large-scale radio arrays with high precision and sensitivity.

Contribution

It introduces the GRANDProto300 array and outlines its expected performance, demonstrating its capability to improve measurements of cosmic rays and neutrinos at ultra-high energies.

Findings

GRANDProto300 aims for 15% energy resolution and 20 g/cm² Xmax precision.

Projected sensitivity for anisotropy detection reaches 5×10⁻³ below 10¹⁷.¹ eV.

GRAND's large area enhances detection capabilities at energies up to 10²⁰ eV.

Abstract

The Giant Radio Array for Neutrino Detection (GRAND) is an envisioned large-scale radio array designed to detect ultra-high-energy cosmic rays (UHECRs, $E > 100$ PeV) and neutrinos. Employing cost-effective antennas distributed across vast areas, GRAND is optimized to observe the rare flux of ultra-high-energy particles with high precision. The GRANDProto300 (GP300) pathfinder array, currently under deployment, targets the $10^{16.5} - 10^{18}$ eV range and is anticipated to achieve approximately 15\% energy resolution and 20g/cm$^2$ $X_{\mathrm{max}}$ precision. This level of precision enables accurate measurements of the fine structure of the energy spectrum, mean logarithmic mass ($\langle \ln A \rangle$), and proton flux within this range. After five years of data collection, the sensitivity for detecting anisotropy could reach $5 \times 10^{-3}$ for energies below $10^{17.1}$ eV. With its substantially larger effective area, GRAND extends these capabilities to the highest energies ($\sim 10^{20}$ eV), offering enhanced statistics and sensitivity for spectral, composition, and anisotropy measurements within one year for UHECRs.