Progress of the GRANDProto300 Project

TL;DR

GRANDProto300 is a prototype array of 300 antennas in China, advancing autonomous detection of ultra-high-energy cosmic rays and providing valuable data on solar and galactic radio emissions, with ongoing hardware and calibration improvements.

Contribution

This paper reports the progress and current status of the GRANDProto300 prototype, including hardware upgrades, calibration, and initial scientific observations, serving as a testbed for the GRAND experiment.

Findings

65 antenna units deployed by June 2025

Detection of solar radio bursts and galactic emissions

Preliminary cosmic ray survey results

Abstract

GRANDProto300 (hereafter referred to as GP300) is a pioneering prototype array of the GRAND experiment. It consists of 300 radio antennas and will cover an area of 200 km$^2$ in a radio-quiet region of western China. Serving as a test bench for the GRAND experiment, GRANDProto300 aims to achieve autonomous radio detection and reconstruction of highly inclined air showers. It is designed to detect ultra-high-energy cosmic rays in the energy range of $10^{16.5}$-$10^{18}$ eV at a rate comparable to that of the Pierre Auger Observatory. Over the past two years, significant improvements have been made to both the hardware and firmware of GP300. Currently, 65 antenna units have been deployed at the site by June 2025. We present the current status of detector commissioning, including updates on hardware, calibration results such as GPS timing and antenna positioning. Additionally, we discuss the solar radio bursts associated with solar flares, the galactic radio emissions detected, and preliminary cosmic ray surveys.