The Tunka Radio Extension (Tunka-Rex): Radio Measurements of Cosmic Rays in Siberia (PISA 2015)

TL;DR

Tunka-Rex is a radio detection array in Siberia that complements existing cosmic ray observatories by enabling cross-calibration and extended measurements of air showers, improving energy and mass reconstruction of cosmic rays.

Contribution

This paper demonstrates the operational feasibility and scientific potential of radio detection for cosmic rays, expanding the capabilities of existing air-shower arrays.

Findings

Tunka-Rex measures radio emissions from air showers with 44 antennas over 3 km².

Radio measurements can be cross-calibrated with Cherenkov data for improved accuracy.

Radio detection extends observation time beyond dark, clear nights, increasing exposure.

Abstract

The Tunka observatory is located close to Lake Baikal in Siberia, Russia. Its main detector, Tunka-133, is an array of photomultipliers measuring Cherenkov light of air showers initiated by cosmic rays in the energy range of approximately $10^{16}-10^{18}\,$eV. In the last years, several extensions have been built at the Tunka site, e.g., a scintillator array named Tunka-Grande, a sophisticated air-Cherenkov-detector prototype named HiSCORE, and the radio extension Tunka-Rex. Tunka-Rex started operation in October 2012 and currently features 44 antennas distributed over an area of about $3\,$km$^2$, which measure the radio emission of the same air showers detected by Tunka-133 and Tunka-Grande. Tunka-Rex is a technological demonstrator that the radio technique can provide an economic extension of existing air-shower arrays. The main scientific goal is the cross-calibration with the air-Cherenkov measurements. By this cross-calibration, the precision for the reconstruction of the energy and mass of the primary cosmic-ray particles can be determined. Finally, Tunka-Rex can be used for cosmic-ray physics at energies close to $1\,$EeV, where the standard Tunka-133 analysis is limited by statistics. In contrast to the air-Cherenkov measurements, radio measurements are not limited to dark, clear nights and can provide an order of magnitude larger exposure.