Angular reconstruction of high energy air showers using the radio signal spectrum

Abstract

The Hellenic Open University extensive air shower array (also known as Astroneu array) is a small scale hybrid detection system operating in an area with high levels of electromagnetic noise from anthropogenic activity. In the present study we report the latest results of the data analysis concerning the estimation of the shower direction using the spectrum of the RF system. In a recent layout of the array, 4 RF antennas were operating receiving a common trigger from an autonomous detection station of 3 particle detectors. The directions estimated with the RF system are in very good agreement with the corresponding estimations using the particle detectors demonstrating that a single antenna has the potential for reconstructing the shower axis angular direction.

A low cost hybrid detection system of high energy air showers

“…particle detectors efficiency) of the 3SDM-nRF with respect to the Astroneu array, assuming that the RF part of the 3SDM-nRF is as efficient as that of Astroneu (i.e. both systems operate at the frequency regime of 30-80 MHz, at the same site and with the same analysis techniques [6][7][8][9] are applied).…”

“…described in [8,9]. The procedure involves a minimization procedure where the shape of the spectrum of the Fourier transformed RF pulse is compared with the simulation prediction.…”

“…The response of the antenna and the signal generation is obtained by convoluting the incident electric field that arrives from a given direction (θ, f) with the antenna's vector effective length (VEL) which on turn is evaluated with the 4NEC2 software. After the convolution, the RF signal is distorted with noise and then the analysis follows the standard reconstruction algorithms which are applied either to simulated events or experimental data; the RF signals (of both polarizations) are filtered in order to keep frequencies in the range 30-80MHz and then selection criteria are applied concerning the pulse rising time (less than 30 ns) and degree of polarization (greater than 0.85) as described in [6][7][8][9].…”