From the Observation of UHECR Radio Signal in [1-200] MHz to the Composition: CODALEMA and EXTASIS Status Report

Antony Escudie (1) , Didier Charrier (1) , Richard Dallier (1) , D. García-Fernández (1) , A. Lecacheux (2) , Lilian Martin (3) , Benoît Revenu (1)

1 SUBATECH - Laboratoire de physique subatomique et des technologies associées
2 Observatoire de Paris
3 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)

Over the years, significant efforts have been devoted to the understanding of the radio emission of extensive air shower (EAS) in the range [20-80] MHz but, despite some studies led until the nineties, the [1-10] MHz band has remained unused for nearly 30 years. The EXTASIS experiment, located within the radio astronomy observatory of Nançay and supported by the CO-DALEMA instrument, aims to reinvestigate the [1-10] MHz band, and to study the so-called "Sudden Death" contribution, the expected radiation electric field created by the particles that are stopped upon arrival to the ground. We present the instrumental setup and the results obtained with EXTASIS. Moreover, CODALEMA has demonstrated that in [20-80] MHz, the commonly used band, the electric field profile of extensive air showers is well understood, and contains all the information needed for the reconstruction of extensive air showers. An analysis pipeline was developed to set up an online reconstruction of the primary cosmic ray properties. Combining the antenna and acquisition system capabilities, CODALEMA extended the observation window up to 200 MHz, permitting to improve the quality of the reconstruction of the primary cosmic ray properties thanks to a fine calibration procedure. We present the results obtained on a large batch of cosmic ray events, notably a first estimate of their mass dependence with energy.

Mots clés: cosmic radiation: primary; showers; air; electric field; radio wave; mass dependence; activity report; observatory; calibration; quality; on-line

Domaines: Phénomènes cosmiques de haute energie [astro-ph.HE]; Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]; Physique des Hautes Energies - Expérience [hep-ex]

Antony Escudie, Didier Charrier, Richard Dallier, D. García-Fernández, A. Lecacheux, et al.. From the Observation of UHECR Radio Signal in [1-200] MHz to the Composition: CODALEMA and EXTASIS Status Report. ICRC2019 : 36th International Cosmic Ray Conference, Jul 2019, Madison, Wisconsin, United States. pp.246, ⟨10.22323/1.358.0246⟩. ⟨hal-02903395v2⟩