The new setup of the CODALEMA experiment installed at the Radio Observatory in Nançay, France, is described. It includes broadband active dipole antennas and an extended and upgraded particle detector array.

Figure: sky map of observed radio events, smoothed by a 10° Gaussian. The zenith is at the center, the azimuth is: North (top, 0°), West (left, 90°), South (bottom, 180°) and East (right, 270°); the direction of the geomagnetic field at Nançay is indicated by the dot. A striking feature is the shape of the azimuthal distribution, and more specifically the large asymmetry in the observed counting rate between the North and South sectors. Figure: sky map of observed radio events, smoothed by a 10° Gaussian. The zenith is at the center, the azimuth is: North (top, 0°), West (left, 90°), South (bottom, 180°) and East (right, 270°); the direction of the geomagnetic field at Nançay is indicated by the dot. A striking feature is the shape of the azimuthal distribution, and more specifically the large asymmetry in the observed counting rate between the North and South sectors.
The latter gives access to the air shower energy, allowing us to compute the efficiency of the radio array as a function of energy. We also observe a large asymmetry in counting rates between showers coming from the North and the South in spite of the symmetry of the detector. The observed asymmetry can be interpreted as a signature of the geomagnetic origin of the air shower radio emission. A simple linear dependence of the electric field with respect to v ^ B is used which reproduces the angular depen- dencies of the number of radio events and their electric polarity.

Published by D. Ardouin, A. Bellétoile, C. Berat, D. Breton, D. Charrier, J. Chauvin, M. Chendeb, A. Cordier, S. Dagoret-Campagne, R. Dallier, L. Denis, C. Dumez-Viou, C. Fabrice, T. Garçon, X. Garrido, N. Gautherot, T. Gousset, F. Haddad, D.H. Koang, J. Lamblin, P. Lautridou, D. Lebrun, A. Lecacheux, F. Lefeuvre, L. Martin, E. Meyer, F. Meyer, N. Meyer-Vernet, D. Monnier-Ragaigne, F. Montanet, K. Payet G. Plantier, O. Ravel, B. Revenu, C. Riviere, T. Saugrin, A. Sourice, P. Stassi, A. Stutz, S. Valcares, in Astroparticle Physics 31, January 2009, P. 192–200 https://doi.org/10.1016/j.astropartphys.2009.01.001