Based on a new approach to the detection of radio transients associated with extensive air showers induced by ultra-high-energy cosmic rays, the experimental apparatus CODALEMA is in operation, measuring about 1 event per day corresponding to an energy threshold ≈5 · 1016 eV.

Figure: electric field variations recorded on different antennas in EW polarisation on the EW axis of CODALEMA for an EAS event (squares, full line) and an anthropic transient (triangles, dashed line). Circles indicate threshold levels. Lines between data points are just a guide for the eye. Figure: electric field variations recorded on different antennas in EW polarisation on the EW axis of CODALEMA for an EAS event (squares, full line) and an anthropic transient (triangles, dashed line). Circles indicate threshold levels. Lines between data points are just a guide for the eye.
Its performance makes possible for the first time the study of radio-signal features on an event-by-event basis. The sampling of the magnitude of the electric field along a 600 m axis is analyzed. It shows that the electric field lateral spread is around 250 m (FWHM). The possibility to determine with radio both arrival directions and shower core positions is discussed.

Published by D. Ardouin, A. Bellétoile, D. Charrier, R. Dallier, L. Denis, P. Eschstruth, T. Gousset, F. Haddad, J. Lamblin, P. Lautridou, A. Lecacheux, D. Monnier-Ragaigne, O. Ravel, T. Saugrin, S. Valcares, in Astroparticle Physics 26, July 2006, P. 341–350 DOI: [10.1016/j.astropartphys.2006.07.002](https://arxiv.org/ct?url=https