Correlations in energy in cosmic ray air showers radio-detected by CODALEMA

A study of the response in energy of the radio-detection method of air showers initiated by ultra-high-energy cosmic rays is presented. Data analysis of the CODALEMA experiment shows that a strong correlation can be demonstrated between the primary energy of the cosmic ray and the electric field amplitude estimated at the heart of the radio signal. Its sensitivity to the characteristics of shower suggests that energy resolution of less than 20% can be achieved. It suggests also that, not only the Lorentz force, but also another contribution proportional to all charged particles generated in the development of the shower, could play a significant role in the amplitude of the electric field peak measured by the antennas (as coherence or the charge excess).