Multiscale image analysis applied to γ/h discrimination for VHE gamma-ray astronomy with ARGO-YBJ

Intrinsic differences in the processes involved in the electromagnetic and hadronic shower development in the atmosphere have been evidenced by means of a careful analysis of the event image given by the ARGO-YBJ detector. The images have been analyzed at different length scales and their multifractal nature has been studied. The use of the multiscale approach together with a properly designed and trained Artificial Neural Network, allowed us to obtain a good discrimination power. If confirmed by further studies on different event categories, this result would allow to nearly double the detector sensitivity to gamma-ray sources.