I. Introduction
The ION acceleration from thin targets, irradiated by pulsed lasers, represents a new research field investigated in the last years. The major interest concerns the thin-film irradiation by femtosecond ultraintense lasers, i.e., at intensities on the order of , which permits accelerating ions at energies on the order of tens of megaelectronvolts per nucleon in forward direction along the normal to the target surface [1]. However, also, the proton acceleration from low laser intensities, on the order of , irradiating thin hydrogenated films, plays an important role because high proton yield can be extracted and because the use of ion postacceleration coupled to laser-generated ion emission can be employed to obtain applicable multienergetic ion beams [2], [3]. The literature does not report many applications at this low-laser-intensity regime because of the major difficulty to detect low-energy protons, to measure their energy distribution, and to analyze their energetic amount.