Proton beams of laser-hydrogenated metal targets

In this paper, we report a study on proton beams produced via laser interaction from hydrogenated solid targets useful for the development of new sources devoted to medical applications, such as hadron therapy and isotope production. The hydrogenation of the targets was made before the laser-matter interaction. In this study, we used as solid targets, pure samples of Ti, Ta and Al which in a first phase were treated by laser cleaning (via KrF excimer laser at the irradiance I = 3x10(7) W/cm(2)) and then they were exposed to laser irradiation (1500 pulses, I = 3 x10(7) W/cm(2)) under a constant flow of H-2 (HiQ Hydrogen 6.0, highly pure). After that, the targets were maintained under H-2 flow for 5 minutes, in order to promote a further hydrogen adsorption. We report laser ablation measurements performed at fluences of 1.3, 2.5 and 5.0 J/cm(2). The results on hydrogenated targets showed an increase of proton yield of 25% (Ti), 64% (Al) and 550% (Ta), with respect to the corresponding untreated ones.