Fig. 1

Experimental setup and proton source characteristics. a Experimental setup in optimal irradiation conditions; b Sketch of the source characterization with description of the virtual point source and the cone half angle θ. These parameters have been used in the Monte Carlo simulations; The virtual point source is not a physical source point, but its distance is calculated by the projection of the proton trajectories stemming out from the back surface of the target; c Example of a typical experimental proton spectrum obtained on the TITAN facility with the TP0°; d Half angle divergence (θ) vs. proton beam energy; e Virtual source point distance against proton beam energy