Simulation of imaging ability of 11 MeV proton radiography with energy-loss imaging lens

Energy loss and scattering angle of penetrating protons are main sources of image blur for proton radiography (PRAD). PRAD relying on Zumbro lens can basically eliminate the image blur caused by scattering angle and achieve spatial resolution of several tens microns. However, the chromatic blur resulted from energy loss cannot be optimized, and it is the major cause for limiting spatial resolution. To eliminate the influence of energy loss and make a further improvement of spatial resolution, a new type of magnetic lens is proposed, called energy-loss focused imaging lens. A 11 MeV low-energy energy-loss imaging beamline is designed and a numerical model is built for energy-loss PRAD by using GEANT4 to study its image ability in simulation. The simulation results show that the 11 MeV low-energy energy-loss PRAD can achieve about 30 μm spatial resolution for 10 μm Al target. Compared with Zumbro lens of the same size, the spatial resolution is improved obviously. (authors)