Laser-accelerated ions from layered targets

We investigated laser-driven ion acceleration with tightly focused femtosecond laser pulses at an intensity of 5×1019 W/cm2. Targets consisting of thin metal foils either back-coated with a μm-thick dielectric layer or uncoated have been used. The observations we report show that proton bunches with energy in the MeV range have been produced. Furthermore, the protons emitted from back-coated targets exhibit a spatial cross-section which is...