Ultrafast laser generation of hard X-rays

Efficient generation of X-rays above 20 keV was demonstrated when the tight focus of a 60-mJ, 120-fs laser was incident on a solid. It is estimated that 0.3% of the laser energy is converted to X-rays between 20 and 1000 keV when the target is solid tantalum. At least 10/sup 6/ photons above 1 MeV are generated with each shot. The X-ray yield is proportional to the Z of the target, and scales as the 3/2 power of the incident laser energy.>