Angular distribution and dose measurements of hard x-ray emission from intense laser-plasma interaction

An experimental study on hard x-ray Bremsstrahlung radiation due to fast electron generation from a planar solid copper target irradiated by 150 mJ, 45 fs Ti:sapphire laser pulses at I∼1018 W∕cm2 is reported. Angular distribution of the hard x-ray dose rate (hν≥40 keV) is observed to be strongly forward peaked in the direction of target normal with a measured peak value of 40 μSv∕h, at a distance of 500 mm from the target. Two sources of this radiation, one at the laser irradiated target and the other at the chamber wall facing the target, are inferred from the measurements of angular distribution and distance dependence of the x-ray dose rate.