Abstract
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 similar to 10(18) W/cm(2) is reported. Angular distribution of the hard x-ray dose rate (h nu >= 40 keV) is observed to be strongly forward peaked in the direction of target normal with a measured peak value of 40 mu Sv/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.(C) 2007 American Institute of Physics.