Gamma-neutron activation experiments using laser wakefield accelerators

Gamma-neutron activation experiments have been performed with relativistic electron beams produced by a laser wakefield accelerator. The electron beams were produced by tightly focusing (spot diameter approximate to6 mum) a high power (up to 10 TW), ultra-short (greater than or equal to 50 fs) laser beam from a high repetition rate (10 Hz) Ti:sapphire (0.8 mum) laser system, onto a high density (> 10(19) cm(-3)) pulsed gasjet of length approximate to1.5 mm. Nuclear activation measurements in lead and copper targets indicate the production of electrons with energy in excess of 25 MeV. This result was confirmed by electron distribution measurements using a bending magnet spectrometer. Measured gamma -ray and neutron yields are also found to be in reasonable agreement with simulations using a Monte Carlo transport code. (C) 2001 American Institute of Physics.