Neutron energy spectra from the laser-induced D(d,n)He-3 reaction - art. no. 016414

Detailed neutron energy spectra were measured for the D(d,n)He-3 reaction i nduced in solid (CD2)(n) targets by irradiation with 50-fs 2 x 10(18) W/cm( 2) light pulses from a 10-TW Ti:Sapphire laser. The neutrons were observed at two angles 5 degrees and 112 degrees relative to the incident laser beam . The neutron spectra at the two angles are characterized by peaks with lar ge widths of about 700 keV full width at half maximum and a shift of 300 ke V between them. Neutron energies of up to about 4 MeV were observed indicat ing that deuterons are accelerated up to an energy of 1 MeV in the laser pr oduced plasma. Simulation calculations can describe qualitatively the neutr on spectra by assuming isotropic deuteron acceleration and a reduction of t he reaction probability by a factor of 1/3 for deuterons emitted from the f ront of the target. These calculations indicate in particular that it is ne cessary to assume deuterons moving both;into and out of the front of the ta rget In order to describe the neutron energy spectra at the mio angles. The highest recorded mean neutron yield was about 10(4) neutrons per pulse. Th e neutron yield increases with the number of electrons emitted from the fro nt of the target and with the intensity of the prompt gamma flash induced b y the bremsstrahlung of energetic electrons.