Neutron emission as high as ${10}^7$ is observed when a high intensity (a few ${10}^{19}\mathrm{W}/{\mathrm{cm}}^2$) subpicosecond laser pulse at 529 nm wavelength is focused on a deuterated polyethylene target. Neutron emission is also measured in different directions. The emission of neutrons along the laser axis is higher than in the transverse direction. Nonisotropic emission is consistent with neutrons generated by $\mathrm{D}(d,n){-}^3\mathrm{He}$ reaction for 0.3–1 MeV deuterons accelerated in the direction of the laser beam. The energy transferred to the ions is roughly estimated and compared with the energy carried out by the electrons.

• Received 5 March 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.1454