Photonuclear Physics when a Multiterawatt Laser Pulse Interacts with Solid Targets

When a laser pulse of intensity 10(19) W cm(-2) interacts with solid targets, electrons of energies of some tens of MeV are produced. In a tantalum target, the electrons generate an intense highly directional gamma-ray beam that can be used to carry out photonuclear reactions. The isotopes C-11, K-38, (CU)-C-62.64, Zn-63, Ag-106, Pr-140, and Ta-180 have been produced by (gamma, n) reactions using the VULCAN laser beam. In addition, laser-induced nuclear fission in U-238 been demonstrated, a process which was theoretically predicted at such laser intensities more than ten years ago. The ratio of the C-11 and the (CU)-C-62 beta(+) activities yields shot-by- shot temperatures of the suprathermal electrons at laser intensities of similar to 10(19) W cm(-2).