Photonuclear physics when a multiterawatt laser pulse interacts with solidtargets

When a laser pulse of intensity 10(19) W cm(-2) interacts with solid target s, electrons of energies of some tens of MeV are produced. In a tantalum ta rget, the electrons generate an intense highly directional gamma-ray beam t hat can be used to carry out photonuclear reactions. The isotopes C-11, K-3 8, (CU)-C-62.64, Zn-63, Ag-106, Pr-140, and Ta-180 have been produced by (g amma, n) reactions using the VULCAN laser beam. In addition, laser-induced nuclear fission in U-238 been demonstrated, a process which was theoretical ly predicted at such laser intensities more than ten years ago. The ratio o f the C-11 and the (CU)-C-62 beta(+) activities yields shot-by-shot tempera tures of the suprathermal electrons at laser intensities of similar to 10(1 9) W cm(-2).