Prof Peter Norreys FInstP;

Abstract:

The use of ultrahigh intensity laser pulses (I>5×1019 W cm-2) to irradiate thin wire targets was analyzed. The current was produced by the escape of fast electrons from the target, which resulted in the well-localised optical emission from the additional wire . The MHD instabilities in the pinching plasmas along with field emission of electrons from nearby objects were also observed. The X-ray power levels can be enchanced from laser driven Z pinches using wire array and X-pinch configurations, the coherent optical transition radiation from adjacent objects was also observed.

Abstract:

A range of laser-driven proton-induced reactions in copper from a petawatt laser-solid interaction were investigated. The experiment was carried out on petawatt arm of VULCAN Nd:Glass laser at the Rutherford Appleton Laboratory, U.K. where Cu foils were exposed to the proton beams from the laser-irradiated target which induced nuclear reactions. This technique used a very thin layer of copper which was inserted into the proton beam which had a smaller impact on the proton beam and was optimized according to the energies and intensities of the protons. The results show that the energy spectrum of the accelerated protons was in the range of 10-40 MeV.

Abstract:

Intense laser-plasma interactions produce high brightness beams of gamma rays, neutrons and ions and have the potential to deliver accelerating gradients more than 1000 times higher than conventional accelerator technology, and on a tabletop scale. This paper demonstrates one of the exciting applications of this technology, namely for transmutation studies of long-lived radioactive waste. We report the laser-driven photo-transmutation of long-lived 129I with a half-life of 15.7 million years to 128I with a half-life of 25 min. In addition, an integrated cross-section of 97±40 mbarns for the reaction 129I(γ,n)128I is determined from the measured ratio of the (γ,n) induced 128I and 126I activities. The potential for affordable, easy to shield, tabletop laser technology for nuclear transmutation studies is highlighted.

Abstract:

Heavy-ion induced nuclear reactions in materials exposed to energetic ions produced from high-intensity ([Formula presented]) laser-solid interactions have been experimentally investigated for the first time. Many of the radionuclides produced result from the creation of “compound nuclei” with the subsequent evaporation of proton, neutron, and alpha particles. Results are compared with previous measurements with monochromatic ion beams from a conventional accelerator. Measured nuclide yields are used to diagnose the acceleration of ions from laser-ablated plasma to energies greater than 100 MeV. © 2003 The American Physical Society.