Laser-accelerated protons for the study of fission in exotic nuclei

Our understanding of nuclear fission is largely based on studies of Californium- 252 and the long-lived isotopes of uranium, plutonium, and thorium. A lack of data on the fission of exotic nuclei precludes the development of a nuclear "standard model". Recent progress in the production of laser accelerated high flux proton beams opens up new possibilities for the study of fission on short-lived isomers. To this end, we are currently pursuing two fronts: the swift gas transport, collection, and identification of fission products, and the creation of high energy density plasmas capable of accessing low-lying excited nuclear states. The former has been recently demonstrated using target normal sheath accelerated protons at the PHELIX laser facility, and feasibility tests of the latter at the OMEGA laser facility are planned. The identification of fission products is achieved using gamma spectroscopy, which has been demonstrated for short-lived fission products with lifetimes down to 40 seconds. Discrepancies between measured and established fission yields were observed, likely due to the measurement apparatus. Aspects of the detector system including fragment stopping, gas flow in the fission chamber, and efficiency of the fragment collection are studied at the Idaho Accelerator Center using their 21 MeV linear electron accelerator. Work performed under the auspices of the U. S. Department of Energy by LLNL under contract DE-AC52-07NA27344.