Resonant Photonuclear Reactions for Isotope Transmutation

概要

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Resonant photonuclear isotope transmutation (RPIT) is shown to be very powerful to produce exclusively radioactive isotopes (RIs) by resonant photonuclear (\gamma,n) and (\gamma,2n) reactions via E1 giant resonances. Photons to be used are medium energy [E(\gamma) \approx 12{\mbox{--}}25 MeV] photons produced by laser photons backscattered off GeV electrons. The cross sections are as large as \sigma \approx 0.2{\mbox{--}}0.5 b (10^{-24} cm2) for all medium-heavy nuclei. A large fraction ({\sim}3%) of photons is effectively used for the photonuclear reactions, while the scattered GeV electrons remain in most storage rings to be re-used. To demonstrate the RPIT feasibility, 99Mo/99mTc and 196Au RIs were produced by RPIT on 100Mo and 197Au with laser photons scattered off 1 GeV electrons at the NewSUBARU storage ring. RPIT with medium energy photons around 10^{12{\mbox{--}}15}/s provides specific/desired RIs with the rate of 10^{10{\mbox{--}}13}/s and the RI density around 0.05--50 G Bq/mg for nuclear science, molecular biology and for nuclear medicines.
2011-09-15