Resonant Photonuclear Reactions for Isotope Transmutation

Resonant photonuclear isotope transmutation (RPIT) is shown to be very powerful to produce exclusively radioactive isotopes (RIs) by resonant photonuclear (γ,n) and (γ,2n) reactions via E1 giant resonances. Photons to be used are medium energy [ E (γ) ≈12–25 MeV] photons produced by laser photons backscattered off GeV electrons. The cross sections are as large as σ≈0.2–0.5 b (10 -24 cm 2 ) for all medium-heavy nuclei. A large fraction (∼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, 99 Mo/ 99 m Tc and 196 Au RIs were produced by RPIT on 100 Mo and 197 Au with laser photons scattered off 1 GeV electrons at the NewSUBARU storage ring. RPIT with medium energy photons around 10 12–15 /s provides specific/desired RIs with the rate of 10 10–13 /s and the RI density around 0.05–50 G Bq/mg for nuclear science, molecular biology and for nuclear medicines.