The alpha emitters 225Ac and 213Bi are of great interest for a-radioimmunotherapy. Both radioisotopes are daughters of 7880-y 229Th, currently obtained via decay of 233U. Alternatively, 229Th can be produced from 226Ra in a nuclear reactor, or by proton irradiation of 230,232Th either directly or through production of isobars that decay into 229Th. To obtain the excitation functions for the relevant nuclear reactions, stacked foils of 232Th were irradiated with 40 MeV protons from the ORNL 25 MV tandem electrostatic accelerator. The excitation functions of 232Th[p,xn](233-x)Pa (x=1-5) reactions were determined by ?-ray spectroscopy, in some cases after chemical separation of the Pa fractions. The experimental threshold for the 232Th[p,4n]229Pa reaction is ~ 22 MeV, and the excitation function peaks at 162.5 mb. Results from benchmark tests conducted with Cu and Ni foils and differential cross-sections for the production of 229Pa and other Pa isotopes from 230,232Th will be presented.

Production of thorium-229 with low energy protons

245th National Meeting (2013)

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