US Patent 7852975 Production of thorium-229 using helium nuclei

A method for producing 229Th includes the steps of providing 226Ra as a target material, and bombarding the target material with alpha particles, helium-3, or neutrons to form 229Th. When neutrons are used, the neutrons preferably include an epithermal neutron flux of at least 1×1013 n s−1·cm−2. 228Ra can also be bombarded with thermal and/or energetic neutrons to result in a neutron capture reaction to form 229Th. Using 230Th as a target material, 229Th can be formed using neutron, gamma ray, proton or deuteron bombardment.