Production of actinium, thorium and radium isotopes from natural thorium irradiated with protons up to 141 MeV

Cross sections O Ac-225, Ac-227, Th-227 and Th-228 in thorium-232 targets irradiated with protons in the energy range 21-141 MeV have been measured. Based on these data, production yields of Ac-225 and Ra-223 in thick thorium targets have been calculated. It is possible to produce in proton energy range 60-140 MeV at out 96 GBq (2.6 Ci) (225)AC per 10-d irradiation with 100 mu A proton beam current and 10-d decay, and much higher amount of Ra-223. The impurities of Ac-227 and Ra-224 are important and need to be assessed for further medical applications.