Cross section measurements of 151 Eu( 3 He,5n) reaction: new opportunities for medical alpha emitter 149 Tb production.

Method for production of alpha emitter ¹⁴⁹ Tb by irradiation of ¹⁵¹ Eu with 70 MeV ³ He nuclei is proposed. For the first time, the cross sections for the formation of isotopes ^{149,150,151,152} Tb were measured experimentally using a stack foil technique in the ³ He particles energy range 70 → 12 MeV. The thick target yield of ¹⁴⁹ Tb is 39 MBq/μAh, or 230 MBq/μA ¹⁴⁹ Tb at saturation. The optimal energy range from the point of view of radioisotopic purity is 70 → 40 MeV. At these conditions about 150 MBq/μA ¹⁴⁹ Tb can be produced in 8 hours irradiation, which is sufficient for therapeutic applications. The main impurities are ¹⁵⁰ Tb (~100% in activity) and ¹⁵¹ Tb (~30% in activity). The proposed method surpasses its counterparts by the high content of the target isotope in the natural mixture and the simplicity of the radiochemical separation of ¹⁴⁹ Tb from the bulk target material.