Measurements and Calculations of Radionuclides Created by ¹⁸¹Ta(γ,xn yp) Reactions for Bremsstrahlung Photons Produced by 150-MeV Electrons

Twenty-three radionuclides, including isomers, from ^168mLu to ¹⁸⁰Ta, having half-lives between 7 min and 1.4 yr, produced by photon interactions with a sample of elemental tantalum, were observed in decay gamma-ray data obtained using high-resolution detection systems. Yields of production range over six orders of magnitude. The measured yield data for masses ≥171 were compared with calculated values. Good agreement was obtained for masses ≥174, but for lighter masses, the calculations tend to overestimate the experimental yields by up to a factor of 5. An empirical “rule-of-two” is proposed, governing reduction in measured mass yield for each additional emitted nucleon following (γ,3n) reactions. These results should have practical use not only for present electron accelerator operation but also for shielding calculations needed for future accelerator designs and applications.