Cross-section measurement of ¹⁶⁵Ho(d,x) reactions and comparison of deuteron and proton activation of holmium for¹⁶⁵Er production.

Abstract

Erbium-165 is a pure Auger electron emitter with high potential for targeted radionuclide therapy of micrometastases. Following our previous study of the proton-induced pathway, this work investigates the production route via ¹⁶⁵Ho deuteron activation. Excitation functions for the ¹⁶⁵Ho(d,x)¹⁶⁵Er, 164m,gHo, and 166gHo reactions were measured using the stacked-foil activation technique in the 6-20 MeV energy range at the U-120M cyclotron. We report the first-ever experimental cross sections for the production of 164m,gHo via the deuteron route. The measured data show good agreement with earlier experiments, but reveal some discrepancies with the TENDL-2025 library. Thick target yield calculations based on the experimental data confirm that deuteron activation is superior for large-scale production, offering a fourfold higher yield compared to the proton-induced route (1092 GBq vs. 236 GBq for a 10 h irradiation at 50 μA). Co-produced ¹⁶⁶Ho may be chemically separated from the product. These findings demonstrate that ¹⁶⁵Ho(d,2n)¹⁶⁵Er reaction is optimal for routine production of ¹⁶⁵Er.