Measurements of the absolute gamma-ray emission intensities from the decay of 166Ho

¹⁶⁶Ho (T_1/2≈ 26.8 h) is an emerging theragnostic radionuclide of interest in nuclear medicine due to its peculiar decay scheme, featuring high-energy β^- emission (≈ 1.8 MeV) coupled with the main gamma-ray emission (≈ 80.6 keV). Using the new ¹⁶⁶Ho activity standard and the well-calibrated, high-energy resolution HPGe detector, both available at ENEA-INMRI, a new determination of several ¹⁶⁶Ho gamma-ray emission intensities, I_γ, was performed with low uncertainty. The new I_γ values contributed to the Decay Data Evaluation Project.