Experimental validation of the 150Gd proton-reaction cross sections

Determine experimentally the cross sections for the 150Gd(p,2n)149gTb reaction and the other proton-induced reaction channels on 150Gd, including the competing channels that determine terbium yield and radionuclidic purity.

Background

The proposed second-stage production route depends on TALYS/TENDL-2025 predictions because no direct measurements of reactions on 150Gd are available. In particular, the predicted 150Gd(p,2n)149gTb cross section determines the projected production rate, while competing 150Gd(p,n), 150Gd(p,3n), and related channels determine contamination by other terbium isotopes.

The paper treats experimental measurement as necessary to validate the predicted clinical-scale production pathway and to establish whether the predicted suppression of the competing 150Gd(p,n)150Tb channel is reliable.

References

No experimental measurements of {150}Gd(p,2n){149\mathrm{g}Tb exist. We therefore rely on TENDL evaluations, referenced to data on the closest measured analog channels.

— Scalable Terbium-149 Production from Highly Enriched Gadolinium-150 Targets  (2609.25554 - Parisi et al., 22 Sep 2026) in Section 3, Section 4, and Appendix subsection “Comparison with measured neighboring reactions”

The true therapeutic dose is not yet established: estimates in the literature range from \sim\qty{10}{MBq} to \sim\qty{1}{GBq}, with considering \qtyrange{0.7}{3.85}{GBq} for a \qty{70}{\kg} patient, more than an order of magnitude above our \qty{50}{MBq} estimate.

— Scalable Terbium-149 Production from Highly Enriched Gadolinium-150 Targets  (2609.25554 - Parisi et al., 22 Sep 2026) in Appendix, Section “Required therapeutic activity per cycle” and Section “Dose Size Sensitivity”