# Cross sections of [image]Sm([image]Li,x) reactions for the production of [image]Tb for targeted alpha therapy

## TL;DR

Researchers studied how to produce Terbium-149g, a promising isotope for cancer treatment, using lithium beams on samarium targets, but found that an excited state of Terbium is produced more readily.

## Contribution

The paper measures cross sections for the production of Terbium-149m and Terbium-149g, revealing a preference for the excited state in Li-induced reactions.

## Key findings

- The excited state of Terbium-149m is preferentially produced over the ground state Terbium-149g in Li-induced reactions.
- Cross sections for the production of Terbium isotopes were measured and reported.
- The study highlights the need to explore alternative production methods for Terbium-149g.

## Abstract

Terbium-149g (\documentclass[12pt]{minimal}
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\begin{document}$$t_{1/2}$$\end{document} = 4.12 h) is of particular interest for targeted alpha therapy cancer treatment due to its ability to decay via both alpha and positron emission, making it a potential theranostic nuclide. Due to many challenges facing its production, there are limited facilities worldwide that have demonstrated the ability to produce this nuclide in quantities sufficient for medical research. Since the Cyclotron Institute at Texas A&M University is a specialized accelerator facility capable of accelerating a wide variety of ions, we are investigating production pathway options. One of the major challenges facing its production is the known co-production of the excited isomeric state, \documentclass[12pt]{minimal}
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\begin{document}$$^{149\textrm{m}}$$\end{document}Tb (\documentclass[12pt]{minimal}
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\begin{document}$$t_{1/2}$$\end{document} = 4.1 min). However, this state does not decay to the ground state of \documentclass[12pt]{minimal}
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\begin{document}$$^{149\textrm{g}}$$\end{document}Tb, negating any potential contribution to its yield. Due to its short-half life, the cross section for the population of this state has never been measured. After calculating several potential reaction yields using predictive models, the reactions of \documentclass[12pt]{minimal}
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\begin{document}$$^{147-149}$$\end{document}Sm(\documentclass[12pt]{minimal}
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\begin{document}$$^{6}$$\end{document}Li,xn)\documentclass[12pt]{minimal}
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\begin{document}$$^{149}$$\end{document}Tb were identified as candidates. Lithium-6 beams of varied energies between 45-65 MeV were impinged on enriched \documentclass[12pt]{minimal}
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\begin{document}$$^{147}$$\end{document}Sm, \documentclass[12pt]{minimal}
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\begin{document}$$^{148}$$\end{document}Sm, and \documentclass[12pt]{minimal}
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\begin{document}$$^{149}$$\end{document}Sm targets at the Cyclotron Institute at Texas A&M University, and the reaction products were measured immediately following irradiation using high-purity germanium detectors, enabling detection of both \documentclass[12pt]{minimal}
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\begin{document}$$^{149\textrm{m}}$$\end{document}Tb and \documentclass[12pt]{minimal}
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\begin{document}$$^{149\textrm{g}}$$\end{document}Tb. Cross sections for all nuclides produced in sufficient activity in these reactions were also measured and reported here. We conclude that the population of \documentclass[12pt]{minimal}
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\begin{document}$$^{149\textrm{m}}$$\end{document}Tb is much preferred over population of the ground state for these \documentclass[12pt]{minimal}
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\begin{document}$$^{6}$$\end{document}Li-induced reactions, and it is necessary to explore other options for \documentclass[12pt]{minimal}
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\begin{document}$$^{149\textrm{g}}$$\end{document}Tb production.