Measurement of the ^natDy(p,x) nuclear reactions cross-sections

Abstract

Excitation functions of the reactions ^natDy(p,x)^159m+gHo, ^161m+gHo, ^162mHo, ^162gHo, ^155m+gDy, ^157m+gDy, ^159m+gDy, ¹⁵⁵Tb^cum, ¹⁵⁵Tb, ¹⁵⁶Tb^cum, ¹⁶⁰Tb, ¹⁶¹Tb, ^159m+gGd were measured in the energy range of 7.4–35.9 MeV using the stacked foil technique and off-line γ-ray spectrometry. The obtained cross-sections were compared with previously published experimental data and prediction of the TALYS nuclear reaction model code adopted from the TENDL-2019 library. Thick target yields were calculated from the experimental data.

Introduction

Radionuclide ¹⁶¹Tb (T_½ = 6.89 d) is a promising alternative to the established therapeutic ¹⁷⁷Lu. It emits low energy β⁻ particles with mean energy of 154 keV and maximum energy of 593 keV. Moreover, it provides more conversion and Auger electrons that may enhance its therapeutic efficacy compared to ¹⁷⁷Lu [1], [2].

Terbium-161 is usually produced in nuclear reactors via neutron capture on highly enriched ¹⁶⁰Gd targets, followed by a β⁻ decay of the short-lived ¹⁶¹Gd (T_½ = 3.66 min) [2]. While the production in nuclear reactors is already well established, its potential production by charged-particle accelerators still deserves our attention. In principle, there are two possible reactions resulting in formation of ¹⁶¹Tb – ¹⁶⁰Gd(d,n) and ¹⁶⁴Dy(p,α). Excitation function of the latter has been measured only once on natural dysprosium target by Tárkányi et al. and results were published in 2013 [3]. It motivated us to re-measure in detail cross-sections of proton-induced reactions on ^natDy for all the radionuclides that we could quantify in the activated targets. Cross-sections for the formation of ^162gHo and ^159m+gGd are published for the first time.