Deuteron-induced reactions on natural Zr from threshold to 50 MeV: production of $^{86}$Y

TL;DR

This study provides a comprehensive measurement of nat Zr(d,x) excitation functions up to $50$ MeV, focusing on the production of $^{86\text{g}}$Y for PET theranostics. Using two stacked targets irradiated at $30$ and $50$ MeV, the authors determine 35 excitation functions via HPGe γ-ray spectroscopy and apply a variance-minimized beam-current analysis to reduce systematic uncertainties. Comparisons with nuclear-model codes (TALYS-2.0, ALICE-2020, CoH-3.5.3, EMPIRE-3.2.3) and the TENDL-2023 library reveal that model predictions generally capture excitation-function shapes but differ in magnitude, with CoH offering the best overall agreement for several channels. The physical yield analysis indicates that nat Zr(d,x) is not competitive with established production routes for $^{86\text{g}}$Y, primarily due to impurities and lower yields, but the data provide valuable benchmarks and motivate future work with enriched Zr targets.

Abstract

Two stacks of thin Zr foils were irradiated with 30 and 50 MeV deuterons, respectively, using the Lawrence Berkeley National Laboratory $88$-Inch Cyclotron, to investigate this production pathway for the promising PET tracer $^{86}$Y. Nineteen excitation functions for $^{\text{nat}}$Zr($d$,$x$) reactions were measured over a beam energy range of $6.3$--$47.64$ MeV, where the independent cross sections for $^{\text{nat}}$Zr($d$,$x$)$^{88}$Nb and $^\text{nat}$Zr($d$,$x$)$^{86\text{m, g}}$Y were measured for the first time. The well-characterized $^{\text{nat}}$Fe($d$,$x$)$^{56}$Co, $^{\text{nat}}$Ni($d$,$x$)$^{56}$Co, $^{\text{nat}}$Ni($d$,$x$)$^{58}$Co, $^{\text{nat}}$Ni($d$,$x$)$^{61}$Cu, $^{\text{nat}}$Ti($d$,$x$)$^{46}$Sc and $^{\text{nat}}$Ti($d$,$x$)$^{48}$V monitor reactions were used to determine the deuteron beam current throughout the stacks. All cross sections were determined using High Purity Germanium (HPGe) detector $γ$-ray spectroscopy. A variance minimization technique was employed to simultaneously constrain the deuteron beam currents with multiple monitor reactions, thus reducing systematic uncertainties. An additional $16$ channels are reported for reactions on the nickel, titanium, and iron monitor foils, leading to a total of $35$ excitation functions, with $7$ reaction channels reported for the first time in this work. The measured excitation functions are compared to calculations provided by the reaction modeling codes $\textsc{TALYS}-2.0$, $\textsc{ALICE}-2020$, $\textsc{CoH}-3.5.3$ and $\textsc{EMPIRE}-3.2.3$, as well as the $\textsc{TENDL}-2023$ data library. The degree of agreement between theory and experiments is discussed. The physical yields for $^{\text{nat}}$Zr($d$,$x$)$^{86}$Y and other yttrium isotopes produced are calculated and compared to other production pathways.

Figures (43)

• Figure 1: The excitation function for the independent production of $^\text{nat}$Zr($d$,$x$)$^{86\text{m}}$Y.
• Figure 2: The excitation function for the independent production of $^\text{nat}$Zr($d$,$x$)$^{86\text{g}}$Y. No feeding from $^{86}$Zr to $^{86}$Y was observed in the energy region covered in this work.
• Figure 3: The excitation function of the cumulative production of $^\text{nat}$Zr($d$,$x$)$^{87\text{m}}$Y.
• Figure 4: The excitation function of the independent production of $^\text{nat}$Zr($d$,$x$)$^{87}$Y.
• Figure 5: The excitation function of the cumulative production of $^\text{nat}$Zr($d$,$x$)$^{87}$Y.