III-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Production cross sections of 68 Ga and radioactive by-products indeuteron-induced reactions on natural zinc†
Ts. Zolbadral,∗1,∗2 M. Aikawa,∗1,∗3,∗2 D. Ichinkhorloo,∗3,∗2 Kh. Tegshjargal,∗4 N. Javkhlantugs,∗4 Y. Komori,∗2
and H. Haba∗2
Ga (T1/2 = 68 min), a positron emitter, is a valuable medical isotope used for positron emission tomography (PET).1) Charged-particle-induced reactions using cyclotrons are preferable routes for 68 Ga production.
One of the routes is the deuteron-induced reaction onzinc. Our literature survey revealed three experimental
studies on the cross sections of the nat Zn(d, x)68 Ga reaction were found,2–4) and there is a large discrepancy
among their experimental data. Therefore, we measured
the cross sections of 68 Ga via the deuteron-induced reaction on natural zinc. In addition, we measured the crosssections of co-produced radioisotopes to investigate possible radioactive impurities.
The experiment was performed at the AVF cyclotronof RIKEN RI Beam Factory. The stacked-foil activation
technique and γ-ray spectrometry were used to measure
the activation cross sections. The target was composedof metallic foils of nat Zn (17.64 mg/cm2 , 99.9% purity,Nilaco Corp., Japan) and nat Ti (9.13 mg/cm2 , 99.6%purity, Nilaco Corp., Japan) and irradiated for 22 min by
a 24-MeV deuteron beam. The incident beam energy wasmeasured using the time-of-ﬂight method. The energy
degradation in the stacked target was calculated using
the srim code.5) A beam intensity of 96 nA was measuredusing a Faraday cup.
The γ-ray spectra of the activated foils without chemical separation were measured using a high-resolution
high-purity germanium (HPGe) detector. The detector
was calibrated using a multiple γ-ray point source. The
dead time was kept less than 7% in the measurement.
Each foil was measured several times after cooling times
ranging from 40 min to 18 d for diﬀerent half-lives ofproducts.
The cross sections of the nat Ti(d, x)48 V monitor reaction were derived to assess the beam parameters. A
comparison of the measured cross sections with the recommended values6) showed that the beam intensity wasincreased by 6.6% relative to the measured value andcorrected to 102.4 nA.
The cross sections of the nat Zn(d, x)68 Ga reaction werederived from the measurement of the 1077.34-keV γ-line(Iγ = 3.22%) from the 68 Ga decay. The measured excitation function is shown in Fig. 1 in comparison with previous data2–4) and the theoretical estimation of TENDL2017.7)
Our result agrees with the data reported by Šimečková250

68†
∗1
∗2
∗3
∗4Condensed from the article in Appl. Radiat. Isot. 159, 109095(2020)
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
School of Engineering and Applied Sciences, National University of Mongolia

natZn(d,x)68Ga

This work
Simeckova+(2017)
Nassiff and Munzel (1972)
Gilly+(1963,68Zn(d,2n))
TENDL2017 (67Zn(d,n))
TENDL2017 (68Zn(d,2n))
TENDL2017 (natZn(d,x))

Cross section (mb)2001501005000510152025

Energy (MeV)

Fig. 1. Excitation function of the nat Zn(d, x)68 Ga reaction incomparison with previous data2–4) and the TENDL-2017data.7)

et al.3) and the normalized data for the (d, 2n) reaction
on 68 Zn reported by Gilly et al.4) However, the data reported by Nassiﬀ and Münzel2) are much lower than thepresent data in the entire energy range. The TENDL2017 data overestimate the experimental data aroundthe peak in the energy range of 8–18 MeV. The contribution of the 67 Zn(d, n)68 Ga reaction is small, and the68Zn(d, 2n)68 Ga reaction is dominant above the threshold energy of 6.1 MeV based on the TENDL-2017 prediction. The production cross sections of co-produced
radionuclides 65, 66, 67 Ga, 63, 65, 69m Zn, 61 Cu, and 58 Co
were also determined. Enriched 68 Zn is preferable forthe production of 68 Ga because radioactive isotopic impurities are not produced below 14.6 MeV, which is thethreshold energy of the 68 Zn(d, 3n)67 Ga reaction.
The physical yield of the nat Zn(d, x)68 Ga reaction
was deduced from the spline-ﬁtted curve of the measured excitation function. The derived yield reaches
2.37 GBq/µAh at 23.2 MeV.
This work is supported by JSPS KAKENHI GrantNumber 17K07004. Ts.Z. was granted a scholarship by
the M-JEED project (Mongolian-Japan Engineering Education Development Program, J11B16).
References

1) S. R. Banerjee, M. G. Pomper, Appl. Radiat. Isot. 76, 2(2013).
2) S. J. Nassiﬀ, H. Münzel, Radiochem. Radioanal. Lett. 12,353 (1972).
3) E. Šimečková et al., EPJ Web Conf. 146, 11034 (2017).
4) L. J. Gilly et al., Phys. Rev. 131, 1727 (1963).
5) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res. B
268, 1818 (2010).
6) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
7) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

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