Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Production cross sections of 45 Ti via deuteron-induced reaction on 45 Sc
Ts. Zolbadral,∗1,∗2 M. Aikawa,∗1,∗3,∗2 D. Ichinkhorloo,∗3,∗2 Kh. Tegshjargal,∗4 Y. Komori,∗2 H. Haba,∗2S. Takács,∗5 F. Ditrói,∗5 and Z. Szücs∗5
The radionuclide 45 Ti (T1/2 = 184.8 min) is a positronemitter (Eβ + = 439 keV, Iβ + = 84.8%) suitable forpositron emission tomography (PET). This radioisotope
can be produced in the deuteron-induced reaction on ascandium-45 target at cyclotrons. However, the quality of experimental data on the cross sections of the45Sc(d, 2n)45 Ti reaction is not satisfactory. The main
purpose of this study is, therefore, to measure the crosssections of the 45 Sc(d, 2n)45 Ti reaction for 45 Ti production. In addition, the physical yield is derived from themeasured cross sections.
The stacked-foil activation technique and γ-ray spectrometry were adopted to determine the cross sections.
The stacked target consisted of metallic foils of 45 Sc(thicknesses of 7.71 mg/cm2 and 76.0 mg/cm2 with apurity of 99.0%), 27 Al (4.99 mg/cm2 , 99.6%), and nat Ti(9.13 mg/cm2 , 99.6%). The target was irradiated for
30 min with a 24-MeV deuteron beam from the RIKEN
AVF cyclotron. The incident beam energy was measured
by the time-of-flight method. The energy degradation in
the stacked target was calculated using the SRIM code.1)
The beam intensity was measured using a Faraday cup
and cross-checked with the nat Ti(d, x)48 V monitor reaction.2) According to the cross checking, the intensity(175.2 nA) was corrected by a decrease of 3% from themeasured value (180.3 nA). The γ-ray spectra of the irradiated foils were measured by a high-resolution andhigh-purity germanium (HPGe) detector. The detector
was calibrated by a standard mixed γ-ray point source.
The dead time was kept below 7% in the measurements.

Fig. 1. Excitation function of the 45 Sc(d, 2n)68 Ti reaction.
∗1
∗2
∗3
∗4
∗5Graduate 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
Institute for Nuclear Research (ATOMKI), HungaryFig. 2. Physical yield of 45 Ti.

The cross sections of the 45 Sc(d, 2n)45 Ti reaction
were derived from the measurement of the 719.6-keV
γ-line (Iγ = 0.154%) associated with the 45 Ti decay.
The excitation function of the 45 Sc(d, 2n)45 Ti reaction
is shown in Fig. 1 in comparison with previous experimental data3) and the theoretical estimation fromTENDL-2017.4) The derived excitation function of the45Sc(d, 2n)45 Ti reaction is consistent with the data reported by Hermanne et al.3) The peak position of theTENDL-2017 data is slightly shifted to a lower energy.
The physical yield of 45 Ti was deduced from a spline
fitted curve of the measured excitation function andstopping power calculated from the SRIM code.1) The
derived yield is shown in Fig. 2. The present yield curveof 45 Ti is slightly higher than the experimental datameasured by Dmitriev et al.5) at 22 MeV. We confirmedthat no radioactive impurities of titanium are producedin the energy range below 15 MeV, which is the threshold energy of 44 Ti production. Above 15 MeV and up
to 24 MeV, the physical yield of 44 Ti is seven or moreorders of magnitude less than that of 45 Ti and negligibly
small. Thus, this reaction with chemical separation allows the production of high-specific-activity 45 Ti in thisenergy range.
This work is supported by JSPS KAKENHI Grant
Number 17 K07004. Ts.Z was granted a scholarship by
the M-JEED project (Mongolian-Japan Engineering Education Development Program, J11B16).
References

1) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res. B
268, 1818 (2010).
2) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
3) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 270, 106 (2012).
4) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
5) P. P. Dmitriev et al., INDC (CCP)-210, 1 (1983).

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