Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production cross sections of 47 Sc via α-particle induced reactions onnatCa†M. Aikawa,∗1,∗2 Y. Hanada,∗3,∗2 D. Ichinkhorloo,∗4,∗2 H. Haba,∗2 S. Takács,∗5,∗2 F. Ditrói,∗5,∗2 and Z. Szücs∗5,∗2†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 515, 1 (2022)
Faculty of Science, Hokkaido University
RIKEN Nishina CenterGraduate School of Biomedical Science and Engineering,Hokkaido University
Nuclear Research Center, National University of Mongolia
Institute for Nuclear Research (ATOMKI)- 167 -out chemical separation. The spectra of the nat Ca targets were measured with cooling times ranging from
3.2 h to 77 d.
The derived cross sections of the nat Ti(α, x)51 Cr
monitor reaction were compared with the IAEA recommended values4) to assess beam parameters and target thicknesses. The beam intensity and thicknessesof both AlH and AlL foils were corrected within theiruncertainties by +5.6% and −1%, respectively. The
measured thicknesses of the nat Ti monitor foil and theCaF2 layer were adopted without any correction.
47
Sc could be produced directly in the 44 Ca(α, p)47 Sc
reaction and indirectly by decay of the co-produced47
Ca (T1/2 = 4.536 d) and 47 K (T1/2 = 17.50 s).
The indirect contribution was at a negligible level because 47 Ca and 47 K can be formed only on the lowerabundant 46 Ca and 48 Ca isotopes. The activity of 47 Sc
was determined by measuring the γ line at 159.381 keV(Iγ = 68.3%) from the decay of 47 Sc. The derived crosssections of the nat Ca(α, x)47 Sc reaction are shown inFig. 1 compared with the literature data2) and the theoretical values provided in the TENDL-2019 library.5)
The literature data on 44 Ca targets were normalized tothose on nat Ca targets. The newly obtained data correspond to a smooth excitation function, in contrast
to the literature data. The TENDL-2019 calculation
overestimates both the experimental datasets. Thus,
the data are expected to contribute to practical use innuclear medicine and aid in improving the theoreticalmodels.
6natCa(α,x)47Sc

5Cross section (mb)

Scandium-47 (T1/2 = 3.3492 d) is a potential radionuclide for therapy.1) Owing to the relatively smallabundance of 46 Ca (0.004%) and 48 Ca (0.187%) in natural calcium, its most possible production route forpractical use is expected to be the α-particle-induced
reaction on 44 Ca (2.086%).
In a literature survey, we found only one experimental study of the 44 Ca(α, p)47 Sc reaction.2) Therefore,
we performed an experiment to provide more credible cross sections of the nat Ca(α, x)47 Sc reaction. Inaddition to the production cross sections of 47 Sc, theactivation cross sections for 46, 44m, 44g, 43 Sc and 47 Ca
were also determined simultaneously.
In the experiment, a 29-MeV α-particle beam wasused to activate the targets at the AVF cyclotron inRIKEN. The stacked-foil activation technique and highresolution γ-ray spectrometry were adopted to performthe measurement.
Calcium-ﬂuoride (CaF2 ) was deposited on a highpurity 27 Al backing foil (AlH , 99.999% purity, Goodfellow Co. Ltd., UK) and used as the nat Ca target. Metallic foils of nat Ti (99.5% purity) for the nat Ti(α, x)51 Cr
monitor reaction and low-purity 27 Al (AlL , >99% purity) to catch recoiled products were purchased fromNilaco Corp., Japan and inserted into the stack. The
average thicknesses of the AlH , AlL , and nat Ti foils
were 2.57, 1.50, and 2.30 mg/cm2 , respectively, determined from the measured lateral sizes and weights ofthe foils. The thickness of the deposited CaF2 layer
was 0.135 mg/cm2 , which was derived from the measured deposited area and net weight. All foils were cut
into a size of 10×10 mm to ﬁt a target holder that also
served as a Faraday cup. Each nat Ca target comprised
two CaF2 layers sandwiched between the AlH backingfoils. Twelve nat Ca targets were stacked with sevensets of nat Ti-AlL foils in the target holder.
The stacked target was irradiated with an α-particle
beam for 30 min. The measured average beam intensity and energy were 175 nA and 29.0 ± 0.2 MeV,
respectively. The energy degradation in the stacked
target was calculated using stopping powers obtained
from the SRIM code.3)The high-resolution γ-ray spectrometry using ahigh-purity germanium detector was performed with-

Levkovski (1991) (44Ca)TENDL-2019
This work

43210051015202530

α-particle energy (MeV)

Fig. 1. Measured cross sections of the nat Ca(α, x)47 Sc reaction with normalized literature data1) and TENDL2019 values.5)

This work was supported by the Japan-Hungary Research Cooperative Program between JSPS and HUS,
Grant number JPJSBP120193808 and NKM-43/2019.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

References
1) I. F. Chaple et al., J. Nucl. Med. 59, 1655 (2018).
2) V. N. Levkovski, Cross Sections of Medium Mass Nuclide Activation (A = 40–100) by medium energy protons and alpha particles (E = 10–50 MeV) (Inter-Vesi,Moscow, USSR, 1991).
3) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
4) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
5) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

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