III-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Production cross sections of medical radioisotope 153 Sm inalpha-particle-induced reaction on natural neodymium
M. Sakaguchi,∗1,∗2 M. Aikawa,∗3,∗2 N. Ukon,∗4,∗2 Y. Komori,∗2 H. Haba,∗2 N. Otuka,∗5,∗2 and S. Takács∗6
Samarium-153 (T1/2 = 46.3 h) is a beta andgamma emitter that can be applied in radiology. This radionuclide is used for the palliation ofmetastatic bone cancer as the ethylenediamino-tetrakismethylenediphosphonic acid (EDTMP) chelate.1)
153
Sm is typically obtained via the neutron capture
reaction on enriched 152 Sm in nuclear reactors, but
its speciﬁc activity is rather low.2) For the practicaluse of 153 Sm in radiotherapy, other production routesof 153 Sm with relatively high speciﬁc activities are required.
This radionuclide can be generated in an alphaparticle-induced reaction on natural neodymium. Only
one excitation-function measurement has been reported
in the literature for the nat Nd(α, x)153 Sm reaction up
to 26.2 MeV.2) To conﬁrm the available data and to obtain new data of this reaction, we decided to perform anexperiment on the nat Nd(α, x) reactions up to 51 MeV.
The experiment was performed at the RIKEN AVF
cyclotron. The standard stacked-foil activation technique was adopted for this experiment. The target
was composed of twenty-one nat Nd foils (purity: 99.0%;
thickness: 16.68 mg/cm2 ; Goodfellow Co., Ltd., UK)and fourteen nat Ti foils (purity: 99.6%; thickness:2.35 mg/cm2 ; Nilaco Corp., Japan). The thicknessesof these foils were derived by measuring their weights
and surface areas. The nat Ti foils were used for thenatTi(α, x)51 Cr monitor reaction to assess the initial
beam parameters and the energy loss of the beam inthe target. The stacked target was irradiated in a target
holder, which served as a Faraday-cup, with an alphaparticle beam for 1 h. The primary incident energy
and average beam intensity were 51.1 MeV and 172 nA,respectively. Energy degradation through the stacked
target was calculated using the srim code.3)
After a cooling time of approximately 30 min, thetarget was disassembled, and the gamma-ray spectrometry of the foils was started. The gamma-ray spectra
were measured using a high-purity germanium (HPGe)
detector (ORTEC GMX30P4-70) without chemical separation and analyzed using the Gamma Studio (SEIKOEG&G) software for each foil.
The cross sections of the nat Ti(α, x)51 Cr monitor reaction were derived from the 320.1-keV gamma-line
∗1
∗2
∗3
∗4
∗5
∗6

Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
School of Science, Hokkaido University
Advanced Clinical Research Center, Fukushima Medical University
Nuclear Data Section, International Atomic Energy Agency
Institute for Nuclear Research, ATOMKI

Fig. 1. Excitation function for the nat Nd(α, x)153 Sm reaction compared with previous experimental data2) andthe TENDL data.6)(Iγ = 9.910%), and the experimental excitation function was compared with the IAEA recommended values.4) The thickness of the nat Nd foils was adjusted by−1.5% to ﬁt the recommended values and found to be
16.43 mg/cm2 according to the comparison. The thickness of nat Ti foils and the beam parameters were unchanged.
The excitation function of the nat Nd(α, x)153 Sm reaction was determined using gamma rays with the relatively low energy of 103.18 keV (Iγ = 29.25%). Therefore, the attenuation eﬀect in the metallic Nd foil wasconsidered and calculated from X-ray mass attenuationcoeﬃcients.5) As a result of the calculation, the net
counts of the gamma rays were corrected by +2.1%.
Figure 1 shows the corrected cross sections in comparison with the results of a previous study2) and theTENDL-2019 data.6) The previous data are not consistent with our experimental data and the TENDL data,
underestimate both experimental data. The maximum
cross section in this work is 1.1 mb, which indicates that
this reaction may be unsuitable for the mass productionof 153 Sm.
This work was supported by JSPS KAKENHI Grant
Number 17K07004.
References

1) I. G. Finlay et al., Lancet Oncol. 6, 392 (2005).
2) S. Qaim et al., Radiochim. Acta 95, 313 (2007).
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) J. H. Hubbell, S. M. Seltzer, X-Ray Mass Attenuation
Coeﬃcients, https://dx.doi.org/10.18434/T4D01F .
6) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).

- 168 -1