Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 51 (2018)

Production cross sections of 177g Lu in α-induced reactions on nat Yb
M. Saito,∗1,∗2 M. Aikawa,∗1,∗2 T. Murata,∗2,∗3 N. Ukon,∗2,∗4 Y. Komori,∗2 H. Haba,∗2 and S. Takács∗5

∗1
∗2
∗3
∗4
∗5Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
School of Science, Hokkaido University
Advanced Clinical Research Center, Fukushima MedicalUniversity
MTA ATOMKI, Hangarian Academy of Sciences- 222 -nat14177gYb(,x)LuThis work
Kiraly et al.
TENDL-201512Cross section (mb)Radioisotopes (RI) are used for therapy and diagnosis in nuclear medicine. The combination of boththerapy and diagnosis (Theranostics) is one of the hot
topics in the field. One of the candidate isotopes suitable for theranostics is 177g Lu (T1/2 = 6.6 d).1) It emits
β particles (Emean = 134.2 keV) and γ rays (Eγ =112.95 keV (Iγ = 6.17%) and 208.37 keV (10.36%)),
which are suitable for therapy and diagnosis, respectively.
There are many possible reactions to produce
177gLu, e.g., neutron-induced reaction on 176 Lu andcharged-particle-induced reactions on 174,176 Yb. Cross
section data of such reactions are required to find thebest production route of 177g Lu. Among them, we focused on the cross sections of 177g Lu in α-induced reactions on nat Yb, because we could find only one data set
for this reaction up to 40 MeV2) in a literature survey.
Therefore, we performed an experiment to measure theexcitation function of the reaction up to 50 MeV.
The experiment was performed at the AVF cyclotronof the RIKEN RI Beam Factory by using a stacked-foil
activation method and high-resolution γ-ray spectrometry. Thin metallic foils of nat Yb (purity: 99%, Goodfellow Co., Ltd., UK) and nat Ti (purity: 99.6 %, Goodfellow Co., Ltd., UK) for the monitor nat Ti(α,x)51 Cr
reaction were stacked together as a target. The average thicknesses of the Yb and Ti foils were determinedby measuring the surface area and weight of the larger
pieces, three Yb foils (25×25 mm2 ) and one Ti foil
(50×100 mm2 ). Their average thicknesses were foundto be 16.43, 16.15, 16.93, and 2.40 mg/cm2 , respectively. The target foils (8×8 mm2 ) were cut from themeasured foils. The stacked target was irradiated by a50-MeV α beam with an average intensity of 207 particle nA for 2 hours. The initial beam energy was determined by using time of flight measurement,3) andthe energy degradation in the target was calculated
by using the SRIM code available online.4) The initial
uncertainty of the α-beam energy was estimated to be±0.1 MeV, and it increased to ±1.1 MeV at the lastYb foil. Nuclear decay data of 177g Lu and 51 Cr weretaken from the online NuDat 2.7 database.5)
Cross sections of the monitor nat Ti(α,x)51 Cr reaction were derived from the γ line of Eγ = 320.08 keV(Iγ = 9.91%) and compared with the IAEA recommended values6) to assess the beam parameters. Our

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1020

30

4050

Alpha-particle Energy (MeV)

Fig. 1. Cross sections of the nat Yb(α,x)177g Lu reaction incomparison with the previous data2) and TENDL-2015
data.7)

result shows a good agreement with the recommendedvalues, and suggests that no adjustment is necessary for the beam parameters. Cross sections of thenatYb(α,x)177g Lu reaction were also derived from theγ line at Eγ = 208.37 keV (Iγ = 10.36%). The preliminary result is shown in Fig. 1, together with the previous data2) and the TENDL-2015 data.7) Our resultshows a smooth and monotonical increase, indicating
disagreements with the other data.
In summary, we performed an experiment on the αinduced reactions on nat Yb to produce 177g Lu by using
a stacked-foil activation method. Thin metallic nat Ybfoils were irradiated by a 50-MeV α beam. Cross section values were determined from the activity of theproduced radioisotopes by using high-resolution γ-rayspectrometry. The result was compared with the previous data and the TENDL-2015 data. We found that
there are disagreements with the other data. A moredetailed analysis is required to finalize the cross sections and confirm this deviation.
References
1) K. Rahbar et al., J. Nucl. Med. 58, 85 (2017).
2) B. Király et al., Nucl. Instrum. Methods Phys. Res. B.
266, 3919 (2008).
3) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), (2014), p.3566.
4) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter, http://www.srim.org/.
5) National Nuclear Data Center: the NuDat 2 database,
http://www.nndc.bnl.gov/nudat2/.
6) Tárkányi et al., IAEA-TECDOC-1211 (2007).
7) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).