Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 51 (2018)

Prodution cross sections of 169 Yb and 167,168,170 Tm isotopes indeuteron-induced reactions on 169 Tm†
M. Saito,∗1,∗2 M. Aikawa,∗1,∗2 Y. Komori,∗2 H. Haba,∗2 and S. Takács∗3

†
∗1
∗2
∗3

Condensed from the article in Appl. Radiat. Isot. 125, 23(2017)
Graduate School of Science, Hokkaido University
RIKEN Nishina Center
MTA ATOMKI, Hungarian Academy of Sciences- 221 -900

169800
Cross section (mb)

The 169 Yb (T1/2 = 32.018 d, EC = 100%) radionuclide is an Auger electron and X-ray emitter, making it suitable for brachytherapy.1,2) Previously measured experimental cross-section data suggest that thedeuteron-induced reaction on 169 Tm3–5) is one of thebest candidates for the production of high-specificactivity 169 Yb owing to the large cross sections of the(d,2n) reaction and 100% natural abundance of the target 169 Tm. However, the available experimental crosssection data of the 169 Tm(d,2n)169 Yb reaction haverelatively large uncertainties and are scattered; therefore, the excitation function is not defined properly.
We report cross-section data of the 169 Tm(d,2n)169 Yb
reaction using pure, thin metallic thulium foils as thetarget material to reduce the uncertainty of the experimental data.
The excitation functions of the deuteron-induced reactions on 169 Tm were measured by using the stackedfoil activation method and high-resolution γ-ray spectrometry of the irradiated target foils. The 169 Tm
metallic target foils (purity: 99%, Goodfellow, UK)
were stacked with nat Ti (purity: 99.9%, Goodfellow,UK) and 27 Al foils (purity: >99.95%, Nilaco, Japan)for monitoring the beam parameters and for degrading
the beam energy. The average thicknesses of Tm, Ti,
and Al foils were determined by measuring the surface area and the weight of larger pieces of the foils
and were found to be 28.65, 4.95, and 13.44 mg/cm2 ,respectively. The irradiation was performed at theAVF cyclotron of the RIKEN RI Beam Factory. The
stacked target was irradiated for 75 min with a 24.36MeV deuteron beam having an average intensity of135.6 nA, which was measured by a Faraday cup. The
incident beam energy was measured by the time-offlight method using plastic scintillator monitors.6) The
beam-energy degradation in the stacked target was calculated using the SRIM code available online.7) Theγ-ray spectra of the activated foils were measured byHPGe detectors. Nuclear decay data were taken fromthe online NuDat 2.7 database.8)
The excitation function of the 169 Tm(d,2n)169 Ybreaction was derived from the γ-line at 177.21-keV(22.28%), as shown in Fig. 1, together with the previously measured experimental data,3–5) and the result of the TALYS calculation.9) Our peak energy is ingood agreement with the previous data3–5) although

169Tm(d,2n)

Yb700

This work
Tarkanyi (2007)
Hermanne (2009)TENDL2015

600
500
400300200
100005101520
Energy (MeV)

2530Fig. 1. Excitation function of the 169 Tm(d,2n)169 Yb reaction. The solid curve shows a spline fit over the experimental data. The result is compared with the previous
experimental data3–5) and TENDL-2015.9)

the cross sections are slightly higher. In addition to169
Yb, we have measured the production cross sectionsof 167,168,170 Tm. The measured data of Tm isotopes
are not included in this report owing to the space limitation, but all data are available in Appl. Radiat. Isot.
125, 23 (2017). The present results for the Tm isotope
production show good agreements with the previous
data in general.
In summary, we determined the cross sections of thedeuteron-induced reactions on 169 Tm to produce 169 Yband 167,168,170 Tm by using the stacked-foil activation
method and γ-ray spectrometry. The thin metallic Tm
foils with Ti and Al foils were irradiated by a 24.36MeV deuteron beam. The obtained excitation functions were compared with previous experimental data,and good agreements were found in general. The excitation function of the 169 Tm(d,p)170 Tm reaction isreported for the first time.
References
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3) F. Tárkányi et al., Appl. Radiat. Isot. 65, 663 (2007).
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5) A. Hermanne et al., Nucl. Instrum. Methods B 383, 81(2016).
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(IPAC2014), (2014), p.3566.
7) SRIM: the Stopping and Range of Ions in Matter,
http://www.srim.org/.
8) National Nuclear Data Center: the NuDat 2 database,
http://www.nndc.bnl.gov/nudat2/.
9) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).