Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Activation cross sections of alpha-particle induced nuclear reactions
on natural palladium†
M. Aikawa,∗1,∗2 M. Saito,∗3,∗2,∗4 Y. Komori,∗2 H. Haba,∗2 S. Takács,∗5 F. Ditrói,∗5 and Z. Szücs∗5

†
∗1
∗2
∗3
∗4
∗5

14nat

12
Cross section (mb)

Production cross sections of radioactive isotopes (RI)
are fundamental information for medical applications
such as therapy and diagnostics. One of the medical RI
is 103 Pd (T1/2 = 16.991 d), which is used for brachytherapy1) and targeted radionuclide therapy as part of the103
Pd/103m Rh in vivo generator.2) In addition to thedirect production of 103 Pd, the contribution from thedecay of its parent, 103g Ag, is worthy of investigation.
There are several charged-particle-induced reactions toproduce 103 Ag. In a literature survey, only one experimental study of 103g Ag production cross sections ofα-induced reactions on nat Pd was found.3) The incident energy of the previous study is limited to below
37 MeV and even lower than that at the peak of thecross sections. Therefore, we are motivated to perform
an experiment to determine the excitation function ofthe nat Pd(α, x)103g Ag reaction up to 50 MeV.
The experiment was performed at the RIKEN AVF
cyclotron. The stacked-foil activation technique andhigh-resolution γ-ray spectrometry were used. Thin
metallic foils of nat Pd (99.95% purity, Nilaco Corp.,
Japan) and nat Ti (99.9% purity, Goodfellow Co., Ltd.,UK) were purchased to fabricate a target. The size andweight of the large foils were measured. The average
thicknesses of the Pd and Ti foils were found to be 9.70
and 4.85 mg/cm2 from the measurement, respectively.
The foils were cut into small pieces of 10 × 10 mm2to fit a target holder. The stacked target consisted of
12 sets of the group of Pd-Pd-Ti-Ti foils. The target
was irradiated for 2 h by a 51.2-MeV α beam with anaverage intensity of 111.4 nA. The intensity was measured using a Faraday cup. The initial beam energy
was determined using the time-of-flight method.4) The
energy degradation of the beam in the target was calculated using the polynomial approximation of stoppingpower data.5) Gamma-ray spectra from each irradiatedfoil were measured four times to follow the decay of thereaction products with half-lives between 50 min and460 days. Nuclear-decay data were taken from NuDat2.7.6)
The 118.74-keV γ rays (Iγ = 31.2%) emitted withthe decay of 103g Ag (T1/2 = 65.7 min) were measured
after a cooling time of 3.6 h. There are minor contributions to the photo-peak area from co-produced isotopes,Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 449, 99 (2019)
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Science, Hokkaido University
Present address: Graduate School of Biomedical Science andEngineering, Hokkaido University
Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI)- 188 -Pd(α,x)103gAg

Hermanne 2005
TENDL2017
This work

108642025303540
Energy (MeV)

4550Fig. 1. Cumulative cross sections of the nat Pd(α, x)103g Ag
reaction.

100Pd and 111m Pd, but their total contribution is negligibly small. The measured counts are used to determine the excitation function of the nat Pd(α, x)103g Ag
reaction. In addition to the direct production, there
are contributions from the decay of its isometric state(T1/2 = 5.7 s) and 103 Cd (T1/2 = 7.3 min). Therefore,
cumulative cross sections are derived in this work. The
result is shown in Fig. 1 in comparison with the experimental data obtained earlier3) and the TENDL-2017
data.7) Our result is slightly higher than the previous
experimental data. The TENDL-2017 data provides an
excitation function with a consistent tendency.
Our result extends cross-section data to the higher
energy region and covers the peak. It enriches nuclear
reaction databases and is available for development oftheoretical calculation models.
This work is supported by the Japan - Hungary Research Cooperative Program, JSPS and HAS and by
JSPS KAKENHI Grant Number 17K07004.
References
1) S. Nag et al., Int. J. Radiat. Oncol. Biol. Phys. 44, 789(1999).
2) Z. Szucs et al., Radiochim. Acta 92, 215 (2004).
3) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 229, 321 (2005).
4) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), (2014), p. 3566.
5) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter (2008).
6) National Nuclear Data Center, The NuDat 2.7 database,
http://www.nndc.bnl.gov/nudat2/ .
7) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).