III-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 55 (2022)

RIKEN Accel. Prog. Rep. 55 (2022)

Production cross sections of 28 Mg via the α-particle-induced reaction
on aluminum
M. Aikawa,∗1,∗2 G. Damdinsuren,∗3,∗2 H. Huang,∗3,∗2 and H. Haba∗2

∗1
∗2
∗3

Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University- 148 -0.5
27Al(,3p)28Mg

0.4
Cross section (mb)The radionuclide 28 Mg has a half-life of T1/2 =20.915 h and decays with the emission of a β − particle and γ rays. These nuclear properties are appropriate for radiotracers in a wide range of applications.1) One of its promising production reactions
is the α-particle-induced reaction on aluminum. We
found ten experimental studies in the production crosssections of 28 Mg in a literature survey in the EXFOR
library.2) However, the cross sections of the previous
studies are largely scattered. Therefore, we conducted
an experiment to determine reliable cross sections ofthe 27 Al(α, 3p)28 Mg reaction.
The experiment to measure the activation cross sections of the reaction was performed at the RIKEN AVF
cyclotron. The stacked-foil activation technique andhigh-resolution γ-ray spectrometry were used. Pure
metal foils of 27 Al (>99% purity) and nat Ti (99.6% purity) were purchased from Nilaco Corp., Japan. The
Ti foil was used for the nat Ti(α, x)51 Cr monitor reaction. The average thicknesses of the Al and Ti foils
were 13.7 and 2.23 mg/cm2 , respectively, which were
derived from the measured size and weight of each foil.
After the thickness measurement, the foils were cutinto small pieces of 10 × 10 mm2 to ﬁt a target holderthat served as a Faraday cup. The stacked target consisted of ten Al foils upstream and seven sets of Ti-TiTi-Al foils downstream of the beam line. The upstream
Al foils were used to derive activation cross sections of
the 27 Al(α, 3p)28 Mg reaction, the threshold energy ofwhich is 24.8 MeV. The following Ti-Ti-Ti-Al foils werestacked for the nat Ti(α, x)51 Cr monitor reaction in alower-energy region. The stacked target was irradiatedfor 30 min with an α-particle beam. The initial energy of the α-particle beam was determined using thetime-of-ﬂight method.3) The average beam intensity
was measured using the Faraday cup and found to be
216 nA. The energy degradation of the α-particle beamin the target foils was calculated using stopping powers
obtained from the SRIM code.4) The γ-ray spectrometry was performed using a high-purity germanium detector (ORTEC GEM30P4-70) and dedicated analysis software (SEIKO EG&G Gamma Studio). γ rays
emitted from each irradiated foil were measured without chemical separation three times (Ser. 1: 2.7–7.5 h,Ser. 2: 8.0–32 h, Ser. 3: 1.9–3.6 d). The dead time
was kept below 1.4% throughout the measurements.
Nuclear data used for cross-section derivation were re-Nethaway (1958)
Martens (1970)
Nozaki (1975)
Probst (1976)
Rattan (1985)
Rattan (1986)
Karamyan (1992)
TENDL-2019
This work

0.3

0.2

0.1

02530

3540

4550

Energy (MeV)

Fig. 1. Excitation function of the 27 Al(α, 3p)28 Mg reaction
in comparison with the previous studies found in theEXFOR library2) and the TENDL-2019 values.6)

trieved from the online database, NuDat 3.0.5)
The γ line at 1342.2 keV (Iγ = 54%) emitted withthe decay of 28 Mg (T1/2 = 20.915 h) was measured
during the cooling time of 8.0–32 h (Ser. 2). The crosssections of the 27 Al(α, 3p)28 Mg reaction were determined using the measured spectra. Figure 1 compares
our preliminary result with the experimental data in
the EXFOR library2) and the TENDL-2019 values.6)
The cross section at the highest energy may be aﬀectedby the recoil eﬀect and slightly decreased. The previous data of Martens et al. 7) and Rattan et al. 8) areconsistent with our data, although their data deviate
from each other in the higher-energy region. The otherprevious data are systematically larger or smaller thanour data. The TENDL-2019 values are fairly smaller
than all the experimental data. We will ﬁnish analysesof the measured γ-ray spectra and determine the production cross sections of radioactive products in thereaction.
References
1) N. P. van der Meulen et al., Appl. Radiat. Isot. 115,
125 (2016) and references therein.
2) N. Otuka et al., Nucl. Data Sheets 120, 272 (2014).
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 (2008), http://www.srim.org/ .
5) National Nuclear Data Center, The NuDat 3.0
database, http://www.nndc.bnl.gov/nudat3/ .
6) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
7) U. Martens et al., Z. Phys. 233, 170 (1970).
8) S. S. Rattan et al., Radiochim. Acta 39, 61 (1986).

1