Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 47 (2014)

Deuteron activation cross sections for monitor reactions
N. Otuka,∗1,∗2 H. Haba,∗1 M. Murakami,∗1 and M.U. Khandaker∗3
Structural materials in fusion energy devices like
ITER are expected to be exposed to intense neutron
flux. Therefore, material tests are important in fusionenergy technology. The International Fusion Material
Irradiation Facility (IFMIF) is a candidate facility formaterial tests. Intense neutrons consisting of a peakaround 15 MeV are planned to be produced in IFMIF
using the 7 Li(d,n) reaction with intense (125 mA +125 mA) deuteron beams that are accelerated to 35 to40 MeV by two linear accelerators1) . The prototype isunder construction in Rokkasho, Japan within IFMIF
Engineering Design Activities (IFMIF/EVEDA). In
addition to generating high energy tail (d,n) neutrons
up to 55 MeV, the deuteron beams also activate thesurrounding materials of the test facility. To perform
activation calculations2) for radiation safety, it is necessary to measure the radioisotope production crosssections for deuteron induced reactions. Accordingly, adeuteron induced reaction sublibrary was added to thelatest version of the Fusion Evaluated Nuclear Data
Library (FENDL-3.0)3) . Deuteron-induced reactions
could also be useful for efficient radioisotope production. For various applications, we have started themeasurements of radioisotope production cross sections for various deuteron-induced reactions by theAVF cyclotron of the RIKEN RIBF.
Radioisotope production cross sections for chargedparticle induced reactions are often measured throughmonitor reactions. Recommended cross sections of various monitor reactions are distributed from the IAEA
Nuclear Data Section4,5) , and we have also adopted
their recommended 27 Al(d,x)24 Na and nat Ti(d,x)48 V
cross sections in our experimental studies6,7) .
In addition to the best estimate of the cross sections,
their uncertainties also become important for modern
applications of nuclear reaction cross sections. This
point has been stressed on for many decades for low energy neutron-induced reaction applications in relation
to critical and radiation safety, and experimentalists
are urged to perform error propagation and its documentation properly8) . This is also a common issue
for people who report charged-particle induced reaction cross sections for applications. The recommended
cross section for the monitor reaction is a major sourceof the correlated uncertainty in various experimental
works, and its uncertainty must be well-known prior
to the error propagation. For the standard neutroninduced reactions like 235 U(n,f), IAEA standard crosssections are provided with their uncertainties and co∗1
∗2
∗3

RIKEN Nishina Center
Nuclear Data Section, International Atomic Energy Agency
Department of Physics, University of Malaya- 268 -variance matrices9) . However, we currently assume anuncertainty of 5% in the IAEA recommended cross sections in its error propagation to our measured crosssections because their uncertainties are not provided.
This issue is currently being discussed in an IAEA Coordinated Research Project10) . However, we decided
to determine the uncertainties in the monitor reaction cross sections by ourselves for more appropriate
error propagation in our future deuteron-induced isotope production cross section experiments. The purpose of this work is to determine the cross sections
and their uncertainties for three monitor reactions
27Al(d,x)24 Na, nat Ti(d,x)48 V, and nat Cu(d,x)65 Zn byusing the stacked target activation technique.
A target stack consisting of Al foils (25 µm and50 µm thick), Ti foils (20 µm thick), and Cu foils(12.5 µm and 25 µm thick) was prepared and irradiated by a deuteron beam (about 200 nA) extracted
from the AVF cyclotron of the RIKEN RIBF for twohours. In order to determine the cross sections without reference cross sections for the monitor reactions,
we provided an electric current of exactly 200 nA to
the target holder and measured the electric current bya current integrator. We have confirmed that the current integrator may be calibrated by a very small correction factor (about 0.995). After the irradiation, thetarget stack was dissembled, and the gamma activity
measurement was started 4.25 hours after the end ofirradiation by using a germanium detector calibrated
by a multiple gamma ray emitting point source covering the gamma energy range between 60 and 1836 keV.
The off-line measurement is ongoing, and we plan toreport the cross sections with well-determined uncertainties for the three monitor reactions (27 Al(d,x)24 Na,natTi(d,x)48 V, nat Cu(d,x)65 Zn) as well as other usefulreactions like nat Cu(d,x)64 Cu for positron-emitter production application.
References
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3) R. A. Forrest et al.: INDC(NDS)-0628, IAEA (2012).
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5) S. Takács et al.: Nucl. Instrum. Meth. B 262, 7 (2007).
6) M. U. Khandaker et al.: Nucl. Instrum. Meth. B 296,
14 (2013).
7) M. U. Khandaker et al.: Nucl. Instrum. Meth. B 316,
33 (2013).
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9) A. D. Carlson et al.: Nucl. Data Sheets 110, 3215
(2009).
10) A. Nicols and R. Capote (ed.): INDC(NDS)-0630,
IAEA (2013).