Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 50 (2017)

Thick-target transmission method for excitation functions ofinteraction cross sections†∗1∗1∗1∗3S.S.Ebata,andM.Aikawa,
Aikawa,∗1,∗2M.
Ebata,and S.
S. ImaiImai∗2σI (x) = −1
I  (x + Δx) I(0),lnnT ΔxI  (0)I(x)(1)

where nT is the number density of target (cm−3 ).
When the LLFP beam is applied in the T3 method,σI (x) is the transmutation cross section.
To obtain σI (ε) by the conventional transmission
method, it is necessary to change the beam energy foreach cross section σI (ε). The T3 method is likely applicable with less eﬀorts to stack a foil on the target
than to change the beam energy.
To test the usefulness of the T3 method, we performed a simulation on the interaction cross sections for the 12 C-induced reaction on 27 Al with theMonte Carlo simulation code PHITS.2) In the simulation, the incident energy of the 12 C beam is set to 100
MeV/nucleon, which is stopped at approximately 1.23
cm from the surface of an Al target. The target of themaximum thickness consists of 21 foils with a thickness of 0.1 cm from 0.0 cm up to 1.0 cm and of 0.02
cm from 1.0 cm up to 1.22 cm. A beam intensity of1000 pps and an irradiation time of 100 s are assumed
and correspond to a trial number of 105 in the PHITS
simulation.
†∗1
∗2

∗3

Condensed from the article in Nucl. Instr. Meth. B383,156(2016).

Faculty of Science, Hokkaido
Hokkaido UniversityUniversity
InstituteNishina
for theAdvancement of Higher Education,
RIKEN
CenterHokkaido
Institute University
for the Advancement of Higher Education,
Hokkaido University- 105 -3.5T3 method
Transmission method

M.Takechi et al.
S.Kox et al.

32.5

σI [b]

Nuclear transmutation is one of the promising technologies to dispose of nuclear waste with high-level radioactivity, such as long-lived ﬁssion products (LLFP).
Although the nuclear data of transmutation reactions
for LLFP are essential to develop the technology, thedata are scarce in the present database because theexperiments are restricted by the radioactivity andchemical instability of LLFP. To avoid these restrictions experiments in inverse kinematics are available
for charged-particle-induced data. Indeed, the crosssection data of nuclear waste composed of 90 Sr and137
Cs have recently been measured at RIBF.1)
The excitation function of the interaction cross sections σI , leads to the thick-target yields of LLFPtransmutation.To measure σI (ε), we propose the thicktarget transmission (T3) method, which extends theconventional transmission method to that with a thicktarget. In the T3 method, the target also plays therole of energy moderator and its thickness corresponds
to the energy degradation I(0) decreases to I(x) afterpassing through a target with the thickness x.By using
the attenuation ratiosI(x)/I(0) andI  (x+Δx)/I  (0) ofdiﬀerent runs, the σI (x) is derived as2
1.5
10.50020406080100

ε [MeV/nucleon]

Fig. 1. Interaction cross section σI (ε) obtained from theT3 method (circles), conventional transmission method(dashed line), and experimental data (triangles and3,4)
squares)squares).3,4)

The results estimated by the T3 method are shownin Fig. 1 by circles. The dashed line is also obtained by
the simulation but with the conventional transmission
method. The ﬁlled symbols indicate the experimental
data (triangles and squares).3,4) Our results well reproduce the tendency of experimental data, although they
have large error bars owing to the low statistics at thintarget foils and propagation of statistical uncertaintiesof I  (x + dx) and I(x). Thus, in spite of the small
number of incident particles, such as 105 , the interaction cross sections can be obtained. We emphasizethat the experiments using the T3 method avoid thebeam-energy re-adjustments, and time savings might
be expected with these experiments.
The T3 method can derive the interaction cross sections through the iterative measurements of the beam
attenuation ratio I(x)/I(0). The energy dependenceof σI is deduced by changing the target thickness. Our
results calculated using PHITS simulation well reproduce the experimental data of the 12 C+27 Al reaction.
The T3 method will contribute to accumulate fundamental data of the transmutation reaction for radiative
targets including rare isotopes.
This work was funded by the ImPACT Program ofthe Council for Science, Technology and Innovation(Cabinet Oﬃce, Government of Japan).
References
1) H. Wang et al., Phys. Lett. B 754, 104 (2016).
2) T. Sato et al., J. Nucl. Sci. Technol. 50, 913 (2013).
3) S. Kox et al., Phys. Lett. B 159, 15 (1985).
4) M. Takechi et al., Phys. Rev. C 79, 061601(2009).