Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 49 (2016)

Simulation of thick-target transmission method for interaction crosssections of 93 Zr on 12 C
M. Aikawa,∗1,∗2 S. Ebata,∗1 and S. Imai∗3The behaviors of the cross sections are in good agreement, and therefore the T3 method may be applicablein real experiments. The derived cross sections, however, have large uncertainties in the low energy region
because the uncertainties are accumulated in the moderator part of the target. We continue to investigate
the method in more detail to propose a new experiment and also perform additional simulations of otherradioactive isotopes.

Ni (L + ∆L)−1ln,nT ∆L
Ni (L)

Beam attenuation

σI =1(1)

∗2
∗3100

0.95

80
60

0.9

40
20

where nT , L, ∆L and Ni (L) are the number densityof the target, thickness of moderator, thickness of reaction target and the number of transmitted incident
particles at L, respectively. In other words, Ni (L)passed through the moderator part with L is used asa beam on the reaction part of the thickness ∆L. We
performed a simulation with the PHITS code3) for theinteraction cross sections of 93 Zr on 12 C, which are typical examples of long-lived ﬁssion fragments and stable
nuclei. The cross sections are equivalent to inclusive
cross sections of 12 C-induced transmutation reaction
on 93 Zr.
The parameters adopted in the simulation are set
to cover the expected peak area. The energy is set to100 MeV/nucleon, which is similar to the recent experiment4) . The target density and thicknesses are 2.260
g/cm3 and 0.02 cm (0 ≤ L ≤ 0.2 cm) and 0.004 cm(0.2 ≤ L ≤ 0.24 cm), respectively. The trial number is 105 which are consistent with an intensity of
1,000 pps and individual irradiation period of 100 s.
Calculations with diﬀerent target thicknesses were iteratively performed in the simulation. The beam attenuation and energy at the downstream of the target
can be obtained in each calculation and are shown as afunction of the target thickness in Fig. 1. The interaction cross sections thus obtained with the moderator
part from Eq. (1) are shown in Fig. 2 with expectedvalues of PHITS derived from the traditional transmission method with thin-targets and energy adjustments.
∗1120

Beam
εε (MeV/nucleon)

The interaction cross section provides valuableknowledge pertaining nuclear physics1) and engineering since it is an essential quantity related to nuclear
radii and the transmutation of nuclear wastes. In addition, its excitation function is also important; however, the data of radioactive isotopes are very few andinsuﬃcient because it requires huge experimental effort at each energy. Therefore, we propose the thicktarget transmission (T3) method to obtain the excitation functions of the interaction cross sections2) .
The T3 method can derive the excitation function
through iterative measurements of beam attenuations
with diﬀerent target thicknesses. Similar to the ordinary transmission method, the interaction cross section σI can be derived from the following equation:

0.85

00.05

0.1
0.15
L (cm)

00.2

Fig. 1. The attenuation (solid circles with solid line) andenergy (open triangles with dotted-line) of the incident
beam are shown as a function of the target thickness.

3.5Result (T3)
Expectation

3σ (b)

2.5
2
1.5
10.5
00204060ε (MeV/nucleon)

80

100Fig. 2. Interaction cross sections of 93 Zr on 12 C. The resultsof the simulation (open circles with solid line) are shownwith the expected values in PHITS (dotted-line).

This work was funded by ImPACT Program ofCouncil for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References
1) I. Tanihata et al., Phys. Rev. Lett. 55, 2676 (1985).
2) M. Aikawa et al., under submission.
3) T. Sato et al., J. Nucl. Sci. Technol. 50, 913 (2013).
4) H. Wang et al., In this report.

Faculty of Science, Hokkaido University
RIKEN Nishina Center
Institute for the Advancement of Higher Education,
Hokkaido University- 88 -