JAEA-Conf 2011-002 - 日本原子力研究開発機構

for such a low energy region should be checked by experimental data, because most of
physical models for proton-induced reactions implemented in the codes were developed to
describe reactions of high-energy particles. In this paper, we describe the systematic
measurements of neutron and -ray energy spectra from various targets ( 9 Be, nat C, 27 Al, nat Cu,
181 18
Ta and H2O) induced by 18 MeV protons, and comparisons between the experimental
data and calculation results.
The experiment were carried out using the AVF cyclotron (K=110) at the Takasaki
Ion Accelerators for Advanced Radiation Application (TIARA) facility of Japan Atomic
Energy Agency (JAEA). A schematic view of the experimental apparatus is illustrated in Fig1.
A proton beam accelerated by the cyclotron was transported to HB-1 beam line, which is
equipped with a 60-cm diameter vacuum chamber. Neutron detectors were set at nine
laboratory angles (0, 15, 30, 45, 60, 75, 90, 120, and 150°) with distances of 2.0 – 4.0 m from
the target. The beam transported to the target was thinned to lower the beam frequency with a
beam chopper in order to obtain TOF spectra down to a lower energy region by avoiding
frame-overlap in the time-of-flight spectrum. In the present experiment, the beam chopper
was operated at 1/7 and the beam frequency was 20.1 MHz. A detailed description of the
target room is given in ref. 4.
150°
120°
Scattering chamber
60 cm
18 MeV Proton
Cu mesh suppresser
90°
target
JAEA-Conf 2011-002
75°
60°
2.0
2.0
– 4.0
m
m
Insulator
Neutron detector
45°
30°
Faraday cup 2.4m
3.0m
15°
Beam stop (Al)
Illustration of experimental setup at the HB-1 course in TIARA (horizontal view)
The thicknesses of targets (2.8 mm, 2.8 mm, 3.0 mm, 2.8 mm and 6 mm for 9 Be, nat C, 27 Al,
nat 181 18
Cu, Ta and H2O, respectively) were determined to be thicker than the full-stop thickness
for 18 MeV proton incidence using the SRIM code 5) . The targets were set on a
0°