CO4-1

Development of Radiation Tolerant Image Sensor
with Field Emitter Array

Y. Gotoh, M. Nagao1, T. Okamoto2, T. Masuzawa3,
Y. Neo3, H. Mimura3, H. Tsuji, M. Akiyoshi, I. Takagi,
N. Sato4

ance against –ray irradiation.

Graduate School of Engineering, Kyoto University
National Institute of Advanced Industrial Science andTechnology
2National Institute of Technology, Kisarazu College
3
Research Institute of Electronics, Shizuoka University
4
Research Reactor Institute, Kyoto University

Current (A)1

INTRODUCTION: One of the most serious problems
for the observation of interior of the nuclear reactor at theElectric Power Plant, Fukushima the 1st, is such that there
are no good cameras that can stand for the irradiationfrom radioactive material can be seen as a commercial
product. Therefore, it is necessary to develop a reliablecamera that can be used under hard radiation. The purpose of the present study is to develop a compact image
sensor for visual light with a field emitter array (FEA).
To ensure the radiation tolerance, it is necessary to show
the resistance of each element against -ray radiation.
Change in the operational characteristics of the key
components of the image sensor, FEA [1] andphotoconducting diode [2] was investigated.

10

−4

10

−6

10

−8

10

−10

10

−12

After irrad.
Before irrad.

Anode

Gate

0

20

40

60

80

Voltage (V)−2Current density (mA cm )Fig. 1. I-V characteristics of FEA in triode configuration before and after -ray irradiation.

EXPERIMENTS: The FEAs were fabricated at National Institute of Advanced Industrial Science and Technology. Photoconducting CdTe/CdS diodes were fabricated at National Institute of Technology, Kisarazu College. The irradiation of -rays to these devices was performed at Kyoto University Research Reactor Institute,
Co-60 Gamma-ray Irradiation Facility. Irradiation of
-ray to the FEAs was performed in a vacuum vessel
made of glass. Current-voltage (I-V) characteristics of the
FEA and CdTe/CdS photodiode were investigated before
and after -ray irradiation. The dose of irradiation was
between 60 and 200 kGy, depending upon the sample
position during the irradiation.

24
20

After irrad.
Before irrad.

16
12
8
4

Substrate type0
0.0 0.1 0.2 0.3 0.4 0.5 0.6
Voltage (V)Fig. 2. I-V characteristics of CdTe/CdS diode in
substrate-type configuration before and after –ray
irradiation.
ACKNOWLEDGMENT: A part of this study is theresult of “Development of radiation tolerant compact
image sensor with a field emitter array”, carried out under the Initiatives for Atomic Energy Basic and Generic
Strategic Research by the Ministry of Education, Culture,
Sports, Science and Technology of Japan.

RESULTS: Fig. 1 shows the I-V characteristics of the
FEA in a triode configuration. No significant change of
the I-V characteristics was observed even after the –ray
irradiation with the dose of 125 kGy. Fig. 2 shows the I-V
characteristics of the CdTe/CdS photodiode prepared on agraphite substrate (Substrate-type configuration). Also forthis case, no significant change of the I-V characteristics
was observed after the –ray irradiation with the dose of
75 kGy. Taking the fact that semiconductor image sensors
have the life of 100 kGy, the FEA and thephotoconducting CdTe/CdS diode have sufficient toler-

REFERENCES:[1] M. Nagao, Proc. of the 21st International Display
Workshops, Dec. 3-5, 2015, Niigata (2015) 588-590.
[2] T. Okamaoto, R. Hayashi, S. Hara, Y. Ogawa, Jpn. J.
Appl. Phys., 52 (2013) 102301/1-3.

採択課題番号 26002
耐放射線性に優れた微小真空冷陰極アレイ撮像素子の開通常採択（京大院・工）後藤康仁、高木郁二、秋吉優史、辻 博司（静岡大・電研）根尾陽一郎（京大・原子炉）佐藤信浩

110CO4-2

Sub-Terahertz Absorption of Ionic Liquid

T. Awano and T. Takahashi1

30Faculty of Engineering, Tohoku Gakuin University
Research Reactor Institute, Kyoto University[1-Ethyl-3-methylimidazolium][BF 4]-1

ABSORPTION COEFFICIENT (cm )

1

295K
273K
258K
227K
-158K

20

for 91K

10

0

4

6
8
10
-1
WAVE NUMBER (cm )12Fig. 1. Absorption increment spectra of [Emim][BF4]. The
baseline is the absorption spectrum at 91K.
-1

ABSORPTION COEFFICIENT (cm )INTRODUCTION:
We have observed millimeterwave absorption bands around 6 and 8 cm-1 in
AgI-superionic conductive glasses. These bands werealso observed in CuI-superionic ones[1-3]. These bands
seems to be due to collective motion of conductive ions,although how conduction ions moves in correlation is notclear.
Ionic liquid (IL) is molten salt at room temperature. It
is interesting to compare ionic motion in ionic liquids
with those in superionic conductor.
Recently, we have measured sub-terahertz absorption
spectra of N,N-Diethyl-N-methyl-N-(2-methoxyethl)
ammonium tetrafluoroborate ([DEME][BF4]) and
N,N-Diethyl-N-methyl-N-(2-methoxyethl)ammoniumbis(trifluoromethanesulfonyl)imide([DEME][TFSI])[4]. Two absorption bands were observed around 6 and 8
cm-1, which are almost coincident with those in
AgI-superionic conductive glasses. These bands havealmost equal peak positions and intensities in both ILs.
This means that these absorption bands are due to cation
motion. However, thermal change of these bands are different. This difference seems to be due to the differenceof their phase transition temperatures and solid states.
The former becomes glassy solid under 182 K. The latterbecomes crystal.
To investigate these difference among ILs, measurements of absorption spectra of several ILs have been executed.

20

10

EXPERIMENTS: Ionic liquids (Tokyo Kasei. co., inc.)were spread into filter paper. Transmission spectra of
single and double papers with ionic liquids were measured at room temperature and low temperatures. Absorption spectra were obtained by subtraction of them.
RESULTS:
Fig. 1 shows absorption spectra of
1-Ethyl-3methylimidazolium
tetrafluoroborate([Emim][BF4]). This ionic liquid becomes solid under
210 K. Fig. 2 shows absorption spectra of
1-Ethyl-3methylimidazoliumbis(trifluoromethanesulfonyl)imide([Emim][TFSI]) .
Temperature dependence was different in these ionic liquids. The intensity of the absorption band of the former
IL decreased gradually at temperatures above 227 K. On
the other hand, that of the latter IL decreased rapidly attemperatures below 213 K. This difference seems to be
due to the difference of their phase transition temperatures and glass or crystal structure of solid states of theseILs due to the anion difference.

0[1-Ethyl-3-methylimidazolium][TFSI]
292K
213K
158K
for 89K

4

6
8
10
-1
WAVE NUMBER (cm )12Fig. 2. Absorption increment spectra of [Emim][TFSI].
The baseline is the absorption spectrum at 89 K. The
spectrum of 158 K was almost coincident with thebaseline.
REFERENCES:[1] T. Awano and T. Takahashi, J. Phys. Conf., 148(2009) 012040/1-4.
[2] T. Awano and T. Takahashi, J. Phys. Soc. Jpn. 79
Suppl. A (2010) 118-121.
[3] T. Awano and T. Takahashi, Proceedings of the 13th
Asian Conference on Solid State Ionics, (2012) 569-576.
[4] T. Awano and T. Takahashi, KURRI Progress Report
2013, CO4-5.

採択課題番号 26015 超イオン導電体におけるコヒーレントミリ波誘起イオン伝導の検証 通常採択
共同通常
（東北学院大・工）淡野照義、（京大・原子炉）高橋俊晴
111

CO4-3Generation of Circular Polarization using Linearly Polarized
Coherent Transition Radiationof the detector.
RESULTS: The observed polarization diagrams of CTRs
from WG1 (horizontal component) and WG2 (verticalcomponent) are shown in Fig.1 and 2, respectively. In
these figures the degrees 0 and 180 represent the verticalplane, and 90 and 270 represent the horizontal plane.
These results demonstrate that CTR from the wire gridhas perfect linear polarizations. The observed
polarization diagram of the superposition of these two
CTRs is shown in Fig.3. This figure represents that thecircular polarized CTR was generated.

T. Takahashi
Research Reactor Institute, Kyoto University
INTRODUCTION: In recent years various types ofcoherent radiation emitted from a short bunch of
relativistic electrons have attracted a considerable
attention as a bright light source in the THz-wave andmillimeter wave regions for the spectroscopic purpose.
Coherent transition radiation (CTR), which is emitted
from a boundary between two media, is one of such a
coherent light source. CTR is usually utilized as a
non-polarized light source, because the electric vector oftransition radiation (TR) emitted from a metallic screen isaxially symmetric with respect to the trajectory of anelectron beam. In my previous reports [1, 2] the propertyof CTR emitted from a pair of wire-grid radiators withthe different polarization was experimentally investigatedin order to develop a new technique of generation of
circular polarized THz radiation. Circularly polarized
light has been useful in the circular dichroism
spectroscopy. Shibata et al. has developed a technique ofgeneration of circularly polarized millimeter-wave
radiation with the phase difference between the forward
TR and the backward one [3]. However, it was difficult tocontrol the polarization degree in that technique. In thisreport circularly polarized CTR has been generated witha new technique. With this technique the polarization
degree is able to be controlled precisely.
EXPERIMENTAL PROCEDURES: The experiment
was performed at the coherent radiation beamline [4] at
the L-band linac of the Research Reactor Institute, Kyoto
University. The energy, the width of the macro pulse, andthe repetition rate of the electron beam were 42 MeV, 33
ns, and 20 Hz, respectively. The average current of theelectron beam was 0.5 A. Two wire-grid polarizers(WG1 and WG2) 10 m thick with 25 m spacing wereused in order to generate the CTR with horizontal andvertical components, respectively. Each CTR was
superposed with phase difference through the opticaldelay system. Although a Martin-Puplett-type
interferometer is usually used as a spectrometer, agrating-type monochromator was used in this experiment.
The monochromator was set for the wavelength of 2.3
mm. The CTR was detected by a liquid-helium-cooled Sibolometer. In order to analyze the polarization degree awire-grid polarizer with a rotary holder was used in front

REFERENCES:[1] T. Takahashi, et al., KURRI-PR 2012 CO4-15.
[2] T. Takahashi, et al., KURRI-PR 2013 CO4-12.
[3] Y. Shibata et al., Rev. Sci. Instrum. 72 (2001) 3221.
[4] T. Takahashi et al., Rev. Sci. Instrum. 69 (1998)
3770.

Fig.1. Polarization diagram of CTR from WG1.

Fig.2. Polarization diagram of CTR from WG2.

Fig.2. Polarization diagram of superposed CTR from
WG1 and WG2.

採択課題番号 26016

コヒーレント遷移放射を用いたミリ波領域円偏光制御と近接場分光法に関する研究（京大・原子炉）高橋俊晴、窪田卓見

112

通常採択

CO4-4

Basic Study on Radiation-induced Luminescence from Natural Mineral

H. Fujita, M. Sakamoto1, T. Saito1

1 min at 50 ºC intervals ranging from 150 to 300 ºC as
preheat treatment. Each remnant of the samples was kept
in dark room without preheating treatment. After the ESR
measurements, all luminescence measurements were
performed using a JREC automated TL/OSL-reader system installed with a small X-ray irradiator (Varian,
VF-50J tube). All preparations were carried out under
dim red light.

Nuclear Fuel Cycle Engineering Laboratories, JAEA
1
Research Reactor Institute, Kyoto University
INTRODUCTION: Dielectric materials such as natural minerals emit radiation induced luminescence such as
thermoluminescence (TL) and optically stimulated luminescence (OSL). OSL is a well-established tool formeasuring radiation doses in unfired sediments [1]. It hasfeatures in common with TL which has long been used inmeasuring radiation doses [2]. Both TL and OSL dosimetry with white mineral do not need to be specially installed in advance, prior to dose estimation. Quartz is an
excellent material for use in dosimetry, because of its
almost ubiquitous availability including an accidental
place. Feldspar is an extensive ternary family of minerals
appropriate for OSL and TL dosimetry as they display astrong luminescence and are quite common in the Earth’s
formation. However, the detailed emission mechanisms
of TL and OSL from natural minerals such as natural
quartz and feldspar are not yet clear. In this study, theemission mechanisms of TL and OSL were investigatedin conjunction with various radiation-induced phenomena
after annealing treatments of quartz samples, involving
TL, OSL and electron spin resonance (ESR) measurements.

RESULTS: In this research, the ESR signals of Al
centers and Ti centers ([TiO4/H+]0, [TiO4/Li+]0 and[TiO4/Na+]0) were detected in the annealed quartz samples. Al centers are hole-trapped centers and Ti centers
are electron-trapped centers. Fig. 1 shows the intensitychanges of the Al
centers and the Ti
centers. ESR signal
intensity of Al centers decreased withpreheating temperatures, gradually.
On the other hand,
ESR signal intensity of Ti centers
showeddifferent
tendency from the
ESR intensity of Al
centers. The intensity of Ti centers
increased or was
Fig.1 Tendency of ESR signal intensity
constant up to 150with preheating temperature.
ºC of preheating
temperature. After
heating over 150 ºC, the intensity of Ti center decreased
with preheating temperatures. The results agreed to ourprevious results. However, the intensity tendency of Ti
centers was different between two quartz samples.
TL and OSL signals were measured using all kinds ofquartz samples. However, their data was not evaluated,completely. Therefore, the data analysis will be conducted in 2015.
In this research, the luminescence emission mechanism
could not be identified. Therefore, further work is necessary to identify luminescence mechanism using ESR
measurement and annealing experiment.

EXPERIMENTS: Two surface soil samples to 5 cm
depth were collected at different places in Ibaraki. Natural quartz samples were extracted from the soils by ausual treatment of 6M hydrochloric acid (HCl), 6M sodium hydroxide (NaOH) followed by 60 min of concentrated hydrofluoric acid (HF). The etching treatment with
HF solution was at room temperature. Further purification of the quartz grains was performed by hand selection
for the sake of elimination of feldspar grains as low as
possible. The purified quartz samples were sieved to adjust the grain sizes ranging from 150 m to 250 m in adiameter for ESR spectrometry, TL and OSL measurements. The quartz samples were annealed at 800 ºC for
24 hours in an electric furnace. The annealed quartz samples were irradiated a dose of 1 kGy with 60Co source(0.73 kGy/h at D-30 cm) at room temperature at Kyoto
University Research Reactor Institute (KURRI). The irradiated samples were stored at room temperature for one
day to eliminate afterglow emission in dark room. The
ESR measurement was carried out using an ESR spectrometer (Jeol Ltd., JES-TE 200) at −196 ºC. Prior to the
ESR measurements, the quartz samples were annealed for

採択課題番号 26027

REFERENCES:[1] Huntley, D. J., et al., Nature 313, 105-107 (1985).
[2] Mckeever, S. W. S., Cambridge University Press,
Cambridge, 103-105 (1985).

天然鉱物からの放射線誘起ルミネッセンスの基礎的研究（原子力機構、核サ研）藤田博喜（京大・原子炉）阪本雅昭、齊藤毅

113

通常採択

CO4-5Complex Structure of Ions Coordinated with Hydrophilic Polymer. 15.
Applied Discussion with Ionic Behavior in Hydrophobic Matrixes.
even with aqueous solvents. On the other hand, increasein mass (m, relative mass at each stage to non-doped
sample) was much less than one for the previous hydrophilic matrixes: m less than 2%.
Furthermore, not only deep diffusion of polyiodide in“(1st) iodine doping” but “elution out” of polyiodide orAg+ ion in “(2nd) Ag-doping”.(Fig.1&2, right) Suchbehavior is analogous to “Stage III” which is observed inexcessive “Ag-doping” to iodine-doped hydrophilicpolymers.[6]These results indicate that existence of polyiodide inpolymeric materials can let ionic diffusion overcome
general activation barrier.
ACKNOWLEDGEMENT: SEBS elastomers as hydrophobic samples, AR-770C and AR-830C, were presented
by Aron Kasei Co.Ltd. The authors express great gratitude for them to inspire unexpected viewpoints.

A. Kawaguchi , Y. Morimoto
Research Reactor Institute, Kyoto University
INTRODUCTION: We have reported composite structure brought by in situ preparation through "secondary
doping" by diffusion of metallic ions into iodine-dopedhydrophilic polymers. Polyiodide ions, Inm- (m, n: integer, n ≠ 1 ), which have been as solutes in aqueous solution, can be diffused into the polymers through immersing operation at room temperature. Or, the polymer
matrix previously iodine-doped enhances following diffusion of other molecules or ions into matrix polymer; if
the additional ion makes precipitates of inorganic saltwith iodide, hybrid composite can be achieved without
melting, nor casting, nor synthesizing.[1-3]Such singularity suggests microscopic behavior of polymer chains as “pseudo solvents”, where ionic diffusion in
nano-scale can be achieved or enhanced under affinity
with polymer matrix keeping its structure: chain orientation, crystalline structure, self-organization,,etc. However, even if matrix is composed by “hydrophilic” polymers, their polarization or ionic affinity are not matchedfor ordinary hydrophilic solvents, such as water, ethanol,,etc.; hydrophilicity of polymeric matrixes should bemuch lower than that of hydrophilic low molecules, andthat is a reason for general difficulty for charged ions todiffuse into the matrixes.
If so, observed rapid diffusion of polyiodides (“(1st) iodine doping”) or additional diffusion of metallic ions(“2nd doping”) should consistent with hydrophobicity ofmatrixes not only their hydrophilicity.[4,5] Then, similar procedures for “(1st) iodine doping” or “(2nd) Ag+ ion
doping” in hydrophobic matrixes were investigated ascomparison with the previous results in hydrophilic matrixes.
EXPERIMENTS: Commercial "SEBS"-elastomer,
AR-770C and AR-830C (Aron Kasei) were used as hydrophobic matrixes, which are composed of both polystyrene (hard segment) and polyethylene-polybutylene
co-polymer (soft segment).
Iodine doping was achieved with I2-KI(aq)/3.0N (for 22
hrs., at R.T.) and secondary doping was done with AgNO3(aq)/0.25M (for 30min., at R.T.).
RESULTS: Present matrixes are just "hydrophobic" depending on their chemical components; generally, theiractivity to aqueous solution is so low that ionic diffusion
or interaction should be negligible. However, ionic diffusion from aqueous solution into the hydrophobic matrixes was explicitly observed in coexistence of polyiodide ions. As shown in Fig. 1 and 2, “(1st) iodine
doping” and “(2nd) Ag-doping” easily advanced into bothhydrophobic matrixes in time of less than an hour at R.T.

Fig. 1. AR-770C iodine-doped with I2-KI(aq) (left)
and following “(2nd) Ag-doping” with AgNO3(aq)(right).

Fig. 2. AR-830C iodine-doped with I2-KI(aq) (left)
and following “(2nd) Ag-doping” with AgNO3(aq)(right).
REFERENCES:[1] A. Kawaguchi, Sens. Actuators B, 73 (2001) 174-178.
[2] Y. Gotoh, et.al., Polym. Prep. Jpn., 51 (2002),
2259-2259.
[3] patent. JPN-5444559 (2014).
[4] KAWAGUCHI Akio, et.al., SPring-8 User Exp. Rep.
5 (2000A), 354-354. (2000)[5] A. Kawaguchi, et.al., Macromol. Sym., 202, 77-83.
(2003)[6] A. Kawaguchi, Polym. Prep. Jpn., 62, 5116-5117.

(2013)

採択課題番号 26052 親水性高分子－金属塩ナノコンポジットの調製と構造（京大・原子炉）川口昭夫、森本幸生

114

一般通常
通常採択

CO4-6

Elucidation of Tritium Dynamics in Neutron Irradiated Tungsten

Y. Oya, M. Sato1, K. Yuyama1, T. Miyazawa2, R. Okumura3, Y. Iinuma3, T. Fujii3 and H. Yamana3

and voids [1-3]. No large difference for Peak 1 was foundamong 0.01 and 0.1 dpa Fe2+ irradiated samples, indicating that the retention of D adsorbed on the sample surface
or trapped by dislocation loops would be almost saturated.
However, for 0.1 dpa sample, major D desorption stage
was shifted toward higher temperature side at 850 K,
showing that voids would be more stable D trapping sites.
In the case of fission neutron irradiation, only D retention
as Peak 1 was increased, but its retention was almost thesame as Fe2+ irradiated W, indicating that the dislocation
loops for D trapping would be almost the saturation andno vacancy for D trapping was produced into the sample
due to its lower damage concentration, or rhenium (Re)which produced by the transmutation caused by thethermal neutron irradiation, would contribute on the enhancement of D re-emission, although vacancies were
produced. According to Ref. [4], due to the smaller sizeof Re atom than that of W atom, substitutional Re atom
tends to bound to self-interstitial atoms (SIA) because
their lattice strain field is opposite. Once the Re-SIA
complex is formed, the mobility of the SIA decreases,
leading to the enhancement of vacancy-interstitial recombination.

College of Science, Academic Institute, Shizuoka University
1
Graduate School of Science, Shizuoka University
2
Faculty of Science, Shizuoka University
3
Research Reactor Institute, Kyoto University
INTRODUCTION: Tungsten (W) is a candidate material for the plasma facing components in the fusion future reactors due to the lower hydrogen isotopes retention.
In a fusion reactor, W will be exposed to 14 MeV neutrons produced by the D-T fusion reaction during theplasma operation. Irradiation defects will be introducedby neutrons where hydrogen isotopes would be stably
trapped, leading to the enhancement of fuel retention.
Therefore, it is important to evaluate the hydrogen isotopes retention in neutron irradiated W. In this study, thedeuterium retention behavior in neutron irradiated W wascompared with that in heavy ion implanted W which has
typical defects such as dislocation loops, vacancies andvoids.

Desorption rate / 1017 D2 m-2 s-1

1.5

EXPERIMENTS: Disk type W (6 mmφ×0.5 mmt) purchased from A.L.M.T. Corp. Ltd was used as the sample.
The samples were heat-treated at 1173 K under ultrahighvacuum to remove the impurity and damages introducedby the polishing process. The neutron irradiation for the
sample was performed at Pn-2 port in Kyoto University
Research Reactor Institute (KUR) with the damage up to
4.3 × 10-4 dpa (displacement per atom). For the heavy ion
irradiation, 6 MeV Fe2+ was irradiated into the samples atroom temperature with the damage concentrations of 0.01
and 0.1 dpa by Takasaki Ion Accelerators for Advanced
Radiation Application (TIARA) at Japan Atomic Energy
Agency (JAEA). Thereafter, the samples were transferred to Shizuoka University for D2+ implantation. The
samples were irradiated at R.T. with 1 keV D2+ with aflux of 8.75×1017 D m-2 s-1 to a fluence of 1.0×1022 D m-2.
The D desorption behavior was evaluated by thermal
desorption spectroscopy (TDS) from room temperature
up to 1173 K and 1273 K for Fe2+ irradiated samples andneutron-irradiated sample, respectively, with the heating
rate of 0.5 K s-1.

1.0

Peak 1 Peak 2 Peak 3

Peak 4

un-damaged
Fe2+0.1dpa
0.01 dpa
fission neutron

0.5

0.0

400

600
800
Temperature / K

1000

Fig. 1. D2 TDS spectra for various damaged W.

REFERENCES:[1] Eleveld H and Van Veen A J. Nucl. Mater. 191(1992) 433-438.
[2] Iwakiri H et al., J. Nucl Mater. 307-311 (2002)
135-138.
[3] Luo G N et al., Fusion Eng. Des. 81 (2006) 957-962.
[4] Hasegawa A et al., Fusion Eng. Des. 89 (2014)
1568-1572.

RESULTS: D2 TDS spectra for various damaged W wereshown in Fig. 1. The D desorption peaks consisted offour peaks at 400 K, 550 K, 650 K, 850 K corresponded
to the adsorbed on the sample surface or trapped by dislocation loops, trapped by vacancies, vacancy clusters

採択課題番号 26063 中性子照射タングステンにおけるトリチウムダイナミックスの解明 通常採択
（静大院・理）大矢恭久、佐藤美咲、湯山健太（静大・技術）宮澤俊義（京大・原子炉）奥村良、
飯沼勇人、藤井俊行、山名元115