CO1-1 Design and Preparation of the Electrode Film for the Study of the Ion Distribution at theElectrochemical Interfaces of Ionic Liquids Using Neutron Reflectometry

EXPERIMENTS: To design the electrode material
that can be used for the sensitive detection of the ion distribution, neutron reflectivity profile (plot of the neutronreflectivity, R, against the momentum transfer, Q) was
simulated for Si/film/IL three phase system. Thin-layer
Al-Ti electrode film was prepared on a silicon wafer using a sputter apparatus. For IL, trioctylmethylammonium bis(nonafluorobutanesulfonyl)amide ([TOMA+][C4C4N−]) was prepared from the hydrophilic salts of the
IL-constituent ions ([TOMA+]Cl− and Li+[C4C4N−]) andpurified using column chromatography. Cyclic voltammograms at the [TOMA+][C4C4N−]/film interface wererecorded using a three-electrode electrochemical cell.
Pt was used as a counter electrode and Ag/AgCl as a quasi-reference electrode.
RESULTS: The calculation of the neutron reflectivity
profile revealed that the scattering length density, , ofthe electrode film strongly affects the sensitivity of theneutron reflectivity profile to the change in the distribution of ions at the IL/electrode interface. Fig. 1 shows
an example of the  profiles and the neutron reflectivity
profiles for Si/film/[TOMA+][C4C4N−] three-phase system when ×10−6 Å−2 for the film. One can seethat neutron reflectivity profiles are sensitive enough todifferentiate three models in which the distribution of
TOMA+ and C4C4N− ions at the electrode/[TOMA+][C4C4N−] interface are different from each other. Suchsensitivity to the ion distribution appears when the  value of the film is between 0.5 and 1.5 (10−6 Å−2).
To fulfill this  condition, we selected Al-Ti alloy as an

採択課題番号 23019（京大院・工）西Silicon
6

Electrode film

Ionic liquid
(a)

Å -2

5

-6

INTRODUCTION: Ionic liquids (ILs), which are liquid salts entirely composed of cations and anions, havepotential applications to electrochemical devices becauseof their several characteristics such as negligible volatility and wide potential window at the IL/electrode interface. The knowledge of the molecular-level structure at
IL/electrode interface is important to optimize the performance of the IL electrochemical devices. Theoreticalstudies have revealed several unique features of the distribution of ions at IL/electrode interface, such as
overscreening effect and lattice-saturation effect [1],while experimental studies that shed light on such features are limited to a few. In this study, we aimed toinvestigate the distribution of ions at the IL/electrodeinterface using neutron reflectometry. In this report, we
will show the results of the design and the preparation ofelectrode film, which is crucial to sensitively detect theion distribution.

 / 10Graduate School of Engineering, Kyoto University
1
Research Reactor Institute, Kyoto University

electrode material and prepared Al-Ti film on a siliconwafer. The thickness and the composition of Al in thefilm were evaluated by using x-ray reflectometry to be 46
nm and ~70%, respectively (~1.0×10−6 Å−2). To confirm the inertness of the film to ILs and to the electric
potentialchange,cyclicvoltammograms
at[TOMA+][C4C4N−]/film electrode interface were recorded. It was found that the Al-Ti film is inert in[TOMA+][C4C4N−] and has a potential window of at least
1 V.

4
3
2
1
0
-1

-300

-200

-100

0

100

z / Å

0

(b)

-1
-2
logR

N. Nishi and M. Hino1

-3
-4
-5
-6
0.00

0.02

0.04

0.06

Q /Å

0.08

0.10

-1

Fig. 1. (a) Scattering length density as a functionof z, the displacement along with the surface normal,
for Si/film/[TOMA+][C4C4N−] when ×10−6
Å−2 for the film. Si, the film and [TOMA+][C4C4N−]
are at z/Å≤−300, −300≤z/Å≤0, z/Å≥0, respectively.
(b) Neutron reflectivity as a function of momentum
transfer. Solid line is from Anion-topmost ALC
model [2], dashed line from Cation-topmost ALC
model, gray line from noncharged DCM model [3],and dotted line in (b) is the Fresnel reflectivity.
REFERENCES:[1] A. A. Kornyshev, J. Phys. Chem., B 111 (2007) 5545.
[2] M. Mezger et al., Science, 322 (2008) 424.
[3] O. M. Magnussen et al., Phys. Rev. Lett., 74 (1995)4444.

イオン液体｜固体界面におけるイオン多層構造の中性子反射率測定による研究
直哉、（京大・原子炉）日野正裕

共同通常CO1-2

Novel Analyzing Method of Amount of Hydrogen in Metal Alloy
Utilizing Small-Angle Neutron Scattering

M. Sugiyama, Y. Nishikawa*, K. Mori and T. Fukunaga

dridesamplessuch(Ti0.31Cr0.33V0.36)D1.7.

Research Reactor Institute, Kyoto University*Graduate School of Engineering, Kyoto University

RESULTS: Fig. 1 shows SANS profiles of the hydrogenstoragealloy,
Ti0.31Cr0.33V0.36
and(Ti0.31Cr0.33V0.36)D1.7. Hydrogen storage increases the
SANS intensity and also changes power of low from -3.0
to -4.0. It is well known that SANS intensity of material
which has surface fractal structure is expressed by,,(Ti0.31Cr0.33V0.36)H1.7,

where d is surface fractal dimension. This result clearly shows that the surface of
Ti0.31Cr0.33V0.36 becomes smooth by deuterium
storage. Now, we are considering the mechanism to make the surface smooth by hydrogenstorage.
1000

-4.0

q

-1

100

I(q) / cm

INTRODUCTION: Hydrogen is expected to be base ofnext generation energy in our world. However, there arestill problems which should be solved from a practicalapplication perspective. One of them is how to store hydrogen. Hydrogen storage alloy could be expectable
candidate for portable hydrogen storage tanks due to its
high hydrogen density in unit volume and also in unit
weight. Therefore, in these years, many researchers havebeing improving hydrogen storage performance of alloy,
such as hydrogen density in unit volume, in unit weight,
plateau temperature and so on. One of difficult problems
for improving the performance of hydrogen storage alloyis `residual hydrogen’, which remains in the alloy underthe external hydrogen pressure less than that of plateau.
In other words, it is considerably effective to reduce anamount of the residual hydrogen to improve an amountof available hydrogen in an alloy. Therefore, we havestarted to research characteristic feature of hydrogen inalloy to reduce the amount of the residual hydrogen inalloy as a final goal.
Among hydrogen absorbing materials, body centeredcubic (bcc) solid solution alloys possess a large hydrogencapacity. For example, Ti-Cr-V bcc alloy transforms
into (Ti-Cr-V)H2, which has the CaF2-type structure (i.e.,
fcc structure), by the hydrogenation reaction at room
temperature (RT). Its hydrogen-to-metal ratio (H/M) is
2.0, compared with 1.1 H/M for LaNi5H7 and 1.3 H/M
for Mg2NiH4. This is the reason why the Ti-Cr-V bcc
alloy has attracted much attention as promising hydrogenstorage applications such as a hydrogen storage tank ofan automobile. However, the detailed hydrogen absorbing mechanism of Ti-Cr-V is still unclear, particularly the surface structure of Ti-Cr-V in the hydrogenation
reaction.
The aim of this experimental proposal is to clarify thesurface (or interface) structure of the Ti-Cr-V bcc alloy inthe hydrogenation reaction, using Small-Angle Neutron
Scattering (SANS).

as(Ti0.31Cr0.33V0.36)D1.7
Ti0.31Cr0.33V0.36

10

1

-3.0

q
0.1

0.01

1E-3
0.01

0.1
-1

q/Å

Fig. 1. SANS profiles of the hydrogen storage
alloy,
Ti0.31Cr0.33V0.36
and(Ti0.31Cr0.33V0.36)D1.7..

METHOD: For the SANS experiments, we have prepared a null-alloy of Ti0.31Cr0.33V0.36 (i.e., bc ~ 0) in orderto enhance the surface (or interface) structure for the hy-

採択課題番号23030 水素貯蔵金属内の繰り返し水素脱着による水素分布揺らぎの研究（京大・原子炉）杉山正明、森 一広、福永俊晴

共同通常

CO1-340

Ar/39Ar Age of Volcanic Tuffs in the Eastern Africa

H. Hyodo and T. Itaya
Research Institute of Natural Sciences,
Okayama University of Science

EXPERIMENTS: Rock samples were crushed, andsieved in #25-50 mesh. After ultrasonic cleaning in distilled water, single mineral grains were handpicked. The
minerals were irradiated in the KUR reactor for 24 hours
at 1 MW for 40Ar/39Ar age determination. The total neutron flux was monitored by 3gr hornblende age standard[2], [3], which was irradiated in the same sample holder.
In the same batch, CaSi2 and KAlSi3O8 salts were used
for interfering isotope correction. A typical J-value of theage standards was (5.499 + 0.022) X10-3. In stepwise
heating experiment, temperature of a mineral grain wasmeasured using infrared thermometer whose spatial resolution is 0.3 mm in diameter [4] with a precision of 5
degrees.
RESULTS: An example of age spectra results fromstepwise heating experiments were shown in Fig. 1. The
first four fractions in the lower temperatures suggest apossibility of a secondary alteration. Preliminary resultsof other samples also indicate significant alterations confirmed under a microscope. In spite of the alterations, theage spectra consistently show plateau-like fractions at thehigh temperatures. The age distributions suggest that thetiming of the volcanic activity is approximately 20-21 Ma,
giving a constraint on the lower limit of the fossiliferous

40

09UG-B230

20.20 + 0.33 Ma

20
10
0
5

39

Ar/ ArApparent Age (Ma)50

37

INTRODUCTION: Recent findings of fossils of great
apes in the eastern Africa have drawn great attention as
their origin seems to have a close correlation to that ofhuman beings [1]. Age determination of these fossils is
often difficult simply due to lack of index fossils in thestrata or lack of suitable minerals for isotopic dating. The
strata often have volcanic ash layers, and the fossils areheld between them. Ages of the upper and lower ash layers of such fossil-bearing layers will constrain the age ofthe fossils. However, technical difficulties also exist in
dating volcanic ash using the K-Ar system.
We carried out 40Ar/39Ar laser step heating experiments
to determine ages of volcanic layers containing feldspar
minerals.

0
0.0

0.2

0.4

0.6

0.8

1.0

39

Fraction of Ar released
40

39

Fig. 1.
Ar/ Ar age and 37Ar/39Ar ratio spectra ofa feldspar from volcanic ash strata in Napak, Uganda. The ratio spectra suggest a presence of relatively
homogeneous gas release from low to high temperatures. This age and other plateau-like age spectra
implies the age of volcanic activity is about 20 Ma.
strata. However, the age of the strata is possibly a few
million years younger, considering other geological factors.
REFERENCES:[1] Y. Kunimatsu and 13 others (H. Hyodo at the 6th).
Proceedings of National Academy of Science 104(2007) 19220-19225.
[2] G. Turner, J.C. Huneke, F.A. Podosek and G.L.
Wasserburg, Earth Planet. Sci. Lett. 12 (1971)
19-35.
[3] J.C. Roddick, Geochim. Cosmochim. Acta 47 (1983)
887-898.
[4] H. Hyodo, S.-W. Kim, T. Itaya and T. Matsuda, J.
Min. Petr. Econ. Geol. J. 94 (1999) 329-3.

採択課題番号 23038
東アフリカ地域火山灰の 40Ar/39Ar 年代（岡山理科大・自然研）兵藤博信・板谷徹丸

一般通常

CO1-4Development of Neutron Accelerator for UCN Focusing

Y. Arimoto, P. Gertenbort1, S. Imajo2, Y. Iwashita3,
M. Kitaguchi4, Y. Seki5, H. M. Shimizu6, T. Yoshioka7
KEK,1ILL, 2Dep. of Phys. Kyoto Univ., 3ICR Kyoto Univ.,
4
KURRI, 5RIKEN, 6Dep. of Phys. Nagoya Univ.,7Dep. of
Phys. Kyushu Univ.
INTRODUCTION: The permanent electric dipole
moment of neutrons (nEDM) signals the violation oftime-reversal (T) invariance. The present upper limit is|dn| < 2.9 10-26 e cm (90% C.L.)[1], which is very close to
the predictions of some physics beyond the standard
model of particle physics, for example, supersymmetry.
For improvement of experimental sensitivity, the densityof neutrons is quite important in order to reduce the systematic errors from the uncertainty of the environment.
We are developing the transport system against loss ofneutron density. In the case of pulsed neutron source, theneutron pulse with high density spreads spatially andloses the density during transport because of their velocity distribution. When fast neutrons are decelerated and/or
slow neutrons are accelerated properly in the middle ofthe transport, these neutrons can be focused on the experimental area at the same time with recovering the density [2].
EXPERIMENTS: We made the adiabatic fast passage(AFP) spin flipper as the neutron accelerator, which consists of a compact static magnet to generate the gradient
field with 1 T at the maximum and an RF coil to generate
the resonance RF field (Fig. 1). When a neutron passes
through the AFP, the neutron’s spin flips with energy gainof loss. The energy can be controlled by selecting thefrequency of the RF. The frequency can be synchronizedwith the neutron pulse. The RF power is supplied by a
wideband amplifier with 1 kW output.
The space-time focusing experiment was performed at
the PF2 TES beam line in the High Flux Reactor at
Institut Laue Langevin. Ultracold neutrons (UCNs) were
provided from the turbine, which decelerates the neutrons
from the reactor by using continuous reflections off rotating mirrors. A mechanical shutter is used to supply
pulsed neutrons. The neutrons were transported with reflections off the mirror inside the guide tube.
RESULTS: We measured the TOF spectrum of theneutrons through this setup. Comparing the cases of RF
ON with the cade of RF OFF, accelerated and decelerated
neutrons can be seen (Fig. 2). The observed histograms
are in good agreement with Monte Carlo simulations.
Upon further analysis, the focusing of UCNs has been
confirmed. The efficiency of the spin flip was low, however, this can be improved with the amplitude of the RF
field.

The combination of this device and an intense pulsed
source, for example, SNS and J-PARC, enable us utilize
neutrons most effectively. We are planning the newnEDM experiment using this focusing technique and the
new type of magnetometers with extremely high precision.

Fig. 1. Neutron accelerator
system with magnet and RF.

Fig. 2. The ratio between TOF spectra with RF
ON and RF OFF. Accelerated and decelerated
neutrons can be seen as excesses.

REFERENCES:[1] C. A. Baker, et. al., Phys. Rev. Lett., 97, 131801(2006).
[2] H. M. Shimizu, et. al., Nucl. Instr. and Meth., A 634,
55-27 (2011).

採択課題番号 23046 中性子共鳴スピンエコー装置のためのデバイス開発 IV（京大・原子炉）北口雅暁、日野正裕、川端祐司（京大院・工）田﨑誠司

共同通常

CO1-5Development of Neutron-Beam Focusing Device

D. Yamazaki, M. Nagano1, F. Yamaga1, K. Soyama,
K. Yamamura1, T. Oda2 and M. Kitaguchi2
J-PARC Center, Japan Atomic Energy Agency
1
Research Centre for Ultra-Precision Science andTechnology, Osaka University
2
Research Reactor Institute, Kyoto University

condensing focal system.
The experiment was carried out on the CN3 beam line.
We mounted, from the upstream , slit1, slit2, the elliptic
mirror and a 3He detector as shown in Fig.1. The two slits
were used to control size of a virtual beam source andbeam divergence. We controlled the mirror alignment andobserved focused beam profiles.

INTRODUCTION: We have been developing supermirror devices for neutron beam focusing, free fromchromatic aberration [1-3]. In order to focus large-size
neutron beam into small spots, it is essential to develop“large acceptances” aspheric mirrors, i.e. large-size mirrors and/or “multiplexed” mirrors (stacked thin mirrors).
In particular, multiplexed mirrors are compact and can bemounted in small interspaces.
One hurdle to fabricate a multiplexed mirror is to produce thin aspheric supermiror-substrates, i.e. figure surfaces of thin substrate of ~1mm in thickness into precise
aspheric shape because the substrates absorb and scatter
neutron beams. In this experiment, we fabricated elliptic
surface of 0.5 m-pv in figure error and 0.2nm rms insurface roughness using the Numerically Controlled Local Wet Etching (NC-LWE) Technique and local
low-pressure grinds. After the surface figuring, we havecoated NiC/Ti (m=4) supermirror on the mirror substrate
at JAEA.
In this experiment, we carried out a performance test ofa single focusing supermirror on thin substrate on theCN3 beam line.

RESULTS: We could not find clear in tensity peaks inany stage axis scans in the mirror alignments and therefore could not focus the neutron beam effectively. This
result can be attributed to distortion of the mirror due tofilm stress. It is known that film stress of GPa order is to
be introduced in the mirror coating process with anion-beam sputtering machine. In this experiment, we
coated both sides of the very thin substrate (1mm inthickness) in order to balance out the film stress. But it
seems that the balancing out was not complete.

EXPERIMENTS: The focusing-mirror substrate wassynthetic quartz of 100mm (L) x 35mm (W) x 1mm (T)in sizes and fabricated by the following for steps: (1) dip
etching in hydrofluoric acid, (2) removal of altered surfaces by grinding, (3) damage-free surface figuring with
NC-LWE, (4) removal of low-frequency roughness bygrinding and (5) removal of high-frequency roughness bygrinding [4]. We fabricated elliptic surface of 0.5mm-pv
in figure error and 0.2nm rms in surface roughness Afterthe surface figuring, we have coated NiC/Ti (m= 4) supermirror on the mirror substrate at JAEA.
The elliptic mirror was designed for beam focusing at
the BL10 “NOBORU” of J-PARC/MLF and ellipsoidal
parameters are a= 3750.08mm and b= 24.64mm, focal
length is therefore 3750mm. This mirror is used on 12:1

Fig.1 Experimental setup at the CN3 beam line.
REFERENCES:[1] K. Yamamura et al., Annals of the CRISP 56/1 (2007)
541-544.
[2] R. Maruyama et al., Nucl. Instrum. Meth. A 600(2009) 68-70.
[3] K. Y amamura et al., Opt. Express 17 (2009) 6414
-6420.
[4] M. Nagano et al., Nucl. Instrum. Meth. A 634 (2011)
S112-S115.

採択課題番号 23050
中性子ビーム集光デバイスの開発
一般通常（原子力機構）山﨑 大，曽山和彦（阪大院工）永野幹典，山家史也，山村和也

CO1-6

Observation of Influence of Absorbing Layer on Neutron Reflectivity

S. Tasaki, J. Miura, Y. Abe and M.Hino1
Department of Nuclear Engineering, Kyoto University
1
Research Reactor Institute, Kyoto University
INTRODUCTION: As a matter wave, neutron forms astationary wave in multilayer system under a certain condition. In such a stationary wave, the amplitude of neutron wave function takes definite value depending on
the position in the multilayer. If we insert a absorbing
layer for neutron, such as Gd layer, into the multilayer,
the neutron reflectivity changes depending on the amplitude of the wave function at the position of the absorbing
layer. By analyzing the reflectivity, the amplitude ofneutron wave function in the multilayer can be estimated.
In the present study, we studied a Fabry-Perot multilayer
consisting of Ni and Ti, where the neutron wave function
forms stationary wave under resonant tunneling condition.
We fabricated a few Fabry-Perot mirrors with absorbing
layer at different positions, made measurement of neutronreflectivity and analyzed to estimate the neutron wave
function in the multilayer.
EXPERIMENTS: In Fig. 1, an example of opticalpotential for neutron is presented. The material with
low-optical potential (Ti) is sandwiched by the material
with high-optical potential. If a neutron whose normal

Fig.1 An example of neutron optical potential of a Fabry-Perot mirror.

Fig.2 Experimental set-up.

wavelength is equal to the thickness of the Ti layer, because of the enhancement of neutron wave function in the
Ti layer by reflecting by the Ni layers at both sides, astationary wave is formed in the Ti layer as shown in
Fig.2. In Fig.2, horizontal axis and vertical axis represent the position in the multilayer and the square of the
wave function, respectively.
The sample Fabri-Perot mirrors with absorbing material
were fabricated on Si wafers with vacuum evaporation.
Neutron reflectivity measurements were performed at
CN-3 beam port of KUR, when the operating power of
5MW.
RESULTS: Figure 3shows examples of measured neutron reflectivity. The left and right figure correspond to
the Fabry-Perot multilayer without and with absorbing
layer, respectively. Black circles with error bar represent the measured reflectivity, and the solid lines standfor calculated. Because of low resolution (about 10%),
the reflectivity dip due to the resonant tunneling issmeared. The calculated results, however, agree wellwith the measured results.
From these results, we estimated the depth of the dip and plotted (1-) as a function of the position in Fig. 4.
The square of amplitude of the wave function is alsoplotted (broken line) in the same figure. As shown in
Fig. 4, (1-) correspond to the square amplitude of the
wave function.

Fig.3 Neutron reflectivity of the Fabry-Perotmultilayers without (left) and with (right) absorbing layer.

Fig.4 The depth of the dip d as a function of theposition of absorbing layer in the multilayer.

採択課題番号 23054
低磁場駆動中性子偏極反射鏡の性能改善（京大院・工）田﨑 誠司、安部 豊、三浦 準（京大・原子炉）日野 正裕

共同通常CO1-7

Improvement of KUR-IBS as a Large-Scale Neutron Supermirror Fabrication Machine

M. Hino, T. Oda1, M. Kitaguchi and Y. Kawabata
Research Reactor Institute, Kyoto University
1
Department of Nucl. Eng., Kyoto University
INTRODUCTION: Supermirror is most important
key component of neutron guide tube. The total lengthof neutron guide tube is, in general, longer than 10 m.
When we fabricate neutron guide tube, the size ofdeposition area is very important. Ion beam sputtering(IBS) technique enables us to fabricate smooth layer
structure with sharp edge and we have succeeded infabricating m>5 supermirrors and very small
d-spacing multilayer [1]. The maximum substratearea at our KUR-IBS machine was limited to 200 mm
in diameter. On the other hand, the maximum substratearea at JAEA is 500 mm in diameter. It is enough large
to fabricate neutron guide tube and they are producing
a lot of supermirrors for J-PARC project [2]. In
FY2011, Kyoto University and KEK started toconstruct a new beam line for neutron spin echo(NSE) spectrometers at BL06 at J-PARC/MLF. The
NSE spectrometers are called “VIN ROSE” and it has
been developed at C3-1-2-2(MINE1) beam line at
JRR-3 reactor. We have designed the BL06 beam line
and start to fabricate supermirrors for the guide tube
by using the KUR-IBS machine. The total length of
the guide tube is about 29 m. It is really big task for us
to fabricate all supermirror components; however, weare going to do it because KURRI has a feasible future
program: Promotion of Leading Research toward
Effective Utilization of Multidisciplinary Nuclear
Science and Technology. It is, fortunately, accepted as
one of “Japanese Master Plan of Large Research
Projects: A Table of 43 Selected Projects” at FY2010
and FY2011. We consider that there is a big demand to
improve manufacturing ability of neutron guide inhouse. We will gain lots of valuable experience byconstructing the VIN ROSE beam line and theexperience contributes to improve neutron guideinstalled at KUR, such as E-3, and to construct newneutron facility for KURRI. In this study, we show
progress of fabrication of large scale supermirror withhigh performance.
EXPERIMENTS: Figure.1 shows photograph of new
substrate holder for fabrication of the BL06 guide tube
at J-PARC. The diameter of substrate holder is limitedby size of process vacuum chamber. The substrateholder and attachments were developed at theworkshop in KURRI. Figure 2 shows reflectivity by
NiC monolayer and m=2.5, 3 supermirror on thesilicon wafer. The wafer is placed on three points, top,
center, bottom on the substrate holder. The centermeans middle of circle (substrate holder), top andbottom is about 200 mm outer from the center. The
measurement was carried out at Time-Of Flight(TOF) instrument installed at CN-3 beam port. These
reflectivities at all points were high and almost
reproduced by the theoretical ones. We succeeded infabrication of large scale neutron supermirror withhigh reflectivity for real neutron guide. As the next
step, we are seeking best sputtering condition toincrease fabrication yield with high quality.

Φ 480mmFig.1. The photograph of new substrate holder in whichdiameter is 480 mm and silicon wafers placed at thesubstrate holder in KUR-IBS.

Fig.2. Measured and theoretical reflectivity of NiC
monolayer, m=2.5, 3 supermirror deposited on siliconwafers .

REFERENCES:[1] M.Hino, et al., Nucl.Inst.Meth., A 574 (2004)292.
[2] R.Maruyama, et al.,Physica B 385-386(2006)1256,
ibid., in this progress report.

採択課題番号 23055
自由曲面多層膜中性子反射ミラーシートの開発と応用（京大・原子炉）日野正裕、川端祐司、北口雅暁（京大・工）小田達郎、田崎誠司

共同通常CO1-8Performance Test of Supermirrors for a Guide Element Fabricated in the JAEA

R. Maruyama, T. Oda1, M. Hino2, M. Kitaguchi2, D.
Yamazaki, H. Hayashida, and K. Soyama
J-PARC Center, Japan Atomic Energy Agency
1
Graduate School of Engineering, Kyoto University
2
Research Reactor Institute, Kyoto University
INTRODUCTION: Neutron supermirror is one of themost useful optical devices for transporting, bending, andfocusing neutron beams. The thickness of the layers
needs to be decreased and the number of the layers increased to extend the effective critical angle of asupermirror. The effective critical angle of thesupermirror is characterized by the ratio m of the criticalangle of the supermirror to that of natural nickel. The
development of high-performance supermirror is important in neutron experiments since it leads to a considerable increase in available neutron intensity. The neutronreflectivity of the fabricated supermirrors needs to bemeasured in order to keep and improve the performanceof our fabrication system based on ion-beam sputtering(IBS) system and to confirm the surface roughness of thesubstrate.
EXPERIMENTS: Neutron supermirrors were fabricated by using an IBS system with dual bucket Ar+ ion
sources, installed in the Japan Atomic Energy Agency.
Test fabrication of NiC/Ti supermirrors [1-3] with m=4
for a guide element were performed using glass substrates (TEMPAX FloatⓇ). The layer sequence was designed by using the algorithm proposed by Hayter and
Mook [4]. The Total number of layers was 1201. Neutronreflectivity measurement was performed on a versatile
instrument of CN-3 at the research reactor, KUR, in the
Research Reactor Institute, Kyoto University. Top viewof the experimental setup is shown in Fig. 1. A polychromatic pulsed beam with a wavelength longer than 0.2
nm is used for the measurement. The wavelength spread
is estimated to be less than 5%. The incident beam wascollimated by a pair of horizontal slits to a divergent angle of 1.4 mrad.

Fig. 1. Top view of experimental setup for neutronreflectivity measurement on a versatile instrument of
CN-3 in the research reactor, KUR (unit: mm).

採択課題番号 23066

RESULTS and SUMMARY: Measured neutron reflectivity profiles are shown in Fig. 2. The deposition of
the supermirrors is completed as we designed since thecritical angle coincides with m=4 for each sample. The
rapid decay in reflectivity is observed at the momentum
transfer range higher than 0.215 nm-1 (m=1). The
reflectivities at the critical angle are 40% for all of thesamples, which is lower than the expected value of 60%.
This can be attributed to the surface roughness of theglass substrates since it is known that the surface roughness of this kind of glass substrates depends on the detailsof the production such as the composition of glass andthe floating process. This result implies that the process
to check the surface roughness before deposition needs tobe established.

Fig. 2. Measured neutron reflectivity profiles of thesupermirrors fabricated in the JAEA. The basereflectivities shown in closed circles and open
squares are shown to be shifted upward by 0.2 and
0.4 units, respectively.
ACKNOWLEDGEMENTS: The authors (R.M., D.Y.,
H.H., and K.S.) would like to express our sincere gratitude for all the people who supported us in our hard days
after the earthquake.
REFERENCES:[1] J. Wood, Proc. SPIE, 1738 (1992) 22.
[2] K. Soyama, Ph.D. thesis, Kyushu University, 1999.
[3] M. Hino et al., Nucl. Instrum. Methods Phys. Res., A
529 (2004) 54.
[4] J. B. Hayter and H. A. Mook, J. Appl. Crystallogr., 22(1989) 35.

中性子スーパーミラーの性能維持及び高性能化の為の中性子反射率測定（原子力機構）丸山龍治、山崎 大、林田洋寿、曽山和彦（京大炉）日野正裕、北口雅暁（京大・工）小田達郎

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