Ⅲ-1

Accelerators andInstruments

101BL7B 成影典之.docx

Ⅲ -1. Accelerators and Instruments

BL7B

Seven Years' Developments and Evaluationss of Optical Components for
CLASP Sounding Rocket Project at UVSOR BL7B
N. Narukage1, M. Kubo1, R. Ishikawa1, Y. Katsukawa1, S. Ishikawa1, T. Kobiki1, G. Giono1,
R. Kano1, T. Bando1 and S. Tsuneta2
1
National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara 252-5210,
JAPAN

2

Our team consisting of Japan, US, Spain, France,and Norway developed a Chromospheric LymanAlpha SpectroPolarimeter (CLASP). CLASP is aimed
at exploring the magnetic fields in the solar
atmosphere (the upper chromosphere and transition
region) via the Hanle effect in the Lyman-alpha (Lyα)
line (121.6 nm) for the first time [1, 2]. This
experiment requires precise spectropolarimetricobservations with a polarimetric sensitivity of 3σ ~0.1% and a wavelength resolution of 0.01 nm.
In order to achieve the polarimetric sensitivity of3σ ~ 0.1%, we designed a new type VUVspectropolarimeter [3] and developed its opticalcomponents (e.g., waveplate [4], polarizer, etc.) andsome types of high reflectivity coatings using
UVSOR BL7B. These developments and evaluations
spent seven years [5].
On September 3rd 2015, CLASP was launched witha NASA sounding rocket at the White Sands Missile
Range in New Mexico, United States. During fiveminutes observation, CLASP successfully observed
linear polarizations (Stokes I, Q, U) in the solar Lyαline with a polarization accuracy of 0.1% for the firsttime [6, 7]. We also took 2D Lyαimages with 0.6 sec
cadence.
This data is very beautiful and its quality is perfect.
Now, we are analyzing the data in detail [6, 7]. This
full success of the CALSP project is significantly due
to the Lyαbeam of UVSOR BL7B, since its beam(that is very intense, strongly linearly polarized, very
pure in wavelength, and very stable) is ideal for theevaluation of the CLASP optical components. We
really acknowledge the staff of UVSOR, especially,
M. Hasumoto and K. Tanaka, S. Kimura at Osaka
University, and K. Fukui at Fukui University for theirsupport of our experiment at UVSOR.

http://hinode.nao.ac.jp/news/CLASP_Launch/
http://hinode.nao.ac.jp/KakenS/CLASP.shtml

Fig. 1. Photo of CLASP and Japanese members of
the CLASP project.

[1] R. Kano et al., SPIE 8443 (2012) 84434F.
[2] K. Kobayashi et al., Proc. Fifth Hinode Science
Meeting, Astronomical Society of the PacificConference Series 456 (2012) 233.
[3] N. Narukage et al., Applied Optics 54 (2015)
2080.
[4] R. Ishikawa et al., Applied Optics 52 (2013) 8205.
[5] UVSOR Activity Reports from 2009 to 2014[6] NAOJ news, 270 (2016), Issue in January 2016
http://www.nao.ac.jp/contents/naoj-news/data/nao_ne
ws_0270.pdf[7] CLASP web pages:

Fig. 2. Photo of the CLASP launch.

31

Ⅲ -1

011Othersand
中村光廣.docx
Ⅲ -1. Accelerators
Instruments

OthersDevelopment of Large Grain Size Nuclear Emulsion
A. Nishio1, M. Moto1, Y. Manabe1, K. Kuwabara1, K. Morishima1,2 and M. Nakamura1,3
2

Ⅲ -1

1
Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
Institute for Advanced Research, Nagoya University, Nagoya 464-8601, Japan
3
Ecotopia Science Institute, Nagoya Universuty, Nagoya 464-8601, Japan

Nuclear emulsion is a kind of photographic film andhas sensitivity for ionizing radiation. The film record
tracks of charged particle with angular accuracy under
several mrad.
Nuclear emulsion is made by coating emulsion gelon plastic base. In Nagoya University, started aemulsion gel production machine in 2010. It was
enable us to develop new-type emulsion gel by ourself.
Emulsion gel is mainly consisted by silver bromide
crystal and gelatin. We report about properties of large
grain size nuclear emulsion developed in Nagoya
University.
We made emulsion gels which have silver bromide
crystal with diameter about 200, 300, 600 nm. The
traditional crystal size (incl. OPERA FILM [1]) is 200
nm. Figure 1 shows electron microscopic view ofsilver bromide crystals (left below : OPERA FILM
~200 nm, center : Large grain size nuclear emulsion~600 nm ). Emulsion gel of each crystal size warechemically sensitized in an optimal way [2]. Nuclear
emulsion films ware prepared using these gel.
Emulsion films ware exposed electron beam at
UVSOR which has equivalent energy with minimum
ionizing particle. We did chemical development in
Nagoya University after exposure.
After development, electron tracks were visible
with a light microscope (Fig. 2). We measured Grain
Density, counts of silver grains per 100 μm. And we
defined Crystal Sensitivity as ratio of Grain Density
divided by Number of penetrated crystals. We show atable of them in each crystal size (Fig. 3).
Figure 2 shows the larger the diameter of the silver
bromide crystal, it also increases the size of thedeveloped silver grains. And Fig. 3 shows the larger
the diameter of the silver bromide crystal, the crystal
sensitivity was high. Crystal sensitivity was 44% at~600 nm crystal nuclear emulsion.
Large grain size nuclear emulsion opens up a new
vision of wide-field automatic nuclear emulsion
scanning by low magnification optical systems. And it
has possibilities to improve latent image fading. Also
this result of latent image formation in large crystals is
efficient performance suggest its potential.

Fig. 1. Electron microscopic view of silver bromide
crystal (left below : OPERA FILM ~200nm, center :Large grain size nuclear emulsion ~600nm ).

Fig. 2. Light microscopic view of electron tracks.

Fig. 3. Basic properties of nuclear emulsion in eachcrystal size.
[1] T. Nakamura et al., Nucl. Instrum. Meth. A556
(2006) 80.
[2] M. Moto et al., 2nd Fall meeting of Federation of
Imaging Societies. (2015) 29.

32

021Accelerators,BL1U 全炳俊.docx

Ⅲ -1. Accelerators and Instruments

Accelerators, BL1U

Transmission Nuclear Resonance Fluorescence Measurement of 208Pb in
Natural Lead Target with Laser-Compton-Scattering Gamma-Ray at BL1U
H. Zen1, Y. Taira2, J. Yamazaki3, T. Hayakawa4, T. Shizuma4, T. Kii1,
H. Toyokawa2, M. Katoh3,5 and H. Ohgaki1

Intitute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan
3
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
4
Japan Atomic Energy Agency, Tokai-mura 319-1184, Japan
5
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585,
Japan
1

2

High intensity and quasi-monochromatic gammarays has been generated by laser Compton scattering
between the high energy electron beams and intenselaser beams at BL1U in UVSOR-III. Gamma-ray
beam with the maximum energy of 5.4 MeV and thetotal flux of 1×107 photons/sec can be generated byuse of 1.94-μm 5-W fiber laser and 300-mA 746-MeV
electron beams. In this fiscal year, we tested thetransmission Nuclear Resonance Fluorescence (NRF)
measurement [1] of 208Pb in a natural lead target.
The schematic diagram of the transmission NRF
measurement and the energy spectra of incident
gamma-ray beams, transmitted gamma-ray beams,
and NRF from the witness foil (a natural lead) are
shown in Fig. 1. The gamma-ray with energy of a
NRF level of 5.291 MeV resonantly absorbed by
208
Pb in the first target (a natural lead) and transmitted
gamma-ray spectrum will be the notch spectrum asshown Fig. 1. The transmitted gamma-rays will hit
the second target, called as the witness foil, whichemits NRF gamma-rays. Therefore we can measure
the nuclear resonance absorption in the first target as
the reduction rate of the NRF peak by using a High
Purity Germanium (HPGe) detector.
In this experiment we measured the NRF yieldfrom the witness foil as the function of thickness ofthe first target. Since the NRF gamma-ray yield from
witness foil depends both on the amount of theresonant (nuclear) absorption and on the atomic
absorption of the first target, we need to measure theatomic absorption of the first target and corrected the
NRF yield. Figure 2 shows the measured result. The
NRF yield clearly shows linearity to the thickness ofthe first target as we have expected for thin target
measurements. The required integration time of NRF
events in case of a 6-mm target was around 2 hours inthis experiment.

Fig. 1. Schematic diagram of NRF transmission
measurement and energy spectrums of incident
gamma-ray beam, transmitted gamma-ray beamthrough the target and NRF from the witness foil.

[1] B. J. Quiter, B. A. Ludewigt, V. V. Mozin and S. J.
Tobin, 50th Annual Meeting of the Institute of
Nuclear Materials Management 1 (2009) 786.

Fig. 2. Measured dependence of the NRF yield fromthe witness foil on the thickness of the first target.

33

Ⅲ -1

031BL1B 木村真一.docx
Ⅲ -1. Accelerators
and Instruments

BL1B

Improvement of Accuracy of Reflectivity Spectrum in the THz Region
S. Kimura

Graduate School of Frontier Biosciences, Osaka University, Suita 657-0871, Japan

Ⅲ -1

Strongly correlated electron systems have acharacteristic electronic structure near the Fermi level(EF) owing to the strong electron correlation, and theelectronic structure is the origins of unusual physicalproperties such as unconventional superconductors,
heavy fermions and so on. To observe the electronic
structure is important to clarify the effect of theelectron correlation.
On of the methods to detect the electronic structurevery near EF is reflectivity (optical conductivity)
measurement in the terahertz (THz) region [1]. The
method is bulk sensitive compared withphotoemission spectroscopies that are widely used
recently. Since results of a THz spectroscopy can be
regarded as from bulk properties, they can be directlycompared with thermodynamic physical properties.
However, since reflectivity of such metallic materials
in the THz region is almost unity, so a tiny change,
typically less than 1%, and the absolute value of thereflectivity must be measured [2]. To perform suchaccurate measurement of reflectivity spectra, we need
intense and stable THz light such as synchrotron
radiation. Then we are developing high accurate THz
reflectivity measurement system at BL1B ofUVSOR-III. The block diagram of the measurement
is shown in Fig. 1.
At UVSOR-III, a top-up operation at one-minuteintervals is now adopted, but the beam current isreduced slightly during the interval. To eliminate theeffect of the beam current reduction, we introduced adigital divider (made by Equipment Development
Center of IMS) in which the output signal from a
detector (a Si bolometer) is instantly normalized by
the beam current of SR. In addition, to eliminate thesignal during the top-up injection, we get the top-up
signal from the accelerator by an personal computer(PC) and put a TTL signal to the data accumulator.
During the top-up injection (the TTL signal is on), thedata accumulator rejects the signal from the detector.
Finally, the data accumulator gives an interferogram(detector intensity vs mirror position of the moving
mirror in the FTIR) to the PC.
The effect of the top-up rejection as a 100% line,
which is the first spectrum divided by the second one
with a same condition, is shown in Fig. 2. Both lines
are used the digital divider. Without the top-up
rejection, the 100% line is 0.9950.003, but it
becomes 1.0000.002 with the top-up rejection in thewavenumber region of 20–100 cm-1. Therefore, thetop-up rejection is effective to determine the accuracyof reflectivity spectra in the THz region.
The PC also operates a temperature controller ofsamples. For the measurement of temperaturedependent reflectivity spectra, we introduced a
specially designed feedback positioning system [3] tomaintain the overall uncertainty level less than 0.5%
at sample temperatures in the range of 4–300 K at
BL1B. By the preparation, highly accurate reflectivity
measurements in the THz region can be performed.

Fig. 1. Block diagram of the measurement systemwith the rejection during top-up injections and thenormalization by the beam current.

Fig. 2. 100% lines with and without top-up rejection.
[1] S. Kimura and H. Okamura, J. Phys. Soc. Jpn. 82(2013) 021004.
[2] S. Kimura, J. Sichelschmidt, J. Ferstl, C. Krellner,
C. Geibel and F. Steglich, Phys. Rev. B 74 (2006)
132408.
[3] S. Kimura, JASCO Report 50 (2008) 6. [inJapanese]34

Ⅲ -1. Accelerators and Instruments

041BL2B 解良聡.docx

BL2B

Reconstruction of the Beamline BL2B for Photoelectron Spectroscopy ofOrganic Materials
K. R. Koswattage1, T. Ueba2, Y. Nakayama3, K. K. Okudaira4 H. Ishii1,4 and S. Kera2,4
Center for Frontier Science, Chiba University, Chiba 263–8522, Japan
2
Institute for Molecular Science, Okazaki 444–8585, Japan3
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of
Science, Noda 278–8510, Japan
4
Graduate School of Advanced Integration Science, Chiba University, Chiba 263–8522, Japan1

The reconstructed beamline 2B is dedicated tophotoelectron emission experiments to investigate
electronic structures of surfaces and interfaces ofwide range of molecular materials. Here wesummarize the three-year program of the beamline
reconstruction.
The beamline is equipped with a spherical grating
dragon type monochromator. The monochromator
covers the photon energy range from 23 to 205 eVwith resolving power of 2000 – 8000 range [1-2].
In the reconstruction process, we have solved amalfunction in the monochromator, introduced a
UHV chamber (monitoring and filtering the photons)
downstream of the M4 mirror chamber, built a newinterlock system, and placed a new end-station wherea load-lock and two sample preparation chambers areconnected. At the deposition chamber, samples can beheated by a radiation heating. By the load-lock andsample transfer systems, samples can be introduced tothe preparation chamber without breaking UHV.
Three evaporators can be equipped from thedownstream. Another chamber so called cleaning
chamber is equipped with surface preparation
apparatus such as IR heater, sputter gun, and LEED
system. At the measurement chamber, VG-Scienta
R3000 angle-resolved photoemission spectrometer isinstalled. The sample is mounted in the sample holder
on cryogenic manipulator with manually operated
5-axis motion in this chamber and the sample can becooled down to around 15 K. The sample temperature
is controlled by a combination of liquid He coolingand a resistive heater.
After the alignment, beam spot size is roughly
estimated to be about 1.5 mm × 0.8 mm (vertical ×
horizontal) after the final refocusing mirror for exist
slit of 300 μm. Also, the photon flux for an exit slit
width of 300 μm are estimated to be 1× 1010 – 3× 1010,
4× 1010 – 2× 1011, and 1× 1010 – 2× 1010 photons/s forG1 (80 – 150 eV), G2 (50– 120 eV) and G3 (25 – 55eV) gratings, respectively using a silicon photodiodeand Au mesh in the monitoring chamber.
A filter (Al20nm/Mg300nm/Al20nm-Ni70nm
mesh, LUXEL) in the monitoring chamber isequipped in order to reduce second order light. It isestimated that the second order light contribution canbe reduced to 2.4% from 10% at photon energy 28 eV
by inserting the filter. Also, the photon energy
accuracy can be checked by using the first and second

order light and it is estimated to be a difference of-0.04 eV at photon energy 28 eV.
The beam line resolution is determined bymeasuring a clean Au(111) at 15 K as shown in the
figure together with ARPES of surface state region.
The energy resolution ΔER of analyzer was set to be
20 meV, giving the photon energy width of ΔEω=30
meV at hv =28eV, which is much greater than that of
the beamline specification and the previously
estimated value (ΔEω=14 meV) in the last year. The
momentum resolution will be saturated by a large
spot size of the beam. Unfortunately, the stabilities ofphoton flux and beam position are not sufficient for along experimental acquisition due to the coolingproblem of M0 system. It may also affect to theresolution problem above mentioned.

Fig. 1. (a) Low-temperature PES spectra of Fermiedge of Au (111). (b) Surface state region of Au(111)
at room temperature (RT) and 15 K at hν = 28 eV.
[1] H. Yoshida et al., J. Synch. Rad. 5 (1998) 774.
[2] M. Ono et al., Nucl. Instrum. Meth. Phys. Res. A
467-468 (2001) 577.

35

Ⅲ -1

051BL5B and豊田光紀.docx
Ⅲ -1. Accelerators
Instruments

BL5B

EUV Multilayer Mirrors for Focusing
Isolated Attosecond Pulse in 40 nm Wavelength Region
M. Toyoda1, Y. Tamaru2,3, S. Mori1, K. Sawada2,4, Y. Fu2, E. J. Takahashi2, A. Suda3,
F. Kannari4, K. Midorikawa2 and M. Yanagihara1

Center for Advanced Microscopy and Spectroscopy, IMRAM, Tohoku Univ., Sendai 980-8577, Japan
2
RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198, Japan
3
Tokyo University of Science, Noda 278-8510, Japan
4
Keio University, Yokohama 233-8522, Japan.

1

Ⅲ -1

In the past decade, coherent light sources based onhigher-order harmonics generation in extreme
ultraviolet (EUV) region have been investigated.
Recently, Takahashi et al. has reported isolated
attosecond pulse (IAP) generation in a 40 nm
wavelength region, where an isolated intense pulse
with pulse energy of a few μJ was demonstrated byapplying the novel two-color excitation technique [1].
When such the intense EUV pulse is focused withdiffraction limited objective so as to produce a small
focal spot with size of a few handled nanometers, we
can generate extremely intense light fields with the
maximum intensity of over 1016 W/cm2, whichenables us to access the new frontier of nonlinear
optics in EUV region.
For the diffraction-limited focusing of the IAP, we
are developing the Schwarzschild objective made of
two-curved multilayer mirrors [2]. The objective has
two practical advantages, i.e., high spatial resolution
resulting from large-numerical aperture optical design,and spectral selectivity based on the Bragg reflection
on multilayer mirrors. To realize the intense lightfields with the objective, firstly, we need multilayer
mirrors with practical high reflectivity. In this report,
we describe design, fabrication, and test of multilayer
mirrors that is suitable for the focusing application in
the 40 nm wavelength region.
Design of the multilayer mirrors are summarized inTable 1. After applying the selection rule for highreflectivity, which has been given by Yamamoto, [3]three material pairs, i.e., SiC/Mg, Cr/Mg, and Sc/Si,
were chosen. The multilayer coating was consisted of
20 bi-layers. The period, ddesign, and thickness ratio, Γ,were numerically optimized with the multilayer
modeling software, IMD, [4] to give the maximum
reflectivity at a wavelength of 40 nm. Then, the threemultilayer coatings were deposited on a Si wafer byusing the magnetron sputtering apparatus (SPL-500,
Canon Anelva Corp.). We also experimentallyconfirmed a period of the multilayer coating withsmall-angle X-ray diffraction (RGXR, Rigaku Corp.).
As shown in Table 1, the actual period of the sample,
dactual, was preciously controlled within 1% of thedesign value.
At-wavelength reflectivity was examined with the
EUV reflectometer equipped on beamline BL5B ofUVSOR. A 300-nm thick Mg filter placed upstreamof the reflectometer removes higher-order lights fromthe monochrometer. Figure 1 shows the measured
reflectivity, as a function of a wavelength. The peakreflectivity, Rpeak, and band width, ΔλHWHM, are alsotabulated on Tab. 1. We observed relativity highreflectivity between 30 to 40% on the Mg-based
multilayer mirrors. Especially in SiC/Mg multilayer
mirror, practical high reflectivity and wide band
width were confirmed simultaneously, where we can
expect the maximum intensity of over 1016 W/cm2
with pulse duration below 800 attosecond on thefocus of the two-mirror objective.
Table 1. Design parameters for the multilayer mirrors.
SiC/Mg
Cr/Mg
Sc/Si
ddesign (nm)
21.2
21.2
21.0
Γ
0.25
0.23
0.33
21.0
21.4
20.9
dactual (nm)Rpeak (%)
38.3
28.7
23.3
ΔλHWHM (nm)
2.8
3.0
4.9

Fig. 1. EUV reflectivity spectra of the mirrors. Data
were measured with an incident angle of 11 deg.
[1] E. J. Takahashi et al., Nat. Commun. 4 (2013)2691.
[2] M. Toyoda et al., Appl. Phys. Exp. 5 (2012)
112501.
[3] M. Yamamoto and T. Namioka, Appl. Opt. 31(1992) 1622.
[4] D. L. Windt, Computers in Physics, 12 (1998)
360.

36

Ⅲ -1. Accelerators and Instruments

061BL5B 吉川一朗.docx

BL5B

Reflectance Measurement of Mo/Si Multilayer Coated Mirror by Using
Pure-Calibrated EUV Beam
M. Kuwabara1, F. Suzuki2, R. Hikida2 and I. Yoshikawa1

Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University ofTokyo, Chiba 277-8561, Japan2
Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Tokyo
113-0033, Japan

1

Ⅲ -1

We are developing space-based imagers for plasma
emissions from the plasmasphere. The main target of
our instruments is He ion in the plasmasphere. He ion
resonantly scatters solar He II (30.4 nm) radiation. He
column densities along the field of view of
instruments can be obtained because intensities ofemissions are proportional to them under theassumption that observational regions are opticallythin. Therefore, the accuracies of the efficiencies ofthe optics systems of instruments are critical for
estimation of the densities and to achieve thescientific goals of our missions.
In space and planetary science, a number ofimaging and spectroscopic observations in the
spectral range of extreme ultraviolet have been andwill be performed. High-reflectivity multilayer
coatings for the He II radiation have been required
and developed for some of these applications. A
multilayer coated mirror of Mo/Si has been usuallyand conventionally used in the He II emission line,
because it is highly stable [1].
In this experiment, we measure the reflectance of
Mo/Si multilayer mirror at the wavelength of 30.4 nm.
We install an Al/Mg/Al filter and an Sn filter at theentrance of the SOR beam in order to achieve thepure 30.4 nm light [2-4].
With the pure 30.4 nm line, we measure thereflectance of the multilayer coated mirror at various
incident angles by using the photo diode.
The result is shown in Fig. 1 and the reflectances of
Mo/Si multilayer mirror are 13, 9, 6, 4, and 3% atincident angles of 10, 15, 20, 25, and 30 degrees,
respectively. Note that the statistical error bars ofreflectivity measurement are over-plotted, but they
are so small (approximately 1%) that you might not
identify them.
For the next step, in addition to the 30.4 nm line,
we plan to measure the reflectance at 83.4 nm line. O
ions have emission line at 83.4 nm and are known as
one of the main components in the plasmasphere.

Fig. 1. Reflectance of the Mo/Si multilayer coatedmirror at the wavelength of 30.4 nm.
[1] Yoshikawa et al., Earth Planets Space 60 (2008)
407.
[2] Ogawa et al., UVSOR Activity Report 36 (2008)
127.
[3] Murakami et al., UVSOR Activity Report 37(2009) 47.
[4] Sakai et al., UVSOR Activity Report 38 (2010)45.

37

071BL6B 手島史綱.docx
Ⅲ -1. Accelerators
and Instruments

BL6B

An Investigation into the Cause of Instability at BL6B
T. Iizuka1, F. Teshima2, E. Nakamura2, H. Zen3 and K. Tanaka2, 4

Toyota Technological Institute, Nagoya 468-8511, JapanUVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
3
Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan
4
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585,
Japan
1

2

Ⅲ -1

Beamline 6B (BL6B) is an Infrared-THz beamline
which has confocal type micro-spectroscope station,reflection/transmission station and IR microscope
imaging station. This beamline can provide
measurement-techniques which are not available inconventional IR sources, utilizing the characteristics
of synchrotron radiation (SR) such as high brilliance,
polarization, or broad spectrum.
Spectroscopy in THz-IR region is performed with
FT/IR: Michelson-type Interferometer which requires
stable right source. However, the top-up operation of
UVSOR induces two type of instability: short term
blinking coincides with electron beam injection on
every minutes, and long term attenuation of power.
The former causes spike noise on interferogram,and it can be solved by excluding those scan data
during the beam injection, by synchronizing datacollection of FT/IR. The latter one might originate
from the drifting of the focal point of M0 mirror, firstmirror of BL6B. And a qualitative observation was
required to eradicate the drifting instability which
influence on S/N ratio.
Because the drift continues for about 10 hours after
the first injection, the most suspected origin is
temperature change caused by heat from synchrotron
radiation. Addition to this, M0 mirror of BL6B andvacuum chamber has no cooling system to avoid
vibration comes from coolant flow. Therefore,
thermal expansion of M0 mirror holder or vacuum
chamber might cause the drift of the focal point. It
can be simply estimated by observing a He-Ne visible
laser spot reflected from M0 mirror. In this study, we
monitored the position of the laser spot to clarify theorigin of the instability at BL6B.
The change of spot position was observed byinterval photographing by a web camera. Each laser
spot positions were then estimated by handmade
LabVIEW program by following procedure. First,
color pictures were converted to grayscale, and regionof interests (ROI) was segmented around the laser
spot, to get two-dimensional distribution. After
substituting the background data, i.e. picture withoutlaser spot, one-dimensional profile were obtained toestimate the center of laser spot in X and Y directions.
After that, base line was subtracted and peak position
were estimated with following formula,

It is applicable not only to laser spot but also the focal
point of M0 mirror which is not circular shape.
Figure 1 shows the change of laser spot position
from M0 mirror during a week. It can be seen theoscillation of mirror angle which moves one direction
during top-up operation and saturate, then moves tothe other direction during shutdown. The
displacement of laser light saturated about 9 hours
later after the start of top-up operation, and it isconsistent with previously observed long term drift of
SR power at the end station. The comparison of thechanges of mirror direction (laser spot) and SR focal
spot is shown in Fig. 2. Two results show pretty close
correlation, and one can thus conclude that the spot
drift originate from mirror direction. From anotherpoint of view, it is available to stabilize the SR focal
spot position by a feedback control with M0 mirror
direction which can be obtained from laser spot
position, and is able to perform simultaneously withuser experiments at the end station.

Fig 1. One week observation result of laser spot
position reflected from M0 mirror. X, Y is horizontal,
perpendicular change to the ground, respectively.
Green areas indicate the operation time of UVSOR.

  f x ,Center   x  f x 

Fig. 2. Comparison of reflected laser spot (gray) andfocal point of SR light (color).

where f(x) is the light intensity at pixel position of x.

38

Ⅲ -1. Accelerators and Instruments

081BL7B 木村真一.docx

BL7B

Performance Evaluation of Spectrometer for High-Resolution
Vacuum Ultraviolet Inverse Photoemission Spectroscopy
2

Y. Ohta1, A. Yoshizumi1, Y. Ohtsubo1,2 and S. Kimura1,2

Graduate School of Science, Osaka University, Suita 565-0043, Japan
Graduate School of Frontier Biosciences, Osaka University, Toyonaka 565-0871, Japan1

Photoemission spectroscopy (PES), which is aphoton-in/electron-out process, is one of experimental
tools to detect electronic structure of materials. Since
the energy resolution of PES has become better thanseveral meV nominally, the method is usually used forthe determination of precise electronic structure aswell as orbital-selective interactions. Even though PES
is widely used at present, it has a serious shortcoming
to be unable to detect unoccupied electronic structure.
In contrast to PES, inverse photoemission
spectroscopy (IPES), which is an electron-in/photonout process, is a method to determine unoccupied
electronic structure [1]. Accordingly, although themethod has been used for a long time, the energy
resolution is not good compared to that of PES. The
best energy resolution of IPES as far as we know is
190 meV [2]. The combination of IPES to PES
provides the perfect information of electronic structureof materials. However, spectra of IPES cannot bedirectly compared with those of PES because of poor
energy resolution of IPES.
To perform IPES experiment with good energy
resolution, for instance better than 100 meV, both theelectron source and the photon detector should be
improved. Since the quantum efficiency of the IPES
process is about five orders of magnitude smaller thanthat of the PES process [3], the throughput of the IPES
system should be improved. Then, we are now
developing a new IPES system using a high brilliant
photo-cathode electron source based on a strained
GaAs-GaAsP superlattice [4] and a VUV spectrometerusing a Seya-Namioka-type monochromator (focal
length: 20 cm, grating: laminar-type, 2400 L/mm)
combined with an X-ray CCD detector (1024x256
pixels). Here, we report the energy resolution andthroughput of the VUV spectrometer.
To check the performance of the VUV spectrometer,
we set the spectrometer at the end of the sample
chamber of BL7B. The entrance slit of themonochromator is located at the off-focus position of
the beamline to reduce the intensity of SR. The center
wavelength of spectrometer was set at elevenwavelengths of 40  120 nm and monochromarized
lights from the beamline with the wavelengths of 30 
120 nm were introduced to the spectrometer. The
intensity images on the CCD detector wereaccumulated. The CCD images content thecorrespondence between wavelengths and CCD pixel
numbers and the efficiency, which is the intensity
normalized by incident photons, and wavelength

resolutions at a center wavelength of the spectrometer.
As a result, we obtained a linear relation between
wavelength and pixel number of the CCD detector at
all center wavelengths. The obtained wavelength
resolutions and efficiency (intensity normalized byincident photon flux) as functions of incident
wavelength and center wavelength of the spectrometerare shown in Fig. 1. From this data, we could knowthat the area of the incident wavelength of 40  70 nm
and the center wavelength of 50  60 nm has both goodefficiency and good resolution.
From the data and considered the monochromatorand spectrometer slit size, the best resolution of thespectrometer can be evaluated as 0.1 nm at 50 nm
wavelength (hν ~ 25 eV). This wavelength resolution
corresponds to the energy resolution of about 50 meV.
Since our electron source is expected to have theenergy resolution of about 50 meV [5], the total energy
resolution of the IPES system is expected as 71 meVideally. This value is better than our target energy
resolution of the IPES system.

Fig. 1. Obtained wavelength resolution (a) andefficiency (b) as functions of incident andspectrometer wavelengths of the newly developed
VUV spectrometer for the IPES system.
[1] P. D. Johnson and S. L. Hulbert, Rev. Sci. Instrum.
61 (1990) 2277.
[2] M. Budke and V. Renken, Rev. Sci. Instrum. 78(2007) 083903.
[3] J. B. Pendry, Phys. Rev. Lett. 45 (1980) 1356.
[4] N. Yamamoto et al., J. Appl. Phys. 102 (2007)
024904 .
[5] S. Pastuszka, M. Hoppe, D. Kratzmann, D.
Schwalm and A. Wolf., J. Appl. Phys. 11 (2000) 88.

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091BL7B and成影典之.docx
Ⅲ -1. Accelerators
Instruments

BL7B

Development of Reflective and Transimissive Polarizers in 280 nm
R. Ishikawa1, N. Narukage1, N. Yoshida2, S. Ishikawa3 and M. Kubo1

National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Mitaka 181-8588,
Japan
3
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara 252-5210,
Japan
1

2

Spectro-polarimetry in the ultra violet (UV) range
is a new astrophysical diagnostic tool to explore themagnetic field of the hot plasma of >104 K.
Following the success of CLASP [1], a team ofresearchers from Japan, the USA, and Europa plans topropose the second flight of CLASP (CLASP2:
Chromospheric LAyer Spectro-Polarimeter 2) toperform the spectro-polarimetry in the MgII lines
around 280 nm at the high polarization sensitivity of<0.1%. In order to meet this stringent requirement on
the polarization sensitivity, the high throughput of>50% and the high extinction ratio of >100 around280 nm are required for new polarization analyzers.
For this purpose, we have fabricated and tested thetwo different types of polarizers. The first one is thereflective type; applied multi-layer coating of MgF2
and Al2O3 over BK7 substrates. This is thehigh-efficiency reflective polarizer based on the same
design concept as what was used for the CLASP1
instrument although the materials are different [2].
Another one is the transmissive type; wire-grid typelinear polarizers that were printed using atomic layer
deposition technology on 1 mm thick fused silica(SiO2) substrates [3]. In order to evaluate theperformance of the polarizers, 100% linearlypolarized beam is required. Thus, we placed the beam
cleaner, which is the SiO2 substrate mounted at the
Brewster’s angle to eliminate the p-polarized beam, atthe upstream of our measurement system.
Two panels in Fig. 1 are the measured reflectivityof 2 samples of the reflective polarizer for s- andp-polarized beams (Rs & Rp) as a function of angle ofincidence (AOI) at 280 nm. It is found that thereflective type has the performance of Rs= 65% and
Rp=0.27% at the Brewster’s angle of 68 degree,
resulting in the extinction ratio of Rs/Rp = 240. The
extinction ratio T1/T2 of the transmissive polarizer
was measured to be >300 around 280 nm, where T1 isthe transmissivity parallel to the grid and T2 is the one
perpendicular to the grid. Note that the fluctuation
over the wavelength is caused by the dark current
fluctuations indicating the detection limit. The
transmissivity T1 was measured to be ~70%.
Based on these measurements, we conclude that wehave successfully developed the high performancereflective and transmissive polarizers. According to
the final decision on the optical design of CLASP2
instrument, one of these polarizers will be applied as

the flight polarization analyzer.

Fig. 1. Measured reflectivity of two reflective
polarizer samples for s- and p- polarization.
500
400
extinction ratio

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300
200
100
278.0

278.5

279.0

279.5 280.0
wavelength [nm]

280.5

281.0

281.5

Fig. 2. Measured extinction ratio of two transmissive
polarizer samples (red and blue).
[1] R. Kano et al., in preparation.
[2] N. Narukage et al., UVSOR Activity Report 40(2012) 47.
[3] T. Berger et al., Proc. of SPIE, 8486 (2012)
8486G-1.

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Ⅲ -1. Accelerators and Instruments

111BL7B 福井一俊.docx

BL7B

Stokes Parameters Measurements for BL7B Beamline
M. Miyashita1, Y. Kubo1, Y. Nasu1, Y. Fujii1, K. Fukui1,
K. Yamamoto2, T. Saito3 and T. Horigome4

Department of Electrical and Electronics Engineering, University of Fukui, Fukui 910-8507, Japan2
Far-infrared region Development Research Center, University of Fukui, Fukui 910-8507, Japan３
Department of Environment and Energy, Tohoku Institute of Technology, Sendai 982-8577, Japan
４
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan

1

Ⅲ -1

Ellipsometers are known as powerful tools todetermine optical constants of materials. However,
due to the fact that all the solid materials cannot havetransparency in the vacuum ultraviolet (VUV) region,
an ellipsometer in VUV region must consist of bothreflection type polarizer and analyzer in vacuum.
Since these requirements make it difficult to construct
the VUV ellipsometer, there is only one beamline (atBESSY) equipped with VUV spectroscopic
ellipsometer (SE) [1] in the world to our knowledge.
The other idea for VUV SE was proposed by Saito etal. which used both Synchrotron radiation (SR) andoblique incidence detector [2]. Compared withstandard ellipsometers, this type SE has an advantageof obtaining not only optical constants of the sample,
but also Stokes parameters (S1/S0, S2/S0, S3/ S0) of theincident beam. In this report, we show Stokes
parameters of the monochromatized output radiationof BL7B beamline (3 m McPherson type normal
incidence monochromator beamline).
Our VUV SE is an improved SE which was
designed and constructed by an AIST group [2], and is
optimized for the use at BL7B. Figure 1 shows
schematic drawing of VUV SE. A sample chamber andan oblique incident photodiode are rotatedindependently along the incident light axis (α and β
rotations) instead of the rotation of a polarizer and ananalyzer, respectively. This system is mounted on thecomputer controlled parallel link mechanism base[3]. Measurements are carried out by rotating α with
fixed β at characteristic angles (0, 45 and 90). Since
the α dependence of the photodiode intensity S0’ ateach three β angles is simply expressed by using M(Ψ,Δ), Ma(Ψa,Δ a) and S(S0, S1, S2, S3) where M and Ma are
Mueller matrixes of a sample and a photodiode, and S
is a Stokes vector of the incident light, sevenparameters Ψ, Δ, Ψa, S1/S0, S2/S0, S3/S0 are obtained
analyticaly. An Au mirror is used as the sample.
Figures 2 shows Stokes parameters of BL7B
monochromatized output radiation as a function ofphoton energy. BL7B has three gratings G1, G2 (Aucoatings) and G3 (Al coating), and lower energy passfilters (quartz and Pyrex glass) are used in the G3
region. As expected, while both S2/S0 and S3/S0
maintain small values S1/S0 have large values overalmost the entire energy region surveyed. The S1/S0
values around the G3 region are in good agreementwith the results using a polarization plate (purple line).

Fig. 1. Schematic drawing of VUV ellipsometer.

Fig. 2. Stokes parameters of the BL7B
[1] T. Saito, M. Yuri and H. Onuki, Rev. Sci. Instrum.
66 (1995) 1570.
[2] W. Budde and R. Dittmann, PTB-Mitt. 83 (1973) 1.
[3] Y. Kubo, K. Fukui, K. Yamamoto, T. Saito and T.
Horigome, UVSOR Activity Reports 41 (2014) 43.

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