Ⅲ-1

Accelerators andInstruments

BL3UⅢ -1. Accelerators and Instruments

BL3U

Soft X-ray Absorption Spectroscopy in the Low Energy Region Explored by
the Argon Gas Window
2

M. Nagasaka1,2Institute for Molecular Science, Okazaki 444-8585, JapanThe Graduate University for Advanced Studies, SOKENDAI, Okazaki 444-8585, Japan
1

Soft X-ray absorption spectroscopy (XAS) is anelement specific method to investigate local electronic
structures of materials. Since soft X-rays are strongly
absorbed by air and liquids [1], XAS spectra of gas andsolid samples under an ultrahigh vacuum condition havebeen extensively studied. Recently, several groups
measured XAS spectra in an atmospheric condition byusing the high soft X-ray transmission of helium gas. A
differential pumping system is used between a soft X-ray
beamline under an ultrahigh vacuum condition and ameasurement chamber in an atmospheric helium
condition [2]. However, the helium gas window is notable to apply XAS in the low energy region below 200 eV
since transmitted soft X-rays mostly consist of high order
X-rays due to the low transmission of first order X-rays.
In this study, we propose the argon gas window for the
newly soft X-ray transmission window in the low energy
region covering K-edges of Li and B and L-edges of Si,
P, S, and Cl [3].
The experiments were performed at soft X-ray
beamline BL3U. The measurement chamber in theatmospheric helium or argon condition is separated by a
Si3N4 membrane with the thickness of 100 nm from thesoft X-ray beamline under an ultrahigh vacuum condition.
Soft X-rays under vacuum pass through the Si3N4
membrane window, the atmospheric helium or argon
environment, and finally reach a photodiode detector. The
distance between the Si3N4 membrane and the photodiodedetector is estimated to be 41 mm.
Figure 1 shows the soft X-ray transmission spectra ofargon gas in the low energy region. Argon gas has a role
to remove high order X-rays above 240 eV due to theabsorption of the Ar L-edge. The absorption peak of the
Si3N4 membrane around 104 eV is observed in the Si Ledge. When the small amount of dimethyl sulfoxide(DMSO) gas is mixed with the argon gas, we havesuccessfully observed the absorption peaks of DMSO gas
at the S L-edge (170 eV), which clearly observes the
spectral difference between DMSO/Ar mixed gas andargon gas. These peaks are not able to be observed in theatmospheric helium condition since the ratio of the highorder X-rays is extremely high in the helium environment.
Figure 2 shows the XAS spectrum of helium gas,
where the small amount of helium gas is mixed in theatmospheric argon condition. The XAS spectrum isderived using the Lambert-Beer law, ln(I0/I), where I0
and I are the transmission signals of argon gas and
Ar/He mixed gas, respectively. The spectrum shows
the helium resonance energy E2 of the n = 2 double
excitation Rydberg series at 60.147 eV [4]. It meansthat soft X-rays at the Li K-edge (60 eV) are transmittablein the atmospheric argon condition. As a result, theargon gas window enables us to measure XAS in theatmospheric condition in the low energy region from60 to 240 eV.

Fig. 1. The soft X-ray transmission spectra of argon
gas in the atmospheric condition in the low energy
region. The transmission spectrum of argon gas mixed
with DMSO gas is also shown.

Fig. 2. The XAS spectrum of helium gas mixed withargon gas in the atmospheric condition.
[1] C. T. Chantler, J. Phys. Chem. Ref. Data 29 (2000)
597.
[2] Y. Tamenori, J. Synchrotron Rad. 17 (2010) 243.
[3] M. Nagasaka, submitted.
[4] M. Domke et al., Phys. Rev. A 53 (1996) 1424.

31
Ⅲ01- 1 -

Ⅲ -1

BL4U
Ⅲ -1. Accelerators
and Instruments

BL4U

Microscopic Study of Li K-edge
T. Ohigashi1,2 and H. Yuzawa1

UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
School of Physical Sciences, The Graduate University for Advanced Studies, SOKENDAI, Okazaki 444-8585, Japan1

2

5f which are corresponded with focal length of +1st
diffractions of 2nd, 3rd, 4th and 5th higher harmonics
respectively. Then intensity of the 3rd order harmonics,
which is the strongest diffractive order, was suppressed
less than 0.1 %.
As a test measurement, Li K-edge of a droplet of LiClsolution on a TEM grid was measured by using a
conventional FZP and the new one. Figure 1 (a) show
an STXM image of the droplet at 60 eV. In Fig. 1 (b),the spectrum analyzed by the new FZP obviously showssome peaks compared to the conventional one. Fromcomparison with Fig. 1 (b) and spectra in reference [6],the droplet of LiCl reacted with CO2 in the air andbecame mixture of LiCl and Li2CO3. As an evaluationof spatial resolution, another FZP with the outermost
zone width of 36 nm was measured and line and its
space pattern of 72 nm pitch was resolved. This
resolution implies diffraction limit of the STXM optics
with the new FZP.
(a)

500 nm

Optical Density [arb. u.]

Ⅲ -1

Lithium is the lightest solid element and is a mainelement for a lithium ion battery (LIB). Currently, theLIBs are widely used and are essentials in our lives asenergy storage devices. Demand of the LIBs is still
increasing and higher performance is expected.
However, behavior of lithium in the LIB, such as
distribution and chemical state during charge/discharge
process, is still unclear. To elucidate this process, it isnecessary to develop an analytical tool which cananalyze lithium with high spatial resolution. So far,analyses of lithium by using an Auger electron
microscope [1], a transmission electron microscopewith electron energy loss spectroscopy [2] and asecondary ion mass spectroscopy were reported [3]. In
addition to these instruments, a scanning transmission
X-ray microscope (STXM) also can be a powerful
technique. STXM performs X-ray absorption
spectroscopy with high spatial resolution in transmission
mode. This technique is bulk sensitive and lower
damage to a sample [4]. To analyze lithium by STXM,
it is necessary to have an access around 55 eV, Li Kedge. This low energy region makes the Li K-edge
analyses difficult because tremendous higher orderharmonics from a monochromator should be suppressedto obtain X-ray absorption spectra of high quality.
Furthermore, focal length of a Fresnel zone plate (FZP)
depends on energy of an incoming X-ray so that focal
length of the FZP around Li K-edge is typically too short(e.g. 266 µm by the FZP with 25 nm outermost zone
width) to construct microbeam optics. Additionally,
efficiency of the FZP is low. In this study, we overcame
these issues by designing a FZP with a new concept [5].
The optics of STXM at BL4U, a combination of the
FZP with chromatic aberration and a pinhole (OSA,order select aperture) is not only to produce a
microbeam but also to work as a linear monochromator.
This optics theoretically suppresses the higher orderharmonics at odd diffractive orders larger than 3rd andcut off even diffractive orders. We designed the new
FZP for analysis below 100 eV. The concept of the new
FZP is a combination of a phase FZP and a substrate asa low pass filter. Then, the silicon substrate was chosenbecause of high transmittance of main harmonics, from50 to 100 eV, and cut-off by Si L2 and L3 edge above
100 eV. The parameters of the new FZP are as follows;
diameter of 240 µm, outermost zone width of 60 nm,
1,000 zones and gold pattern on silicon substrate ofthickness of 200 nm. The focal length of the new FZP is
639 µm at 55 eV. Intensities of the higher orderharmonics was evaluated by changing the focal positionof the FZP, f, along an optical axis, such as 2f, 3f, 4f, and(b)

New FZP

Conventional FZP

Energy [eV]Fig. 1. STXM measurement at Li K-edge of a dropletof LiCl solution, (a) an STXM image at 60 eV and (b)its spectra by using the new and the conventional FZPs.

[1] N. Ishida, H. Fukumitsu, H. Kimura and D. Fujita,
J. Power Sources 248 (2014) 1118.
[2] J. Kikkawa, T. Akita, M. Tabuchi, M. Shikano, K.
Tatsumi and M. Kohyama, Electrochem. Solid-State
Lett. 11 (2008) 399.
[3] H. Masuda, N. Ishida, Y. Ogata, D. Ito and D. Fujita,
J. Power Sources 400 (2018) 527.
[4] R. Qiao, Y-D. Chuang, S. Yan and W. Yang, PLOS
ONE 7 (2012) e49182.
[5] T. Ohigashi, in preparation[6] J. Tsuji, H. Nakamatsu, T. Mukoyama, K. Kojima,
S. Ikeda and K. Taniguchi, X-Ray Spectrom. 31 (2002)
319.

32
Ⅲ01- 2 -Accelerators

Ⅲ -1. Accelerators and Instruments

Accelerators

Development of Long-term Stable Nuclear Emulsion
for Cosmic-ray Imaging
A. Nishio, K. Morishima, K. Kuwabara, T. Yoshida and M. Nakamura
Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan

Cosmic ray imaging is the a new non-destructive
inspection technique of large-scale constructions withcosmic ray muon. Cosmic ray muon has highpenetrating power and it always comes from the wholesky. In the same way of taking a X-ray photograph, we
can obtain integrated density of constructions which
thickness are several tens cm to several km. We had
ever applied this technique to the pyramid of khufu at
Egypt, and discovered a large void [1].
In cosmic-ray imaging observations, we used nuclear
emulsion as a detector. Nuclear emulsion is a kind ofphotographic film and has sensitivity for ionizing
radiation. The film record tracks of charged particle
with angular accuracy under several mrad. In Nagoya
University, started a emulsion gel production machinein 2010. It was enable us to develop new-type emulsion
gel by ourselves.
We have succeeded to develop the Long-term
Stable Nuclear Emulsion for the purpose of long-term
observation of cosmic ray imaging. The problem was
Latent image fading which is phenomenon decreasing
Grain density (GD, indicator of sensitivity) with time.
To enable long-term observation and outdoor use
throughout the year, we investigated factors that affectthe latent image fading of nuclear emulsion. We foundthat gelatin, additive chemicals, and packing material
affected. The developmental version of newly nuclear
emulsion are shown in Table 1.
The latent image fading characteristics of Versions
1 to 5 were investigated. The test was conducted at atemperature of 30 °C and a humidity of 40 % RH.
Version 5 was also tested at a humidity of 20 % RH.
The results are shown in Fig. 1. Figure 2 shows optical
micrographs of tracks on days 0, 30, and 180.
The new stable nuclear emulsion achieved its goal ofa GD that remained at 25 or more for half a year at
30 °C. The developed stable nuclear emulsion is being
used for cosmic-ray imaging observations in the
pyramid of Khufu and is expected to be used for futurecosmic-ray imaging observations and other elementary
particle research.
Table 1. Developmental version history and thecomponents of each version of the nuclear emulsion.
Version 1 is a conventional nuclear emulsion. Versions 2
to 4 are the stages of development, and Version 5 is thestable nuclear emulsion developed.

Ⅲ -1

Fig. 1. Latent image fading of Versions 1 to 5 at 30 °C,
40 % RH. The Version 3 samples after day 90 and Version
4 samples on day 180 were impossible to evaluate for the
GD due to the large amount of noise.

Latent image fading (30 degree, 40 %RH)
0d

30 µm

30d

30 µm

30 µm

(ver. 1)
0d
30d

30 µm

30 µm

(ver. 2)30 µm(ver. 3)

30 µm

30 µm

30 µm

30 µm

30 µm

30 µm

180d

30 µm

(ver. 4)(ver. 5)30 µm(ver. 5, 20%RH)

Fig. 2. Optical micrographs of electron beam (several
tens of MeV) tracks exposed to Versions 1 to 5 nuclear
emulsion on days 0, 30, and 180. Latent image fadingat 30 °C, 40 % RH. The length of the black bar is 30
μm. The electron beam was exposed at UVSOR. In the
Versions 1, 2, 3, and 4 samples on day 180, there wasno track that could be recognized due to the low GD
or large amount of noise.

[1] K. Morishima et al., Nature 552 (2017) 386.

33
Ⅲ01- 3 -BL1U
Ⅲ -1. Accelerators
and Instruments

BL1U

Construction of Laser Transport System for CHG Experiment at BL1U
M. Hosaka1, Y. Matsunaga1, A. Mano1, Y. Takashima1, M. Fujimoto2 and M. Katoh2,3Nagoya University, Nagoya 464-8603, JapanUVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
3
Hiroshima University, Higashi-hiroshima 739-0046, Japan
1

2

Ⅲ -1

Coherent harmonic generation (CHG) is a method toimprint external laser information to an electron beamand produce coherent radiation from it with various
properties such as polarization [1], temporal and spectral
structures [2]. We are planning to conduct the CHG study
using an optical klystron and a short pulse Ti:Sa mode
lock laser at BL1U. The optical klystron consists of two
Apple-II variable polarization undulators and a buncher
inserted between them [3]. The laser is injected into thefirst part of the undulators and energy exchange between
it and an electron beam circulating in the storage ringoccurs. This leads energy modulation inside the electron
beam, that is further converted to density modulation withlaser wavelength (micro-bunch) in the buncher section.
Coherent radiation is emitted from the micro-bunchedbeam in the second part of the undulators. Polarization of
the emitted radiation can be controlled by tuning theundulator.
In order to perform the CHG experiment, weconstructed a laser transport system from the laser room
to a laser injection window, whose path length is about 10
m. For simplification, vacuum chamber of the optical
klystron is used for laser transportation as seen in Fig.1.
The laser is returned to the injection window using a
waveplate and a polarization beam splitter. The coherent
radiation and the returned laser after the interaction withthe electron beam separated using a dichroic mirror. We
also prepared a monitoring system to make precisealignment between the laser beam and the electron beam,
temporally and spatially.
The CHG experiment was made with an electronenergy of 600 MeV. Radiation wavelength of Apple-II
undulators was adjusted by changing a magnetic gap
length. Fundamental radiation of the first undulator tuned
to the wavelength of Ti:Sa laser (800 nm) for the resonantinteraction and that of the second undulator is tuned to awavelength of 267 nm, which corresponds to the 3rd
harmonics of the micro-bunching. Spatial alignment
between the electron beam and the laser was madelooking at radiation from the first undulator. Observed
image at the position using a CMOS camera coupled witha telescope is shown in Fig. 2. Laser position in the figure
was shifted on purpose and the power was kept low (~10μW). The laser beam could be well focused on theelectron beam using the monitoring system. We also
carried out temporal alignment using a streak camera.
Figure 3 shows the measured streak camera images. The
laser pulse of 1psec could be well overlapped on thesynchrotron radiation (the electron beam) of 100 psec.
After the alignment, we increased the laser power to 1W(1 mJ per pulse) to generate the CHG. We used the streak
camera and a narrow band pass filter (2 nm-FWHM) for

the observation but no signal arising from the CHG could
be seen. We noticed that focusing position of the laser
moved considerably with increased laser power. This
weaken the laser electric field at the interaction point andsuppressed the CHG. We think that the degradation of
focusing comes from non-linear effects in transmission
type optical elements such as polarization beam splitters.
We are planning to remodel the laser transport system forthe experiment.

Fig. 1. Schematic of the laser transport system.

Fig. 2. SR and laser image at interaction point.
Electron beam size is around 0.5 mm.

Fig. 3. Streak camera images of SR and laser.
The vertical axis is synchronized with accelerator RF
signal.

[1] M. Labat et al., Phys. Rev. Lett. 102 (2009) 014801.
[2] S. Bielawski et al., Nat. Phys. 4 (2008) 390.
[3] M. Adachi et al., Proc. IPAC’ 10 (2010) 2573.

34
Ⅲ01- 4 -BL1U

Ⅲ -1. Accelerators and Instruments

BL1U

Feasibility Study of Measurement of Polarized Pulsed Gamma-ray by Laser
Compton Scattering at 90°
Y. Takashima1, M. Hosaka1, U. Shikano1, A. Mano1, M. Fujimoto2 and M. Katoh2,3Synchrotron Radiation Research Center, Nagoya University, Nagoya 464-8603, JapanUVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
3
HiSOR, Hiroshima University, Higashi-hiroshima, 739-0046, Japan1

2

Ultra-short pulse gamma-rays of the pulse width ofseveral picoseconds are generated in UVSOR by 90°
scattering of short pulse laser with the electron beam
circulating in the storage ring [1]. When the laser iscircularly polarized, it is expected that gamma rays
generated by Compton scattering are also circularly
polarized. There have been some experiments
conducted to confirm the polarization of gamma rays
generated by the head-on collision of the electron beamand the laser [2]. However, there are no experiments
performed to measure the polarization of gamma rays
generated in the condition of which the laser and theelectron beam collided at a 90° in a laboratory system.
We performed measurements of the spatial
distribution of gamma-rays by laser Compton scattering
at 90° as a feasibility study to measure the polarizationof gamma-rays. In the experiment, we stored 750 MeV
electron beam of 30 mA as a single bunch. We used amode-locked Ti:Sa laser synchronized to the RF
frequency of the storage ring. The wavelength and thepulse power of the laser were 800 nm and 1.5 mJ/pulse,
respectively. In order to change the direction of thepolarization of the laser, we installed a λ/2 waveplate infront of the injection window on the beam duct of thestorage ring. The maximum energy of the gamma-ray is
about 6.6 MeV. Figure 1 shows the spectrum of thescattered gamma-rays detected by a NaI scintillator.
We installed photostimulable phosphor plates after
the extraction window of BL1U in order to measure thespatial distribution of the gamma-rays. The size of theplate was 11.5 cm x 11.5 cm, and the resolution is 100
μm. Figure 2 show the images of spatial distributions of
the gamma-rays generated by 90° scattering of the laser
and the electron beam. Fig. 2(a) is the image obtainedby the Compton scattering of the laser with linear
polarization perpendicular to the direction of theelectron beam in the horizontal plane. Fig. 2(b) shows
the image by using the laser with linear polarization
parallel to the direction of the electron beam. There aresome differences in those spatial distributions. The
figures indicate that the spatial distribution varies
according to the polarization of the incident laser, assuggested by theoretical consideration.
In farther studies, we plan to measure the polarizationof the scattered gamma-rays quantitatively by themethod of magnetic Compton scattering [2].

Ⅲ -1

Fig. 1. Energy spectrum of gamma-ray detected by
NaI scintillator.

Fig. 2. Spatial distribution of gamma-rays detected byphotostimulable phosphor plates. (a) is the image using
the horizontally linear polarized laser, and (b) is theimage using the laser with linear polarization parallelto the direction of the electron beam.

[1] Y. Taira et al., Nucl. Instrum. and Meth. A 637 (2011)
S116.
[2] M. Fukuda et al., Phys. Rev. Lett. 91 (2003) 164801.

35
Ⅲ01- 5 -BL1U
Ⅲ -1. Accelerators
and Instruments

BL1U

Study on Isotope 3D Imaging Using NRF Absorption Method in UVSOR-BL1U
H. Ohgaki1, H. Zen1, T. Kii1, K. Ali1, T. Hayakawa2, T. Shizuma2, H. Toyokawa3, Y. Taira3,
V. Iancu4, V. G. Turturica4, M. Fujimoto5 and M. Katoh5

Institute of Advanced Energy, Kyoto University, Kyoto 611-0011, Japan
Tokai Quantum Beam Science Center, National Institutes for Quantum and Radiologicl Science andTechonology, Tokai 319-1106, Japan
3
National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Central 2-4,
Tsukuba 305-8568, Japan
4
Extreme Light Infrastructure - Nuclear Physics, s/ Horia Hulubei National Institute for R&D in Physics andNuclear Engineering, Bucharest-Magurele, Judet Ilfov, RO-077125, Romania
5
UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
1

2

Ⅲ -1

A Nuclear Resonance Fluorescence (NRF) method is a
powerful tool for investigation not only of the nuclear
physics but also of isotope imaging inside the spent
nuclear fuel canisters and nuclear wastes. We have beendeveloping an isotope imaging technique by using NRF[1] as well as by Nuclear Resonance Absorption (NRA)[2].
A demonstration experiment of the NRF-CT imaging
by using a LCS gamma-ray beam with a natural leadtarget has been carried out at the LCS gamma-ray
beamline BL1U at UVSOR-III [3]. In 2019, two enrichedisotope targets 206Pb (>93.3 %) and 208Pb (>97.8 %) wereprepared as the CT target which is made of an aluminum
holder as shown in Fig.1.
The LCS gamma-ray beam with a maximum energyof 5.528 MeV was generated by using a fiber laser(wavelength of 1,896 nm, 50 W). The gamma-ray
beam with a flux of approximately 1×108 photons/s
was used for the experiment with a 1-mm leadcollimator and the excited J π = 1- state at 5.512 MeVof 208Pb was populated through NRA. By using the
NRF absorption method a NRF-CT image has beentaken by 2-mm step in the horizontal direction (x=-14
to 14 mm) and 30-deg. step in the rotation angle (θ=0
to 150°). The NRF signals from the witness target(208Pb enriched) were measured by two Ge detectors
with 120 % and 130 % relative efficiencies. At thesame time, the transmission gamma-rays have beenmeasured by a 3.5” × 4” LaBr3(Ce) detector, which
gives a density distribution of the sample target. We
have developed the segmented CT reconstruction
method [3] and we obtained clear a 208Pb distribution
as shown in Fig. 2. On the other hand, by using the γray transmission CT, we cannot distinguish between
206
Pb and 208Pb as shown in Fig. 3. We demonstrated
the isotope selectivity of the NRF-CT technique at the
UVSOR-BL1U beamline.
[1] N. Kikuzawa et al., Appl. Phys. Express 2 (2009)
036502.
[2] H. Zen et al., Energy Procedia 89 (2016) 335.
[3] H. Zen et al., AIP Advanced 9 (2019) 35101.

Blank
A
208

206

Pb

Fig. 1. NRF-CT target.

Fig. 2. NRF-CT image.

Blank

208

Pb

206

Pb

Fig. 3. γ-ray transmission CT image.

36
Ⅲ01- 6 -

Pb

BL1U

Ⅲ -1. Accelerators and Instruments

BL1U

Study on Temporal Structure of Synchrotron Radiation by Using
Interferometer
S. Notsu1, S. Matsuba2, K. Kawase3 and M. Katoh1,4Hiroshima University, Higashi-Hiroshima, 739-0046, Japan
2
JASRI, Sayo-cho 679-5198 Japan
3
QST, Tokai-mura 319-1106, Japan
4
UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan1

Temporal structure of synchrotron radiation may beseparated into two categories. The first one is the that ofa photon wave packet emitted from a single electron.
Another temporal structure is the width of the light pulse
emitted from a bunch of electrons, which comprises ofmany wave packets randomly distributing over thelength of the electron bunch.
Usually the pulse length of synchrotron radiation,
which is typically 10 to 100 psec, is measured with astreak camera. However, there is no report on the direct
measurement of the wave packet length. In the laser
field, it was demonstrated to measure both the lightpulse width and the wave packet length (coherence
length) by using an interferometer based on the photon
correlation [1]. By using same method, it wasdemonstrated to measure the pulse width of the bending
radiation [2].
We constructed an interferometer as shown in Figs.
1 and 2, which is a modification of Michelson-type
interferometer. Two experiments can be conducted on
this interferometer. The first one is two-photon
correlation and another is autocorrelation. We
conducted these experiments by using an undulator
beamline BL1U (Fig. 3). We extracted the undulator
radiation at a wavelength of 355 nm and introduced it
to the interferometer.
The details of the results will be presented in a future
paper. Here, we only give a short summary. Concerning
two-photon correlation, so far, we could not get asignificant result, which gives the information on thepulse length. The reason is presumably on the alignmentof two light beams at the detector. We shall improve thealignment method and try this experiment in near future.
On the other hand, in the autocorrelation experiment, we
can get a promising result on the coherence length. Also,
we note that the mechanical vibration produces asignificant effect on the results. We shall improve themechanical stability of the interferometer and try thenext experiment in the nearest future.

Ⅲ -1

Fig. 1. Interferometer (Autocorrelation setup is shown).

Fig. 2. Interferometer (Two photon correlation setup
is shown).

Fig. 3. Interferometer set at BL1U.
[1] Y. Miyamoto et al., Opt. Lett. 18 (1993) 900.
[2] T. Mitsuhashi and M. Tadano, Proc. EPAC2002(Paris, 2002), 1936.

37
Ⅲ01- 7 -BL2A
Ⅲ -1. Accelerators
and Instruments

BL2A

X-ray Transmission Measurements for Optical Blocking Filters on Board
the Third Focusing Optics X-ray Solar Imager (FOXSI-3) Sounding Rocket
I. Mitsuishi1, S. Shimizu1, T. Yamaguchi1 and N. Narukage2

Nagoya University, Nagoya 464-8601, Japan
National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
1

2

Ⅲ -1

The solar corona is full of dynamic phenomena.
They are accompanied by interesting physicalprocesses, namely, magnetic reconnection, particle
acceleration, shocks, waves, flows, evaporation,
heating, cooling, and so on. The understan dings ofthese phenomena and processes have been progressing
step-by-step with the evolution of the observation
technology in EUV and X-rays from the space. But,
there are fundamental questions remain unanswered,or haven’t even addressed so far. Our scientificobjective is to understand underlying physics ofdynamic phenomena in the solar corona, coveringsome of the long-standing questions in solar physics
such as particle acceleration in flares and coronalheating, and so on. In order to achieve these scienceobjectives, we identify the imaging spectroscopy (theobservations with spatial, temporal and energy
resolutions) in the soft X-ray range (from ~0.5 keV to~10 keV) is a powerful approach for the detection andanalysis of energetic events [1]. This energy range
contains many lines emitted from below 1 MK to
beyond 10 MK plasmas plus continuum component thatreflects the electron temperature.
For the first imaging spectroscopic observation of
the solar corona in soft X-ray range, we launched aNASA’s sounding rocket (FOXSI-3) on September 7th,2018 [2] and successfully obtained the unprecedented
data [3] using a combination of X-ray mirror and highspeed X-ray camera with a back-illuminated CMOS
sensor [4-6].
In this instrument, filters made of thin polyimide
films with aluminum coating were deployed to reject
the intense visible light from the sun and to adjust theincident X-ray flux into the camera. These optical
blocking filters (hereafter OBFs) are located in front ofboth X-ray optics and the CMOS detector. Actually, we
confirmed our OBFs worked successfully during theobservation. To achieve our scientific goals, X-ray
transmission through OBFs should be taken into
account accurately and thus, X-ray transmission
measurements were conducted in BL2A as shown in
Fig. 1. We took X-ray transmission data at 830, 1000,
1200, 1400, 1600, 1800, and, 2000 eV to obtain aproper model representing the observed transmission.
Consequently, the observed thicknesses of polyimide
and aluminum coating films are 2.8 µm / 180 nm and5.0 µm / 320 nm and we extracted the expected models
with accuracies of typically <10 % and <5 % for OBFs
of X-ray optics and the CMOS detector, respectively as
shown in Fig. 2.

Fig. 1. Overview of our experimental setup (left) andOBFs for X-ray optics (top right) and the CMOS
detector (bottom right) on board FOXSI-3.

Fig. 2. Observed transmission of OBFs for X-ray
optics (top) and CMOS detector (bottom) and the ratioof the observed to the expected value.
[1] N. Narukage et al., White paper of the “soft X-ray
imaging spectroscopy”, arXiv:1706.04536 (2017).
[2] Web Release: https://hinode.nao.ac.jp/en/news/topics/
foxsi-3-180907/[3] Web Release: https://hinode.nao.ac.jp/en/news/
topics/foxsi-3-data-release-en-20190115/[4] N. Narukage et al., Nuclear Instruments and Methods
in Physics Research Section A 950 (2020) 162974.
[5] S. Ishikawa et al., Nuclear Instruments and Methods
in Physics Research Section A 912 (2018) 191.
[6] N. Narukage and S. Ishikawa, UVSOR Activity
Report 2018 46 (2019) 36.

38
Ⅲ01- 8 -BL3B

Ⅲ -1. Accelerators and Instruments

BL3B

Study on the Electronic State of Fine-grained AgBr:I Crystals by
Luminescence under Low Temperatures
2

T. Naka1, T. Shiraishi1, S. Kurosawa2 and H. Sone3

Department of Physics, Toho University, Funabashi 274-8510, JapanNew Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8577, Japan3
Industrial Technology Institute, Miyagi Prefectural Government, Sendai 981-3206, Japan
1

This is a study on the electronic state of AgBr:I nanocrystals in the nuclear emulsion by their luminescence
response. The nuclear emulsion in which AgBr:I
crystals are dispersed in gelatin is a particle tracking
detector with sub-micrometric accuracy. Each crystal
behaves a charged particle sensor of the indirecttransition semiconductor. Among electrons and holes
excited in the crystal by the ionizing loss of charged
particles, a few electrons are contributed to the track(latent image) formation. On the other hand, we foundin previous studies that luminescence occurs with highefficiency at below the liquid nitrogen temperature byrecombination of electrons and holes through iodine
center [1].
For the AgBr:I crystal of the nuclear emulsion, thetypical crystals are sub-micro sizes; in particular, a Nano
Imaging Tracker (NIT) [2,3] in which super fine-grained
crystals of approximately 40 nm are dispersed with a highdensity of 10,000 crystal/μm3 was implemented as a track
detector with the world's highest spatial resolution. It is
used for the directional dark matter search, neutrons or
heavy ions detector. However, their response for charged
particles is still under studying. Because the behavior ofelectrons in nanoscale AgBr:I crystals leads to the greater
understanding of the latent image formation mechanism,
we study their electronic states, such as electron traps or
the band structure, through the luminescence response byphotoexcitation. In this year, we compared them with theprevious knowledge by using a 200 nm crystal size,
which is well understood in photographic science.
In thermo-luminescence measurement, after exciting
with 240 nm light at 10 K for 10 min, the luminescence
spectrum was measured at a constant temperature
increase rate up to 300 K. A result at the rate of 4.9 K/min
is shown in Fig. 1. The depth of the electron trap
calculated from this measurement was estimated to be
several tens meV. This is consistent with the trap due tointerstitial silver ions [4], however such a very shallow
trap is not considered to be contributed to the latent image
formation. It is expected the existence of deeper electron
traps by measuring up to more high temperature.
In addition, we measured the excitation spectrum
dependency of the luminescence intensity (Fig. 2), andshowed that this result was consistent with the predictedband structure by the calculation in bulk crystals [5].

Ⅲ -1

Fig. 1. Thermo-luminescence spectrum of AgBr:I
crystal of 200 nm size at temperature increase rate of
4.9 K/min.

Fig. 2. Excitation spectrum of AgBr:I crystal of 200
nm size at 10 K.
[1] T. Shiraishi, H. Ichiki and T. Naka, Nucl. Inst. Meth.
A 927 (2019) 202.
[2] T. Naka et al., Nucl. Inst. Meth. A 718 (2013) 519.
[3] T. Asada, T. Naka, K. Kuwabara and M. Yoshimoto,
Prog. Theor. Exp. Phys. 063H01 (2017).
[4] S. Sakuragi and H. Kanzaki, Phys. Rev. Lett. 38(1977) 1302.
[5] V. Oleshko, M. Amkreutz and H. Overhof, Phys.
Rev. B 67 (2003) 115409.

39
Ⅲ01- 9 -BL4B
Ⅲ -1. Accelerators
and Instruments

BL4B

Photoelectron Based Soft X-ray Detector for Removing High Order X-rays
2

Ⅲ -1

M. Nagasaka1,2 and H. Iwayama1,2Institute for Molecular Science, Okazaki 444-8585, JapanThe Graduate University for Advanced Studies, SOKENDAI, Okazaki 444-8585, Japan
1

Soft X-ray absorption spectroscopy (XAS) in the low
energy region below 200 eV is important to investigate
chemical and biological phenomena since this energy
region includes K-edges of Li and B and L-edges of Si, S,
P, and Cl. However, it is difficult to measure XAS in the
low energy region because transmitted soft X-rays mainly
consist of high order X-rays due to the low transmissionof first order X-rays. There are several techniques forremoving high order X-rays, such as metal filters, energy
analysis by the silicon drift detector [1], controlling theincident angle of a focused mirror in the beamline [2].
However, these methods are not able to apply theselection of the first order X-rays below 200 eV fromthose of the high order X-rays. In this study, we havedeveloped a photoelectron based soft X-ray (PBSX)
detector that removes contributions of high order X-rays
for XAS below 200 eV [3].
The experiments were performed at soft X-ray
beamline BL4B. Figure 1 shows schematics of our
PBSX detector system, which consists of an Au plate,an Einzel lens, and an MCP detector. Transmitted soft
X-rays from a sample film are irradiated to the Au plate,
and the emitted Au 4f photoelectrons are collected into
the MCP detector with the Einzel lens. The Einzel lenshave three electrodes (P1, P2, and P3). V1 is a constantvoltage, whereas V2 is a pulsed gate voltage. The Au 4f
photoelectrons excited by both the first order X-rays
and the high order X-rays detects with the gate-off
voltage, whereas those excited by the high order Xrays only detect with the gate-on voltage. The photon
flux of the first order X-rays is obtained by subtracting
the intensities of the photoelectrons with the gate-on
voltage from those with the gate-off voltage.
Figure 2 shows Si L-edge XAS spectra of thepolymer/SiC film, where the thickness of the polymer(MOXTEK ProLINE) and SiC membrane (NTT AT) is
150 and 100 nm, respectively. Both photodiode (IRD
AXUV100) and PBSX detectors are settled behind thesample films. XAS spectra in transmission mode arebased on the Lambert-Beer law, ln(I0/I), where I0 and I
are the transmission signals of blank and sample,
respectively.
As observed in the Si L-edge XAS of SiC wafers [4],the XAS spectra show the large peak around 103.63 eV
and small peaks around 112.5, 115.5, 120, and 142 eV.
The broad peak is also observed around 158 eV. Since thecontributions of the high order X-rays around 97 eV are
removed by the PBSX detector, the intensity of the first
SiC peak (103.63 eV) becomes higher than that obtainedby the photodiode detector. In addition, due to removing
the contributions from the fifth order X-rays at the O Kedge, the peak width also becomes narrower and is nearlysame as that in the SiC film. The contribution from thesecond order X-rays at the C K-edge is also removed in
the XAS spectra. As a result, we have successfullymeasured Si L-edge XAS spectra of the polymer/SiC filmwith avoiding the contribution of the high order X-raysby using the PBSX detector.

Fig. 1. Schematics of the PBSX detector. Photon fluxof the first order X-rays is separately collected fromthose of the high order X-rays by using the energy
difference of the Au 4f photoelectrons.

Fig. 2. Si L-edge XAS spectra of the polymer/SiC
film by using the photodiode and PBSX detectors.
[1] P. Lechner et al., Nucl. Instrum. Methods Phys. Res.
A 377 (1996) 346.
[2] Y. Kitajima et al., J. Electron Spectrosc. Relat.
Phenom. 101-103 (1999) 927.
[3] M. Nagasaka and H. Iwayama, in preparation.
[4] S. Muto and T. Tanabe, J. Appl. Phys. 93 (2003)
3765.

40
Ⅲ01- 10 -BL5B

Ⅲ -1. Accelerators and Instruments

BL5B

Multilayer Reflectometry for Evaluation of Second Harmonic Spectral
Impurity in 100 nm Wavelength Output of BL5B UVSOR
T. Hatano1, Y. Matsuda2 and T. Ejima1

IMRAM, Tohoku University, Sendai 980-8577, Japan
Department of Chemistry, Graduate School of Science, Tohoku Universuty, Sendai 980-8578, Japan
1

2

VUV generation of rare gas excited by intense laser
pulse can be used for ionization experiments when it isfocused using a suitable condenser optics. VUV of a 118
nm wavelength from Xe is used [1], and VUV of a 100
nm wavelength from Ar is proposed as a new source. Al
even with an oxide film on the surface is a highreflectance material in VUV region above 160 nm, and
LiF overcoat extends the high reflectance region down
to 101 nm [2]. Around 100 nm, however, no normal
incidence mirror has been developed so far. Therefore,
a condenser mirror having a high normal reflectance at
100 nm is demanded for 100 nm wavelength VUVsources. For that purpose, authors are planning to test
thick large-k material or Al overcoated with thin smalln material. In any case, characterization accuracy is
crucial. The spectral purity of the output of grating
monochromators, especially, is important rather than thegeometrical alignment in normal incidence reflectancemeasurements. In the present study, the second
harmonic spectral impurity has been investigated at
BL5B UVSOR, which is one of most useful beamlines
for calibration of optical elements around a wavelengthof 100 nm.
A 20 period Al (17 nm)/Si (16 nm) multilayer
reflecting 50 nm (24.8 eV) VUV at an angle ofincidence of 18.1° was fabricated for the second
harmonic detection at 100 nm (12.4 eV). When the
monochromator setting is for 100 nm, the multilayer
reflection has an additional signal due to the 50 nm
second order diffraction of the grating. The detailed
analysis of the measured spectral reflectance gives theratio of the power of the second order light to that of
the total output [3]. The measured spectral reflectanceat an angle of incidence of 18.1° is shown in Fig. 1 byblue line. The grating and mirror choice of themonochromator was G3M5. The major peak where thegrating diffraction order mG and the multilayer Braggreflection order mM are both 1, was found at 24.8 eV.
It gives the reflectance at 24.8 eV as 5.4 %.
The second peak was found at 12.4 eV. Orders of thegrating diffraction and the multilayer reflection of thispeak were assigned as mG = 2 and mM = 1. The evidence
can be seen in the spectral reflectance of anothermultilayer, 15 period Al (50 nm)/Si (17 nm) which isshown in Fig. 1 by green line. This multilayer is similar
to the first one if the Si layers were alternatively
replaced with Al layer. Therefore it reflects 24.8 eV
VUV at a similar angle of incidence of the first one with
mM = 2. Two other peaks appeared at lower energy side.
There might be a question; which is of the fundamental
Bragg reflection (mG = 1 and mM = 1)? The answer iseasy when the dispersion of refractive index n isconsidered. Since n of Al rapidly decrease from 24.8 eV
to 12.4 eV, the mM = 1 peak is expected to appear atmuch higher energy than 12.4 eV by the refraction effect.
Thus, the second peak around 18.6 eV can be attributed
to mG = 1 and mM = 1. The third peak located at exactly
the half energy of mG = 1 and mM = 2 must be mG = 2
and mM = 2.
Back to the 12.4 eV peak of the first multilayer, thepeak height on the baseline of the mG = 1 backgroundreflectance was 2.2 %. It corresponds to the product of
the second harmonic ratio and the 24.8 eV reflectance[3]. The conclusion is that 41 % of the monochromator
output power is the second harmonic, which meansthat the experimental result around 100 nm (12.4 eV)must be analyzed with the spectral purity of 59 % athighest taken into account.

Fig. 1. Measured spectral reflectances of Al/Si
multilayers.
[1] Y. Matsuda, A. Yamada, K. Hanaue, N. Mikami
and A. Fujii, Angew. Chem. Int. Ed. 49 (2010) 4898.
[2] W. R. Hunter, J. F. Osantowski and G. Hass, Appl.
Opt. 10 (1971) 540.
[3] T. Hatano and T. Harada, J. Electron Spectrosc.
Relat. Phenom. 196 (2014) 156.

41
Ⅲ01- 11 -

Ⅲ -1

BL5B
Ⅲ -1. Accelerators
and Instruments

BL5B

Investigation of the Source of the Photon-Energy Drift of BL5B
H. Zen1, E. Nakamura2, K. Hayashi2 and K. Tanaka2,3Institute of Advanced Energy, Kyoto University, Uji 611-0011, JapanUVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan3
School of Physical Sciences, The Graduate University for Advanced Studies, SOKENDAI, Okazaki 444-8585, Japan
1

2

Ⅲ -1

The variation of the photon beam properties, such as
beam position, photon energy, and so on, during user
operation in the beamline is a big issue in synchrotron
radiation (SR) facilities. After introducing the top-up
operation in 2010, the average photon flux of the UVSOR
has been doubled. Then the heat load on to the mirrors
have been doubled and heat induced mirror deformation
could induce the variation of the photon beam properties
in some beamlines. A photon-energy drift at BL5B has
been observed during user experiments [1]. We havestarted a detailed investigation of the source of thephoton-energy drift. Results of our investigation andefforts to reduce the drift are reported.
The first candidate of the source of the photon-energy
drift was the M0 mirror, which is water cooled but
directly illuminated with SR. At first, a system to monitor
the angle of the M0 mirror using a laser diode and a CCD
camera was developed to investigate the deformation of
M0 mirror and its influence to the photon energy. As theresult of the continuous measurement of the photon
energy and the M0 mirror angle (Fig. 1), we found thatthe angle of M0 mirror is not the main source of thephoton-energy drift.
The M1 mirror, which is not water cooled, was thesecond candidate of the source. Several thermocouples
were installed to measure the temperature of the M1
mirror and its holder. The measured results of thetemperature rise are shown in Fig. 2. After opening thefront end valve at 10 o’clock, temperature of M1 mirror
and its holder gradually increased. The temperature of thecenter of the M1 mirror (CH2) was significantly higher
than those of the upstream (CH3) and downstream (CH1).
This large temperature gradient may cause thedeformation of the M1 mirror. Moreover, the temperatureof the mirror holder (CH4) has higher temperature thanthat of M1 mirror. Even after 10 hours from the start of
SR injection, the holder temperature continuously
increased. This continuous temperature rise could be thesource of the continuous photon-energy drift shown in
Fig. 1 which lasted for 20 hours.
We found that some stray light of SR directly hit theholder of M1 mirror. This could be the reason why thetemperature of the holder (CH4) was higher than that of
the M1 mirror (CH2). A horizontal slit after the M0 mirror
was adjusted to reduce the amount of the stray lighthitting on the M1 mirror holder without significant
reduction of SR intensity. This treatment worked well andthe amount of temperature rise of the M1 mirror holder
could be significantly suppressed from 73 to 57 ºC (Fig.
3).
Moreover, a heater was installed to compensate theSR induced temperature rise of M1 mirror. The

temperature of M1 mirror was stabilized by a feedback
control. Then the amount of photon-energy drift was
decreased from -0.19 to -0.08 eV@73.1 eV. In thepresent condition, some stray light still hitting on theholder. Further improvement can be achieved byinstalling a metalic mask in front of the M1 mirror.
This will enable us complete cutting out of the straylight and more reduction of the photon-energy drift.

Fig. 1. Result of continuous measurement of the M0
mirror angle and the relative photon-energy of the SR
after the monochrometer of BL5B.

Fig. 2. (Left) Photograph of thermocouples attachedto the M1 mirror. (Right) Measured temperature rise.

Fig. 3. Measured temperature rise with insertion ofslit to reduce the stray light hitting on the holder.
[1] K. Hayashi, UVSOR Activity Report 2011 39 (2012)
121.

42
Ⅲ01- 12 -BL7B

Ⅲ -1. Accelerators and Instruments

BL7B

Interference Analysis by Composite Type VIS-VUV Complex Refractive
Index Measurement Device
1

J. Omae1, K. Fukui1, K. Yamamoto2 and T. Saito3

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

There is spectroscopic ellipsometry (SE) as ameasurement method for obtain accurate complex
refractive index spectrum of solid material. However,a commercially available SE device has measurement
upper limit of about 5.5 eV. Therefore, based on the
instrument designed by the AIST group, we had
developed a SE that can measure from visible (VIS) tovacuum ultraviolet (VUV) using BL7B [1].
The VIS-VUV SE can obtain the accurate complex
refractive index, but it cannot obtain a wavelength
continuous spectrum due to the measurement principleof this SE. On the other hand, there is Kramars-Kronig
analysis (KKA) as a method to obtain a wavelength
continuous spectrum of complex refractive index.
KKA obtains a complex refractive index spectrum
through the Kramars-Kronig relation to the reflection
spectrum measured in a sufficiently wide wavelength
range. However, considering that the quantitative
measurement of the reflection spectrum is extremely
difficult, the absolute value of the complex refractive
index obtained by KKA is uncertain. However, the
VIS-VUV SE and KKA have complementary features.
Therefore, with the aim of obtaining complex
refractive indeies spectra from these two analysis
methods, we have been incorporating reflectometer
into this VIS-VUV SE. However, this combined
system cannot take advantage of both features whenthe measurement target is thin film and the opticalinterference occurs. Then, in this report, we tried toestablish an analytical method in wavelength region
where optical interference occurs.
In our combined system, the absolute value of thereflection spectrum obtain by the reflection
measurement can be corrected by calculating thereflectance from VIS-VUV SE. The optical interference
can be expressed using an appropriate optical model bycomplex refractive indices n and k. Therefore, applying
the fitting calculation with the appropriate optical modelto the corrected reflectance spectrum in opticalinterference energy region allows the complex
refractive indices spectra to be obtained directly fromthe reflection spectrum. Figure 1 shows the correctedreflection spectrum of AlN thin film evaporated on
SiO2 substrate by RF sputtering method. Opticalinterference was observed at 2 to 5.5 eV, and thisanalysis was performed in this wavelength region.
Figure 2 shows the complex refractive index obtainedby this analysis. To evaluate the analysis results, theabsorption coefficient was calculated from theextinction coefficient k, and the shape was comparedwith the absorption spectrum of this AlN thin film.

Fig. 1. Reflection spectrum of AlN thin film

Fig. 2. Complex refractive indices, absorption coefficientand absorption spectrum of AlN thin film

[1] T. Saito, M. Yuri and H. Onuki, Rev. Sci. Instrum.
66 (1995) 1570.

43
Ⅲ01- 13 -Ⅲ -1

Installation of Momentum
Microscope at BL6U