BL3U

Construction of an Endstation of BL3U for X-Ray Emission Studies

T. Hatsui1, T. Horigome2, K. Matsushita3, H. Yoshida4, M. Suzui4, N. Kosugi11Dept. of Vacuum UV photoscience, Institute for Molecular Science, Okazaki 444-8585 Japan
2
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 Japan
3
Technical Center, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
4
Equipment Development Center, Institute for Molecular Science, Okazaki, 444-8585 JapanS1X matches FWHM of the beam at the sample
position, which is estimated within Fraunhofer
diffraction.

Optical Design
High-resolution soft-x-ray emission spectroscopy(XES) generally requires small beam size at the
sample position, because a smaller opening of thespectrometer entrance slit is needed to achieve higher
energy resolution. Such a beam is usually produced
by refocusing optics downstream of the exit slit. In
the case of BL3U, installation of such refocusing
optics is impossible, due to a very limited space.
On the other hand, monochromators with short arm
lengths, such as BL3U, are operated with small
exit-slit opening for practical energy resolution. It is
feasible to carry out XES studies at the exit-slit
position. The constant exit-arm length of the BL3U
monochrometer is essential for such design. Based on
the above consideration, an XES endstation has been
constructed at the exit-slit position of the in-vacuum
undulator beamline BL3U.
Figure 1 represents the optical layout of the XES
endstation. X-rays dispersed by the variedline-spacing plane grating are horizontally focused by
the plane-elliptical mirror, M2X, with thedemagnification of 20 [1]. The exit slit, S1X,
monochromatizes the x-rays. The ray-trace
calculations based on the upgraded lattice parameters(the lowest emittance mode), which will be operated
from May 2005, indicate that the beam on the sample
position has a Gaussian profile with full width at half
maximum (FWHM) in horizontal direction of 62 Pm.
On the other hand, the vertical beam size isdetermined by the slit opening of S1X, and thediffraction effect. The distance between S1X and thesample position is set to 22.5 mm. The smallest
vertical beam size limited by diffraction through S1X
is shown in Fig. 2. Here the smallest beam size isdefined as the beam size, where the slit opening ofResults and Discussion
Horizontal beam size is evaluated by using aknife-edge scanning method. Obtained profile waswell fitted a Gaussian function with FWHM of 68 Pm(Fig. 2, left), which is slightly larger than thetheoretical prediction of 62 Pm. This deviation arises
from the operation with the moderate emittance mode
(60 nm-rad). The horizontal beam size will be
improved after the user operation with the upgradedlattice (27.4 nm-rad).
Vertical size was evaluated by measuring the 0thorder diffraction of the recently developed
transmission-grating spectrometer for XES (Fig. 1)[1,2]. The Wolter type I mirror has a magnification of
10, which enables the measurement of the verticalbeam size at the sample position. Fig. 2(right) shows
the observed image of the beam at 110 eV with the
S1X opening of 18.5 Pm, corresponding to
E/'E=7000. In the vertical direction, the beam shows
only a simple Gaussian profile with FWHM of 24 Pm,
slightly larger than the theoretical prediction. No
undulated tail originated from the diffraction throughS1X is observed. This may indicate slightmisalignment of the Wolter type I mirror, whichcauses blur in the image. The obtained flux was
1010-1011 ph/sec.
In summary, a new XES endstation was
successfully constructed at BL3U. The beam size of
68 (horiz.) x 24 (vert.) Pm2 is obtained.

Fig. 2 Horizontal beam profile (left), and a image ofthe beam (right) at 110 eV.
[1] T. Hatsui, et al., AIP Conf. Proc. 705, 921 (2004).
[2] T. Hatsui, et al., J. Electron Spectrosc. Relat.
Phenom., in press.

Fig. 1 Schematic layout of the XES endstation(left), and theoretical prediction of the vertical beam
size (right).

40

BL5U

Improvement of the SGM-TRAIN Monochromator at UVSOR-II BL5U for
Low Excitation-Energy Photoemission

T. Ito1,2, H.J. Im2, S. Kimura1,2, E. Nakamura1, T. Horigome1
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
2
School of Physical Science, The Graduate University for Advanced Studies, Okazaki 444-8585,
Japan
1

BL5U at UVSOR-II storage ring has beenreconstructed in 2004’s for high-resolution
photoemission (HRPES) study for solids and surfaces[1]. The energy and angular resolutions of thephotoemission apparatus constructed at the end-stationof BL5U have been improved to 'E ~ 1.2 meV and'T~ ±0.1°, which is sufficient to study the anomalous
physical properties such as the metal-insulatortransition, superconductivity, magnetic phasetransition, etc. However, it has been hard to study theabove properties at BL5U because of the old-type
beamline designed in 1995’s, in spite of the extensive
improvement of the end-station and the storage ring
[1,2]. Main problems interrupting a high-resolution
study were as follows. (1) Mechanism for optimizing
the front mirror was too rough to operate the focus
position of the undulator light. (2) Entrance slit has no
cooling system. (3) The grating G3 with normal
incident mount for the low energy region (hQ = 5 – 25eV) has been optimized to the bending magnet
radiation [3]. The above has caused the extremely low
throughput at the low-energy region and restricted the
HRPES experiment.
Taking account of the problems listed above, wehave reconstructed the beamline in the following way
to improve the efficiency in the PES experiment withusing the low-energy photons at BL5U. (1) The
mechanics at the front mirror was updated to thehigh-precision system controlled by the pulse-motors.
(2) The water-cooling system was attached at theholder of the entrance slit. (3) The monochromator(SGM-TRAIN) was re-arranged to the optimum
condition to the undulator light.
Figure 2 shows the improved throughput from the
SGM-TRAIN monochromator after the present
reconstruction. Comparing with the previous
throughput spectra (Fig. 1), we can clearly find thatthe mesh current increases about 30 times higher, andthe energy resolution becomes better because of the
sharper interference from the optical klystron-type
undulator as shown in Fig. 2. Due to thehigh-throughput of the photocurrent at the low-energy
region, the HRPES measurement at BL5U becomes
available. For example, HRPES spectrum at the
Fermi-level of gold (Fig. 3) has been corrected within
1 hour with the resolution of hQ/'E ~ 1000. We
believe that the present reconstruction makes it
possible to explore the origin of the anomalous
physical properties by using the high-resolutionbulk-sensitive
angle-resolved
photoemission

apparatus at UVSOR-II BL5U.

Fig. 1 Throughput spectra from the SGM-TRAIN
monochromator with the normal incident grating G3
measured before the present reconstruction [1].

Fig. 2 Same as Fig. 1, but measured after thepresent reconstruction.

Fig. 3 HRPES spectrum at the Fermi level of gold
measured after the present reconstruction.
[1] T. Ito et al., UVSOR Activity Report 2003, 40.
[2] M. Katoh et al., UVSOR Activiry Report 2003, 5.
[3] M. Kamada et al., Rev. Sci. Instrum. 66 (1995)
1537.

41

BL5B

Aging Stability of Mg-Based Reflection Multilayers in the 2535 nm Region
T. Ejima1, A. Yamazaki1, T. Banse1, K. Saito1,2, Y. Kondo1,3, S. Ichimaru4, H. Takenaka4
1
IMRAM, Tohoku University, Sendai, 980-8577 Japan
2
Venture Business Laboratory, Saga University, Saga 840-8502, Japan3
Akita Research Institute of Advanced Technology, Akita 010-1623, Japan
4
NTT-AT Co., Tokai 319-1193, Japan
humidity atmosphere. The condition will be easily
achieved in the EUV instruments.

Reflection measurements in the 2535 nm region
are made for Mg/SiC- and Mg/Y2O3- multilayers kept
under a low humid atmosphere for 4 or 5 years. Bothaged Mg/SiC and Mg/Y2O3 multilayers keep theirreflectances.

Introduction
In the 2535 nm wavelength region, Mg/SiC- andMg/Y2O3-multilayers have been proposed andfabricated as a reflection multilayer [1, 2]. However,magnesium is known to have a high reactivity and isusually found in nature in the form of oxide,
carbonate or silicate, often in combination withcalcium. This aspect of high reactivity presents a
demerit for the practical application of Mg-based
multilayers, despite their high reflectance.

Experiments
All samples used for the aging-stability
measurements were kept in a desiccator at RT and ahumidity estimated at lower than 50%, except for
during the time of the measurements.
Reflectances of the aged and heated multilayers
were measured with the reflectometer at the beamline
BL5B. In the measurements, a combination of the G3
grating and the M24 mirror was used. The resolving
power of the wavelength, O/'O, was about 500 at 30
nm. Reflectances of the non-aged multilayers were
measured with a home-made reflectometer [3], a 166°
constant-deviation type using a grating that was 600
grooves/mm concave with a 3 m radius of curvature.
The resolving power of the wavelength was estimatedto be 240 at 25.6 nm.

Experimental Results

Fig. 1 Reflectance of Mg/SiC multilayer after 4
years storage (a), and before storage (b).

One of measured reflectances of the aged
Mg/SiC-multilayers is represented with thesimulation result in Fig. 1(a). The ordinate of the
figure is s-polarized reflectance. The measured results
are represented by solid curves and the simulation
results, by broken ones. As can be seen in the figure,measured reflectances were well reproduced by thesimulated ones. The reflectance of the non-aged
multilayer measured before storage is represented inFig. 1(b). The ordinate of the figure is non-polarizedreflectance. A comparison of reflectances between
before and after storage, and a comparison of themeasured reflectances with the simulated ones showthat the multilayer represents high reflectance after 4
years storage. Mg/Y2O3-multilayers retained also
their reflectance even after 5 years storage in a low[1] Y. Kondo, T. Ejima, K. Saito, T. Hatano, and M.
Watanabe, Nucl. Inst. Meth. Phys. Res. A 467-468(2001) 333.
[2] T. Ejima, Y. Kondo, and M. Watanabe, Jpn. J.
Appl. Phys., 40 (2001) 376.
[3] S. Nakayama, M. Yanagihara, M. Yamamoto, H.
Kimura, and T. Namioka, Physica Scripta, 41 (1990)
754.

42

BL5B

Thermal Stability of Mg-Based Reflection Multilayers
T. Ejima1, A. Yamazaki1, T. Banse1, K. Saito1,2, Y. Kondo1,3, S. Ichimaru4, H. Takenaka4
1
IMRAM, Tohoku University, Sendai, 980-8577 Japan
2
Venture Business Laboratory, Saga University, Saga 840-8502, Japan3
Akita Research Institute of Advanced Technology, Akita 010-1623, Japan
4
NTT-AT Co., Tokai 319-1193, Japanover 400°C. This temperature-durability will be highenough in the EUV instruments.

Reflection measurements in the 2535 nm region
are made for Mg/SiC- and Mg/Y2O3- multilayers
annealed from room temperature to 400qC with 50qC
intervals. Both Mg/SiC and Mg/Y2O3 multilayers
keep their reflectances under 200qC annealing.

Introduction
In the 2535 nm wavelength region, Mg-based
multilayers have been proposed and fabricated as areflection multilayer [1, 2]. Reflection multilayers
used for practical optics are usually exposed to highheat-load circumstances through being baked in a
vacuum chamber or enduring a high flux of incident
light. Magnesium is known to have a low melting
point (648.8°C), much lower than that of typicalmolybdenum (2622°C) and silicon (1414°C). This
low melting-point presents a demerit for the practicalapplication of Mg-based multilayers, despite theirhigh reflectance.

Experiments
The multilayers used for the thermal-stability
measurements were heated from RT to 400°C at 50°C
intervals in an IR furnace with an Ar atmosphere for 1
hour. Temperature was monitored by threethermocouples in contact with the sample surface.
Reflectances of the heated multilayers were
measured with the reflectometer at the beamline
BL5B. In the measurements, a combination of the G3
grating and the M24 mirror was used. The resolving
power of the wavelength, O/'O, was about 500 at 30
nm. The resolution of the angle of incidence wasabout 0.1°. To suppress high ordered light from themonochromator, a reflection-type filter was placed in
front of the sample.

Fig. 1 Reflectances of Mg/Y2O3 multilayers
annealed from 150°C to 300°C with 50°C intervals(a), and the relative reflectance of each annealing
temperature normalized by that of RT (b).

[1] Y. Kondo, T. Ejima, K. Saito, T. Hatano, and M.
Watanabe, Nucl. Inst. Meth. Phys. Res. A 467-468(2001) 333.
[2] T. Ejima, Y. Kondo, and M. Watanabe, Jpn. J.
Appl. Phys. 40 (2001) 376.

Experimental Results
The measured reflectances of the annealed
Mg/Y2O3 multilayers are represented in Fig. 1(a).
Bragg reflection peaks are observed at around 25.5
nm, and no movement of the peak positions isobserved with increases in the annealing temperature.
Temperature dependence of the reflectance that arenormalized by the reflectance at RT is represented inFig. 1(b). The value obtained for the measured
reflectance in the Mg/Y2O3 multilayer at RT was 0.43,
and in Mg/SiC multilayer it was 0.42. The
temperature dependence of both multilayers is thatthe reflectance remained constant from RT to 200°C,
but decreases with increases of temperature above
200°C, becomes half at 300°C, and then vanishes

43

BL5B

Development of Multi-Layer Mirror for Imager of O+ Ions
Flowing from Planets

T. Murachi1, K. Okada1, M. Kanao1, A. Yamazaki2, I. Yoshikawa3,
W. Miyake4, M. Nakamura1
1
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency,
Sagamihara, Kanagawa 229-8510 Japan
2
Planetary Plasma and Atmospheric Research Center, Graduate School of Science,
Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578 Japan
3
Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 Japan
4
National Institute of Information and Communications Technology, Koganei,
Tokyo 184-8795 Japan
It is known that the hydrogen atoms and ions andthe oxygen ions are main components of outflow
from the atmospheres of the Venus and the Earth tothe interplanetary space. The oxygen ions makeimportant roles in the interaction with the solar windplasma. In order to investigate the 2 dimensional
distribution and temporal variation of the oxygen ions,which is difficult for the in-situ observation using thesatellites, we think of the remote sensing of the solar
photons resonant-scattered by the oxygen ions (O II:
83.4 nm).
However, resonant-scattered light of the hydrogenatoms (the Lyman Į line: 121.6 nm) has the
wavelength near that of the O II (83.4 nm). The
hydrogenatoms
surroundingtheplanets
resonant-scatter the solar light and shine to form acorona. The brightness of the hydrogen Lyman Į line
is 100 - 10000 times stronger than that of the O II.
Therefore, it is necessary to produce the optics, whichhave little sensitivity at the hydrogen Lyman Į line.
Until now, we produce the optics using amolybdenum mono-coated mirror (Mo mirror) and an
indium filter, and it rejects the Lyman Į line. In thisexperiment in order to make the sensitivity of thehydrogen Lyman Į line lower, we design and produce
a multi-coated mirror of molybdenum and MgF2 (1pear of Mo: 8.0 nm over MgF2: 8.5 nm, Mo/MgF2
mirror) on an aluminum substrate.
Fig. 1 shows the measurements of the reflectivityof the Mo mirror and the Mo/MgF2 mirror in the
EUV facility (using the atomic spectral line, whose
wavelength is discrete) of the Institute of Space andAstronautical Science (ISAS), Japan Aerospace
Exploration Agency (JAXA). At the hydrogen LymanĮ line the reflectivity of the Mo mirror and theMo/MgF2 mirror is 28 % and 5 % respectively. The
reflectivity of the Mo/MgF2 mirror is 6 times lower
than that of the Mo mirror.
Like the calculated value of the reflectivity shownin Fig. 2, the reflectivity of the Mo/MgF2 mirror
should become very low in the vicinity of 121.6 nm.
Then we measured the reflectivity of the Mo/MgF2
mirror with continual radiation of the UVSOR BL-5B
line. Fig. 2 represents the measurement result(because of P polarized light of UVSOR BL-5B, thereflectivity in Fig. 2. differs from that in Fig. 1.). The
calculation of the reflectivity of the Mo/MgF2 mirror
becomes very low near 121.6 nm, but theexperimental result does not become so. We elucidate
this cause in future.

Fig. 1
The reflectivity of the Molybdenum
mono-coated mirror (red) and the multi-coated mirrorof Molybdenum and MgF2 (blue) in the EUV facilityof ISAS of JAXA.

Fig. 2The experimental value (red) and thecalculated value (blue) of the reflectivity of themulti-coated mirror of Molybdenum and MgF2 in the
UVSOR BL5B.

44

BL6B

Construction and Performance Test of BL6B(IR)S. Kimura1,2, E. Nakamura1, T. Nishi2, Y. Sakurai1
1
UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan2
Deparment of Molecular Structural Science, The Graduate University for Advanced Studies,
Okazaki 444-8585, Japan
We have newly installed an IR-THz beam line at
UVSOR-II. UVSOR had the oldest IR beamline(BL6A1) dedicated at 1986 [1]. Recently, UVSOR
storage ring was upgraded to be a low emittance ringand to be able to equip six undulators at three longand three short straight sections. Since the old IR
beam line locates on the extended line of one of shortstraight sections (S6), the emission point was moved
to the downstream position in the bending magnet(B6) to make a new undulator beam line at S6. The
name of the IR beam line was changed to BL6B(IR).
The beam line has a large acceptance angle of215(H) x 80(V) mrad2 to obtain the high flux in the
IR and THz regions. So-called “magic mirror” withvertical angle focusing that has been installed at
SPring-8 BL43IR at first [2] was employed as thefirst mirror. The mirror chamber was directly
connected to the bending magnet chamber forcollecting high photon flux [3]. To avoid heat loadfrom SR, the orbital plane on the mirror was masked
by a copper rod with water cooling. The SR is
focused to the imaging source point that locates out of
the ultra-high vacuum area of the bending and mirror
chambers only by the magic mirror. The beam size at
the first focus in the distance of 2640 mm from themagic mirror was 1.17(H) x 1.20(V) mm2 that issimilar to the corresponding ray-tracing result of1.0(H) x 2.0(V) mm2.
The beam line equips two rapid-scan-type
interferometers, one is old Michelson-type (Bruker
66v)
and
the
other
newly
installed
Martin-Puplett-type (JASCO FARIS-1). The former

covers in the photon energy range of 6 meV – 3 eV
(50 – 25,000 cm-1) and latter of 1.2 – 25 meV (10 –200 cm-1). One of the results produced by the latterinterferometer is shown in this issue [4].
The obtained and expected brilliance and photon
flux are plotted in Fig. 1. In the figure, the results ofSPring-8 BL43IR and an expected intensity of a black
body light source (The temperature of 1400 K is
assumed.) are also plotted. BL6B is higher brilliancein the THz region and higher photon flux in the whole
region than BL43IR. This result indicates that BL6B
is suitable for the microspectroscopy in the whole
region, on the other hand, BL43IR is good for the
mid-IR microscopy with diffraction limit resolution.
The present end station is only for areflection-absorption spectroscopy for mm-size
samples. In spring of 2005, a new spectromicroscopy
apparatus is installed. The apparatus employs large
schwartzschild mirrors with 140 mm in diameter tocover the THz region.
[1] T. Nanba et al., Int. J. Infrared and Millimeter
Waves 7 (1986) 1769.
[2] S. Kimura et al., Nucl. Instrum. Meth. A 467-468(2001) 437.
[3] S. Kimura et al., AIP Conf. Proc. 705 (2004) 416.
[4] S. Kimura, S. Kunii, in this issue.

BL6B(IR)(I=500mA)

15

SPring-8 BL43IR
I=100mA

Photon flux (ph/s/0.1% b.w.)

Brilliance @ first focusing point22(ph/s/mm /mrad /0.1%b.w.)

12

10

11

10

BL6B
I=500mA

10

10

old-BL6A1
I=300mA
9

10Black body
(T=1400K)

10

old-BL6A1(I=300mA)
SPring-8 BL43IR(I=100mA)

1410Black body source(for large sample)(1400K, I5mm, 0.015sr)

1310Black body source(for microscope)(1400K, I1mm, 0.015sr)

12

10

8

10 -3
10

-2

10

-1

10

0

10

-3

10

1

10

-2

10

-1

10

0

10

hQ (eV)hQ (eV)

Fig. 1 Brilliance (left) and photon flux (right) spectra of UVSOR BL6B, SPring-8 BL43IR and black bodylight sources. The dashed and solid lines are calculated and measured spectra, respectively. UVSOR BL6B isbrighter in the THz region and higher photon flux in the whole region than SPring-8 BL43IR.

45

BL7U

Design of a High-Resolution and High-Flux Monochromator for VUVAngle-Resolved Photoemission at BL7U

S. Kimura1,2
UVSOR Facility, Institute for Molecular Scinece, Okazaki 444-8585, Japan2
Deparment of Molecular Structural Science, The Graduate University for Advanced Studies,
Okazaki 444-8585, Japan1

We plan to construct a new undulator beam line forstudying electronic structures of condensed mattersbyahigh-energy-resolution
angle-resolved
photoemission in the VUV region. The beam line
equips an undulator light source, a VUVmonochromator and a photoelectron spectrometer.
The APPLE-II type undulator [1] will be installed to
produce not only horizontal but also vertical linear
polarization in the photon energy range of 7 – 40 eV.
The undulator period length (Ou) and the number of
period are 70 mm and 40, respectively. The
photoemission end station equips a 200-mm-radiushemispherical photoelectron analyzer. The target of
the total energy resolution in the angle-resolved
photoemission spectroscopy is below 1 meV. To
attain the purpose, the monochromator must be highenergy resolution below 1 meV and high photon flux
above 1011 ph/s on samples. Here we propose thedesign of the new type normal-incident
monochromator for such purpose.
The schematic figure of the monochromator isshown in Fig. 1. The monochromator has no entrance
slit because the very small vertical beam size at thecenter of the undulator after upgraded UVSOR-II.
The beam size (2V) is calculated to be 0.07(V) x
1.2(H) mm2 in 3-%-coupling operation [2]. When thelight is derived to a grating without extrance slit, notonly high photon flux but also high energy resolution
is expected because of the long distances between theemission point and the grating and between the
Top view

grating and the exit slit. The similar monochromator
has already installed at SRC, Wisconsin [3].
The distances from the emission point to the grating
and from the grating to the exit slit are 22 m and 6.67
m, respectively. Then the radius of the sphericalgrating is 10 m. The source size is reduced by 1/3 on
the exit slit. The focusing element is only thespherical grating to reduce the focusing errors. The
dispersion direction of the grating is vertical and theincident angle is 0.5 deg.
Three gratings of 1,200, 2,400 and 3,600 l/mm
optimized at 10, 20 and 30 eV, respectively, areinstalled for keeping the energy resolution below 1
meV. The highest energy resolution is expected to be
E/'E ~ 6u104 with the grating of 3600 l/mm and1-%-coupling operation. The photon flux keeps above
1011 ph/s in 0.01-% band width.
The beam line equips three branches. The first is forthe angle-resolved photoemission, the second for thephotochemistry and the third for micro-focus
photoemission.
The beam line will be constructed at BL7U in thesummer of 2006.
[1] S. Sasaki et al., Jpn. J. Appl. Phys. 31 (1992)
L1794.
[2] M. Hosaka, private communication.
[3] J. Bisognano et al., Nucl. Instr. Meth. A 467-468(2001) 492.

Plane mirror(M0)

Undulator(APPLE-II type)10msphericalgrating (G)Planemirror (M1)Planemirror (M2)

Exit slit(S)

PostmirrorSide view
G
U

M2

S
M0

M1

Fig. 1 Schematic figure of the new normal incident monochromator at BL7U.

46

Quality Evaluation of Mass-Produced Nuclear Emulsion Films for OPERA
Neutrino Oscillation Experiment
S. Hiramatsu, N. Naganawa, A. Ariga, J. Kawada, S. Miyamoto, T. Ban, K. Hamada, N. Koike,
K. Miyanishi, K. Narita, T. Nakamura, M. Nakamura
F-Laboratory, Faculty of Science, Nagoya University, 464-8602, Japan
Nuclear Emulsion Film can record trajectories ofhigh-energy charged particles with sub-micron
position accuracy. The trajectories are recorded as
three-dimensional images in the emulsion layers of the
film.
Nuclear emulsion has been used in the study ofelementary particle physics from 1950s, but at the endof 60s it became a minor detector in that field, because
other useful electric detectors were emerged. But, by
the recent development of automated image read-out
system by us, Nuclear emulsion came back to thefrontier of elementary particle physics. The frontier,where the recent nuclear emulsion is working, is
Neutrino physics.
In 2000, we have succeeded to detect Tau neutrinos
at the first time in the world. Following this success,we are preparing a large scale neutrino oscillation
experiment, named OPERA. In this experiment, we
intend to confirm the existence of the neutrino masses.
We intend to detect Tau-neutrinos oscillated from
Mu-neutrinos during the 2.4 msec (732 km) flightfrom Geneve (Switzerland) to Gran Sasso (Italy). We
need a large detector that the mass is around 1700 ton
to detect the oscillated Tau neutrinos with high S/Nratio.
About 12 M films corresponding to the area of
150,000m2 is required to realize the experiment. The
emulsion film, so-called OPERA film, has beendeveloped by us with the collaboration of Fuji Photo
Film Co., Ltd. We have succeeded to implement a
special function “Refreshing”. By this function, we
can reset or erase the images recorded in the film
before its use.
For OPERA, we are applying the refreshing process
after the delivery from Fuji Photo Film Co., Ltd. Thentransport the film to Gran Sasso.
We must evaluate the quality of the films in each step,i.e., after the delivery from Fujifilm and after therefreshing, Also we must evaluate the quality of therefreshing process. In order to do those, high energy
electrons available in the UVSOR facility has beenused.
The exposed electrons were produced during theelectron beam transfer from the Booster Synchrotron
to the Electron Storage ring. Those are the converted
electrons and positrons of gamma rays produced byelectron interactions with residual gas or materials
surrounding the beam transport. The average energy ofthe produced electron (positron) is around 50 MeV.
Figure 1 shows a photograph of an electron trackrecorded in an OPERA film to be evaluated thesensitivity of a film is defined as a density of theFig. 1 A recorded trajectory of electron tracks.
Horizontal scale is 120 microns.
recorded grains along electron tracks. The size of therecorded grains is around 0.6 micron. The grain
density was measured by eye and machines. We
specified the grain density of 32 grains/100 microns asa threshed for good quality.
By the exposure and measurement, all of the
production batches and the refreshed films show
enough sensitivity for our purpose. In Fig.2, themeasured sensitivities of the first ten batches areshown. Though some fluctuation can be seen, thesensitivity is over 32 grains/100 microns in all
samples.
The evaluation Job using the UVSOR electron willcontinue until the middle of 2006.

Fig. 2 Measured sensitivity of the films(grain density) of the first 10 production
batches.

47