2

Contents
1

Preface .......................................................................................................................52

Research digest ..........................................................................................................73

Messages from foreign visitors ..............................................................................35

4

Members of Yoshikawa Lab ..................................................................................41

5

Prizes and awards ....................................................................................................46

6

List of research collaborations ...............................................................................50

7

Research funds ........................................................................................................54

8

List of patents ..........................................................................................................62

9

List of abstracts .......................................................................................................63

10

Copies of TV, journal and newspaper items .......................................................1023

4

Preface
Dear Colleagues,
Thank you for downloading the Annual Report of the Yoshikawa Laboratory in the Institute forMaterials Research (IMR) and Yoshikawa Project in the New Industry Creation Hatchery Center (NICHe),
Tohoku University. As usual, we have prepared the Annual Report as an electrical version so as to savecouple of trees necessary for the paper production and to make it easier for you to access the copy of theReport at any time when you have your computer in your hands.
It contains a summary of our research activities and selected papers published in FY2014. Current issue
covers our progress within academic year from April 2014 to March 2015. Within this period we had
continued development of our basic technologies considering both practical and fundamental points of view.
Some of our achievements are summarized below:
 Further progress in studies of Ce: GAGG crystals for their application as gamma-ray scintillators. It
should be noted that the performance was further enhanced by divalent ion codoping and explainedby the stabilization of Ce4+ center and its participation in scintillation mechanism. This strategy
appeared successful in case of aluminum garnets and orthosilicates. Food survey monitoring system
and gamma camera for environment inspection are under development.
 Establishment of crystal growth technology of halide materials. As an example, Eu:SrI2 crystals
were grown by the micro-pulling down method including crystals of one inch in diameter.
 Development of La-substituted GPS crystal that has exceptionally high temperature stability.
 Bulk crystal growth of langasite type crystals. Al-substituted CNGS and CTGS crystals are studied
for their application in oscillators, resonators, and combustion pressure sensors. The homogeneity as
well as material constants were evaluated by the UMS technology.
Our long term strategy is to develop chains of research capabilities that connect three areas of expertise
including (1) materials production (crystal growth and solid-state synthesis), (2) materials physics andcharacterization, and (3) application of the materials in contemporary devices. Such chain was already built
for the scintillating materials. Now we are on the way to apply this strategy to piezoelectric materials.
Our projects are always supported by our colleagues from all over the world, and we note that thiscollaboration is in most cases very successful. The details of their contribution can be found in the papers
published within the above period and included into the Report.
Many laboratory members took part in preparation of this Report. I appreciate their efforts and kind
help very much. I wish also thank all of our colleagues from Japan and overseas that had participated in our
research projects and significantly contributed to their progress.
We will do our best to contribute to the human happiness in order to return a favor from all of you.
Akira YOSHIKAWA

Professor,
Institute for Materials Research (IMR), Tohoku University
New Industry Creation Hatchery Center (NICHe), Tohoku University
March, 20155

6

Research digest

7Research Activities in 2014
Development of
scintillators, lasers, piezoelectric crystals
and crystal growth technology
Int’l  collaboration
Inst. Phys. (Czech), Pisa Univ. (Italy), Milan-Bicocca Univ. (Italy),
Ecole Polytechnique (France), Univ. Lyon 1 (France), General Physics Inst. (Russia)
Soltan Institute for Nuclear Studies (Poland), Delft Univ. (New Zealand)

Fluoride
Scintillators

Oxide
Scintillators
PEM
PET/MRI
Dosimeter

Neutron imager,
VUV scintillator

HalideScintillators

Multidisciplinary Researchfor“Crystals”  and  “Ceramics”

Survey meter
Resonator,
Combustion sensor,
SAW  filter,  …

Piezoelectric
Crystals

Transparent
Ceramics
Scintillators

G-PMT, APD, MPPC,
MSGC,  GaN,  …

Development of
new photodetectors

Univ., National Inst.
Univ. of Tokyo (Kamiokande, Takahashi Lab.), Kyoto Univ. (Tanimori Lab),
Osaka Univ. (Sarukura Lab), Nagoya Univ. (Iijima Lab, Uritani Lab, Iguchi Lab),
Hiroshima Univ. (Fukazawa Lab), Kyushu Univ. (Ishibashi Lab), JAEA (Fukushima headquarters)

Company
Tokuyama, Furukawa, TDK, Hamamatsu Photonics, Canon, Mitsui Kinzoku,
Chiyoda Technol, Nihon Kessho Kogaku, Hitachi-Aloka Medical, Pony Industry, Oxide, GES
Tanaka Kikinzoku Kogyo, Furuya, Star seiki, TEP, Toei Scientific IndustrialReference： http://www.jst.go.jp/pr/announce/20140905/index.html

High light yield(~40,000ph./MeV) andhigh energy resolution(~5% FWHM) for 662 keVVUV scintilltors
100

100
3+

Tm

Tm

4000

3+ 4

4f-5d

Nd

D

4

4

3

3

H -> P
6

40

2

Tm
3

3+

Tm
3

H -> P
6

1

3

3+

Tm
1

3

H -> I66

3+
1

H -> D
6

Transmittance

Tm

3+

150

200

250

300

13/2

60

Tm
3

3+
3

H -> P
6

40

2

Tm
3

3+

Tm
3

H -> P
6

2

LuF3:Tm1%
LuF3:Tm5%
LuF3:Tm10%

20

1

0

3

3+

Tm
1

H -> I
6

6

3

3+
1

H -> D6

2

LuF3:Tm1%
LuF3:Tm5%
LuF3:Tm10%

20

350

3/2

I

80

60

0

Tm
3+

4f-5d

80

Transmittance(X-ray 40Kv40mA CuKα)

150

200

Wavelength

250

300

350

Intensity (arb. units)

Nd3+ observed in some fluoride crystal hosts

Radioluminescemce

Transmittance

Schematic of energy transfer from Tm3+ to

11/2

3000

3+

1

D -> F +1

I -> H

3

2

4

3

6

4

Nd
2

4

4

P -> I

Nd1%
Tm1%
Tm1%Nd1%
Tm5%Nd5%

3+ 2

G

D

4

Nd

3+

9/2

3/2

9/2

9/2

->

D

5/2
3+ 2

G

L

2

Nd

2000

Tm
1

Tm

3+

1
3

D -> H2

3+
2
3

D -> H
2

15/2

0
350

->

9/2

I

11/2

5

6

1000

Wavelength

Examples of the cut and polished crystals

I

->

??

400

450 500 550 600
Wavelength (nm)

650

700

Light yield(241 Am 5.5 MeV alpha rays, shaping time 500ns)
1000

LaF3:Nd8%
LuF3:Nd1%
LuF3:Tm1%Nd1%
LuF3:Tm5%Nd5%

Counts100

10

LuF3:Nd1%

LuF3:Tm1%

LuF3:Tm5%Nd5%

Eutectic composite scintillators
Concept of eutectic composite
scintillators for neutron detection

1

500

1500
Channel number

As-grown eutectic
composite scintillators

Channel numbers:
LaF3:Nd8% : 421
LuF3:Nd1%: 1550
LuF3:Tm1%Nd1%: 1670
LuF3:Tm5%Nd5%: 1230

2500

Backscattered Electron Images
Transverse cross-section

Eu doped CaF2/Li3AlF6 eutectic crystal

Vertical cross-section along the growth direction

Radioluminescemce spectrum

Powder X-ray diffraction pattern

3

70x10

60

Transmission Electron
Microscope analysis

0.5% Eu

Intensity / a.u.

50

40

Transverse cross-section

30
20

10
0

300
400
500
600
Wavelength, λ / nm

700

Pulse height spectrum and decay curve under 252Cf neutron excitation
1000

Counts / Channel

0.5% Eu
Li glass

100

10

1

0

100

200

300 400
Channel500

600Electron diffraction pattern from [001]incidence direction of b) CaF2 rod phaseAim of this work was to prepare new halide materials for radiation detectors(scintillators and photodetectors) and study their optical properties. Single crystalsof In:SrI2, Sn:SrI2, Eu:SrI2, Pr:CeBr3, were prepared by the atmosphere-controlled
modified micro-pulling-down (-PD) method and by the vertical Bridgman method.
Experimental arrangement of halide -PD machine.
High-frequency induction coil

CCD camera

Turbo molecular pump

Removable chamber

CrystalgrowthSetting ofexperimentin globe box

Removable chamber

Halides are hygroscopic materials which easily reacts with air and air moisture under formation of oxy- and hydroxyhalides, therefore careful handling of starting materials under protective argon atmosphere in a globe box is required.

Crystals prepared by micro-pulling-down method

As grown Pr3+:CeBr3 single crystals prepared by -PD method doped with Pr3+ in nominal concentrations 1, 5, and 10
mol%. Crystals were characterized by measuring the photoluminescence emission spectra (ex=340 nm), pulse heightspectra (-ray source 137Cs at 662 keV), and scintillation decay time.
Growth of SrI2 crystal by -PD

66_SrI2, undoped

Bi Ge O (BGO)

61_1%In:SrI2

4

10 mm

SrI2 single crystals doped with ns2 ions (In+ and Sn2+)
were grown by the -PD method. Radioluminescence
spectra were measured showing one broad emission
band at 510 nm related to the SrI2 host.

10 mm

65_1%Sn:SrI2

RL amplitude

5,6 103

12

61_1%In+:SrI

4

2

2+

65_1%Sn :SrI2
66_SrI , undoped
2

3,2 10

4

8000

10 mm

320

400

480

560

640

720

Wavelength [nm]Crystals grown by vertical Bridgman method using modified -PD furnace
Eu:SrI2 single crystals
were grown by vertical
Bridgman method using
modified -PD furnace.
Light yield for Eu3%:SrI2
reached of 78,000 ph/MeV
with energy resolution of
4.4 % at 662 keV.

Eu3%:SrI2
1 inchAs grown

Eu3%:SrI2

137Cs

Polished

NaI(Tl)Transparent ceramic scintillators
Introduction
Spark plasma sintering(SPS), Collaboration with Goto lab, IMR

Advantages of ceramics
Better chemical uniformity than single crystals.

Advantages of SPS
A rapid consolidation rate appropriate for densification of variety

Can be produced with high dopant concentration.

of ceramics.

Economical especially for high-melting materials.

Highly reductive condition due to carbon die and punch and vacuum

Defects present in single crystals due to high melting

environment.

temperature (for example anti-site defects in Lu3Al5O2:Ce lead

High degree of densification.

to sub-microsecond slow components in scintillation decay)
intensity [arb.units]

Carbon sheet

sampleLuAG:Ce0.12%

1Anti-site defect (Luresides onoctahedral Al site)

Pressure

prompt and delayed component
0.1

DC
pulse
oscillati
ons

54 ns

0.01

PL decay, exc = 335 nm
Scint.decay, exc = 511 keV

0.001
100

200

300

400

500

600

Carbon die

700time [ns]Antisite-defects absent in ceramics →  submicrosecond
components also expected to be absent

Experimental methodology of SPS
Pressure

Lu3Al5O12 :Ce(LuAG:Ce) nanoceramics
LuAG:Ce Nanopowder prepared by unique radiationinduced precipitation 20-60 nm size, Ce concentration
around 1.5 mol%(see J. Barta, V. Cuba et al.: J. Mater. Chem., 2012, 22,16590 for details)
Napowders sintered by SPS at 1700C at 100MPapressure for 45 minutes.
Sintering temperature 1700C
Rapid pre-heating to 1000C in 4 min

Backscattered electron images (BSE)

LuAG samples sintered by SPS method
LuAG undoped – small amount of pores, large grains

LuAG:Ce – large amount of pores, no grains apparent

Photoluminescence decay kinetics

Intensity (arb. units)

10

LuAG undoped-transparent!

BGO
LuAG undop nano
LuAG:Ce nano6

Intensity [arb. units]

I=7276exp(-t/7.8us)++43exp(-t/149us)+4.4

1000
100

0

40

5

6 105

Radioluminescence intensity
for the nanopowder ceramic 5times higher of that of the
Bi4Ge3O12 standard
scintillator!

5

4 10

2 105

240

320

400 480 560 640
Wavelength [nm]720

Defect emission observed forboth samples at 313 nm

120

160 200
Time (us)

240

280

320

LuAG:Ce nano Ex=452 nm, Em=520 nm
exp
fit
instr

1000

I=1791exp(-t/56ns)+4.4

100

10

1

0

100

200

300

400 500
Time (ns)

600

700

800

Ce3+ emission under direct excitation (452nm)

Samples from nanopowder sintered with rapid pre-heating:
Undoped sample clearly transparent, few pores, large grains
Ce-doped sample opaque, many pores, no grains
distinguishedDifferent nature of defect luminescence when compared tosamples prepared without rapid preheating

J. Pejchal et al., WGMSC1 2014, Shanghai, China

Ce:SrHfO3
Hf : High Z, but highmelting point.
Crystal growth
impossible → Task for
the SPS method.

80

313nm defect emission under band-to-band excitation(193nm) – slower components related to other complex
defects

8 10

0

4

1

1.2 106

104

exp
fit
instr

10

LuAG:Ce

1 10

LuAG:Ce nano Ex=205nm Em=313nm

5Intensity (arb. units)

10

Ce/Al:BaHfO3
Ce/Al:CaHfO3

10 mm
Sintered SrHfO3:Ce

SrHfO3:Ce
after annealing

Annealed
SrHfO3:Ce
Under UV
excitation

Ce/Al:SrHfO3

Radioluminescenceof other Ce-doped
hafnate ceramics

Photodetectors
We investigate radiation response of our scintillators using a photomultiplier tube andsemi-conductor in a specially designed temperature chamber.

1, Pulse-height Measurement System
We use several photo-detectors for pulse height measurements.

 PMT (Photo multiplier tube)


Ultra and super –bialkali (UBA and SBA)
PMTs for basic measurement and applications
Ruggedized PMTs for oil well logging
Multi-anode PMTs for medical imaging or otherexciting fields

Ultra Bialkali (UBA)
R7600U-200

 APD (avalanche photodiode)High quantum efficiency (up to ~80%)
Wide sensitive range(ex: 320 -1000 nm for S8664 HPK)APD

 MPPC (Multi-Pixel Photon Counter)

Photon counting
multi-channel MPPC (MPPC array)
MPPC array

2, New Spectrometers
We have developed new spectrometers with a wavelength dynamic rage for emission
spectra from VUV to near Infra-red

Piezoelectric Single Crystals
Target area of resonators

Development and evaluation of CTGAS
evaluation

Quartzfeedback

CTGAS

Smaller
low frequency
low impedance

Ultrasonic Micro-Spectroscopy
UMS
technology piezoelectric characteristic
in tapplication
application

Development for new type resonator

Energy harvester using
oscillation energy

Wide
IMPEDANCE

Oscillation

oscill
ation

Use
for

Electrode

Low
FREQUENCY
Piezoelectricmaterial

Smaller, low-power consumption, rapid booting
and high electro-mechanical coupling resonator

Clean energy harvester

Crystal growth by Cz method

Characterization by the UMS technology

Ca3Ta(Ga1-XAlX)3Si2O14 crystals

LSAW velocities measured for Y-cut CTGAS(x=0.50)

Al CONTENT [mol%]

7
6.9
6.8
6.7
6.6
6.5
3168

3170 3172 3174 3176
LSAW VELOCITY [m/s]3178

Temperature dependence of resonant frequency for
rotatedY-cut CTGAS(x=0.25)
resonator
150.66°Y-CTGAS25(shear 5th)300

Resonant frequency

FREQUENCY CHANGE [ppm]200

100000100

Z
Impedance
(5th)

10000

0
1000

-100
DF
-200

Z

100

-300
-400

10

@25℃

-500
-40

-20

0

20

40

60

TEMPERATURE [℃]

80

100

1
37.23

37.24

37.25

37.26

37.27

37.28

37.29

37.3

＜ Garnet type ＞

＜ Garnet type ＞＜ Ilmenite type ＞＜ Perovskite type ＞＜ Sesquioxide type ＞

＜ Apatite type ＞＜ Spinel type ＞＜ ZnO type＞＜ Vanadate type＞＜ Aluminate type＞＜ Corundum type＞＜ Langasite type＞

＜ Silicate type＞＜ Borate type＞

Instruments in 2014
Growth Equipment (µ-PD Method)
Fluorides (RF-Heated µ-PD System)
TDK, MPD-HT
Anti-vibration system
Temperature: ～ 2500ºC
Atmosphere: Ar,N2,H2,CF4,O2

TDK, MPD-HT
Anti-vibration system
Temperature: ～ 2500ºC
Atmosphere: Ar,N2,H2,CF4,O2

Halides (RF Heated µ-PD System)
Toei scientific industrial co., ltd.
Temperature: ～ 1200ºC
Atmosphere: Ar,N2,H2,CF4,O2

Oxides (RF Heated µ-PD System)SAPOIN,
CNMPD
Anti-vibration system
Atmosphere: Ar,N2,H2,O2

TACHIBANA RIKO,
SCF-600M
Anti-vibration system
Temperature: ～ 2000oC
Atmosphere: Ar,N2,H2,O2

TDK, M-PD2-A
Anti-vibration system
Temperature: ～ 2500oC
Atmosphere: Ar,N2,H2,O2

Sapoin 2
Anti-vibration system
Atmosphere: Ar,N2,H2,O2

Growth Equipments (Cz Method)
Fluorides (RF Heated Cz System)
Nisshin Giken
Temperature: ～ 1600ºC
Atmosphere: Ar,N2,H2,CF4,O2

Oxides (RF Heated Cz System)CYBERSTAR,OXYPULLER 05-03
Heating system: RF
Vacuum: 30Pa
Atmosphere: Air, Ar, N2,O2
Temperature: ～2200oC

30kW-Cz
Heating system: RF
Atmosphere: Air, Ar, N2,
O2
Temperature: ～ 2000oC

Sample Preparation

Fine cutting machine
HeiwaTechnica, HS-25A
Glove box

Automatic lapping
polishing machineElectric balance
Shimadzu
Diamond Wire Cutting Machine
New Metals & Chemical corporation

Measurement & Analysis Equipment
Nomarski-Type Differential
Interference Contrast Microscope
NIKON, Eclipse ME600,TYPE 120
Light Source: White light
DIC Microscope System
Magnification: ×1000

Polarized microscope
NIKON, Eclipse, E600POL
Light Source: White Light
DIC Microscope System
Magnification: ×500
NIKON, SMZ-U
Light Source: Halogen lamp

Horiba, EDX, EMAX X-act
Analyzer & Mapping & Point and
ID & Broad Area
Automatic Analysis

SEM, Hitachi S-3400N

Thin Film HRXRDRIGAKU

Rotary Type XRD
RIGAKU

Powder XRD
RIGAKU

Laue Camera
RigakuR-AXIS DS3

TG-DTASETARAM
Piezoelectric ConstantMeasurement System

IP Reader
Rigaku R-AXIS DS3C

Absorption andfluorescence spectrometer

UV-VIS spectrophotometer
Shimadzu,UV-2550

Si Avalanche
Photodiode

Radiation measurement modules(Light yield, Scintillation decay time)
Edinburg Instruments
Spectrometer:
Photoluminescence & Decay
timeMeasurements & Analysis Equipment
for Piezo-electrical Materials

Density Measurement
SystemThickness Measurement
SystemUltrasonic Material Characterization
System for Practical Use (Ver. 5)

Ultrasonic Material
Characterization System
for General Use (Ver. 6)

Vacuum Evaporation System

Dilatometer

Dielectric and Impedance Measurements System

Furnaces & Ovens

Drying oven
AS ONE, DO-450-V
Temperature: 100º C

Anneal furnace
Nisshin-giken,
Temperature: ~1600℃

YAMATO, FO200

DENKEN, KDF007F
Temperature: 1100℃

SiC furnace
Motoyama Super-C
Max temperature: ~1450ºC

High Temperature Furnace
V&H Technology

Tube Furnace
ALPHA

Muffle Furnaces
ISUZU, STR-12K

34

Messages from foreign visitors

35

Message for 2015 annual report from Robert Kral (Institute of Physics, Czech Academyof Sciences, Prague, Czech Republic)
I have been visiting Prof.   Yoshikawa’s   laboratory, Institute for Materials Research (IMR),
Tohoku University, Sendai, Japan, continuously for short term stays since 2009 during a longand very successful collaborative researcher of Prof. Akira Yoshikawa and Dr. Martin Nikl,
Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic. However, in 2014,
I was awarded by Japan Society for the Promotion of Science (JSPS) by a fellowship“FY2014   JSPS   Postdoctoral Fellowship for Foreign Researchers, P14040”   to   conduct  research in Japan under the leadership of Prof. Yoshikawa for a period of 12 consecutive
months from April 2014 to May 2015.
During this stay, our research was focused mostly on preparation, growth, and study of
hygroscopic halide materials to investigate and to improve their luminescence andscintillation properties. Preparation of strontium iodide single crystals doped with ns2 (Sn2+and In+) or Eu2+ ions as well as of ternary halides (RbPb2Cl5 and KPb2Cl5) was performed
using modified micro-pulling-down method. In total, more than 60 experiments of both the
preparation of starting materials as well as their crystal growth were conducted. Furthermore,
prepared single crystals were characterized by methods available in IMR (XRD, ICP, lightyield) and in the Institute of Physics (absorption, radioluminescence, photoluminescence,
decay kinetics).
My wife, Kristyna Kralova, joined me in Sendai in July 2014 and stayed here until April
2015. It was her first visit in Japan, so, her fascination of Japan reminded me my feelings andimpressions when I visited Japan for the first time. Together, we visited new places around
Sendai or other parts of Japan. Moreover, I am deeply grateful to Prof. Yoshikawa that hegave a permission to my wife allowing her to access IMR to continue in her PhD studies here
Japan. Beside that we are very thankful to Kawaguchi-san, who helped us very much withorganizing all necessities related to arranging a moving of me and my wife to a newapartment at the end of August 2014.
During my stay I presented results by oral or poster contributions at following
conferences: 6-IWCGT (June 15-19, 2014, Berlin, Germany,   poster:   “Growth andluminescence properties of pure and RE-doped RbPb2Cl5 crystals prepared by vertical
Bridgman method”), 5-ISFM Summer symposium (August 7-11, 2014, Rizzan Seapark HotelTancha-bay, Okinawa, oral: “Study of vertical Bridgman growth of halide materials”), 75JSAP Automn meeting (September 17-20,   2014,   Sapporo,   Japan,   oral:   “Crystal growth ofpure and Sn-doped SrI2 by atmosphere-controlled micro-pulling-down method and its
luminescence and scintillation properties”), 44-NCCG (November 6-8, 2014, Tokyo, Japan,
poster:   “Crystal growth of SrI2-based scintillators and characterization of luminescence
properties”), 6-ISFM Winter symposium (March 5-7, 2015, Hakodate, Japan, oral:“Preparation, crystal growth, and luminescence properties of SrI2 single crystals doped with
In(I) and Sn(II) ions grown by modified micro-pulling-down method”),  and 62-JSAP (March
11-14, 2015, Tokai University, Kanagawa, Japan,   oral:   “Luminescence properties of SrI2
single crystals doped with s2-group ions grown by modified micro-pulling-down method”).
Hereby, I would like to express my acknowledgement to Ito(T)-san, Murakami-san, andNagura-san for perfect organization of 5-ISFM Summer symposium, August 7-11, 2014,
Rizzan Seapark Hotel Tancha-bay, Okinawa and of the secondary program. It was my first
visit to Okinawa as well as for my wife, who accompanied me, and beside of very interesting36

lectures at the symposium, we enjoyed our stay at Okinawa very much. Due to colorfulprogram we could visit Okinawa Churaumi Aquarium, taste famous Okinawa pork ribs ramen,
and visit traditional Okinawa restaurants. Moreover, I would like to thank very much to Prof.
Yokota, who was during the stay our excellent guide and always watched over us.
Similarly, we experienced memorable moments when attending the 6-ISFM Wintersymposium (March 5-7, 2015, Hakodate, Japan), where we travelled by shinkansen and had abrief stop for a lunch at Hachinohe fish market. There, we could taste fresh fish and seashells
served either raw (as sashimi or sushi) or prepared by ourselves on a grill. After arriving to
Hakodate, we visited watchtower on the Mount Hakodate, where we had wonderful nightview on the Hakodate bay with bright full Moon rising on the horizon.
Furthermore, I was very glad that we could be with my wife in Sendai during a Hanami
festival (Cherry Blossoms Festival) in April 2015. I have already been in Sendai during
Hanami Festival once, however, I always enjoy this festival very much. I must admit that I
cannot get tired of watching the beautiful scenes of Cherry trees in full blossom looking likenever ending white sea.
I am very grateful for the opportunity  to  stay  in  Prof.  Yoshikawa’s  laboratory  for one year,
it was an unforgettable experience. I had full support from all the lab members whenever I
needed help and I was honored to participate and continue in our collaborative research. I
would like to give a special thanks to Dr. Pejchal for all his help and support. Moreover, I wasamazed how rapidly Prof.  Yoshikawa’s  laboratory  developed on the level of equipment used
for growth of various single crystals as well as on the level of characterization techniques
used for evaluation of material, optical, luminescence, and scintillation properties of preparedsingle crystals. This stay helped me to develop and extended my skills in crystal growth by
micro-pulling-down method and in the characterization of prepared single crystals. I hope ourcooperation will successfully continue and I am already looking forward for the next visit inProf.  Yoshikawa’s  laboratory.

37

Message for 2015 annual report from Vitezslav Jary (Institute of Physics, Czech
Academy of Sciences in Prague, Czech republic)

I have been a member of Dr. Martin Nikl´s team from Institute of Physics, Czech Academy of
Sciences in Prague, Czech republic, since 2008 and thanks to his fruitful collaboration with
Prof. Yoshikawa group I received an invitation to visit his laboratory at Tohoku University in
Sendai for joint experiments on characterization of the Ce3+-doped gadolinium pyrosilicate
crystal grown by   the   μ-PD method. Furthermore I was kindly ask to participate and give alecture at 5th International Symposium on Functional Materials 2015 which was held 5th –7th March 2015 in Hakodate, Japan. The lecture was called Ce3+-doped silicate-based
scintillators and was followed by an interesting discussion.
Almost immediately after the invitation, I started preparations for the visit with great
assistance of Hiroshi Uemura-san, who made excellent job to complete all the formalities intime and booking BelAir hotel in Sendai. Hereby I would also like to express my thanks to
Jan Pejchal-san and Robert Kral-san whose help was also deeply appreciated.
e, Cz ech R epub lic

I departed from Prague on February 28th and after 30-hours of stop-over in Dubai I arrived toHaneda-airport in Tokyo. I took the first shinkanzen train to get to Sendai on 3rd March earlymorning. The first colleague I met in Sendai was Dr. Robert Kral, who escorted me to the lab.
I was very happy to meet with the members of the laboratory and to be introduced to theirresearch. During my stay in IMR, I was also lucky to participate at the research meeting of
Yoshikawa Lab and to discuss there various aspects of the laboratory activities, including
luminescent properties and fabrication of novel functional materials.
a

Ins t itute of Phy sics A S CR v. v . i., Cuk r ovar nic ka 10 , 162 53 P rag u

During the rest of my stay, I was shown all the experimental equipment of IMR and also
participated in the optical experiments when, together with Kurosawa-san and Murakami-san
we measured scintillation light yield and scintillation decay curves on selected Ce3+-doped
GPSLa crystals grown at IMR by µ-PD techique. Those measurements were followed by adetailed discussion concerning software evaluation of the measured data and possible
differences in the experimental data obtained in IMR and those obtained in Prague.
I(t) = -0.47exp(-t/3.2 ns) ++ 0.17exp(-t/59.7 ns) ++ 0.059exp(-t/282.7 ns) + 0.00497

Counts per channel

0.1

GPSLa:Ce137

Excitation by Cs
RT scintillation decay
Japan
Experimental data
3-exp. fit
Instrumental response

0.01

0

t [ns]

1000# 1. Mon Mar 16 13:42:11 2015

From my point of view, the great success of the Yoshikawa Lab is based on highprofessionalism of its leader, a great friendly team of highly qualified enthusiasts, andexcellent growth and characterization equipment. As a result, fundamental and practicalachievements of this research group are well recognized by the world scientific community.
Loaded from ASCII XY file
A B
Passes: 10, Iterations: 810, Chi2=1.93297e-05
T0=59.6906
A0=0.9(74.5 %, 0.173284)
T1=282.695
A1=0.307811(25.5 %, 0.0592654)
T2=3.19492
A2=-2.45302(-203.1%, -0.472299)
Full ampl=0.185864 (*0.192538)
Background=0.00497
Shift=-10.7633
Spike=0.21125 (7.7%)
Run time 0.718 s (0.88642 ms per iteration)

38

Before leaving Sendai, I found some time to discover couple of cities around worth visiting,like Matsushima or Yamadera. After departure from Haned airport 14th March, I enjoyedview of beautiful night Tokyo from the window of the airplane.
Travel to Japan and visit the Yoshikawa Laboratory gave me the great opportunity to meet
new people and new culture. That was an unforgettable experience.
Looking forward to further cooperation,
Vitezslav Jary

39

40

Members

41

2014 年度 吉川研究室
Members (2014 academic year)

4. 1. 2014
教授

Professor
Dr.

Akira Yoshikawa

Associate Professor

NICHe 兼任

吉川 彰
准教授

Dr.

Yuui Yokota

横田 有為

NICHe

Dr.

Kei Kamada

鎌田 圭

NICHe

Research Assistant Professor

助教

Dr.

Shunsuke Kurosawa

黒澤 俊介

Dr.

Yuji Ohashi

大橋 雄二

Dr.

Jan Pejchal

ヤン ペジャール
顧問

AdviserProf

Masae Kikuchi

菊地 昌枝

Prof

Touetsu Shishido

宍戸 統悦

Technical Counsellor
Hiroshi Uemura

技術参事
上村 博
技術補佐研究員

AssistantKeiko Toguchi

戸口 景子

Megumi Sasaki

佐々木 愛美Chouichi Takyu

田久 長一
42

NICHe

秘書

Secretaries
Yuka Takeda

武田 悠佳

Kuniko Kawaguchi

川口 邦子
研究員

Researcher
Yasuhiro Shoji

庄子 育宏

Takuya Sato佐藤 拓也

Masatoshi Ito

伊藤 正敏

Toshio Sannomiya

三野宮 利男Robert Kral

ロバート クラル

Graduate Students

外国人特別研究員

大学院生

Akihiro Yamaj

山路 晃広

D3

Tetsuo Kudo

工藤 哲男

M2

Kousuke Hishinuma

菱沼 康介

M2

Tomoki Ito

伊藤 友樹

M1

Rikito Murakami

村上 力輝斗M1

Aya Nagura

名倉 亜耶

M1

民間等共同研究員

Researchers
Masato Sato佐藤 真人

TDK 株式会社
TDK Co., Ltd. ～2014.8 月

Takayuki Nihei

二瓶 貴之

TDK 株式会社
TDK Co., Ltd. ～2014.8 月

Nobuhiro Yasui

安居 伸浩

キヤノン株式会社／
Canon Co., Ltd.
43

Tatsuya Iwasaki

岩崎 達哉

キヤノン株式会社／
Canon Co., Ltd.

Ryota Ohashi

大橋 良太

キヤノン株式会社／
Canon Co., Ltd.

Osamu Eguchi

江口 治

株式会社 C＆A／
C＆A Co., Ltd.

Hisakazu Nagato

長門 久和株式会社 C＆A／
C＆A Co., Ltd.

Syouki Hayasaka

早坂 将輝

株式会社 C＆A／
C＆A Co., Ltd.

Idzumi Chida

千田 いづみ株式会社 C＆A／
C＆A Co., Ltd.

Satoshi Suzuki

鈴木 智司(株)ASE ジャパン

Tsuneyoshi Miki

三木 常義

由利工業(株)

Visiting Professors/Researchers

客員教授

Prof. Georges Boulon

ジョージ ブーロン

FranceProf. Martin Nikl

マーチン ニクル

Czech Republic

ヴラディミール カチューリッヒン

RussiaDr.

VladimirV.Kochurikhin

Visiting Researchers

客員研究員

Dr.

TCHANI Valery

チャニ ワレリー

CanadaDr.

Andrey Medvedev

アンドレ メドベージェフ

Russia44

45

Prizes and awards

46

47

48

49

List of research collaborations

50

Visits by International Collaborator 2014
Affiliation
General Physics Institute(Russia)
Fomos Materials

Researcher

Research Theme
Growth of bulk single crystals and automatic

Dr. V. Kochurikhin

diameter control in Czochralski growth
Langasite-type piezoelectric single crystals and

Dr. A. Medvedev(Russia)
LPCML, CB Lyon1 Univ.

(France)
Svetchatheir piezoelectric properties
Ceramic laser materials with

Pr. G. Boulon

a nonpress vacuum sintering method

Dr. V. Chani(Canada)Institute of Physics CAS(Czech Republic)
Institute of Physics CAS(Czech Republic)
Institute of Physics CAS(Czech Republic)

Growth of bulk oxide single crystals
Characterization of various scintillator

Dr. M. Nikl

materials

Dr. R. Kral

Growth of bulk halide scintillator crystals

Dr. V. Jary

Growth of bulk halide scintillator crystals

Seminar at Yoshikawa Laboratory 2014
Date

Affiliation

AugustInstitute of Physics CAS

8-10(Czech Republic)

Speaker

Title of speech
Study of vertical Bridgman growth

Dr. R.Kralof halide materials

Preparation, crystal growth, andMarchInstitute of Physics CAS

5-7(Czech Republic)

Dr. V. Jary

51

luminescence properties of SrI2
single crystals

Visits to International Collaborator 2014
Affiliation

Researcher

Period of stay

The Pennsylvania State
University (USA)Pr. Yoshikawa
Assoc. Pr. Yokota
Mr. Kudo

May 12-16

University of Michigan(USA)

Assist. Pr. Kurosawa

June 10-12

Institute of Physics CAS(Czech Republic)

Assist. Pr. Pejchal
Assoc. Pr. Kamada
Mr. ShojiJune 9-14

Leibniz-Institut fürKristallzüchtung(German)Pr. Yoshikawa
Assoc. Pr. Yokota
Assoc. Pr. Kamada
Assist. Pr. Pejchal
Mr. Shoji, Mr. Kudo

June 15-20

University of Wroclaw(Poland)

Pr. Yoshikawa
Assist. Pr. Kurosawa

July 14-18

Leeds University(UK)

Pr. Yoshikawa
Assoc. Pr. Kamada

July 28-29

Assoc. Pr. Yokota
Assist. Pr. Kurosawa
Mr. ItoMr. Murakami

November 17-18

Pr. Yoshikawa

December 1-3

Pr. Yoshikawa
Assist. Pr. Kurosawa

March 10-11

The University of Tennessee(USA)

University of Wroclaw(Poland)

CERN(Switzerland)

52

53

Research funds54平成 26 年度 研究資金
Research funds (2014 fiscal year)【経済産業省－東北経済産業局】
Tohoku Bureau of Economy, Trade and Industry
The Ministry of Economy, Trade and Industry
1. 戦略的基盤技術高度化支援事業(サポイン)
Funding Program for Strategic Supporting Industry, 2014
株式会社インテリジェント・コスモス研究機構からの再委託研究
Truster: Intelligent Cosmos Research Institute, Miyagi pref.
「Ce:GAGGシンチレータ結晶の量産化における大型結晶製造プロセスの低コスト化」“ Cost reduction of the mass-production of large-sized Ce:GAGG scintillator
crystals”
期間 Term: 2014.10 - 2017.3
本年度 Total: 12,110,000 yen for our team, 2014.10 - 2015.3
2. 中小企業による技術シーズの事業化・実用化事業のうち橋渡し研究支援事業
Funding Program for small business innovation research, 2014
株式会社東栄科学産業からの再委託研究
Truster: Toei Kagaku Co.Ltd「量産型マイクロＰＤ装置の開発」“Development of mass-production of micro-pulling-down apparatus”
期間 Term: 2014.11 - 2015.3
本年度 Total: 6,480,000 yen for our team, 2014.11 - 2015.3

3. 先端技術実証･評価設備整備費等補助金(企業等の実証･評価等設備の開発)
Funding Program for small business in promoting innovation, 2013
株式会社ジー･イー・エスからの再委託研究
Truster: GES Co.Ltd「無坩堝で高融点酸化物シンチレータ結晶の製造を実現するスカルメルト法
溶解技術の開発」
55

“Development   of Skull Melt method to produce oxide scintillator crystals of highmelting point without  using  crucible”  期間 Term: 2014.3 - 2015.3
本年度 Total: 15,000,000 yen for our team, 2014.4 - 2015.3【JST プロジェクト】
Japan Science and Technology Agency
1. JST研究成果展開事業 【先端計測分析技術・機器開発】
Development of Systems and Technology for Advanced Measurement and Analysis
Technology, 2012
「無人ヘリ搭載用散乱エネルギー認識型高位置分解能ガンマカメラの実用化開発」“Research and development of scattered energy recognition type and high positional
resolution gamma camera for unmanned helicopter survey”
古河機械金属株式会社からの再委託研究
Truster: Furukawa Co. Ltd.
期間 Term: 2012.4 - 2015.3
本年度 Total: 13,000,000 yen for our team, 2014.4 - 2015.3
2. JST研究成果最適展開支援プログラム （A-STEP）シーズ育成タイプ
Adaptable and seamless technology transfer program through targetdrive R&D, 2012
「核物質セキュリティ用3He 代替中性子計測装置の開発」“Development of neutron scanning apparatus for homeland security using scintillator
instead of 3He gas detector ”
期間 Term: 2012.10 – 2015.3
本年度 Total: 9,420,000 yen for our team, 2014.4 - 2015.3
3. JST研究成果展開事業 【先端計測分析技術・機器開発】
Development of Systems and Technology for Advanced Measurement and Analysis
Technology, 2013「高エネルギー分解能・高スループットの国産放射測定検査装置」“Development of radiometry tester having high energy resolution and high efficiency”  株式会社千代田テクノルからの再委託研究
Truster: Chiyoda Technol Corporation
56期間 Term: 2013.10 - 2016.3
本年度 Total: 18,200,000 yen for our team, 2014.4 - 2015.3
4. JST研究成果展開事業
研究成果最適展開支援プログラム（A-STEP）
実用化挑戦ステージ実用化挑戦タイプ （中小・ベンチャー開発）
Foundation for Small and Medium Enterprise Promotion, 2013
(Supporting small and medium-sized and the venture company of the research anddevelopment.)「高温域で劣化しない資源探査用シンチレーター」“Scintillator for Resources Exploration Equipment having high performance at hightemperature”  株式会社Ｃ＆Ａからの再委託研究
Truster: C&A Corporarion
期間 Term: 2013.12 - 2017.3
本年度 Total: 20,000,000 yen for our team, 2014.4 - 2015.3
5. JST研究成果展開事業
研究成果最適展開支援プログラム（A-STEP）
ハイリスク挑戦タイプ
Foundation for High-risk challenging, 2014
「Ｘ線位相イメージングを飛躍させる超高解像度、高感度Ｘ線検出器の実用化開発」“Development of ultra-high resolution and highly sensitive X-ray detector for
innovative X-ray phase imaging”
キヤノン株式会社からの再委託研究
Truster: Canon Inc.
期間 Term: 2014.12 - 2015.3
本年度 Total: 11,590,000 yen for our team, 2014.12 - 2015.3
6. JST研究成果展開事業
FS 探索タイプ
FS stage「新規ランガサイト型圧電単結晶を用いた高安定・広帯域弾性波デバイスの開発」
57

大橋 雄二 (Yuji Ohashi)“Development of highly stable and broadband SAW device using a new Langasite
type piezoelectric single crystal”
期間 Term: 2014.4 - 2016.3
本年度 Total: 400,000 yen for our team, 2014.4 - 2015.3「共晶体構造を応用した、超高分解能、高感度中性子イメージング装置の開発」
鎌田 圭 (Kei Kamada)“Development of ultra-high resolution and highly sensitive neutron imaging apparatus
using a eutectic structure”
期間 Term: 2014.4 - 2016.3
本年度 Total: 710,000 yen for our team, 2014.4 - 2015.3「ナノ秒以下の高速応答を示す放射線素子の開発と医療への応用」
ペジャール ヤン (Jan Pejchal )“Development of scintillator crystal having a high-speed response of nanoseconds, andits medical applications”
期間 Term: 2014.4 - 2016.3
本年度 Total: 1,500,000 yen for our team, 2014.4 - 2015.3【NEDO プロジェクト】
New Energy and Industrial Technology Development Organization
1. 平成２５年度課題設定型産業技術開発費助成金（希少金属代替・低減技術実用化開発助成事業）
Rare Metal Substitute Materials Development Project, 2013
ＴＤＫ株式会社からの再委託研究
Truster: TDK Corporation
期間

Term: 2013.10 - 2015.2

本年度 Total: 25,000,000 yen for our team, 2014.4 - 2015.2
2. 平成２６年度戦略的省エネルギー技術革新プログラム・実用化開発
Strategic energy-saving innovation programs, 2014
東芝照明プレシジョン株式会社からの再委託研究
58

Truster: Toshiba Shomei Precision Corporation
期間 Term: 2015.2 – 2016.6
本年度 Total: 15,000,000 yen for our team, 2015.2 – 2015.3
3. 平成２６年度新エネルギーベンチャー技術革新事業
Grand renewable energy innovation programs, 2014
株式会社Ｃ＆Ａからの再委託研究
Truster: C&A Corporation
期間 Term: 2014.12 – 2015.9
本年度 Total: 1,040,000 yen for our team, 2014.12 - 2015.3【復興庁】

Reconstruction Agency

1. 平成２４年度地域イノベーション戦略支援プログラム
Funding Program for “Invest Japan” promotion for reconstruction, 2012宮城県インテリジェントコスモス研究機構からの再委託プログラム
Truster: Intelligent Cosmos Research Institute, Miyagi pref.
「次世代自動車のための人材育成プログラム」“Manpower training program for innovation in automotive industry”
期間

Term:

本年度 Total:

2012.4 - 2017.3
10,600,000 yen for our team, 2014.4 - 2015.3【厚生労働省科学研究費補助金】
Ministry of Health, Labour and Welfare
平成２５年度科学研究費助成
東京大学からの再委託研究
Truster: Tokyo University

Health Science Research Grants, 2013

「非侵襲血中 RI 濃度測定を可能にするウエアラブル・サブミリ解像度 PET 装置の開発」“Development of wearable and sub-millimeter resolution type PET apparatus
that enables non-invasive measurement of RI concentration in blood”
期間 Term: 2013.4 - 2016.3
本年度 Total: 20,000,000 yen, 2014.4 - 2015.3

59

【文部科学省科学研究費補助金】
Ministry of Education, Culture, Sports, Science and Technology
日本学術振興会 Japan Society for the Promotion of Science
科学研究費助成 Grants-in-Aid for Scientific Research
1.

特別研究員奨励費 Fellowship吉川 彰 (Akira Yoshikawa)、ロバート クラル(Robert Kral)
1,2000,000 yen, 2014.4-2015.3

2.

萌芽 Grants-in-Aid for young scientists(Sprout)
吉川 彰 (Akira Yoshikawa)
1,200,000 yen, 2014.4-2015.3

3.

萌芽 Grants-in-Aid for young scientists(Sprout)鎌田 圭 (Kei Kamada)1,500,000 yen, 2014.4-2015.3

4.

基盤研究（Ｃ） Grants-in-Aid for young scientists(Scientific Research (C))
大橋 雄二 (Yuji Ohashi)
1,000,000 yen, 2014.4-2015.3

5.

基盤研究（Ｃ） Grants-in-Aid for young scientists(Scientific Research (C))
黒澤 俊介
(Shunsuke Kurosawa)
1,000,000 yen, 2014.4-2015.3

6.

特別研究員
Fellowship
山路 晃広 (Akihiro Yamaji)
1,000,000 yen, 2014.4-2015.3【国立大学法人 事業化推進事業型研究】
事業化推進型研究補助金
Foundation for Business Incubation Program
期間

Term: 2014.2 - 2015.3

本年度 Total:

50,000,000 yen, 2014.2 - 2015.3

60

【企業・財団・個人からの受託・共同研究，寄付金および小型プロジェクト】
Funds from industry, foundations, personal donation and small project1.

株式会社トクヤマTokuyama Corporation

2.

TDK 株式会社

TDK Corporation3.

古河機械金属株式会社

Furukawa Co. Ltd.

4.

株式会社千代田テクノル

Chiyoda Technol Corporation

5.

キヤノン株式会社

Canon Inc.

6.

株式会社Ｃ＆Ａ

C&A Corporation

7.

東芝照明プレシジョン株式会社

Toshiba Shomei Precision Corporation

8.

由利工業株式会社

Yurikogyo Co. Ltd

9.

株式会社ジー･イー・エス

GES Co. Ltd

10. 株式会社東栄科学産業

Toei Kagaku Co. Ltd

11. 浜松ホトニクス株式会社

Hamamatsu Photonics K.K

12. TANAKA ホールディングス株式会社 Tanaka Holdings Co. Ltd.
13. 日立金属株式会社

Hitachi Metals, Ltd

14. 大阪大学レーザーエネルギー学研究センター 共同研究

Collaboration program with Institute of Laser Engineering, Osaka Univ.
「真空紫外域に発光する新規発光結晶の開発」

61

平成２６年度申請特許

List of patents

1. 発光体及び放射線検出器
鎌田 圭、吉川 彰、黒澤俊介、横田 有為、庄子

育宏(Kei Kamada, Akira Yoshikawa, Shunsuke Kurosawa, Yuui Yokota, Yasuhiro Shoji)
2. 圧電振動子
吉川 彰、大橋 雄二、横田

有為、鎌田 圭、天野

宏之、

江口 治
(Akira Yoshikawa, Yuji Ohashi, Yuui Yokota, Kei Kamada, Hiroyuki Amano,
Osamu Eguchi)
3. シンチレータおよび放射線検出器
鎌田 圭、吉川 彰、横田

有為、黒澤 俊介、菱沼

康介、山路

晃広

(Kei Kamada, Akira Yoshikawa, Yuui Yokota, Shunsuke Kurosawa, Kosuke Hishinuma,
Akihiro Yamaji)

他

国内出願 ２ 件62

List of abstracts

63

JOURNAL OF CRYSTAL GROWTH 393, 134, Published: MAY 2014

Czochralski   growth   of   Gd3(Al5−xGax)O12   (GAGG)   single   crystals   and   their   scintillation  properties
S.  Kurosawa1,2,  Y.  Shoji1,  Y.  Yokota2,  K.  Kamada2,3,  V.  I.  Chani1,  A.  Yoshikawa1,2,3
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  C&A  Corporation,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Ce:Gd3(AlxGa1−x)5O12   (x=2.5/5   and   3/5,   Ce:GAGG-2.5   and   Ce:GAGG-3)   crystals   were   grown   by   the   Czochralski  process   in   order   to   reduce   cost   of   the   starting   materials   as   compared   with   conventional   Ce:Gd3Al2Ga3O12  (Ce:GAGG-2)   crystal   which   have   high   light   output.   Although   perovskite   phase   was   detected   in   Ce:GAGG-3,  Ce:GAGG-2.5   had   single-phase   garnet   structure.   Solidification   fraction   for   the   Ce:GAGG-2.5   growth   was   0.52.  
Optical  properties  including  transmittance,  emission,  and  excitation  spectra  of  30  samples  cut  from  the  Ce:GAGG2.5  bulk  ingot  did  not  depend  on  their  original  position  along  the  growth  axis.  These  samples  had  light  outputs  of  approximately   58,000±3000   photons/MeV.   However,   scintillation   decay   times   varied   from   140   to   200   ns   and  depended  on  the  position  clearly.

E-mail  Address:
y_shoji@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0022024813007410

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JOURNAL OF CRYSTAL GROWTH 393, 163, Published: MAY2014

Optical  properties  of  a  Nd-doped  SrBr2  crystal  grown  by  the  Bridgman  technique
S.  Kurosawa1,2,  Y.  Yokota2,  Y.  Yanagida3,  J.  Pejchal1,4,  A.  Yamaji1,  Y.  Shoji1,  K.  Kamada2,5,  A.  Yoshikawa1,2,5
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  World  Engineering  System,  122  Oyakesekishocho,  Yamashina-ku,  Kyoto  607-8188,  Japan
4.  Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  Prague  6,  16200,  Czech  Republic
5.  C&A  Corporation,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
We  have  investigated  the  optical  properties  of  1  mol%  Nd-doped  SrBr2  crystal  grown  by  the  Bridgman  technique  for  an   X-ray   scintillator   application.   We   succeeded   in   obtaining   a   transparent   crystal,   whose   X-ray   diffraction   was  measured   under   dry   condition   because   of   its   hygroscopic   nature.   Roughly,   we   estimated   that   90%   of   this   crystal  dissolved  within  300  min.  under  25°C  and  65–70%  humidity.  Under  excitation  by  270  and  400  nm  photons  several  emission  peaks  originating  from   4F3/2  or   4Gi1→4Ii2  (i1=5/2  and  7/2  and  i2=13/2,  11/2,  and  9/2)  transitions  of  Nd3+  were  observed.  1  mol%  Nd:SrBr2  had  a  maximum  quantum  yield  of  approximately  45%.  Additional  emission  peaks  were  observed  under  X-ray  excitation.

E-mail  Address:
kurosawa@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0022024813008361

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JOURNAL OF CRYSTAL GROWTH 393, 138, Published: MAY2014

Crystal  growth  of  CaYAlO4  single  crystals  grown  by  the  micro-pulling  down  method  and  their  luminescent  properties
A.  Yamaji1,  A.  Suzuki1,  Y.  Shoji1,  S.  Kurosawa1,2,  J.  Pejchal1,  K.  Kamada2,  Y.  Yokota2,  Akira  Yoshikawa1,2
1.  IMR,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai  980-8577,  Japan
2.  NICHe,  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai  980-8579,  Japan

Abstract:
Nd   and   Yb   doped   CaYAlO4   crystals   have   been   grown   by   the   micro-pulling   down   method.   The   segregation  coefficient   along   the   growth   direction   and   the   radial   dopant   distribution   were   measured   by   using   electron   probe  micro-analysis  (EPMA).  The  X-ray  induced  luminescence  spectra  in  the  spectral  range  from  300  to  1500  nm  were  measured:  Nd  and  Yb  doped  CaYAlO4  showed  intense  peaks  at  990  and  1045  nm,  respectively.  These  crystals  would  be  promising  materials  for  near  infrared  emission  scintillators.

E-mail  Address:
yamaji-a@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0022024813008439

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JOURNAL OF CRYSTAL GROWTH 393, 142, Published: MAY2014

Crystal   growth   and   optical   properties   of   Ce:(La,Gd)2Ge2O7   grown   by   the   floating   zone  methodS.  Kurosawa1,2,  T.  Shishido1,  T.  Sugawara1,  K.  Yubuta1,  J.  Pejchal1,3,  A.  Suzuki1,  Y.  Yokota2,  Y.  Shoji1,  K. Kamada2,4,    A.  Yoshikawa1,2,4
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Institute  of  Physics  AS  CR,  10  Cukrovarnicka,  Prague  6  16200,  Czech  Republic
4.  C&A  Corporation,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Some   pyrosilicate   scintillators   such   as   Ce:Gd2Si2O7   and   Ce:Lu2Si2O7   have   a   good   light   output,   and   especially  Ce:(Gd,La)2Si2O7  has  an  excellent  light  output  of  over  36,000  ph/MeV.  In  order  to  search  novel  scintilators,  we  have  developed  a  pyrogermanate-based  scintillation  material  (Ce0.01,Gd0.90,La0.09)2Ge2O7  using  the  floating  zone  method.  
Although  the  light  output  was  decreased  due  to  quenching,  5d–4f  transition  of  Ce3+  was  observed  around  480  nm  in  photo-  and  radio-luminescence  spectra.  This  emission  wavelength  was  longer  than  that  of  (Ce 0.01,Gd0.90,La0.09)2Si2O7  with  an  emission  wavelength  of  390  nm.

E-mail  Address:
kurosawa@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0022024813008968#

67

JOURNAL OF CRYSTAL GROWTH 401, 833, Published: SEP2014

Crystal   growth   and   scintillation   properties   of   selected   fluoride   crystals   for   VUV  scintillators
J.  Pejchal1,2,  K.  Fukuda3,  A.  Yamaji1,  Y.  Yokota1,4,  S.  Kurosawa1,4,  R.  Kral2,  M.  Nikl2,  A.  Yoshikawa1,4
1.  Institute  for  Materials  Research,  2-1-1  Katahira,  Aoba-ku,  Sendai  9808577,  Japan
2.  Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  Prague  6  16200,  Czech  Republic
3.  Tokuyama  Corporation,  Shibuya  3-chome,  Shibuya-ku,  Tokyo  1508383,  Japan
4.  NICHe,  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  9808579,  Japan

Abstract:
Single   crystals   of   orthorhombic   and   monoclinic   BaLu2F8   doped   with   Nd   and   Tm   were   grown   by   micro-pullingdown  method.  The  monoclinic  (low  temperature   modification)  was  grown  using  LiF  flux,  while  the  orthorhombic  (high  temperature  modification)  was  grown  with  special  hot-zone  with  shallow  gradient  and  employing  quenching  process.  Reasonable  scintillation  efficiency  was  achieved  for  the  crystals  of  the  former  modification,  while  no  rareearth  ion  emission  was  observed  in  the  latter  due  to  preferential  energy  transfer  to  defects.  The  orthorhombic  (low  temperature)   modification   of   ErF3   was   grown   using   LiF   flux   and   hot   zone   with   steep   gradient.   Quite   low  scintillation  efficiency  was  found  for  the  Nd-doped  sample  due  to  energy  migration  over  the  Er 3+  levels.  Possibility  of  using  pure  ErF3  as  an  infra-red  scintillator  is  discussed.

E-mail  Address:
pejchalj@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0022024813009044

68

JOURNAL OF EUROPEAN CERAMIC SOCIETY 34, 2095, Published: OCT2014

Growth   and   luminescent   properties   of   Ce-doped   LiF/LiLuF4   eutectic   fibers   grown   by  micro-pulling-down  method
Y.  Yokota1,  S.  Kurosawa1,2,  K.  Nishimoto1,  V.  Chani2,  A.  Yoshikawa1,2
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1,  Katahira,  Aoba-ku,  Sendai  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center  (NICHe),  Tohoku  University,  6-6-10,  Aoba,  Aramaki,  Aoba-ku,  Sendai  980-8579,  Japan

Abstract:
The  undoped  and  Ce-doped  LiF/LiLuF4  eutectic  fibers  with  various  ratios  of  LuF3  to  LiF  were  grown  by  the  micropulling-down   method   for   their   application   as   neutron   scintillators   with   light   guiding   structure.   The   differential  thermal  analysis  (DTA)  of  undoped  eutectic  materials  indicated  that  the  eutectic  point  of  LiF/LiLuF 4  was  positioned  around   LiF   80   mol%–LuF3   20   mol%   composition.   Some   of   the   as-produced   eutectic   solids   had   rod-like   regular  array  structures.  This  was  observed  using  SEM  images  of  cross-sectional  and  parallel  cuts  of  the  grown  solids.  In  the  range   of   x   ≥   0.28,   the   dendrites   appeared   between   the   eutectic   areas.   Ce   doped   LiF/LiLuF4   eutectic   fibers  demonstrated  two  emission  peaks  around  310  and  326  nm  in  the  photoluminescence  spectrum,  and  the  decay  time  of  the  emission  at  326  nm  was  32.3  ns.

E-mail  Address:
yokota@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0955221914000041

69

NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH A, 744, 30, Published: APR2014

Performance  of  Ce-doped  (La,  Gd)2Si2O7  scintillator  with  an  avalanche  photodiodeS.  Kurosawa1,2,  T.  Shishido1,  A.  Suzuki1,  J.  Pejchal1,3,  Y.  Yokota2,  A.  Yoshikawa1,2,4
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Institute  of  Physics,  AS  CR,  Cukrovarnická  10,  162  53  Prague,  Czech  Republic
4.  C&A  Corporation,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Scintillation   properties   of   Ce-doped   (La,   Gd)2Si2O7   (Ce:La-GPS)   crystal   were   measured   with   Si   avalanche  photodiode  (APD,  Hamamatsu  S8664-55).  Since  Ce:La-GPS  is  a  novel  scintillator,  its  scintillation  properties  have  been  evaluated  using  the  APD  for  the  first  time.  This  crystal  grown  by  floating  zone  method  had  a  good  light  output  of  41,000±1000  photons/MeV  and  FWHM  energy  resolution  at  662  keV  was  4.4±0.1%  at  23.0±0.2  °C.  The  photon  non-proportional  response  (PNR)  of  Ce:La-GPS  was  approximately  65%  at  32  keV,  where  light  output  at  662  keV  was   normalized   to   100%.   Moreover,   the   temperature   dependence   of   the   light   outputs   was   determined   to   be  approximately  0.15%/°C  from  −10  to  30  °C.

E-mail  Address:
kurosawa@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0168900214000266

70

OPTICAL MATERIALS, 36, 1665, Published: AUG2014

Studies   of   light   yield   as   a   function   of   temperature   and   low   temperature  thermoluminescence  of  Gd3Al2Ga3O12:Ce  scintillator  crystals
W.  Drozdowski1,  K.  Brylew1,  M.E.  Witkowski1,  A.J.  Wojtowicz1,  P.  Solarz2,  K.  Kamada3,  A.  Yoshikawa4
1.   Institute   of   Physics,   Faculty   of   Physics,   Astronomy   and   Informatics,   Nicolaus   Copernicus   University,  Grudziadzka  5/7,  87-100  Torun,  Poland
2.  Institute  of  Low  Temperature  and  Structure  Research,  Polish  Academy  of  Sciences,  Okolna  2,  50-422  Wroclaw,  Poland
3.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  6-6-10  Aoba,  Amaraki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
4.  Institute  of  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
In  this  paper  we  report  the  measurements  of  pulse  height  spectra,  radioluminescence  spectra  at  various  temperatures  between  10  and  325  K,  and  low  temperature  thermoluminescence  glow  curves  of  Gd 3Al2Ga3O12:Ce.  It  is  shown  that  the  scintillation  yield  of  the  studied  material  correlates  with  the  concentration  of  cerium  and  anti-correlates  with  the  thermoluminescence  intensity.  However,  regardless  of  the   cerium  content,   the   yield  at  room  temperature   is  almost  twice  lower  than  below  180  K.

E-mail  Address:
wind@fizyka.umk.pl

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714000020

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JOURNAL OF INSTRUMENTATION, 9, C07015, Published: JUL2014

Radiation  imaging  with  a  new  scintillator  and  a  CMOS  camera
S.  Kurosawa1,2,  Y.  Shoji1,  J.  Pejchal1,3,  Y.  Yokota2,  A.  Yoshikawa1,2
1. Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
2. New  Industry  Creation  Hatchery  Center  (NICHe),  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3. Institute  of  Physics,  AS  CR,  Cukrovarnická  10,  162  53  Prague,  Czech  Republic

Abstract:
A  new  imaging  system  consisting  of  a  high-sensitivity  complementary  metal-oxide  semiconductor  (CMOS)  sensor,  a  microscope   and   a   new   scintillator,   Ce-doped   Gd3(Al,Ga)5O12 (Ce:GAGG)   grown   by   the   Czochralski   process,   has  been  developed.  The  noise,  the  dark  current  and  the  sensitivity  of  the  CMOS  camera  (ORCA-Flash4.0,  Hamamatsu)  was   revised   and   compared   to   a   conventional   CMOS,   whose   sensitivity   is   at   the   same   level   as   that   of   a   charge  coupled  device  (CCD)  camera.  Without  the  scintillator,  this  system  had  a  good  position  resolution  of  2.1  ±  0.4  μm  and   we   succeeded   in   obtaining   the   alpha-ray   images   using   1-mm   thick   Ce:GAGG   crystal.   This   system   can   be  applied  for  example  to  high  energy  X-ray  beam  profile  monitor,  etc.

E-mail  Address:
kurosawa@imr.tohoku.ac.jp

Site  Address:
http://iopscience.iop.org/1748-0221/9/07/C07015

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JOURNAL OF INSTRUMENTATION, 9, C05045, Published: MAY2014

Development   of   a   30   cm-cube   Electron-Tracking   Compton   Camera   for   the   SMILE-II  ExperimentY.   Mizumura1,2,   T.   Tanimori2,   H.   Kubo2,   A.   Takada2,   J.   D.   Parker2,   T.   Mizumoto3,   S.   Sonoda4,   D.   Tomono2,  T. Sawano2,   K.   Nakamura2,   Y.   Matsuoka2,   S.   Komura2,   S.   Nakamura2,   M.   Oda2,   K.   Miuchi5,   S.   Kabuki6,  Y. Kishimoto7,  S.  Kurosawa8,  S.  Iwaki2
1. Unit  of  Synergetic  Studies  for  Space,  Kyoto  University,  Kyoto,  606-8502,  Japan  2.  Department  of  Physics,  Kyoto  University,  Kyoto,  606-8502,  Japan  3.  Research  Institute  for  Sustainable  Humanosphere,  Kyoto  University,  Uji,  Kyoto,  611-0011,  Japan  4.  Advanced  Biomedical  Engineering  Research  Unit,  Kyoto  University,  Kyoto,  606-8501,  Japan  5.  Department  of  Physics,  Kobe  University,  Kobe,  Hyogo,  657-8501,  Japan  6.  Department  of  Radiation  Oncology,  Tokai  University,  Isehara,  Kanagawa,  259-1193,  Japan  7.  Radiation  Science  Center,  KEK,  Tsukuba,  Ibaraki,  305-8501,  Japan  8.  Institute  for  Materials  Research,  Tohoku  University,  Sendai,  Miyagi,  980-8577,  Japan

Abstract:
To   explore   the   sub-MeV/MeV   gamma-ray   window   for   astronomy,   we   have   developed   the   Electron-Tracking  Compton  Camera  (ETCC),  and  carried  out  the  first  performance  test  in  laboratory  conditions  using  several  gammaray  sources  in  the  sub-MeV  energy  band.  Using  a  simple  track  analysis  for  a  quick  first  test  of  the  performance,  the  gamma-ray  imaging  capability  was  demonstrated  with  clear  images  and  5.3  degrees  of  angular  resolution  measure  (ARM)  measured  at  662  keV.  As  the  greatest  impact  of  this  work,  a  gamma-ray  detection  efficiency  on  the  order  of  10−4 was   achieved   at   the   sub-MeV   gamma-ray   band,   which   is   one   order   of   magnitude   higher   than   our   previous  experiment.   This   angular   resolution   and   detection   efficiency   enables   us   to   detect   the   Crab   Nebula   at   the   5σ   level  with  several  hours  observation  at  balloon  altitude  in  middle  latitude.  Furthermore,  good  consistency  of  efficiencies  between   this   performance   test   and   simulation   including   only   physical   processes   is   very   important;;   it   means   we  achieve   nearly   100%   detection   of   Compton   recoil   electrons   and   means   that   our   predictions   of   performance  enhancement  resulting  from  future  upgrades  are  more  realistic.  We  are  planning  to  confirm  the  imaging  capability  of  the   ETCC   by   observation   of   celestial   objects   in   the   SMILE-II  (Sub-MeV   gamma   ray   Imaging   Loaded-on-balloon  Experiment  II).  The  SMILE-II  and  following  SMILE-III  project  will  be  an  important  key  of  sub-MeV/MeV  gammaray  astronomy.

E-mail  Address:
mizumura@cr.scphys.kyoto-u.ac.jp

Site  Address:
http://iopscience.iop.org/1748-0221/9/05/C05045

73

OPTICAL MATERIALS, 36, 1484, Published: JUL2014

Crystal   Growth   and   Luminescence   Properties   of   Yb-doped   Gd3Al2Ga3O12 Infra-red  Scintillator
A.   Suzuki1   ,   S.   Kurosawa1,2,   S.   Nagata1,   T.   Yamamura1,   J.   Pejchal2,3,   A.   Yamaji1,   Y.   Yokota2,   K.   Shirasaki1,  Y. Homma1,  D.  Aoki1,  T.  Shikama1,  A.  Yoshikawa1,2
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center  (NICHe),  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Institute  of  Physics  ASCR,  Cukrovarnicka  10,  162  53  Prague,  Czech  Republic

Abstract:
1-mol%-Yb-doped   Gd3Al2Ga3O12 infra-red   scintillator   crystal   has   been   studied   as   a   novel   implantable   radiation  monitor   in   radiation   therapy.   Powder   X-ray   diffraction   measurement   and   chemical   analysis   with   a   field   emission  scanning  microscope  and  wavelength  dispersive  spectrometer  determined  its  garnet  structure  and  average  chemical  composition  of  Yb0.03±0.01Gd2.99±0.07Al2.21±0.08Ga2.64±0.09O12.10±0.09.  Transmittance  measurements  reached  high  values  of  approximately  70%  in  the  human  body  transparency  region  between  650  to  1200 nm.  Photoluminescence  peaks  were   detected   around   970   and   1030 nm   under   the   940 nm   excitation   with   a   Xe   lamp.   Infra-red   scintillation  emissions   were   clearly   observed   around   970   and   1030 nm   due   to   Yb3+ 4f–4f   transitions   under   X-ray   excitation.  
Therefore,  these  results  suggest  that  Yb-doped  Gd3Al2Ga3O12 might  be  used  as  an  infra-red  scintillator  material.

E-mail  Address:
akira_suzuki@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714001748

74

OPTICAL MATERIALS, 36, 1938, Published: OCT2014

Luminescent  properties  of  Cr-doped  (GdX,  Y1−X)3Al5O12 infra-red  scintillator  crystals
A.  Suzuki1,  S.  Kurosawa1,2,  A.  Yamaji1,  Y.  Shoji1,  J.  Pejchal2,3,  K.  Kamada2,  Y.  Yokota2,  A.  Yoshikawa1,2,4
1.  Institute  for  Materials  Research,  Tohoku  University,  Sendai,  Miyagi,  Japan
2.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  Sendai,  Miyagi,  Japan
3.  Institute  of  Physics  AS  CR,  Cukrovarnická,  Prague,  Czech  Republic
4.  C&A  Corporation,  Sendai,  Miyagi,  Japan

Abstract:
Cr-doped   (GdX Y1−X)3Al5O12 (X = 0,   0.25,   0.50)   crystals   prepared   by   the   micro-pulling   down   method   were  investigated   to   develop   a   infra-red   scintillator   for   implantable   patient   dosimeter   in   radiation   therapy.   In   order   to  evaluate   their   optical   and   scintillation   performance,   the   following   properties   were   measured:   (i)   transmittance  between  ultra-violet  and  near-infra  red  region,  (ii)  photoluminescence  spectra  under  Xe-lamp  excitation,  and  (iii)  Xray   excited   radio-luminescence   spectra.   Cr:Y3Al5O12 and   Cr:(Gd0.25Y0.75)3Al5O12 crystals   showed   increased  transmittance   of   80%,   while   Cr:(Gd0.50 Y0.50)3Al5O12 had   a   lower   transmittance   of   40%   due   to   its   polycrystalline  structure.  In  addition,  all  the  Cr:(GdX Y1−X)3Al5O12 crystals  showed  sharp  scintillation  luminescence  peaks  ascribed  to  Cr3+ d–d  transitions.  Therefore,  these  results  suggested  that  Cr:Y 3Al5O12 and  Cr:(Gd0.25 Y0.75)3Al5O12 crystals  can  be  candidate  materials  for  the  dosimeter  use.

E-mail  Address:
akira_suzuki@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714001694

75

CRYSTAL GROWTH AND DESIGN, 14, 3327, Published: MAY2014

Structural   Investigations   of   Lu2O3 as   Single   Crystal   and   Polycrystalline   Transparent  Ceramic
M.  Guzik1,  J.  Pejchal2,3,  A.  Yoshikawa2,  A.  Ito2,  T.  Goto2,  M.  Siczek1,  T.  Lis1,  G.  Boulon4
1.Faculty  of  Chemistry,  University  of  Wroclaw,  Joliot-Curie  14,  50-383  Wroclaw,  Poland
2.Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-Ku,  980-8577  Sendai,  Japan
3.Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  Prague  6,  16200,  Czech  Republic
4.Institute   Light   Matter,   UMR5306   CNRS-University   of   Lyon   1,   University   of   Lyon,   Bât.   Kastler,   69622  Villeurbanne,  France

Abstract:
The   X-ray   single   crystal   structure   determination   of   Lu2O3 sesquioxide   and   of   polycrystalline   transparent   ceramic  fabricated  by  the  unconventional  spark  plasma  sintering  (SPS)  method  is  presented  for  the  first  time.  High  quality  single  crystals  of  Lu2O3 samples  were  obtained  by  using  both  the  micropulling-down  (μ-PD)  method  and  the  laser  heated  pedestal  growth  (LHPG)  technique.  The  SPS  method  is  promising  for  obtaining  high-density  ceramics  with  fine   grains   at   a   relatively   low   temperature   within   a   short   holding   time.   The   structural   characterizations   helped   to  complete  information  about  the  cubic  structure  of  Lu2O3  sesquioxide,  not  clear  until  now  in  the  literature  from  only  polycrystalline  samples  and  has  raised  doubts  among  many  researchers.

E-mail  Address:
goguzik@poczta.fm

Site  Address:
http://pubs.acs.org/doi/full/10.1021/cg500225v

76

OPTICAL MATERIALS, 36, 1959, Published: OCT2014

Effects   of   Eu   concentration   control   on   crystal   growth   and   scintillation   properties   for  Eu:LiSrAlF6 crystals
S.  Suzuki1,  Y.  Yokota2,    A.  Yamaji1,  S.  Kurosawa1,2,  K.  Kamada2,  A.  Yoshikawa1,2
1.  Institute  for  Materials  Research,  Tohoku  University,  Sendai,  Miyagi,  Japan
2.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  Sendai,  Miyagi,  Japan

Abstract:
Eu  doped  LiSrAlF6 (Eu:LiSAF)  crystals  with  various  Eu  concentrations  were  grown  by  a  micro-pulling-down  (μPD)  method  and  the  effects  of  Eu  concentration  control  on  crystal  growth  and  scintillation  properties  for  Eu:LiSAF  crystals  were  investigated  as  a  neutron  scintillator.  As-grown  Eu0.3%:LiSAF  crystal  had  no  visible  inclusion  while  milky   parts   were   observed   in   the   crystals   with   higher   Eu   contents.   The   secondary   phases   with   the   chemical  composition  of  EuF2 or  EuF3 in  the  Eu:LiSAF  matrix  were  observed  for  the  crystals  with  high  Eu  contents  while  the  secondary  phase  couldn’t  be  observed  in  the  powder  XRD  patterns.  In  the  radioluminescence  spectra  of  Eu:LiSAF  crystals  under  α-ray  irradiation,  emission  peaks  around  375 nm  originated  from  5d–4f  transition  of  Eu2+ ion  were  observed.   The   light   yields   systematically   increased   with   an   increase   of   actual   Eu   contents   in   the   crystals   and   the  decay  times  were  1490–1620 ns.

E-mail  Address:
suzuki_s@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714000755

77

JOURNAL OF LUMINESCENCE, 154, 452, Published: OCT2014

Studies   of   low   temperature   thermoluminescence   of   GAGG:Ce   and   LuAG:Pr   scintillator  crystals  using  the Tmax–Tstop method
K.  Brylew1,  W.  Drozdowski1,  A.  J.  Wojtowicz1,  K.  Kamada2,  A.  Yoshikawa3
1.   Institute   of   Physics,   Faculty   of   Physics,   Astronomy   and   Informatics,   Nicolaus   Copernicus   University,  Grudziadzka  5,  87-100  Torun,  Poland
2.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  6-6-10  Aoba,  Amaraki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.   Institute   of   Multidisciplinary   Research   for   Advanced   Materials,   Tohoku   University,   2-1-1   Katahira,   Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Low  temperature  thermoluminescence  of  GAGG:Ce  and  LuAG:Pr  scintillator  crystals  has  been  studied  by  means  of  the Tmax–Tstop method.  It  is  shown  that  the  glow  curves  of  both  materials  are  superpositions  of  discrete  glow  peaks  and  broad  bands  due  to  quasi-continuous  Gaussian  distributions  of  trapping  levels.  A  model  function  has  been  built  and  trap  parameters  have  been  evaluated.

E-mail  Address:
brykam@fizyka.umk.pl

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0022231314003275

78

JOURNAL OF EUROPEAN CERAMIC SOCIETY, 344, 3849, Published: DEC2014

Orientation  relationships  of  unidirectionally  aligned  GdAlO3/Al2O3eutectic  fibers
Y.  Ohashi1,  N.  Yasui1,  T.  Suzuki1,  M.  Watanabe1,  T.  Den1,  K.  Kamada2,  Y.  Yokota2,  A.  Yoshikawa2
1.  Corporate  R&D  Headquarter,  Canon  Inc.,  30-2  Shimomaruko  3-chome,  Ohta-ku,  Tokyo  146-8501,  Japan
2.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Unidirectionally   solidified   rare-earth   activated   GdAlO3(GAP)/Al2O3 eutectic   crystal   with   well-aligned   fibrous  structure  exhibits  excellent  light   guiding  property  and  can  be  used  as  a   scintillator  plate   for  high-resolution  X-ray  imaging.   In   this   paper,   the   microstructures   and   orientation   relationships   of   the   GAP/Al 2O3eutectic   fibers   were  investigated.   The   regular   GAP   single   crystal   fibers   with   a   hexagonally   close-packed   arrangement   grew   straight   in  the   same   direction   along   the   solidification   direction,   and   were   embedded   in   ac-axis   oriented   Al2O3 single   crystal  matrix.   The   majority   of   GAP   fibers   had   the   orientation   relationships   of   [0 1 0]GAP//[0 0 0 1]Al2O3 to   the   growth  direction  and  (100)GAP//(1120(Al2O3) to  the  interface  plane,  while  slight  misorientation  angle  of  both  [0 1 0]GAP  axis  and  (1 0 0)GAP  plane  were  observed.  In  the  GAP/Al2O3 interface  boundary,  the  lattice  misfit  between  the  two  phases  was  relieved  by  insertion  of  extra  half-planes  on  the  Al2O3 side.

E-mail  Address:
yoshihiro@canon.co.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0955221914002453

79

COMPUTERS  &  MATHEMATICS  WITH  APPLICATIONS, 68, 1107, Published: NOV2014

An  alternative  lattice  Boltzmann  model  for  three-dimensional  incompressible  flow
L.  Zhang1,2,  Z.  Zeng1,2,  H.  Xie1,2,  X.  Tao3,  Y.  Zhang1,  Yiyu  Lu2,  A.  Yoshikawa4,  Y.  Kawazoe5
1.  Department  of  Engineering  Mechanics,  College  of   Aerospace   Engineering,  Chongqing  University,  Chongqing  400044,  PR  China
2.  State  Key  Laboratory  of  Coal  Mine  Disaster  Dynamics  and  Control,  Chongqing  University,  Chongqing  400044,  PR  China
3.  State  Key  Laboratory  of  Crystal  Material,  Shandong  University,  Jinan  250100,  PR  China
4.  Institute  for  Materials  Research,  Tohoku  University,  Sendai  980-8577,  Japan
5.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  Sendai  980-8579,  Japan

Abstract:
In   this   work,   an   alternative   lattice   Boltzmann   (LB)   model   for   three-dimensional   (3D)   incompressible   flow   is  proposed.  The  equilibrium  distribution  function  (EDF)  of  the  present  model  is  directly  derived  in  accordance  with  the  incompressibility  conditions  by  applying  the  Hermite  expansion.  Moreover,  an  alternative  formula  for  pressure  computation   is   designed   from   the   second   order   moment   of   the   distribution   function.   The   present   3D   LB   model  inherits  the  advantageous  features  of  Guo’s  LB  model:  the  density  is  a  constant,  the  fluid  pressure  is  independent  of   density   and   the   Navier–Stokes   (N–S)   equations   for   incompressible   flow   can   be   derived.   Two   benchmark   tests,  flow  over  a  backward-facing  step  and  the  lid-driven  cavity  flow,  are  applied  to  validate  the  present  model.  Accurate  results  for  these  tests  are  obtained  with  the  present  model,  and  further  comparisons  with  the  previous  LB  models  (the  standard  LB  model,  the  He–Luo  model  and  Guo’s  LB  model)  demonstrate  that  the  present  model  provides  better  accuracy  in  the  region  of  high  deviatoric  stress  and  such  advantage  is  further  enhanced  by  using  the  D3Q27  lattice.

E-mail  Address:zzeng@cqu.edu.cn

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0898122114003691

80

NUCLEAR  INSTRUMENTS  AND  METHODS  IN  PHYSICS  RESEARCH  A, 767, 289, Published: DEC2014

Development   of   GAGG   depth-of-interaction   (DOI)   block   detectors   based   on   pulse   shape  analysis
S.   Yamamoto1,   T.   Kobayashi1,2,   J.   Y.   Yeom3,   Y.   Morishita1,   H.   Sato4,   T.   Endo4,   Y.   Usuki4,   K.   Kamada5,  A. Yoshikawa5,6
1.  Nagoya  University  Graduate  School  of  Medicine,  Nagoya,  Japan
2.  Department  of  Radiology,  Daiyukai  General  Hospital,  Ichinomiya,  Japan
3.  Kumoh  National  institute  of  Technology,  Gumi,  South  Korea
4.  Furukawa  Corporation,  Ichihara,  Japan
5.  New  Industry  Creation  Hatchery  Center  (NICHe),  Tohoku  University,  Sendai,  Japan
6.  Institute  for  Materials  Research  (IMR),  Tohoku  University,  Tohoku,  Japan

Abstract:
A  depth-of-interaction  (DOI)  detector  is  required  for  developing  a  high  resolution  and  high  sensitivity  PET  system.  
Ce-doped   Gd3Al2Ga3O12 (GAGG   fast:   GAGG-F)   is   a   promising   scintillator   for   PET   applications   with   high   light  output,   no   natural   radioisotope   and   suitable   light   emission   wavelength   for   semiconductor   based   photodetectors.  
However,  no  DOI  detector  based  on  pulse  shape  analysis  with  GAGG-F  has  been  developed  to  date,  due  to  the  lack  of  appropriate   scintillators  of  pairing.   Recently  a  new  variation  of   this  scintillator   with   different   Al/Ga  ratios—Cedoped  Gd3Al2.6Ga2.4O12 (GAGG  slow:  GAGG-S),  which  has  slower  decay  time  was  developed.  The  combination  of  GAGG-F  and  GAGG-S   may   allow   us  to  realize   high  resolution   DOI  detectors  based  on  pulse  shape  analysis.   We  developed   and   tested   two   GAGG   phoswich   DOI   block   detectors   comprised   of   pixelated   GAGG-F   and   GAGG-S  scintillation  crystals.  One  phoswich  block  detector  comprised  of  2×2×5 mm pixel  that  were  assembled  into  a  5×5  matrix.   The   DOI   block   was   optically   coupled   to   a   silicon   photomultiplier   (Si-PM)   array   (Hamamatsu   MPPC  S11064-050P)   with   a   2-mm   thick   light   guide.   The   other   phoswich   block   detector   comprised   of   0.5×0.5×5 mm  (GAGG-F)  and  0.5×0.5×6 mm3 (GAGG-S)  pixels  that  were  assembled  into  a  20×20  matrix.  The  DOI  block  was  also  optically  coupled  to  the  same  Si-PM  array  with  a  2-mm  thick  light  guide.  In  the  block  detector  of  2-mm  crystal  pixels  (5×5  matrix),  the  2-dimensional  histogram  revealed  excellent  separation  with  an  average  energy  resolution  of  14.1%  for  662-keV  gamma  photons.  The  pulse  shape  spectrum  displayed  good  separation  with  a  peak-to-valley  ratio  of  8.7.  In  the  block  detector  that  used  0.5-mm  crystal  pixels  (20×20  matrix),  the  2-dimensional  histogram  also  showed   good   separation   with   energy   resolution   of   27.5%   for   the   662-keV   gamma   photons.   The   pulse   shape  spectrum   displayed   good   separation   with   a   peak-to-valley   ratio   of   6.5.   These   results   indicate   that   phoswich   DOI  detectors  with  the  two  types  of  GAGGs  are  promising  for  developing  a  high  resolution  PET  system.

E-mail  Address:s-yama@met.nagoya-u.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0168900214009930

81

NUCLEAR  INSTRUMENTS  AND  METHODS  IN  PHYSICS  RESEARCH  A, 753, 84, Published: JUL2014

Development  of  a  prototype  of  time-over-threshold  based  small  animal  PET  scanner
K.  Shimazoe1,  H.  Takahashi1,  K.  Kamada2,  A.  Yoshikawa2,  K.  Kumagai2,  J.  Kataoka3,  S.  Itoh4,  H.  Sato4,  Y.  Usuki4
1.  Department  of  Nuclear  Engineering  and  Management,  University  of  Tokyo,  Bunkyo-Ku,  Tokyo  113-8656,  Japan
2.    Tohoku  University,  Sendai,  Japan
3.    Waseda  University,  Tokyo,  Japan
4.    Furukawa  Corporation,  Tsukuba,  Japan

Abstract:
A  time-over-threshold  (ToT)-based  positron  emission  tomography  (TODPET)  scanner  was  designed  and  fabricated.  
The   PET   scanner   consisted   of   eight   block   detectors,   each   of   which   is   composed   of   a   12×12   array   of   2×2×
10 mm3 Pr:LuAG   crystals   individually   coupled   with   a   12×12   UV-enhanced   avalanche   photodiode   (APD)   array.  
The  APDs   were   individually   read  out  using  a  custom-designed  time-over-threshold  application-specific  integrated  circuit   (ASIC)   and   field-programmable   gate   array   (FPGA)   readout   system.   The   PET   scanner   has   an   energy  resolution  of  10%  and  a  time  resolution  of  4.2 ns.  A  spatial  resolution  of  1.17 mm  (FWHM)  was  demonstrated  in  the  initial  results.

E-mail  Address:
shimazoe@it-club.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0168900214003866

82

CRYSTAL GROWTH AND DESIGN, 14, 4827, Published: SEP2014

Defect  Engineering  in  Ce-Doped  Aluminum  Garnet  Single  Crystal  Scintillators
M.   Nikl1,   K.   Kamada2,   V.   Babin1,   J.   Pejchal1,2,   K.   Pilarova3,   E.   Mihokova1,   A.   Beitlerova1,   K.   Bartosiewicz1,  S. Kurosawa2,4,    A.  Yoshikawa2,4
1. Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  16253  Prague,  Czech  Republic
2.  New  Industry  Creation  Hatchery  Center  (NICHe),  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi,  Japan
3.  Faculty  of  Nuclear  Sciences  and  Physical  Engineering,  Czech  Technical  University  in  Prague,  Brehova  7,  115  19  Prague,  Czech  Republic
4.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  980-8577  Japan

Abstract:

Mg2+  codoping  in  the   cerium-doped  Lu3Al5O12  single  crystal  stabilizes  a  part  of  the   cerium  ions  in  the   tetravalent  charge  state.   Stable  Ce4+  centers  in  aluminum   garnet  scintillators  create  an  additional  fast  radiative   recombination  pathway   in   the   scintillation   mechanism   which   effectively   diminishes   the   unwanted   slow   delayed   recombination  processes  and  transforms  them  into  the  fastest  part  of  the  scintillation  response.

E-mail  Address:
nikl@fzu.cz

Site  Address:
http://pubs.acs.org/doi/abs/10.1021%2Fcg501005s

83

JOURNAL OF MATERIALS RESEARCH, 29, 2288, Published: OCT2014

Polycrystalline   Yb3+–Er3+-co-doped   YAG:   Fabrication,   TEM-EDX   characterization,  spectroscopic  properties,  and  comparison  with  the  single  crystal
J. Hostaša1,   L. Esposito2,   A. Malchère3,   T. Epicier3,   A. Pirri4,   M. Vannini5,   G. Toci5,   E. Cavalli6,   A. Yoshikawa7,  M. Guzik8,  G. Alombert-Goget9,  Y. Guyot9, G. Boulon9
1. CNR   ISTEC,   National   Research   Council   of   Italy,   Institute   of   Science   and   Technology   for   Ceramics,   Faenza  48018,  Italy;;  and  Department  of  Glass  and  Ceramics,  Institute  of  Chemical  Technology,  Prague,  166  28  Prague  6,  Czech  Republic2.   CNR   ISTEC,   National   Research   Council   of   Italy,   Institute   of   Science   and   Technology   for   Ceramics,   Faenza  48018,  Italy
3.  University  of  Lyon,  INSA  of  Lyon,  MATEIS  UMR  CNRS  5510,  Villeurbanne  69621,  France
4.  CNR  IFAC,  National  Research  Council  of  Italy,  Institute  of  Applied  Physics  “Nello  Carrara”,  FI  10  50019,  Italy
5.  CNR  INO,  National  Research  Council  of  Italy,  National  Institute  of  Optics,  Sesto  Fiorentino  (FI)  10  50019,  Italy
6.  Dipartimento  di  Chimica,  Università  di  Parma,  Parma  (PR)  43121,  Italy
7.  Advanced  Crystal  Engineering,  IMR,  Tohoku  University,  Sendai  980-8577,  Japan
8.  Faculty  of  Chemistry,  University  of  Wrocław,  Wrocław  PL-50-383,  Poland
9.   Institute   of   Light   and   Matter   (ILM),   UMR5306   CNRS-University   Lyon1,   University   of   Lyon,   Villeurbanne  69622,  France

Abstract:
Yttrium  aluminum  garnet  (YAG)-based  ceramics  represent  a  valuable  alternative  to  single  crystals  as  active  media  in  laser  devices  for  specific  applications.  In  this  connection,  the  1.5–1.65  µm  emission  channel  of  Er3+-doped  YAG  is  of  particular  importance  for  the  realization  of  diode  pumped  solid  state  lasers  operating  in  the  so-called  ‘eye-safe’  region.  A  well-known  drawback  of  this  material  is  related  to  its  small  absorption  cross  section  in  correspondence  to  the   diode   pumping   radiation   at   940–980   nm.   However,   its   emission   performance   can   be   significantly   improved  through   sensitization   with   Yb3+ ions   that   can   efficiently   absorb   the   excitation   radiation   and   transfer   it   to   the  Er3+ ions.  This  work  deals  with  the  fabrication  of  polycrystalline  YAG  co-doped  with  Er3+ and  Yb3+ ions  from  oxide  powders  via  solid  state  sintering  in  high  vacuum  conditions  and  its  microstructural  analysis  by  transmission  electron  microscopy–energy-dispersive  x-ray  spectroscopy  to  determine  the  dopants  distribution  and  to  assess  their  influence  on  the  sintering  process  and  on  the  spectroscopic  properties.  For  this  purpose,  the  absorption  and  emission  spectra  of  the  prepared  material  have  been  measured  and  compared  with  those  of  a  single  crystal  having  the  same  composition,  appositely  prepared  by  the  micro-pulling  down  method.  Suitable  calculations  have  been  finally  carried  out  to  verify  the  effective  perspectives  of  application  of  the  investigated  ceramics  as  active  lasing  medium.

E-mail  Address:
jan.hostasa@vscht.cz

Site  Address:
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9361915&fulltextType=RA&fileId=S0884291414002064

84

OPTICAL MATERIALS, 41, 3, Published: MAR2015

Nd3+-doped   Lu2O3 transparent   sesquioxide   ceramics   elaborated   by   the   Spark   Plasma  Sintering   (SPS)   method.   Part   1:   Structural,   thermal   conductivity   and   spectroscopic  characterization
G.  Alombert-Goget1,  Y.  Guyot1,  M.  Guzik1,2,  G.  Boulon1,  A.  Ito3,  T.  Goto3,  A.  Yoshikawa3,  M.  Kikuchi3
1. Institute   Light   Matter   (ILM),   UMR5306   CNRS-University   Lyon   1,   University   of   Lyon,   69622   Villeurbanne,  France2.  Faculty  of  Chemistry,  University  of  Wroclaw,  PL-50-383  Wroclaw,  Poland
3.  Institute  for  Materials  Research  (IMR),  Tohoku  University,  980-8577  Sendai,  Japan

Abstract:
We  report  the  detailed  analysis  of  both  structural  characterization  by  SEM,  thermal  conductivity  of  high  value  and  high   resolution   spectroscopic   properties   of   Nd 3+-doped   Lu2O3 transparent   ceramics   fabricated   by   the   nonconventional   SPS   method.   The   emission   spectra   of   the   main   C2 site   shows   two   close4F3/2 → 4I11/2 laser   lines   at  1076.3   and   1080.5 nm,   respectively.   The   optical   properties   of   the   two   C 2 and   C3isites   and   of   C2–C3i and   C2–C2 Nd3+ pairs  have  especially  been  analyzed.

E-mail  Address:
boulon@univ-lyon1.fr

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714004558

85

OPTICAL MATERIALS, 41, 12, Published: MAR2015

Nd3+-doped   Lu2O3 transparent   sesquioxide   ceramics   elaborated   by   the   Spark   Plasma  Sintering  (SPS)  method.  Part  2:  First  laser  output  results  and  comparison  with  Nd3+-doped  Lu2O3 and  Nd3+-Y2O3 ceramics  elaborated  by  a  conventional  method
G.  Toci1,  M.  Vannini1,  M.  Ciofini2,  A.  Lapucci2,  A.  Pirri3,  A.  Ito4,  T.  Goto4,  A.  Yoshikawa4,  A.  Ikesue5,  G.  AlombertGoget6,  Y.  Guyot6,  G.  Boulon6
1. National   Institute   of   Optics,  National   Research   Council,   INO-CNR,   Via   Madonna   del  Piano   10,  50019   Sesto  Fiorentino,  Italy
2.  National  Institute  of  Optics,  National  Research  Council,  INO-CNR,  Largo  Enrico  Fermi  6,  50125  Firenze,  Italy
3.  Istituto  di  Fisica  Applicata  “Nello  Carrara”,  National  Research  Council,  IFAC-CNR,  Via  Madonna  del  Piano  10,  50019  Sesto  Fiorentino,  Italy
4.  Institute  for  Materials  Research  (IMR),  Tohoku  University,  980-8577  Sendai,  Japan
5.  World  Lab.  Co.,  Ltd.,  2-4-1  Mutsuno,  Atsutaku,  Nagoya  456-8587,  Japan
6.   Institute   Light   Matter   (ILM),   UMR5306   CNRS-University   Lyon1,   University   of   Lyon,   69622   Villeurbanne,  FranceAbstract:
We   report   the   first   demonstration   of   laser   oscillation   of   two   close   IR   emission   lines   at   1076.3 nm   and   1080.5 nm  using   a   1%   Nd3+-doped   Lu2O3 transparent   ceramics   fabricated   by   the   non-conventional   Spark   Plasma   Sintering  (SPS)   method.   A   comparison   is   made   with   Nd3+-doped   Lu2O3 and   Nd3+-doped   Y2O3ceramics   elaborated   by   HIP  conventional  method.

E-mail  Address:
boulon@univ-lyon1.fr

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714004418

86

NUCLEAR  INSTRUMENTS  AND  METHODS  IN  PHYSICS  RESEARCH  A, 772, 72, Published: FEB2014

Scintillation  properties  of  Ce:(La,Gd)2Si2O7 at  high  temperatures
S.   Kurosawa1,2,   T.   Shishido1,   T.   Sugawara1,   A.   Nomura1,   K.   Yubuta1,   A.   Suzuki1,   R.   Murakami1,   J.   Pejchal2,3,  Y. Yokota2,  K.  Kamada2,  A.  Yoshikawa1,2,4
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai  980-8577,  Miyagi,  Japan
2.  New  Industry  Creation  Hatchery  Center  (NICHe),  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai  980-8579,  Miyagi,  Japan
3.  Institute  of  Physics,  AS  CR,  Cukrovarnická  10,  162  53  Prague,  Czech  Republic
4.  C&A  Corporation,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Temperature   dependence   of   scintillation   properties   was   investigated   for   (Ce 0.01,   Gd0.90,   La0.09)2Si2O7   grown   by  floating  zone  method.  The  light  output  over  35,000  photons/MeV  was  found  constant  in  the  temperature  range  from  0  °C  to  150  °C.  In  addition,  FWHM  energy  resolution  of  Ce:La-GPS  (roughly  7–8%)  at  662  keV  remained  constant  up  to  100  °C.  Thus,  this  crystal  can  be   applied  to  oil   well   logging  or  other  radiation  detection   application  at  high  temperature  conditions.

E-mail  Address:
kurosawa@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0168900214011553

87

OPTICAL MATERIALS, 41, 58, Published: MAR2015

Luminescence  and  scintillation  properties  of  rare-earth-doped  LuF3  scintillation  crystals
J.  Pejchal1,2,  K.  Fukuda3,  S.  Kurosawa1,4,  Y.  Yokota1,  A.  Yoshikawa1,4
1. NICHe,  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai  9808579,  Japan
2.  Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  Prague  6  16200,  Czech  Republic
3.  Tokuyama  Corporation,  1-1  Mikage-cho,  Shunan-shi,  Yamaguchi  7458648,  Japan
4.  Institute  for  Materials  Research,  2-1-1  Katahira,  Aoba-ku,  Sendai  9808577,  Japan

Abstract:
The   Nd-doped   and   Er-doped   LuF3 single   crystals   were   grown   by   the   micro-pulling-down   method   to   study   their  scintillation   properties   in   the   vacuum-ultraviolet   (VUV)   region.   The   doubly   Nd–Er   codoped   single   crystal   was  grown  to  study  possibility  of  scintillation  performance  improvement  by  energy  transfer  from  Er 3+ to  Nd3+ ions.  The  LiF   flux   was   to   avoid   phase   transition   below   melting   temperature.   The   1%Nd-doped   sample   showed   the   highest  overall  scintillation  efficiency  under  X-ray  excitation  which  was  7  times  as  high  as  that  of  the  LaF3:Nd  8%  standard.  
The  leading  Nd3+ 5d–4f  emission  was  situated  at  176 nm,  while  the  Er3+ 5d–4f  emission  for  Er-doped  samples  was  observed  at  163 nm,  which  better  matches  the  sensitivity  of  some   VUV-sensitive  photodetectors.  The  optimum  Er  concentration  was  determined  to  be  around  1–3 mol%.  No  Er3+ 5d–4f  emission  was  observed  for  the  doubly  Er,Ndcodoped   sample   due   to   energy   transfer   from   the   Er 3+ to   Nd3+ ions.   Slight   improvement   of   the   light   yield   was  observed  in  the  doubly-doped  sample  with  respect  to  the  Nd-only  doped  one.

E-mail  Address:
pejchalj@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714004479

88

JOURNAL OF CRYSTAL GROWTH 410, 14, Published: JAN 2015

Czochralski   growth   of   Gd3(Al5−xGax)O12   (GAGG)   single   crystals   and   their   scintillation  properties
S.  Kurosawa1,2,  Y.  Shoji1,  Y.  Yokota2,  K.  Kamada2,3,  V.  I.  Chani1,  A.  Yoshikawa1,2,3
1.  Institute  for  Materials  Research,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  C&A  Corporation,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Ce:Gd3(AlxGa1−x)5O12   (x=2.5/5   and   3/5,   Ce:GAGG-2.5   and   Ce:GAGG-3)   crystals   were   grown   by   the   Czochralski  process   in   order   to   reduce   cost   of   the   starting   materials   as   compared   with   conventional   Ce:Gd 3Al2Ga3O12  (Ce:GAGG-2)   crystal   which   have   high   light   output.   Although   perovskite   phase   was   detected   in   Ce:GAGG-3,  Ce:GAGG-2.5   had   single-phase   garnet   structure.   Solidification   fraction   for   the   Ce:GAGG-2.5   growth   was   0.52.  
Optical  properties  including  transmittance,  emission,  and  excitation  spectra  of  30  samples  cut  from  the  Ce:GAGG2.5  bulk  ingot  did  not  depend  on  their  original  position  along  the  growth  axis.  These  samples  had  light  outputs  of  approximately   58,000±3000   photons/MeV.   However,   scintillation   decay   times   varied   from   140   to   200   ns   and  depended  on  the  position  clearly.

E-mail  Address:
y_shoji@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0022024813007410

89

OPTICAL MATERIALS, 41, 63, Published: MAR2015

Alkali   earth   co-doping   effects   on   luminescence   and   scintillation   properties   of   Ce   doped  Gd3Al2Ga3O12 scintillator
K.  Kamada1,2,  M.  Nikl3,  S.  Kurosawa1,4,  A.  Beitlerova3,  A.  Nagura4,  Y.  Shoji2,4,  J.  Pejchal1,3,  Y.  Ohashi4,  Y.  Yokota1,  A.  Yoshikawa1,2,4
1. Tohoku  University,  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
2.  C&A  Corporation,  T-Biz,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  16253  Prague,  Czech  Republic
4.  Tohoku  University,  Institute  for  Material  Reseach,  2-1-1  Katahira  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
The   Mg   and   Ca   co-doped   Ce:Gd3Al2Ga3O12 single   crystals   were   prepared   by   micro   pulling   down   method   with   a  wide   concentration   range   0–1000 ppm   of   the   codopants.   Absorption   and   luminescence   spectra   were   measured  together   with   several  other  scintillation  characteristics,  namely  the   scintillation  decay  and  light   yield  to  reveal  the  effect  of  Mg  and  Ca  co-doping.  The  scintillation  decays  were  accelerated  by  both  Mg  and  Ca  codopants.  Comparing  to   Ca   co-doping,   the   Mg   co-doped   samples   showed   much   faster   decay   and   comparatively   smaller   light   output  decrease  with  increasing  Mg  dopant  concentration.

E-mail  Address:
kamada@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714004467

90

NUCLEAR  INSTRUMENTS  AND  METHODS  IN  PHYSICS  RESEARCH  A, 772, 112, Published: FEB2015

Characterization  of  GAGG:Ce  scintillators  with  various  Al-to-Ga  ratio
P.   Sibczynski1,   J.   Iwanowska-Hanke1,   M.   Moszyński1,   L.   Swiderski1,   M.   Szawłowski1,   M.   Grodzicka1,  T. Szczęśniak1,  K.  Kamada2,3,  A.  Yoshikawa2,3
1.  National  Centre  for  Nuclear  Research,  PL  05-400  Otwock,  Poland
2.  C&A  Corporation,  Sendai,  Japan
3.  IMRAM,  Tohoku  University,  2-1-1  Katahira,  Aoba-ku,  Sendai  980-0812,  Miyagi,  Japan

Abstract:
Temperature   dependence   of   scintillation   properties   was   investigated   for   (Ce 0.01,   Gd0.90,   La0.09)2Si2O7   grown   by  floating  zone  method.  The  light  output  over  35,000  photons/MeV  was  found  constant  in  the  temperature  range  from  0  °C  to  150  °C.  In  addition,  FWHM  energy  resolution  of  Ce:La-GPS  (roughly  7–8%)  at  662  keV  remained  constant  up  to  100  °C.  Thus,  this   crystal  can  be   applied  to  oil   well   logging  or  other  radiation  detection  application  at  high  temperature  conditions.

E-mail  Address:
pawel.sibczynski@ncbj.gov.pl

Site  Address:
http://www.sciencedirect.com/science/article/pii/S016890021401198X

91

OPTICAL MATERIALS, 41, 41, Published: MAR2015

Luminescence  and  scintillation  properties  of  Ce  dope  SrHfO3 based  eutectics
K.  Kamada1,2,  S.  Kurosawa2,3,  Y.  Shoji1,3,  J.  Pejchal2,4,  Y.  Ohashi3,  Y.  Yokota1,  A.  Yoshikawa1,2,3
1. C&A  Corporation,  T-Biz,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
2.  Tohoku  University,  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Tohoku  University,  Institute  for  Material  Reseach,  2-1-1  Katahira  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
4.  Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  16253  Prague,  Czech  Republic

Abstract:Ce  doped  SrHfO3/SrAl12O19 eutectics  were  grown  by  the  micro  pulling  down  (μ-PD)  method  and  their  directionally  solidified   eutectic   system   has   been   investigated.   Investigations   of   obtained   eutectic   structure,   luminescence   and  scintillation   performances   were   also   performed.   Eutectics   were   grown   at   the   speed   of   0.60–0.90 mm/min.   In   the  eutectics,   Ce3+ 4f–5d   emission   was   observed   at   410 nm.   The   eutectics   showed   light   yield   of   around  300 photon/5.5 meV  alpha-ray  by 241Am  excitation.   Scintillation  decay  time   was  26.4 ns  (45%)   with   slower  decay  component  of  263 ns  (55%).

E-mail  Address:
kamada@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714004480

92

OPTICAL MATERIALS, 41, 80, Published: MAR2015

Luminescence  study  on  Eu  or  Tb  doped  lanthanum–gadolinium  pyrosilicate  crystal
S.   Kurosawa1,2,   T.   Shishido1,   T.   Sugawara1,   A.   Nomura1,   K.   Yubuta1,   J.   Pejchal2,3,   R.   Murakami1,   Y.   Yokota2,  Y. Shoji1,4,  Y.  Ohashi1,  K.  Kamada2,4,  A.  Yoshikawa1,2,4
1. Institute  for  Materials  Research,  2-1-1  Katahira,  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
2.  NICHe,  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  Prague  6,  16200,  Czech  Republic
4.  C&A  Corporation,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan

Abstract:(Eu0.01,  Gd0.90,  La0.09)2Si2O7 (Eu:La–GPS)  and  (Tb0.01,  Gd0.90,  La0.09)2Si2O7 (Tb:La–GPS)  crystals  were  grown  by  the  floating  zone  method,  and  their  optical  and  scintillation  properties  were  investigated.  Gd 3+-to-Tb3+ or  –Eu3+ energy  transfer   processes   were   found,   and   photo-luminescence   and   radio-luminescence   emission   spectra   showed 5D0–
7
Fi (i = 1–4)   Eu3+ transitions   in   Eu:La–GPS,   and 5D3–7Fi (i = 3–6)   and5D4–7Fi (i = 3–6)   transitions   in   Tb:La–GPS.  
Using  these  scintillators,  alpha-ray  imaging  was  possible  with  a  CMOS  camera.  These  materials  can  be  used  for  Xray  detection  as  well.

E-mail  Address:
kurosawa@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714006089

93

JOURNAL OF INSTRUMENTATION, 10, C01054, Published: JAN2015

Performance  of  a  new  Electron-Tracking  Compton  Camera  under  intense  radiations  from  a  water  target  irradiated  with  a  proton  beamY.   Matsuoka1,   T.   Tanimori1,   H.   Kubo1,   A.   Takada1,   J.D.   Parker1,   T.   Mizumoto1,   Y.   Mizumura1,2,   S.   Iwaki1,  T. Sawano1,   S.   Komura1,   T.   Kishimoto1,   M.   Oda1,   T.   Takemura1,   S.   Miyamoto1,   S.   Sonoda3,   D.   Tomono1,  K. Miuchi4,  S.  Kabuki1,  S.  Kurosawa6
1. Division  of  Physics  and  Astronomy,  Graduate  School  of  Science,  Kyoto  University,  Kyoto,  Kyoto,  606-8502,  Japan
2.Unit  of  Synergetic  Studies  for  Space,  Kyoto  University,  Kyoto,  Kyoto,  606-8502,  Japan
3.  Advanced  Biomedical  Engineering  Research  Unit,  Kyoto  University,  Kyoto,  Kyoto,  606-8502,  Japan
4.  Department  of  Physics,  Graduate  School  of  Science,  Kobe  University,  Kobe,  Hyogo,  657-8501,  Japan
5.  Department  of  Radiation  Oncology,  Tokai  University,  Isehara,  Kanagawa,  259-1193,  Japan
6.  Institute  for  Materials  Research,  Tohoku  University,  Sendai,  Miyagi,  980-8577,  Japan

Abstract:
We   have   developed   an   electron-tracking   Compton   camera   (ETCC)   for   use   in   next-generation   MeV   gamma   ray  telescopes.   An   ETCC   consists   of   a   gaseous   time   projection   chamber   (TPC)   and   pixel   scintillator   arrays   (PSAs).  
Since   the   TPC   measures   the   three   dimensional   tracks   of   Compton-recoil   electrons,   the   ETCC   can   completely  reconstruct   the   incident   gamma   rays.   Moreover,   the   ETCC   demonstrates   efficient   background   rejection   power   in  Compton-kinematics   tests,   identifies   particle   from   the   energy   deposit   rate   (dE/dX)   registered   in   the   TPC,   and  provides   high   quality   imaging   by   completely   reconstructing   the   Compton   scattering   process.   We   are   planning   the  ``Sub-MeV  gamma  ray  Imaging  Loaded-on-balloon  Experiment''  (SMILE)  for  our  proposed  all-sky  survey  satellite.  
Performance  tests  of  a  mid-sized  (30  cm)3 ETCC,  constructed  for  observing  the  Crab  nebula,  are  ongoing.  However,  observations  at  balloon  altitudes  or  satellite  orbits  are  obstructed  by  radiation  background  from  the  atmosphere  and  the  detector  itself  [1].  The  background  rejection  power  was  checked  using  proton  accelerator  experiments  conducted  at  the  Research  Center  for  Nuclear  Physics,  Osaka  University.  To  create  the  intense  radiation  fields  encountered  in  space,  which  comprise  gamma  rays,  neutrons,  protons,  and  other  energetic  entities,  we  irradiated  a  water  target  with  a  140  MeV  proton  beam  and  placed  a  SMILE-II  ETCC  near  the  target.  In  this  situation,  the  counting  rate  was  five  times   than   that   expected   at   the   balloon   altitude.   Nonetheless,   the   ETCC   stably   operated   and   identified   particles  sufficiently   to   obtain   a   clear   gamma   ray   image   of   the   checking   source.   Here,   we   report   the   performance   of   our  detector  and  demonstrate  its  effective  background  rejection  based  in  electron  tracking  experiments.

E-mail  Address:
matsuoka@cr.scphys.kyoto-u.ac.jp

Site  Address:
http://iopscience.iop.org/1748-0221/10/01/C01053

94

OPTICAL MATERIALS, 41, 45, Published: MAR2015

Photoluminescence   studies  Gd3Al2Ga3O12 crystalson  energy  transfer  processes  in  cerium-doped  M.  Kitaura1,  A.  Sato1,  K.  Kamada2,  S.  Kurosawa2,3,  A.  Ohnishi1,  M.  Sasaki1,  K.  Hara4
1. Department  of  Physics,  Faculty  of  Science,  Yamagata  University,  Yamagata  990-8560,  Japan
2.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  Sendai  980-8579,  Japan
3.  Institute  for  Materials  Research,  Tohoku  University,  Sendai  980-8679,  Japan
4.  Research  Institute  of  Electronics,  Shizuoka  University,  Hamamatsu  432-8011,  Japan

Abstract:
We   have   measured   photoluminescence   properties   of   cerium-doped   Gd3Al2Ga3O12 (Ce:GAGG)   crystals   at   low  temperatures   with   use   of   synchrotron   radiation.   Excitation   spectra   for   the   Ce 3+ 5d–4f   emission   exhibit   prominent  peaks   at   Gd3+ intra-4f   absorption   bands.   The   Gd3+ intra-4f   emission   band   is   observed   at   3.91 eV,   but   is   not   in  resonance   with   the   lowest   energy   Gd3+ intra-4f   absorption   band   at   3.95 eV.   The   temperature   dependence   of   the  Gd3+ emission  intensity  is  not  correlated  with  that  of  the  Ce 3+ emission  intensity.  Decay  curves  of  the  Ce3+ emission  were   also   measured   at   9 K   under   excitation   at   various   photon   energies.   The   decay   curve   is   remarkably   changed,  depending   on   the   excitation   photon   energies.   The   present   results   give   us   hints   to   understand   the   whole   of   energy  transfer  processes  in  Ce:GAGG  crystals.

E-mail  Address:
kitaura@sci.kj.yamagata-u.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346715000336

95

OPTICAL MATERIALS, 41, 32, Published: MAR2015

Growth   of   Nd   doped   (Lu,   Gd)3(Ga,   Al)5O12 single   crystal   by   the   micro   pulling   down  method  and  their  scintillation  properties
K.  Kamada1,2,  S.  Kurosawa1,3,  A.  Yamaji3,  Y.  Shoji2,3,  J.  Pejchal1,4,  Y.  Ohashi3,  Y.  Yokota1,  A.  Yoshikawa1,2,3
1. Tohoku  University,  New  Industry  Creation  Hatchery  Center,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
2.  C&A  Corporation,  T-Biz,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Tohoku  University,  Institute  for  Material  Reseach,  2-1-1  Katahira  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan
4.  Institute  of  Physics  AS  CR,  Cukrovarnicka  10,  16253  Prague,  Czech  Republic

Abstract:
Nd  1  mol%  doped  (Lu,  Gd)3(Ga,  Al)5O12  (LGGAG)  single  crystals  were  grown  by  the  micro-pulling  down  (μ-PD)  method.   Luminescence   and   scintillation   properties   such   as   absorption,   excitation   and   emission   spectra,   light   yield  and  decay  time   were   evaluated.  Nd1%:Lu3Al5O12  showed  the   highest  light  output  of  around  8200  photons/MeV  among   the   grown   crystals.   Scintillation   decay   time   of   Nd:Y3Al5O12   was   1.32   μs   (36%)   2.02   μs   (64%).  
Nd:Lu3Ga3Al2O12  was  relatively  high  dense  scintillator  of  7.38  g/cm3  with  good  light  yield  of  6800  photons/MeV  and  scintillation  decay  time  of  0.20  μs  (5%)  2.60  μs  (95%).

E-mail  Address:
kamada@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714004455

96

JAPANESE  JOURNAL  OF  APPLIED  PHYSICS, 54, 04DH04, Published: FEB2015

LiF/CaF2/LiBaF3 ternary  fluoride  eutectic  scintillator
K.  Hishinuma1,  K.  Kamada2,3,  S.  Kurosawa1,2,  A.  Yamaji1,  J.  Pejchal2,4,  Y.  Yokota2,  Y.  Ohashi1, A.  Yoshikawa1,2,3
1.   Institute  for  Materials  Research,  Tohoku  University,  Sendai  980-8577,  Japan
2. New  Industry  Creation  Hatchery  Center,  Tohoku  University,  Sendai  980-8579,  Japan
3. C&A  Corporation,  Sendai  980-8579,  Japan
4.  Institute  of  Physic  AS  CR,  Cukrovarnicka  10,  16253  Prague  6,  Czech  Republic

Abstract:
LiF/CaF2/LiBaF3 ternary  eutectic  scintillators  were  grown  by  the  µ-PD  method.  In  the  solidified  eutectic  the  phases  were   uniformly   distributed   in   the   transverse   direction   and   aligned   along   the   growth   direction.   For   the   Eu-doped  samples,  the  expected  emission  peak  observed  at  425  nm  was  ascribed  to  Eu2+ 5d–4f  transition  from  Eu:CaF2 under  X-ray   excitation.   The   LiF/CaF2/LiBaF3 ternary   eutectic   scintillators   showed   a   light   yield   around   7,000  photons/neutron  and  decay  time  of  260  ns  (73.6%)  and  50  ns  (26.4%).

E-mail  Address:
kosuke123@imr.tohoku.ac.jp

Site  Address:
http://iopscience.iop.org/1347-4065/54/4S/04DH04

97

CRYSTAL GROWTH AND DESIGN, 15, 1642, Published: MAR2015

Growth,   Structural   Considerations,  (La,Gd)2Si2O7 Scintillating  Crystals

and  Characterization  of  Ce-Doped  A.  Yoshikawa1,2,3  ,  S.  Kurosawa1,2,  Y.  Shoji1,3,  V.  I.  Chani1,  K.  Kamada2,3,  Y.  Yokota2,  Y.  Ohashi1
1. Institute  for  Materials  Research  (IMR),  Tohoku  University,  Sendai,  980-8577,  Japan
2.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  Sendai,  980-8579,  Japan
3.  C&A  Corporation,  Sendai,  980-8579,  Japan

Abstract:
Ce-doped  lantanium-gadolinium  pyrosilicate  (La,Ce,Gd)2Si2O7 (Ce:La-GPS),  crystals  with  various  content  of  rareearth  elements  were  produced  from  the  melt,  and  their  optimal  La/Gd  ratio  was  examined.  It  was  found  that  Ce:LaGPS   single   crystals   of   acceptable   optical   quality   can   be   produced   from   the   melts   ranging   from   La 0.5Gd1.5Si2O7 to  La1.0Gd1.0Si2O7 and   containing   about   1   atom   %   Ce   with   respect   to   the   host   rare-earths   of   La   and   Gd.   The   crystal  growth  was  performed  by  the  micro-pulling-down  and  Czochralski  methods.  The  crystals  were  chemically  uniform  along   the   growth   axis,   and   their   composition   was   equal   to   that   of   the   melt,   thus   corresponding   to   vicinity   of  congruent   melting   composition.   Spatial   distribution   of   Ce   in   La-GPS   was   also   inspected,   and   no   variation   of   Ce  content  was  detected  as  a  result  of  its  similarity  to  one  of  the  host  cations  (La)  regarding  the  size.  Basic  optical  and  scintillation  properties  of  the  Ce:La-GPS  crystals  are  also  reported,  and  it  is  demonstrated  that  partial  substitution  of  Gd  with  La  has  no  negative  impact  on  crystal  growth  and  physical  performance  of  the  crystals.

E-mail  Address:
yoshikawa@imr.tohoku.ac.jp

Site  Address:
http://pubs.acs.org/doi/abs/10.1021/cg501416u

98

OPTICAL MATERIALS, 36, 1934, Published: OCT2014

Growth  of  Sc  doped  RE3Al5O12 (RE = Y,  Lu)  single  crystals  by  micro-pulling-down  method  and  their  scintillation  properties
K.  Kamada1,2,  J.  Pejchal1,3,  M.  Nikl3,  S.  Kurosawa4,  Y.  Yokota1,  A.  Yoshikawa1,2,4
1. New  Industry  Creation  Hatchery  Center  (NICHe),  Tohoku  University,  6-6-10  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
2.  C&A  Corporation,  T-Biz,  6-6-40  Aoba,  Aramaki,  Aoba-ku,  Sendai,  Miyagi  980-8579,  Japan
3.  Institute  of  Physics,  AS  CR  Cukrovarnická  10,  162  53  Prague,  Czech  Republic
4.  Institute  for  Material  Research,  Tohoku  University,  2-1-1  Katahira  Aoba-ku,  Sendai,  Miyagi  980-8577,  Japan

Abstract:
Sc   doped   YyLu3−yAl5O12 (y = 0–1)   single   crystals   were   grown   by   the   μ-PD   method.   EPMA   techniques   were  employed   to   check   their   chemical   composition.   Luminescence   characteristics   were   measured.   Anti-site   defectrelated   host   emission   was   observed   within   280–360 nm   wavelength.   The   light   yield   was   increasing   with   Y  concentration  and  with  an  optimum  for  Sc2%  concentration.  The  Sc  2%  doped  Y 3Al5O12 showed  the  highest  light  yield   value   around   30,000 photon/MeV   and   670 ns   scintillation   decay   time   using   a   photomultiplier   detector  (R7600U).  Substitution  effects  of  the  Lu  site  and  their  influence  on  luminescence  and  scintillation  properties  were  studied.

E-mail  Address:
kamada@imr.tohoku.ac.jp

Site  Address:
http://www.sciencedirect.com/science/article/pii/S0925346714001700

99

JAPANESE  JOURNAL  OF  APPLIED  PHYSICS, 54, 04DH17, Published: MAR2015

Improvement   of   scintillation   properties   on   Ce   doped   Y3Al5O12scintillator   by   divalent  cations  co-doping
A.  Nagura1,  K.  Kamada2,3,  M.  Nikl4,  S.  Kurosawa1,2,  J.  Pejchal2,4,  Y.  Yokota2,  Y.  Ohashi1, A.  Yoshikawa1,2,3
1.   Institute  for  Material  Research,  Tohoku  University,  Sendai  980-8577,  Japan  2.  New  Industry  Creation  Hatchery  Center,  Tohoku  University,  Sendai  980-8579,  Japan  3.  C&A  Corporation,  Sendai  980-8579,  Japan  4.  Institute  of  Physics  AS  CR,  16253  Prague,  Czech  Republic

Abstract:
The  Mg  co-doped  Y3Al5O12:Ce  single  crystal  scintillators  were  prepared  by  micro  pulling  down  method  in  a   wide  concentration   range   0–3000   ppm   of   Mg   co-dopant.   Absorption   and   luminescence   spectra   were   measured   together  with  several  other  scintillation  characteristics,  namely  the  scintillation  decay,  light  yield  to  reveal  the  effect  of  Mg  co-doping.   The   scintillation   decays   were   accelerated   by   Mg   co-doping.   The   Mg   co-doped   samples   showed   much  faster  decay  with  increasing  Mg.

E-mail  Address:a_nagura@imr.tohoku.ac.jp

Site  Address:
http://iopscience.iop.org/1347-4065/54/4S/04DH17/

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Yoshikawa Lab.
Research Report
Published on 25 Jan. 2016

ANNUAL REPORT2014
  Edited and published by
A. Yoshikawa
Yoshikawa Laboratory
Institute for Materials Research,
Tohoku University