2

Contents
1.

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

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

Messages from foreign participants .......................................................................32

4.

Members of Yoshikawa Lab ..................................................................................35

5.

Research life in Yoshikawa Lab ............................................................................41

6.

Prizes and awards ....................................................................................................44

7.

List of research collaborations ...............................................................................47

8.

Research funds ........................................................................................................51

9.

List of patents ..........................................................................................................60

10. List of conferences ..................................................................................................61
11. List of abstracts .......................................................................................................63
12. Copies of TV, journal and newspaper items .......................................................100
13. Events and memories of Yoshikawa Lab ..............................................................1063

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. Similarly to the previous year, we had decided to avoid publishing the Report as a
hard copy to save couple of trees necessary for the paper production and to make it easier for you to accessthe copy of the Report at any time when you have your computer in your hands.
This is the second report of the laboratory that was originally established in April, 2007 as Yoshikawa
Group at the Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University.
It contains a summary of our research activities and selected papers published in FY2013. Current issue
covers our progress within academic year from April 2013 to March 2014. 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 GAGG crystals for their application as gamma-ray scintillators. Foodsurvey monitoring system and gamma camera for environment inspection are under development.
 Improvement of 6LiCAF and 6LiSAF growth yield. They are studied for neutron detection as analternative to the detectors based on application of 3He.
 Establishment of crystal growth technology of halide materials. As an example, Eu:SrI2 crystals weregrown 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 and shaped crystal growth of langasite type crystals. Al-substituted CNGG and CTGS crystals
are studied for their application in oscillators, resonators, and combustion pressure sensors.
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. Our current goal is 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 photos
and 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 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.
Akira YOSHIKAWA

Professor,
Institute for Materials Research (IMR), Tohoku University
New Industry Creation Hatchery Center (NICHe), Tohoku University
March, 20145

6

Research Digest

7Research Activities in 2013
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

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

Gamma-ray detection(PET, SPECT, Gamma-camera, oil logging)

Ce:LaGPS

Ce-doped and La-admixed gadolinium
pyrosilicate(Ce0.01Gd0.90La0.09)2Si2O7

The as-grown crystal under UV illumination

Ce:LaGPSHigh light yield
41000 photons/MeV
46 ns decay time
5% energy resolution
for 662keV gamma
rays
Light yield (photons/MeV)

CZ-grown crystal

Temperature (C)Emission at 390 nm

Good thermal stability until high temperature

Infra-red scintillators
Real-time patient
dosimetry systemwith infra-red
scintillators forradiation therapy

Cr3+ emission– matches tissuetransparency
window
A. Yamaji et al.,PosterPresentation,
SCINT2013(2013)

Kurosawa et al., IEEE TNS (2013).

Neutron scintillators - alternative to 3He
Reaction
6Li ＋ n → 3H ＋α-ray

Neutron

6Li
6Li

Single crystal for neutron system
grown by Cz method

Electronic transition
Luminescence of RE ionsA

Scintillation
α-ray
RE

B

Cut andpolished

Scintillation crystal

2

10

A

A

B

60
40

B

Counts / Channel

80

Intensity / a. u.

Transmittance, T / %100

Li-glass
A
B

1

10

20
0
200

Security applications
employing neutron systems

0300

400 500 600 700
Wavelength,  / nm

800

Transmittancespectra

300

400
500
600
Wavelength,  / nm

Radioluminescence(241Am)

10

0

200

400
600
Channel

800

1000

Pulse heightspectra (252Cf)

Eutectic composite scintillators
Concept of eutectic composite
scintillators for neutron detection

Backscattered Electron Images

As-grown eutectic
composite scintillators

On transverse cross-section

LiGdF4-LiF undoped
Pulling rate:
0.15 mm / min
1%Ce doped LiGdF4-LiF

1%Ce and 0.5%Ca co-doped LiGdF4-LiF
Rods dispersed well.
About 6600 rods / mm2

Along the growth direction

Photoluminescence spectra (ex.=270nm)

Flux growth

Rod fibers were grown well.
The length of longest rod : 800 µm

Photoluminescence decay
curve (em.=340,
ex.=320nm)
1000

Er3+ HS
Intensity (arb. units)

ErF3

TmF3

LuF :Er1%
3800

LuF :Er1%Nd1%
3

LaF3:Nd8%
600

Nd

400

3+

Er3+
LS
200

0

YF3

LuF3:Er1%,Nd1%
YbF3

150

200
250
Wavelength (nm)300Radioluminescence spectra of VUV and IR scintillators

The aim of this work was to develop new halide scintillator materials for some
applications for example gamma-ray survey meter, spectrometer, foodradiation detector and so on. In this year, we have challenged to improve
scintillation performance of Eu doped SrI2 single crystals grown by the micropulling-down (m-PD) method. They are displayed below.
Experimental arrangement of halide m-PD machine.

Setting chamberin glove box

Stable crystal growth

Crystal growthHigh-frequency induction coil

CCD camera
Turbo molecular pumpLiquid-solid interface during crystal growthobserved by the CCD camera. (left)
initiation of growth with first seed contact
with the melt and (right) stable growth.

Removable chamber

Halides are hygroscopic materials which easily react with air moisture to form oxy- and hydroxy- halides. Therefore,
careful handling of starting materials under protective argon atmosphere in glove box is required.

Scintillation properties

As-grown and polished RE(La, Gd or Lu)1mol%, Eu5,
7.5mol doped SrI2 crystals grown by the modified μ-PD
method.

RE-codoped
Eu:SrI2
crystalswerestudiedby
X-ray
radioluminescence measurements and showed Eu2+ emission peakaround 430 nm. Under 137Cs g-ray irradiation light yield and energy
resolution was decreased by approximately 20% and 5~7%
respectively.

Intensity (Normalized)

Grown rare-earth codoped Eu:SrI2

Wavelength / nm

As-Grown 1 inch Eu5%:SrI2 bulk crystal

Pulse-height spectra

As-Grown 1 inch Eu7.5%:SrI2 bulk crystal

1 inchPulse-height spectra of 1 inch Eu:SrI2 crystals were measured
under 137Cs g-ray irradiation. Eu7.5mol%:SrI2 1 inch crystal
showed high light yields and good energy resolutions: of
85,000ph/MeV and 6% respectively.

Transparent ceramic scintillators
Introduction
Spark plasma sintering(SPS)

Advantages of ceramics

Advantages of SPS

Better chemical uniformity than single crystals.

A rapid consolidation rate appropriate for densification of varietyof ceramics.

Can be produced with high dopant concentration.

Highly reductive condition due to carbon die and punch andvacuum environment.

Economical especially for high-melting materials.

High degree of densification.

Pressure

Carbonsheet

Defects present in single crystals due to high melting
sampletemperature are often absent in ceramics → improvement ofDC
pulse
oscillationssome properties (for example anti-site defects in Lu3Al5O2:Ce
are absent, which leads to absence of sub-microsecond slow
Carbon die

components in scintillation decay)

Experimental methodology of
SPS

Pressure

Lu3Al5O12 :Ce(LuAG:Ce)

Nano powder

1600 C

1600 C

1600 C

1700 C

1700 C

1700 C

LuAG:Ce presintered BSE (back-scattered electron) image

LuAG:Ce Nanopowder 1700C
ex=452nm,em=505nm

LuAG:Ce samples sintered by SPS method

2.5 10Intensity [arb. units]

2 10

1.5 10

1 10

5 10

5

Nanopowder
1700C
presintered
1700C
Single Crystal
BGO

5

5

5

Other oxygen-related efectAnti-site
defectPores stillpresent – causeof opacity

The above powders sintered by SPS at various
sintering temperatures at 100MPa pressure for 45
minutes

Radioluminescenceintensity for the nanopowder3+
Ce ceramic comparable to thatof single crystal!
Anti-site (AD) defect self
trapped exciton (STE)
emission observed for the
single crystal
Intensity of the defectemission for nanopowder
sample much lower

4

Intensity [arb. units]

Not presintered1500 C

1700 C center –grains visible

99.99% Powders of Lu2O3, Al2O3 and CeO2 mixed in
mortar for 3 hours
1) Part of the mixture presintered at 1600C for 8 hours.
Ce-concentration: 0.2 mol%2) Non-presintered mixture Ce-concentration: 0.2 mol%3) 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)

I=338exp(-t/54.05ns) + 0.76
100
LuAG:Ce 1700C
1exp fit1
100 200 300 400 500 600 700 800
time [ns]

100

240

320

400 480 560 640
Wavelength [nm]720

LuAG:Ce NOT presintered - BSE image

LuAG:Ce Nanopowder 1700C
ex=193nm,em=512nm

1700 C-large grains –grain growth

I=44.5exp(-t/64.19ns)+ 2.56exp(-t/870ns) + 1.17
101LuAG:Ce 1700C
2 exp fitpulse

100 200 300 400 500 600 700 800
time [ns]01700 C Grains
visible – pores muchlargerpulse

10

Ce3+ emission under direct excitation (452nm)

Intensity [arb. units]

Reference LuAG:Ce single crystal

Presintered

Ce3+ emission under band-to-band excitation (193nm) –slower components related to other complex defects

Large compact
areas
LuAG:Ce nanopowder - BSE image

J. Pejchal et al., STAC7 2013

Ce:SrHfO3
Hf : High Z, but high melting point.
→ Using SPS method.
Sintered SrHfO3
sample and surface SEM images
before and after annealing

Transmittanceof Ce:SrHfO3

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) Ruggedized photomultiplierfor oil well logging
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 regime

2, New Spectrometer
We have developed a new spectrometerfor visible and near Infra-red (NIR)
scintillators including halide crystals.

3, New Imaging system
We have developed a new imaging
system for visible and near Infra-red(NIR) scintillators.

Development of Piezoelectric Single Crystals
Langasite-type crystals

Superior properties•

Electromechanical coupling
factor is 2-3 times higher thanthat for quartz.

•

The curie point not observed.

•

High electrical resistivity athigh temperature found for
rare-earth-free langasite type
crystals•

Small impedance at Low
frequency

Applications
Combustion Sensors
Improvement of engine
efficiency by pressure
monitoring
andcombustion control todecreaseamountofexhaust gases.
Stability up to 400℃ is required.

Oscillators
Developmentofnext-generation
smartphones and tablets employing
smaller oscillators operating at low
frequencies
withlowenergyconsumption.

Growth of Ca3Ta(Ga1-xAlx)3Si2O14 crystals
Lattice constants

Ca3Ta(Ga0.5Al0.5)3Si2O14crystal
grown by Cz method

We successfully grew
Ca3Ta(Ga1-xAlx)3Si2O14
crystals with various Al
concentrations keeping
the langasite-type
structure.

Development of shaped crystals
Development of fiber Ir alloy crystal with difficult workability ( H23
Support Industry [Ministry of Economy, Trade and Industry] with
TKK, Sutar Seiki ,TEP, Toei kagaku sangyo)

Necessity of development of low cost manufacturing
technology of functional metal alloy with difficult workability

Manufacturing
technique

Crucible withhigh resistance

Manufacturing of ceramics

Heat-resistantcrucible ( > 2000ºC)

Applications

m-PD furnace forshaped crystal

Ir alloy fiber

Fiber crystal

Growth methodof shaped crystal

Growth furnace

＜ 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 2013
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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

31

Messages from foreign visitors

32

Message for 2013 annual reportfrom Iaroslav Gerasymov and Evgeny Galenin (ISMA NANU, Kharkov, Ukraine)

We had met Prof. Yoshikawa at the conference on
Advanced Scintillation Materials in September 2013 in
Kharkov (Ukraine). At that time, he invited us to visit hislaboratory at Tohoku University in Sendai for joint
experiments on gadolinium pyrosilicate crystal growth by
the μ-PD method. Almost immediately after that, we had
started preparations for the visit with great assistance ofHiroshi Uemura, who made excellent job to complete all
the formalities in time.
We had departed from Kharkov on December 8, when our city was full of snow, and the next
day we arrived to spring-like warm Sendai. The first colleague we met in Sendai was Dr. Valery
Chani, who escorted us to the lab. We were very happy to meet with the members of thelaboratory and to be introduced to their research. At first day in IMR, we were also lucky toparticipate at the research meeting of Yoshikawa Lab and to discuss there various aspects of thelaboratory activities, including luminescent properties of mixed garnets and fabrication of novel
functional materials.
During the rest of the week, we participated in about ten crystal growth experiments withassistance and under guidance of Prof. Kamada. His introduction to principles of GPS crystal
growth by the μ-PD was priceless. He was also very helpful explaining us the role of the μ-PD
method in selection of optimal composition of the crystals considering their crystalline quality
and physical properties.
Additional pleasant surprise forus was a welcome party that washeld in honor of our visit. This
informal event accompanied withdelicious plum wine and a bowlof soup from Prof. Kamada
should be also considered ascontribution
toUkrainianJapanese cooperation.
From our point of view, the great success of the Yoshikawa Lab is based on high professionalism
of its leader, a great friendly team of highly qualified enthusiasts, and excellent growth andcharacterization equipment. As a result, fundamental and practical achievements of this researchgroup are well recognized by the world scientific community.
Before leaving Sendai, we discovered that the city was covered with snow. This reminded us
snowy winter in Ukraine. After departure from Narita airport, we shared our impressions about
visiting Japan and enjoyed view of beautiful Fuji mountain from the window of the airplane.
Travel to Japan and visit the Yoshikawa Laboratory gave us the opportunity to meet new people
and new culture. That was an unforgettable experience.
Looking forward to further cooperation,
Iaroslav Gerasymov and Evgeny Galenin.
33

34

Members

35

Professor
A. Yoshikawa

Associate Professor

Associate Professor

Research AssistantProfessor

Research AssistantProfessor

Y. Yokota

K. KamadaS. Kurosawa

J. Pejchal

Technical Counselor

Reseacher

Reseacher

Reseacher

H. UemuraY. Shoji

H. Nagato

S. Hayasaka

Secretary

Secretary

Secretary

Secretary

M. Sasaki

K. Toguchi

Y. Takeda

Y. Saijo

Second grade
Doctoral course

Second grade
Master course

Second grade
Master course

Second grade
Master course

A. Yamaji

S. Suzuki

M. SekiK. Nishimoto

Second grade
Master courseFirst grade
Master courseFirst grade
Master course

A. Suzuki

K. Hishinuma

T. KudoReseacher

Reseacher

Visiting Professor

Visiting Professor

M. SatohT. NiheiProf. M. Nikl

Prof. G. Boulon

Visiting Professor

Prof.
Visiting Resarcher Visiting Resarcher
V. V. Kochurikhin Dr. V. Chani
Dr. A. Medvedev

２

年度 吉川研究室
２

Academic year

Professor

教授

Prof.

吉川 彰

Akira Yoshikawa

Members

NICHe 兼任

Associate Professors

准教授

Prof.

Yuui Yokota

横田 有為

NICHe

Prof.

Kei Kamada

鎌田 圭

NICHe

Research Assistant Professors

助教

Dr.

Shunsuke Kurosawa

黒澤 俊介

Dr.

Jan Pejchal

Researchers
Yasuhiro Shoji
Dr.

ン

ー

レ ー チ ニ長門 久和

Shoki Hayasaka

早坂 将輝

Advisors

研究顧問

Dr.

Touetsu Shishido

宍戸 統悦

Dr.

Masae Kikuchi

菊地 昌枝

Secretaries

NICHe

庄子 育宏

Hisakazu Nagato

Hiroshi Uemura

金研

研究員

Valery Chani

Technical Counselor

NICHe 兼任

東北福祉大学 特任教授

技術参
上村 博

秘書

Megumi Sasaki

佐々木 愛美Keiko Toguchi

戸口 景子

Yuka Takeda

武田 悠佳

2013.11.

Yumiko Saijo

西条

2013.6

美子

38

まで

大学院生

Grade

Akihiro Yamaji

山路 晃

D2

Kei Nishimoto

西本 けい

M2

Mafuyu Seki

関

真冬

M2

Akira Suzuki

鈴木 彬

M2

Shotaro Suzuki

鈴木 祥太朗M2

Kosuke Hishinuma

菱沼 康介

M1

Tetsuo Kudo

工藤 哲男

M1

Students

Researchers (Company)

民間共同研究員

Dr.

Andrey Medvedev

ン レ

Dr.

Kentaro Fukuda

福田 健太郎株式会社 クKou Onodera

小野寺 晃

TDK 株式会社

Masato Satoh佐藤 真人

TDK 株式会社

Takayuki Nihei

瓶 貴之

TDK 株式会社

Tatsuya Iwasaki

岩崎 達哉

株式会社キ ノン

Ryota Ohashi

大橋 良太

株式会社キ ノン

Visiting Professors

メー ェ

Fomos-Materials

短期滞在：客員教授 客員研究員

Prof.

Gorges Boulon

ョー

ー ン

Prof.

Martin Nikl

ーチン ニクProf.

Vladimir V. Kochurikhin

ーFranceCzech Republic

カチ ー

ッヒン

Russian Fed.
Prof.

Christophe Dujardin

クン
France39

40

Research life41

Research Life

Tetsuo Kudo

During my first year in Yoshikawa laboratory, I have been studying crystal growth and evaluationof piezoelectric materials. I found the research life in this laboratory very exciting.
Crystal growth has been a big challenge for me. In the beginning my research, I could not makegood crystal to evaluate. However, thanks a useful advice from many researchers in Yoshikawa
laboratory, I was successful in growing a crystal. First time after success in growing large bulk
crystal by Czochralski method, I was so excited and I wanted to research so much about crystal
growth.
For this year, I had many opportunities to study about crystals. For example, I went Poland andRussia to participate in international conference “ICCGE-17”. In the conference, I had discussed
about my research and listened to interesting presentations.
Next year, I will be 2nd grade master course student. For accomplishment to write master thesis, I
am going to research much more than the last year and learn many things in Yoshikawa laboratory.

Kousuke Hishinuma
One year has passed since I came to Yoshikawa Laboratory. There are many respectable people inthis lab and they are living a busy life. At first, I had never heard the word “scintillator” until I comethis lab. That was a new material for me and strongly attracted my attention.
I am studying directionally solidified eutectic scintillators. The motivation of the study is todevelop materials for high resolution radiation imaging taking the advantage of the light-guiding
ability caused by eutectic micro-structure. I feel that is very difficult but challenging. I will explore
the promising eutectic materials. Thank you for your reading.

42

43

Prizes and awards

44

45

46

List of research collaborations

47

Visits by International Collaborator 2013
Affiliation
General Physics Institute(Russia)

Researcher

Growth of bulk single crystals and automatic

Dr. V. Kochurikhin

General Physics InstituteDr. M. Ivanov(Russia)

Mrs. L. Gushchina

Fomos Materials

Research Theme
diameter control of Czochralski growth
Growth of bulk single crystals
Langasite-type piezoelectric single crystals and

Dr. A. Medvedev(Russia)
LPCML, CB Lyon 1 Univ.

(France)
LPCML, CB Lyon 1 Univ.

(France)
Svetchatheir piezoelectric properties
Ceramic laser materials with

Pr. G. Boulon

a nonpress vacuum sintering method
Ceramic scintillator materials with

Pr. G. Boulon

a nonpress vacuum sintering method

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

Growth of bulk oxide single crystals
Characterization of various scintillator

Dr. M. Nikl

materials

Institute for Scintillation

Mr. I. Gerasymov

Materials (Ukraine)

Mr. E. Galenin

Growth of bulk halide scintillator crystals

Seminars at Yoshikawa Laboratory 2013
Date

Affiliation

Speaker

Title of speechProf. Nikl’s Seminar

June 5

Institute of Physics ASCR

–July 24

(Czech Republic)(total 5

times)
Dr. M. Nikl

Luminescent materials andOptical spectroscopy of
inorganic solids

Mar. 6-7

Institute of Physics ASCR

2014

(Czech Republic)

Dr. M. Nikl

48

Inorganic scintillation materials

Visits to International Collaborator 2013
Affiliation
Scintillation Materials RC

Researcher

Period of stay

Assoc. Prof. Kamada
Mr. Shoji
Mr. Yamaji

July 17-19

Siemens Corporation,
Tennessee (USA)

Assoc. Prof. Kamada
Mr. Shoji
Mr. Yamaji

July 17-19

Institute of Physics ASCR
(Czech Republic)

Prof. Yoshikawa
Assoc. Prof. Yokota

July 21-26

Institute of Physics ASCR
(Czech Republic)

Assist. Prof. Pejchal

August 8-26

General Physics Institute(Russia)Prof. Yoshikawa
Mr. Shoji
Mr. Nishimoto
Mr. S. Suzuki

August 8-10

Prof. Yoshikawa
Mr. Shoji
Mr. Nishimoto
Mr. S. Suzuki

August 8-10

Prof. Yoshikawa

August 18 - 20

Prof. Yoshikawa

September 26 - 28

The University of Tennessee,(USA)

Fomos Materials(Russia)

TPS corporation(Korea)Institute for Scintillation
Materials (Ukraine)

49

50

Research funds51

成 25 度 研究資金
Research funds (2013 fiscal year)
経済産業省 東 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 支援事業( ポ ン)
Funding Program for Strategic Support Industry
難加工性機能性 金の形状制御結晶育成技術の開発“Development of functional metallic products by shape-controlled growthtechniques”
期間
本

Term:
度 Total:2012.1 - 2014.3
26,929,000 yen, 2013.4 - 2014.3

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 the small and medium enterprise for promotion of innovation2.

無坩堝 高融 酸 物 ンチ
タ結晶の製造を実現する
法
溶解技術の開発“Development of Skull Melt method to produce high-melting point oxide scintillator
crystals without crucible”
株式会社･
Truster: GES Co.Ltd
期間
本

Term:

度 Total:の再委託研究2014.3 - 2014.12
15,000,000 yen for our team, 2014.3 - 2014.12

52

ク

JST

Japan Science and Technology Agency
1. JST研究成果展開事業
端計測分析技術 機器開発
Development of Systems and Technology for Advanced Measurement and Analysis
Technology
無人

搭載用散乱

認識型高

置分解能

ン

ラの実用

開

発
“Research and development of high position resolution gamma camera borne by an
unmanned helicopter employing photon scattering for radiation survey”
古河機械金属株式会社
Truster: Furukawa Co. Ltd.

の再委託研究期間
Term: 2012.4 - 2015.3
本 度 Total: 21,250,000 yen for our team, 2013.4 - 2014.3
2. JST研究成果最適展開支援
ラム
A-STEP
育成タ
Adaptable and seamless technology transfer program through target-driven R&D
核物質 キ
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 度 Total: 14,500,000 yen for our team, 2013.4 - 2014.3
3. JST研究成果展開事業
端計測分析技術 機器開発
Development of Systems and Technology for Advanced Measurement and Analysis
Technology
高
分解能 高
ッ の国産放射測定検査装置“Development of radiometry tester with high energy resolution and high efficiency”
株式会社千代田 クの再委託研究Truster: Chiyoda Technol Corporation
53

期間 Term: 2013.10 - 2016.3
本 度 Total: 29,900,000 yen for our team, 2013.10 - 2014.3
4. JST研究成果展開事業
研究成果最適展開支援
実用 挑戦
実用

ラム A-STEP
挑戦タ
中小

ンチ

開発

Foundation for Small and Medium Enterprise Promotion(Supporting small and medium-sized and the venture company of the research anddevelopment.)
高温域 劣
い資源探査用 ンチ
タ“Scintillator for Resources Exploration Equipment with high performance at hightemperature”
株式会社 ＆Ａの再委託研究Truster: C&A Corporarion.
期間 Term: 2013.12 - 2017.3
本 度 Total: 7,000,000 yen for our team, 2013.12 - 2014.3

5. JST研究成果展開事業
FS 探索タFS stageコラを実現する高分解能を する型 ク
ンチ
タの開発“Development of pyrosilicate type pixel scintillator with a high energy resolution
allowing fabrication of low cost array camera for PET application”
PET用

期間 Term: 2013.4 - 2014.3
本 度 Total: 1,300,000 yen for our team, 2013.4 - 2014.3
次世代周波数資源の活用に向けた光フ
子の開発

54

一体型高効率 THz 光機能素

“Development of next-generation optical fiber-integrated THz devices”
期間 Term: 2013.4 - 2014.3
本 度 Total: 650,000 yen for our team, 2013.4 - 2014.3

6. JST復興促進

ラム

A-STEP

Funding Program for Revitalization Promotion
燃焼圧
横田

ン

用ラン
(Yuui Yokota)

型圧電結晶の形状制御結晶育成用坩堝の開発

環境
を持つ

タ 医療用
ラへの応用をンチ
タの開発
黒澤 俊介 (Shunsuke Kurosawa)

以下の 間分解能を(Jan PEJCHAL )つンチ

た高阻止能 高タの開発と医療への応用

期間 Term: 2012.4 - 2014.3
本 度 Total: 600,000 yen for our team, 2013.12 - 2014.3

55

分解能

NEDO

ク

New Energy and Industrial Technology Development Organization
1.

成度課題設定型産業技術開発費助成金
希少金属代替減技術実用 開発助成事業

Rare Metal Substituted Materials Development Project, 2013
Ｔ Ｋ株式会社の再委託研究Truster: TDK Corporation
期間 Term: 2013.10 - 2015.3
本 度 Total: 20,000,000 yen for our team, 2013.10 - 2014.3

復興庁
1.

Reconstruction Agency

成度地域
ョン戦略支援ラム
Funding Program for “Invest Japan” promotion for reconstruction
宮城県 ン
ン コ
研究機構
の再委託
Truster: Intelligent Cosmos Research Institute, Miyagi pref.
次世代自動車のた の人材育成
ラム“Manpower training program for innovation in automotive industry”
期間 Term: 2012.4 - 2017.3
本 度 Total: 10,600,000 yen for our team, 2013.4 - 2014.3

56

ラム厚生労働省科学研究費補助金
Ministry of Health, Labour and Welfare
科学研究費助成 Health Science Research Grants
非侵襲血中 RI 濃度測定を 能にするウラ
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”
東京大学の再委託研究Truster: Tokyo University
期間 Term: 2013.4 - 2016.3
本 度 Total: 20,000,000 yen, 2013.4 - 2014.3

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

1-1.

若手研究 B Grants-in-Aid for young scientists (B)横田(Yuui Yokota)
600,000 yen, 2013.4-2014.3

1-2

萌芽Grants-in-Aid for young scientists (Sprout)
吉川 彰(Akira Yoshikawa)
1,600,000 yen, 2013.4-2014.3

1-3

特別研究員
Fellowship
山路
広 (Akihiro Yamaji)
1,000,000 yen, 2013.4-2014.3

57

国立大学法人 事業推進事業型研究事業 推進型研究補助金
Foundation for Business Incubation Program
期間 Term: 2014.2 - 2015.1
本 度 Total: 50,000,000 yen,

2014.2 - 2015.1

58

企業 財団 個人の受託 共同研究 寄 金お び小型

Funds from industry, foundations, personal donation and small projects
1.

株式会社 ク

Tokuyama Corporation

2.

TDK 株式会社

TDK Corporation

3.

株式会社 ＆Ａ

C&A Corporation

4.

キCanon Inc.

5.

浜松ホ

6.

TANAKA ホ

7.

大阪大学

ン株式会社
ク 株式会社ン

Hamamatsu Photonics K.K
株式会社 TANAKA HOLDINGS Co. Ltd.
学研究

ンタ

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

59

ク

成 25 年度申請特許

List of patents

1. 結晶の製造方法
吉川 彰、横田

有為、黒澤

俊介、鈴木

祥太郎、福田健太郎、石津澄人(Akira Yoshikawa, Yuui Yokota, Shunsuke Kurosawa, Shotaro Suzuki,
Kentaro Fukuda, Sumito Ishizu )2. シンチレーター結晶、放射線検出器
吉川 彰、黒澤俊介、横田び非破壊検査装置

有為、庄子

育宏、鎌田

圭

(Akira Yoshikawa, Shunsuke Kurosawa, Yuui Yokota, Yasuhiro Shoji, Kei Kamada )3. シンチレーター
鎌田 圭、吉川び放射線検出器
彰、横田

有為、黒澤

俊介、菱沼

康介

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

外国出願 ２件60

学会、学内における役員 委員等

Committees of academic societies and conferences
吉川 彰
Dr. Akira YOSHIKAWA, Professor
Optical Materials

Associate Editor

Elsevier

Radiation Measurement

Guest Editor

Elsevier

International Association on Inorganic Scintillators andtheir Applications (SCINT)International Advisory
Committee

International Conference on Luminescent Detectors andTransformers of Ionizing Radiation (LUMDETR)

Scientific Advisory
Committee

日本結晶成長学会
Japanese Association for Crystal Growth Cooperation

理事 新技術 新材料
分科会担当
Trustee (responsible for new
technology and new materials
branch)編集委員
Member of the editorial staff

日本フラック 研究会
Japanese Association for Flux Growth

常任理事
Trustee

日本学術振興会第 186 委員会
No. 186 committee, Japan Society for the Promotion of
Science

代表幹事
Chief secretary

日本学術振興会第 161 委員会
No. 161 committee, Japan Society for the Promotion of
Science

運営委員
Manager

61

2013

度

成 25

吉川研究室

度

吉川研究室行事

学会

研究会 講演会

4

4/15-19
4/26-285

5/20-24 第 30 回強誘電体応用会議 京都 5/20 学振 ８６委員会(金沢)5/10 学振 ６ 委員会()

6

6/30-7/4

CLEO-PR2013(京都)77/19-20
7/21-26
7/21-25

STAC-7 横浜
ACCGE-19 (USA)
ISAF(Czech)

8

8/11-16

ICCGE-17(Poland)

9

9/16-20 第 74 回応用物理学会秋季学術講 9/12 学振演会

SCINT2013(China)
REMAT 2013(Poland)

7/5-6 学振８６委員会( 幌)7/19 学振６委員会(東京)８６委員会(福島)京都9/20-23 日本物理学会 2013

秋季大会(高知)
9/24-27 SSDM2013(福岡)10

10/20-23
10/27-11/2

ISLNOM-6(China)
2013 IEEE(Seoul)11

11/30-12/1

IWIRM9 (大洗)12 12/17 忘

10/11 学振６委員会(東京)11/6 学振 ８６委員会(千葉)11/6-8 第 43 回結晶成長国内会議会

長野

12/6 第 8 回日本フラック 成長研究発表会
東京
12/13-14 第 24 回光物性研究会 大阪
12/13 学振 ６ 委員会(伊豆)11/28-30 研究会

放射線検出器とその応用(つくば)
1/30-31 学振 ８６委員会(東京)23 3/6-7 研究室 ンポ 3/17-20 応用物理学関連講演会(神奈川)
ウム＆ キ 旅行(秋田)62

3/7-8 学振６委員会(東京)63List of abstracts

64

APPLIED PHYSICS LETTERS 102, 161907, Published: APR2013

Scintillation characteristics of LiCaAlF6-based single crystals under X-ray excitation
M. Nikl1, P. Bruzaβ, D. Panekβ, M. Vrbovaβ, E. Mihokova1, J. A. Mares1, A. Beitlerova1, N. Kawaguchiγ,4,K. Fukudaγ,4, A. Yoshikawaγ,51. Institute of Physics AS CR, Cukrovarnicka 10, 16β00 Prague 6, Czech Republic
β. Faculty of Biomedical Engineering, CTU Prague, Nam. Sitna γ105, Kladno, Czech Republic
γ. Tohoku Univ, IMR, β-1-1 Katahira, Aoba Ku, Sendai, Miyagi 9808577, Japan
4. Kasumigaseki Common Gate West Tower β-1, Kasumigaseki γ-chome, Chiyoda-ku, Tokyo 100-898γ,
Japan
5. Tohoku Univ, NICHe, Aramaki, Aoba Ku, Sendai, Miyagi 9808579, Japan

Abstract:

LiCaAlF6-based scintillators are studied under X- and soft gamma-ray excitations. Under nanosecond pulsed
soft X-ray laser excitation the scintillation decay is measured with extremely high dynamical resolution andbroad time scale. The undoped LiCaAlF6 shows complex temperature dependence of exciton luminescence andtunneling-driven energy transfer process in scintillation decay. In both the Ce and Eu-doped LiCaAlF6 thedominant part of measured scintillation decay is due to prompt recombination of electrons and holes at the
doped emission centers. Nevertheless, the measured light yield value is considerably lower with respect to thederived upper limits. Possible origin of its deterioration is discussed.

E-mail Address:

nikl@fzu.cz

Site Address:

http://scitation.aip.org/content/aip/journal/apl/10β/16/10.106γ/1.480γ047

65

FERROELECTRICS 449, 147, Published: SEP2013

Effects of growth atmosphere on crystal growth and optical properties for
Ca3NbGa3Si2O14 single crystals
Y. Yokota1, M. Satoβ, K. Totaβ, S. Kurosawa1, K. Onoderaβ, A. Yoshikawa1,γ
1. Tohoku Univ, IMR, β-1-1 Katahira, Aoba Ku, Sendai, Miyagi 9808577, Japan
β. TDK corporation, 1-1 Okinota, Kisakata, Nikaho 018019γ, Japan
γ. Tohoku Univ, NICHe, Aramaki, Aoba Ku, Sendai, Miyagi 9808579, Japan

Abstract:

CaγNbGaγSiβO14 (CNGS) single crystals were grown by the micro-pulling-down (μ-PD) method under various
atmosphere, Air, Ar + γ%Oβ and Ar 100%, and the effects of growth atmosphere on crystal growth and opticalproperties were investigated. While the CNGS crystal grown in Air indicated orange color, the crystal grown in
Ar was colorless. CNGS crystal grown in Air indicated several large absorption peaks around γ60 and 500 nm in
the transmittance spectrum. In contrast, the crystal grown in Ar didn't indicate these absorption peaks.

E-mail Address:

yokota@imr.tohoku.ac.jp

Site Address:

http://www.tandfonline.com/doi/abs/10.1080/0015019γ.β01γ.8ββ780

66

RADIATION MEASUREMENTS 55, 132, Published: AUG2013

Eu and Rb co-doped LiCaAlF6 scintillators for neutron detection
A. Yamaji1, T. Yanagidaβ, N. Kawaguchiγ, Y. Yokota1, Y. Fujimoto1, S. Kurosawa1, J. Pejchal1, K. Watanabe4,
A. Yamazaki4, A. Yoshikawa1,β1. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japanβ. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan
γ. Tokuyama Corporation, Shibuya γ-chome, Shibuya, Japan
4. Department of Material, Physics and Energy Engineering, Nagoya University, Japan

Abstract:

Eu and Rb co-doped LiCaAlF6 (LiCAF) single crystals with different dopant concentrations were grown by the
micro-pulling-down method for neutron detection. Their transmittance spectra showed strong absorption bands
at β00-ββ0 and β90-γ50 nm, and under β41Am alpha-ray excitation, their radioluminescence spectra exhibited an
intense emission peak at γ7γ nm that was attributed to the Euβ+ 5d-4f transition. These results were consistent
with those for the Rb-free Eu:LiCAF. The highest light yield among the grown crystals was γ6,000 ph/n, whichwas β0% greater than that of the Rb-free crystal. In addition, the neutron-excited scintillation decay times were
650-750 ns slower than that of the Rb-free Eu:LiCAF.

E-mail Address:

Yamaji-a@imr.tohoku.ac.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S1γ5044871γ00β151

67IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 419, Published: NOV2013

Growth and Scintillation Properties of Ce:Li(Ca,Ba)AlF6 Scintillator Crystals
Y. Yokota1, S. Kurosawa1,β, K. Fukudaγ, K. Kamadaβ,4, A. Yoshikawa1,β,4
1. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan
β. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japan
γ. Tokuyama Corporation, Shibuya γ-chome, Shibuya, Japan
4. C&A Corporation, Sendai 980-8576, Japan

Abstract:

Ba co-doped Ce:LiCaAlF6 [Ce:Li(Ca,Ba)AlF6] and LiCaAlF6 [Li(Ca,Ba)AlF6] crystals with various Ba
concentrations were grown and their structures, optical and scintillation properties were investigated. As-grown
Ceβ%Ba1% and Ceβ%Baβ%:Li(Ca,Ba)AlF6 crystals were high transparency in all parts while an end part of asgrown Ceβ%Ba5%:Li(Ca,Ba)AlF6 crystal and all parts of as-grown Ba5%:Li(Ca,Ba)AlF6 crystal included milky
parts which decreased transmittance. Ce:Li(Ca,Ba)AlF6 crystals indicated the emission peaks at β88 and γ08 nm
from which was attributable to the 5d-4f transition of Ce ion in the radioluminescence spectra under -rayirradiation. In the case of Ce1%Baβ%:Li(Ca,Ba)AlF6 crystal, light yield under thermal neutron irradiation were
improved. Decay times of Ce:Ce:Li(Ca,Ba)AlF6 under thermal neutron irradiation systematically increased withan increase of Ba concentration.

E-mail Address:

yokota@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6658909

68

NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH A 732, 599, Published: DEC2013

Development of a single crystal with a high index of refraction
S. Kurosawa1,β, V. V. Kochurikhinγ, A.Yamaji1, Y. Yokotaβ, H. Kubo4, T. Tanimori4, A. Yoshikawa1,β1. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japanβ. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan
γ. General Physics Institute, Moscow, Russia
4. Department of Physics, Kyoto University, Kyoto, Japan

Abstract:

Time-of-flight Positron emission tomography (TOF-PET) is one of the next-generation medical imaging
methods, which requires scintillators with a very short decay time. However, the shortest scintillation decay
times are typically β0–γ0 ns, and these values are not sufficient for TOF-PET. Cherenkov counters are used inhigh energy physics and they are expected to be applied in medical imaging due to their short decay time. Here,high-refractive index materials are necessary for Cherenkov radiators to reach a high light output. We measured
refractive indices of GdγGa5O1β (GGG), YγGa5O1β (YGG) and LuγGa5O1β (LuGG) crystals grown by a micropulling-down μPD method. The GGG, YGG and LuGG crystals were found to have refractive indices of β.5, β.γand β.γ at 400nm, respectively. Then we grew a 40mm diameter GGG crystal by the Czochralski method, andthe emission decay times of the GGG crystals irradiated with muons and gamma rays were 1071 ns and 107β ns,
respectively, using a photo- multiplier tube (HamamatsuR6βγ1-100). Cherenkov light of the GGG crystal could
be observed for the gamma-ray irradiation.

E-mail Address:

kurosawa@imr.tohoku.ac.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S0168900β1γ01144γ69IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 293, Published: FEB2013

Czochralski growth and scintillation properties of Ce:(Gd,Y,Lu)3(Al,Ga)5O12 single
crystals
K. Kamada1,β, P. Prusaγ, M. Niklγ, K. Blazekγ, T. Endo4, K. Tsutsumi4, S. Kurosawa5, Y. Yokota1,
Yoshikawa1,β,5A.

1. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan
β. C&A Corporation, Sendai 980-8576, Japan
γ. Institute of Physics AS CR, Cukrovarnicka 10, 16β00 Prague 6, Czech Republic
4. Materials Research Laboratory, Furukawa Co. Ltd., Tsukuba, γ05-0856, Japan
5. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japan

Abstract:

1-inch size Ce1%:GdβLu1AlβGaγO1β, Gd1LuβAlβGaγO1β, Gd1YβAl1.5Gaγ.5O1β and LuβY1AlβGaγO1β were grownby the Czhocralski (Cz) method. The EPMA techniques is employed to check their chemical composition.
Luminescence and scintillation properties were also evaluated. The Ce1%: Gd1YβAlβGaγO1β sample showed thehighest light yield of around 40 000 photon/MeV. The scintillation decay time was 46.6 ns (6γ%) and 157 ns(γ7%).

E-mail Address:

kamada@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=670486β

70

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 411, Published: FEB2014

Luminescence and Scintillation Properties of Scintillators Based on Orthorhombic andMonoclinic BaLu2F8 Single Crystals
J. Pejchal1,β, K. Fukudaγ, S. Kurosawa1,4, Y. Yokota1, R. Kralβ, M. Niklβ, A. Yoshikawa1,4
1. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japan
β. Institute of Physics AS CR, Cukrovarnicka 10, 16β00 Prague 6, Czech Republic
γ. Tokuyama Corporation, Shibuya γ-chome, Shibuya, Japan
4. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan

Abstract:

The rare-earth-doped orthorhombic BaLuβF8 vacuum-ultra-violet scintillator crystals have been studied. The fast
emission around 185 nm with a decay time of several nanoseconds was due to the allowed 5d-4f transition of theNdγ+ ion. The high temperature phase BaLuβF8 orthorhombic crystals have been prepared by micro-pullingdown method. Unfortunately, no 5d-4f emission (neither from Ndγ+ nor from Tmγ+) was observed in the crystals
under excitation by ionizing radiation at all. This was explained by preferential energy transfer from the host to
the lattice defect states. Further improvement of the scintillation efficiency by facilitating the energy transferfrom the host matrix to the Ndγ+ luminescence center by Tmγ+-codoping was attempted. The energy transferfrom the Tmγ+ ions to the Ndγ+ ones has been proved, however, no improvement of the overall scintillation
efficiency was observed.

E-mail Address:

pejchalj@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=66γ609β

71

RADIATION MEASUREMENTS 55, 128, Published: AUG2013

Neutron detection with LiCaAlF6 scintillator doped with 3d-transition metal ionsN. Kawaguchi1,β,γ, T. Yanagida4, Y. Fujimotoβ, Y. Furuyaβ, Y. Futamiβ, A. Yamajiβ, K. Watanabe5, A. Yamazaki5,
A. Uritani5, S. Kajimotoγ, H. Fukumuraγ, S. Kurosawaβ, Y. Yokotaβ, J. Pejchalβ, A. YoshikawaβAbstract:

1. Tokuyama Corporation, Shibuya γ-chome, Shibuya-ku, Tokyo 150-8γ8γ, Japanβ. IMR, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
γ. Department of Chemistry, Graduate School of Science, Tohoku University, 6-γ Aoba, Aramaki, Aoba-ku,
Sendai, Miyagi 980-8578, Japan
4. Kyushu Institute of Technology, β-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-01γ5, Japan
5. Department of Quantum Engineering, Nagoya Univ., Furo-cho, Chikusa-ku, Nagoya 464-860γ, Japan

Capability of thermal neutron detection was examined for LiCaAlF6 (LiCAF) scintillators doped with γdtransition metal ions. Their radioluminescence spectra were measured with an β41Am source to simulate 6Li(n,α)γH reaction. The sufficiently intense radioluminescence was observed for the Mn, Co and Cu dopants, while
only a weak one was observed for Ti, V, Fe and Ni. A Mn doped LiCAF crystal, which showed the highest
radioluminescence intensity, was coupled with a Si avalanche photodiode for the examination of its neutron
response. It was confirmed that the average current of the photodiode clearly increased under excitation with
1γ.5 meV neutron flux.

E-mail Address:

kawaguchi@imr.tohoku.ac.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S1γ5044871γ001571

72

OPTICAL MATERIALS 35, 2329, Published: OCT2013

Structural and optical properties of neodymium-doped lutetium fluoride thin films
grown by pulsed laser deposition
M. Ieda1, T. Ishimaru1, S. Ono1, K. Yamanoiβ, M. Cadatal-Radubanβ, T. Shimizuβ, N. Sarukuraβ, Y. Yokotaγ,
T. Yanagida4, A. Yoshikawaγ
1. Nagoya Institute of Technology, Nagoya 466-8555, Japan
β. Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan
γ. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
4. Kyushu Institute of Technology, Kitakyushu 808-0196, Japan

Abstract:

Neodymium-doped lutetium fluoride (Ndγ+:LuFγ) thin films were successfully grown on MgFβ (0 0 1) substrates
by pulsed laser deposition (PLD). It is void of cracks that are otherwise prevalent due to structural phasetransitions in Ndγ+:LuFγ during thin film deposition and bulk crystal growth. Cathodoluminescence (CL) spectra
revealed multiple emission peaks, with a dominant peak in the vacuum ultraviolet (VUV) region at 179 nm. This
peak has a decay time of 6.7 ns. The ability to grow high quality Ndγ+-doped fluoride thin films would enablefabrication of VUV light-emitting devices that will enhance applications requiring efficient VUV light sources.

E-mail Address:

doremino11@yahoo.co.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S09β5γ4671γ00γγ9X

73

RADIATION MEASUREMENTS 56, 107, Published:SEP2013

Photo- and radio-excited luminescence properties of Eu-doped La2O3–Al2O3 based
eutectics
Y. Fujimoto1,β, K. Kamada1,γ, T. Yanagidaβ,γ, S. Wakahara1,γ, S. Suzuki1,γ, S. Kurosawa1,γ, A. Yoshikawa1,γAbstract:

1. Institute for Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577,
Japan
β. Kyushu Institute of Technology, β-4, Hibikino, Wakamatsu-ku, Kitakyushu 808-0196, Japan
γ. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku,
Sendai, Miyagi 980-8579, Japan

Eutectic crystal of 0.5% Eu-doped γ0LaAlOγ–70AlβOγ (vol %) was prepared by micro-pulling down (μ-PD)
technique under nitrogen atmosphere. Being excited at a wavelength of γβ0 nm, the crystal exhibited intenseemission band with a maximum at 450 nm which is corresponding to 4f 65d-4f7(8S7/β) transitions of Euβ+. The
decay time and fluorescence quantum efficiency (QE) were determined to be about 475 ns and 60%,
respectively. When alpha-ray excited the crystal, both Euβ+ 4f65d-4f7(8S7/β) and Euγ+ 4f6-4f6 (5D0-7F1,β) emission
peaks were observed at 4γ5 nm and 600 nm. By the pulse height spectra, the relative scintillation light yield of
the crystal was about 4% compared with that of BGO commercial scintillator.

E-mail Address:fuji-you@imr.tohoku.ac.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S1γ5044871γ001996

74

NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH A 726, 155, Published:OCT2013

Spatial resolution of a μPIC-based neutron imaging detector
J. D. Parker1, M. Haradaβ, K. Hattori1, S. Iwaki1, S. Kabuki1, Y. Kishimoto1, H. Kubo1, S. Kurosawa1, Y.
Matsuoka1, K. Miuchi1, T. Mizumoto1, H. Nishimura1, T. Okuβ, T. Sawano1, T. Shinoharaβ, J. Suzukiβ, A.
Takada1, T. Tanimori1, K. Ueno1
1. Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyoku, Kyoto 606-850β, Japan
β. Materials and Life Science Facility Division, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki γ191195, Japan

Abstract:

We present a detailed study of the spatial resolution of our time-resolved neutron imaging detector utilizing a
new neutron position reconstruction method that improves both spatial resolution and event reconstruction
efficiency. Our prototype detector system, employing a micro-pattern gaseous detector known as the micro-pixel
chamber (μPIC) coupled with a field-programmable-gate-array-based data acquisition system, combines
100μm-level spatial and sub-μs time resolutions with excellent gamma rejection and high data rates, making itwell suited for applications in neutron radiography at high-intensity, pulsed neutron sources. From data taken at
the Materials and Life Science Experimental Facility within the Japan Proton Accelerator Research Complex (JPARC), the spatial resolution was found to be approximately Gaussian with a sigma of 10γ.48±0.77μm (after
correcting for beam divergence). This is a significant improvement over that achievable with our previous
reconstruction method (γγ4±1γμm), and compares well with conventional neutron imaging detectors and withother high-rate detectors currently under development. Further, a detector simulation indicates that a spatial
resolution of less than 60μm may be possible with optimization of the gas characteristics and μPIC structure. We
also present an example of imaging combined with neutron resonance absorption spectroscopy.

E-mail Address:

jparker@cr.scphys.kyoto-u.ac.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S0168900β1γ008188

75

NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH A 726, 37, Published: OCT2013

Scintillation properties of Yb3+-doped YAlO3 in the temperature range from 4.2 to 175 K
T. Yasumune1,β, M. Kurihara1, K. Maehata1, K. Ishibashi1, A. Yoshikawaγ,4Abstract:

1. Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, 744 Motooka,
Nishi-ku, Fukuoka 819-0γ95, Japanβ. Oarai Research and Development Center, Japan Atomic Energy Agency, 400β Narita, Oarai-machi,
Higashiibaraki-gun, Ibaraki γ11-1γ9γ, Japan
γ. Institute for Materials Research, Tohoku University, β-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
4. New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 9808579, Japan

We measured the temperature dependence of the emission wavelength spectrum of YAP:Yb by irradiating with-rays from a 90Sr/90Y source in the temperature range from 4.β to 175 K. The light yield of YAP:Yb wascharacterized using an avalanche photodiode in the detection of 66β-keV -rays from a 1γ7Cs source in thetemperature range from 50 to 175 K. The light yield was found to increase with decreasing temperature andreached γ840 photons/MeV at a temperature of 50 K. By extrapolating the temperature dependence of the lightyield using that of the integrated emission spectra, the experimental light yield was evaluated to be 4γ00
photons/MeV at a temperature of 4.β K.

E-mail Address:

yasumune.takashi@jaea.go.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S0168900β1γ007γ90

76

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 452, Published: FEB2014

Read Out Test of Pr:LuAG Scintillator Coupled to Organic Wavelength Shifter Using Si
Based Photodetectors
K. Kamada1,β, T. Yanagidaγ, S. Kurosawa4, Y. Yokota1, T. Endo5, K. Tsutsumi5, A. Yoshikawa1,β,4
1. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan
β. C&A Corporation, Sendai 980-8576, Japan
γ. Kyushu Institute of Technology, β-4, Hibikino, Wakamatsu-ku, Kitakyushu 808-0196, Japan
4. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japan
5. Materials Research Laboratory, Furukawa Co. Ltd., Tsukuba, γ05-0856, Japan

Abstract:

Functional possibilities of Pr:LuAG single crystal covered with plastic scintillators are demonstrated. Shift ofluminescence wavelength of the hybrid scintillators towards the region of higher spectral sensitivity ofphotodetectors and radiation responses of the hybrid scintillators were investigated. The Pr:LuAG sample coatedwith bis-MSBPVD showed the better light output and energy resolution than the Pr:LuAG itself. Light output
was increased up to 55% and energy resolution was also improved to 6.5%@66β keV using APD (Hamamatsu
S8664-8ββ0). In the case of MPPC (Hamamatsu S10γ6β_γγ_050 γ600 pixel-type), light output was increased
up to γ5% and energy resolution was also improved to 9.8%@66β keV. Decay curve of the Pr:LuAG sample
coupled with the WLS was also measured and successfully modeled.

E-mail Address:

kamada@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6678β94

77

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 452, Published: FEB2014

Development of a Prototype Detector Using APD-Arrays Coupled With Pixelized
Ce:GAGG Scintillator for High Resolution Radiation Imaging
K. Kamada1,β, K. Shimazoeγ, S. Ito4, M. Yoshino4, T. Endo4, K. Tsutsumi4, J. Kataoka5, S. Kurosawa6, Y.
Yokota1, H. Takahashiγ, A. Yoshikawa1,β,6
1. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan
β. C&A Corporation, Sendai 980-8576, Japan
γ. Department of Bioengineering, University of Tokyo, Tokyo 11γ-8656, Japan.
4. Materials Research Laboratory, Furukawa Co. Ltd., Tsukuba, γ05-0856, Japan
5. Research Institute for Science and Engineering, Waseda University, Shinjuku, Tokyo, Japan.
6. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japan

Abstract:

A novel digital PET scanner based on Time over Threshold method is developed. The positron emission
tomography (PET) is composed of 144 channel Ce:GdγAlβGaγO1β (GAGG)-Avaranche photodiode (APD)
detector arrays individually coupled with custom designed Time over Threshold (ToT) application-specificintegrated circuit (ASIC) to realize the high count rate and good spatial resolution. Such an imaging systemprovides a simple front-end circuit and flexible digital signal processing like multiplexing such as a pulse train
method. The measured energy resolution of the detector system was 6.7% for the 511 keV peak, and 4.β5 nstime resolution was measured with a single detector module. The measured spatial resolution for a point source
was 1.γ7 mm FWHM for our initial data with a columnar Na source.

E-mail Address:

kamada@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=67ββ988

78

ACTA PHYSICA POLONICA A 124, 250, Published: DEC2013

Czochralski Growth and Properties of Scintillating Crystals
A. Yoshikawa1,β, V. Chani1, M. Niklγ
1. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japanβ. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,
Japan γ. Institute of Physics ASCR, Cukrovarnicka 10, 16β 5γ Prague, Czech Republic

Abstract:

The Czochralski method is one of the very few melt growth techniques that are industry friendly when
considering the combination of quality, dimensions, and cost of the produced crystals suitable for theircommercialization in scintillation detectors. This method is one of the oldest and most developed crystal growth
processes regarding an adequate understanding the physical phenomena observed during solidification process
and its practical expansion especially in the industrial scale production. It allows controllable formation of
single-crystalline cylindrical ingots of various inorganic scintillation materials. The review summarizes recent
progress on the Czochralski growth of a number of scintillation materials. The oxide crystals are mainly
considered including the Ce and Pr-doped REγAl5O1β, RE = Y, Lu, aluminum garnets and newly discovered
ultraefficient Ce-doped Gdγ(Ga,Al)5O1β multicomponent garnet, high density PbWO4 and CdWO4 tungstates,
Ce-doped REβSiO5, RE = Y, Gd, Lu, oxyorthosilicates and (Y,Lu)AlOγ aluminum perovskites and finally theclassical Bi4GeγO1β scintillator. Additionally, the details of the growth of other practically important non-oxide
crystals, namely the Ce and Eu-doped LiCaAlF6 neutron and ultraefficient Ce-doped LaBrγ scintillators, arediscussed. The potential of novel micro-pulling down growth method is briefly described in the combinatorial
search for new scintillator materials. Selected luminescence and scintillation characteristics including the spectraand decay kinetics, light yield and radiation resistance are also illustrated and overviewed.

E-mail Address:

yoshikawa@imr.tohoku.ac.jp

Site Address:

http://przyrbwn.icm.edu.pl/APP/PDF/1β4/a1β4zβp1γ.pdf

79

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 339, Published: FEB2014

Scintillation Properties of a Non-Doped Ca3TaGa3Si2O14 Crystal
S. Kurosawa1, M. Kitahara1, Y. Yokotaβ, K. Hishinuma1, T. Kudo1, O. Buzanovγ, A. Medvedevγ, V. I. Chani1,
A. Yoshikawa1
1. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japanβ. New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai,Japan
γ. FOMOS-materials OAO, Moscow,1070βγ, Russia

Abstract:

In order to search for a new scintillation material consisting of tantalum (Ta) with a high atomic number of 7γ,
we have investigated scintillation properties of langasite type crystal containing Ta. Non-doped CaγTaGaγSiβO14(CTGS), which is well known as a piezoelectric material, was grown by the Czochralski method. Radioluminescence spectrum of this crystal peaked around γ40 nm. Its light output was approximately1,β00
photons/MeV. This crystal is expected to be a scintillation host material.

E-mail Address:

kurosawa@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=67048γ580

JOURNAL OF CRYSTAL GROWTH 375, 51, Published: JUL2013

Preparation and characterization of pure and Pr(III)-doped lead chloride single crystals
grown by modified micro-pulling- down method
R. Král1, K. Nitsch1, V. Jarý1, Y. Yokotaβ, F. Futamiβ, A. Yoshikawaβ, M. Niklβ
1. Institute of Physics ASCR, Cukrovarnicka 10, 16β 5γ Prague, Czech Republic
β. Institute of Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Japan

Abstract:

Single crystals of lead chloride pure and doped with Pr(III) were grown for the first time using the modified
micro-pulling-down method. Due to hygroscopicity of both lead chloride and doping Pr(III) chloride thestandard micro-pulling-down apparatus had to be equipped with a removable protective chamber. Preparedsingle crystals β5 mm long and γ mm in diameter were characterized by powder X-ray diffraction and DSC
thermal analysis. Optical and luminescence characteristics of lead chloride single crystals, such as absorption,
radioluminescence, photoluminescence, and decay curves, were measured as well.

E-mail Address:

kralr@fzu.cz

Site Address:

http://www.sciencedirect.com/science/article/pii/S00ββ0β481γ00β674

81

RADIATION MEASUREMENTS 55, 72, Published: AUG2013

Optical properties in Ag+-doped phosphate glass irradiated with X-rays and α-particles
Y. Miyamoto1,β, T. Ohnoβ, Y. Takeiβ, H. Nantoβ, T. Kuroboriγ, T. Yanagida4, A. Yoshikawa5, Y. Nagashima1,
T. Yamamoto1
1. Oarai Research Center, Chiyoda Technol Corporation, γ681 Narita-cho, Oarai-machi, Higashi-ibaraki-gun,Ibaraki γ11-1γ1γ, Japan
β. Advanced Materials, Science Research & Development Center, Kanazawa Institute of Technology, γ-1
Yatsukaho, Hakusann-shi, Ishikawa 9β4-08γ8, Japan
γ. Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa-shi,Ishikawa 9β0-119β, Japan
4. Kyushu Institute of Technology, β-4 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0196, Japan
5. Institute for Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577,
Japan

Abstract:

The objective of this study is to investigate the emission mechanism of radiophotoluminescence (RPL) in the
Ag+-doped phosphate glass (glass dosimeter), which is now used as individual radiation dosimeter, because theemission mechanism of RPL in glass dosimeter has been not fully understood. We have investigated theassignments and characteristics of the X-ray induced colour centres in the Ag+-doped phosphate glass up to now(Miyamoto et al., β010). Optical properties such as optical absorption spectra related with X-ray and α-particles
irradiation were measured for commercially available glass dosimeter.
In this study optical properties such as optical absorption spectrum as a function of X-rays and α-particles
irradiation were measured for commercially available glass dosimeter. Comparison of the RPL in Ag +-doped
phosphate glass irradiated with X-rays and α-particles is discussed.

E-mail Address:

miyamoto-y@c-technol.co.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S1γ5044871β00γ150

82

RADIATION MEASUREMENTS 56, 98, Published: SEP2013

Deep trapping states in cerium doped (Lu,Y,Gd)3(Ga,Al)5O12 single crystal scintillators
E. Mihóková1, K. Vávrůβ, K. Kamadaγ, V. Babin1, A. Yoshikawa4, M. Nikl1
1. Institute of Physics AS CR, v.v.i. Cukrovarnická 10, 16β 5γ Prague 6, Czech Republic
β. Faculty of Nuclear Sciences and Physical Engineering, CTU, Brehová 7, 115 19 Prague 1, Czech Republic
γ. Materials Research Laboratory, Furukawa Co. Ltd., Tsukuba γ05-0856, Japan
4. Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577, Japan

Abstract:

We study deep trapping states in Ceγ+-doped garnet crystals with the composition (Lu,Y,Gd) γ(Ga,Al)5O1β,
recently shown as having remarkably high light yield. We use thermally stimulated luminescence (TSL)
technique above room temperature and determine the composition Gd γGaγAlβO1β as the host showing the lowest
concentration of traps. This host consistently manifests very low afterglow comparable to that of the standard
BGO crystal. We also perform TSL glow peak analysis based on the initial rise technique to evaluate trap depth
and other characteristics associated with TSL peaks.

E-mail Address:

mihokova@fzu.cz

Site Address:

http://www.sciencedirect.com/science/article/pii/S1γ5044871γ0001γ983

RADIATION MEASUREMENTS 56, 62, Published: SEP2013

Light yield of (Lu, Y, Gd)3Al2Ga3O12:Ce garnets
P. Prusa1, K. Kamadaβ, M. Nikl1, A. Yoshikawaγ, J.A. Mares1
1. Institute of Physics, Czech Academy of Sciences, Cukrovarnicka 10, 160 00 Praha, Czech Republic
β. Materials Research Laboratory, Furukawa Co. Ltd., 1-β5-1γ, Kannondai, Tsukuba γ05-0856, Japan
γ. IMR, Tohoku University, Sendai 980-8577, Japan

Abstract:

Two sets of Ce-doped multicomponent garnet scintillator samples were prepared using Czochralski method.
Best performing sample from the first group was Gd γAlβGaγO1β doped by 1% of Ce. Therefore, samples of
GdγAlβGaγO1β with different thickness have been prepared for the second set. Light yield, its dependence on
amplifier shaping time, energy resolution, and non-proportionality have been measured using hybrid
photomultiplier. Best performing sample exhibits following parameters: light yield of 50 600 photons/MeV,
energy resolution of 5.5%@66β keV, fast scintillation component intensity 91%, and good proportionality.
Performance of other samples was negatively affected presumably either by ionization of 5d 1 excited state ofCeγ+ center or electron traps.

E-mail Address:

petr.prusa@fjfi.cvut.cz

Site Address:

http://www.sciencedirect.com/science/article/pii/S1γ5044871γ000784

84

OPTICAL MATERIALS 36, 214, Published: DEC2013

Growth and optical properties of RE-doped ternary rubidium lead chloride single
crystals
R. Král1, K. Nitsch1, V. Babin1, J. Šulcγ, H. Jelínkováγ, Y. Yokotaβ, A. Yoshikawaβ, M. Nikl1
1. Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10/11β, 16β 00 Prague 6,
Czech Republic
β. Institute for Materials Research (IMR), Tohoku University, β-1-1, Katahira, Aoba-ku, Sendai 980-8577,
Japan
γ. Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7,
115 19 Prague 1, Czech Republic

Abstract:

This paper reports on the growth of pure and Nd γ+, Prγ+, Ybγ+, and Dyγ+ doped rubidium lead chloride(RbPbβCl5) crystals by the atmosphere-controlled micro-pulling-down method. Structural and composition
measurements are reported, further completed by the absorption, radio- and photoluminescence spectra anddecay measurements on the prepared single crystals. Potential of these materials and preparation method for theapplication in the infrared solid state laser field are discussed.

E-mail Address:

kralr@fzu.cz

Site Address:

http://www.sciencedirect.com/science/article/pii/S09β5γ4671γ004710

85

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 320, Published: FEB2014

Luminescence Properties of Gd3Ga5O12:Cr Single Crystals
A. Yamaji1, V. V. Kochurikhinβ, S. Kurosawa1, A. Suzuki1, Y. Fujimoto1, Y. Yokotaγ, A. Yoshikawa1
1. Institute for Materials Research (IMR), Tohoku University, β-1-1, Katahira, Aoba-ku, Sendai 980-8577,
Japan
β. General Physics Institute, 119991Moscow, Russia
γ. New Industry Creation Hatchery Center, Tohoku University, Sendai, Miyagi, 980-8577, Japan

Abstract:

We evaluated optical and scintillation properties of a 0.0γ% Cr-doped GdγGa5O1β (GGG:Cr) single crystal
grown by Czochralski method for medical use. Since human body has low absorption region fromapproximately 700-1100 nm, near infrared scintillators would be applied to the real time dose monitor system.
In the X-ray excited radioluminescence, the emissions related to βE → 4Aβ transitions of Crγ+ were observed ataround 7β5 nm. The scintillation light yield of GGG: Cr 0.0γ% single crystal under 5.5 MeV alpha-ray
excitation was determined to be γ0% of BGO.

E-mail Address:

yamaji-a@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6704860

86

JAPANESE JOURNAL OF APPLIED PHYSICS 52, 062402, Published: MAY2013

Electronic States of Trivalent Praseodymium Ion Doped in 20Al(PO3)3–80LiF Glass
M. Tsuboi1, K. Takeda1, T. Nakazato1, M. Kono1, K. Yamanoi1, M. Cadatal-Radubanβ, K. Sakai1, R. Nishi1,
Y. Minami1, M. V. Luong1, Y. Arikawa1, T. Shimizu1, N. Sarukura1, T. Norimatsu1, M. Nakai1, H. Azechi1,
T. Murataγ, S. Fujino4, H. Yoshida5, A. Yoshikawa6, N. Sato6, H. Kan7, K. Kamata8
1. Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871, Japan
β. Institute of Natural and Mathematical Sciences, Massey University, Albany, Auckland 06γβ, New Zealand
γ. Kumamoto University, Kumamoto 860-8555, Japan
4. Kyushu University, Fukuoka 81β-8581, Japan
5. Ceramic Research Center of Nagasaki, Hasami, Nagasaki 859-γ7β6, Japan
6. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
7. Hamamatsu Photonics K.K., Hamamatsu 4γ0-8587, Japan
8. Furukawa Co., Ltd., Chiyoda, Tokyo 100-8γ70, Japan

Abstract:

We investigate the photoluminescence (PL) and photoluminescence excitation (PLE) spectra of β0Al(PO γ)γ–80LiF+Pr glass (APLF+Pr) and Prγ+-doped LiCaAlF6 crystal (Pr:LiCAF) in order to determine the electronic
states of Prγ+ in APLF glass host and to improve APLF+Pr scintillation properties. Ultraviolet (UV) emission
bands at around β50 and γ40 nm were observed from both materials and these can be ascribed to 4f5d→4fβtransitions in Prγ+. Emission at around 400 nm was also obtained and is principally attributed to 1S0→4fβ
transition. Difference in the emission profiles of these two materials was found to be due to the extent of the 5dband and its position relative to the 1S0 state. Increasing the concentration of Prγ+ up to β mol % was found to
improve UV emission ratio due to the faster cross-relaxation of 4f states. This could improve the quantum
efficiency of APLF+Pr as a neutron scintillator for scattered-neutron diagnostics in laser fusion research.

E-mail Address:

tsuboi-m@ ile.osaka-u.ac.jp

Site Address:

http://iopscience.iop.org/1γ47-4065/5β/6R/06β40β/87

JOURNAL OF PHYSICS D: APPLIED PHYSICS 46, 365303, Published: AUG2013

Effect of the Pr3+ → Gd3+ energy transfer in multicomponent garnet single crystal
scintillators
V. Babin1, M. Nikl1, K. Kamadaβ, A. Beitlerova1, A. Yoshikawaβ,γ1. Institute of Physics AS CR, Cukrovarnicka 10, Prague, 16β5γ, Czech Republic
β. NICHe, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan
γ. Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577, Japan

Abstract:

Luminescence processes in the undoped and Prγ+-doped (Gd,RE)γ(Ga,Al)5O1β, RE = Lu,Y, multicomponent
garnets are studied by time-resolved photoluminescence spectroscopy. Energy transfer processes between Pr γ+
and Gdγ+ causing significant deterioration of the scintillation performance are considered in detail. As is shownin current work, an overlap of the 5d1–γH4 emission transition of Prγ+ and 8S–6Px absorption transition of Gdγ+
results in unwanted depletion of Prγ+ 5d1 excited state and is further intensified by the concentration quenchingin the Gdγ+-sublattice. This process explains a drastic decrease of light yield in Prγ+-doped Gdγ+-containing
multicomponent garnets observed in a previous work.

E-mail Address:

babinv@fzu.cz

Site Address:

http://iopscience.iop.org/00ββ-γ7β7/46/γ6/γ65γ0γ/

88

JOURNAL OF INSTRUMENTATION 8, C10023, Published: OCT2013

Simulation of gas avalanche in a micro pixel chamber using Garfield++
A. Takada1, T. Tanimoriβ, H. Kuboβ, J. D. Parkerβ, T. Mizumotoβ, Y. Mizumuraγ, S. Iwakiβ, T. Sawanoβ,
K. Nakamuraβ, K. Taniueβ, N. Higashiβ, Y. Matsuokaβ, S. Komuraβ, Y. Satoβ, S. Namamuraβ, M. Odaβ, S.
Sonoda4, D. Tomonoβ, K Miuchi5, S. Kabuki6, Y. Kishimoto7, S. Kurosawa8

Abstract:

1. Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto, 611-0011, Japan
β. Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Kyoto, 606-850β, Japan
γ. Unit of Synergetic Studies for Space, Kyoto University, Kyoto, Kyoto, 606-850β, Japan
4. Advanced Biomedical Engineering Research Unit, Kyoto University, Kyoto, Kyoto, 606-850β, Japan
5. Department of Physics, Graduate School of Science, Kobe University, Kobe, Hyogo, 657-8501, Japan
6. Department of Radiation Oncology, Tokai University, Isehara, Kanagawa, β59-119γ, Japan
7. Radiation Science Center, KEK, Tsukuba, Ibaraki, γ05-8501, Japan
8. Institute for Materials Research, Tohoku University, Sendai, Miyagi, 980-8577, Japan

A micro pixel chamber (μ-PIC), the development of which started in β000 as a type of a micro pattern gas
detector, has a high gas gain greater than 6000 in stable operation, a large detection area of 900 cmβ, and a fineposition resolution of about 1β0 μm. However, for its development, simulation verification has not been very
useful, because conventional simulations explain only part of the experimental data. On the other hand, some μPIC applications require precise understanding of the fluctuation of the gas avalanche and signal waveform fortheir improvement; therefore, there is a need to update the μ-PIC simulation. Hence, we adopted Garfield++,
which is developed for simulating a microscopic avalanche in an effort to explain experimental data. The
simulated avalanche size was well consistent with the experimental gas gain. Moreover, we calculated a signal
waveform and successfully explained the pulse height and time-over-threshold. These results clearly indicatethat the simulation of μ-PIC applications will improve and that Garfield++ simulation will easily facilitate the μPIC development.

E-mail Address:

takada@cr.scphys.kyoto-u.ac.jp

Site Address:

http://iopscience.iop.org/1748-0ββ1/8/10/C100βγ/

89

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 61, 316, Published: FEB2014

Scintillation Properties of Nd3+-Doped Lu2O3 Ceramics in the Visible and Infrared
Regions
S. Kurosawa1,β, L. An1, A. Yamaji1, A. Suzuki1, Y. Yokotaβ, K. Shirasaki1, Y. Tomoo1, A. Ito1, T. Goto1, G.
Boulonγ, A. Yoshikawa1,β1. Institute for Materials Research (IMR), Tohoku University, β-1-1, Katahira, Aoba-ku, Sendai 980-8577,
Japan
β. New Industry Creation Hatchery Center, Tohoku University, Sendai, Miyagi, 980-8577, Japan
γ. Institute LightMatter (ILM),UMR5γ06 University of Lyon 1-CNRS, University of Lyon, 696ββ
Villeurbanne, France.

Abstract:

Ndγ+-doped LuβOγ (Nd: LuβOγ) is a candidate for an infrared scintillator because (i) LuβOγ has a high density of
9.5 g/cmγ and a high atomic number of 67 and (ii) Ndγ+-doped materials emit in the infrared range and theemission lines from Ndγ+ can be used in medical applications since human body has a transparency window
between 600 and 1,100 nm. However, it is extremely difficult to fabricate Lu βOγ single crystals using
conventional crystal growth methods because of the high melting point (β,510 ° C). Using solid-state reactions,
it is much easier to fabricate LuβOγ into a ceramic structure. Therefore, Nd: LuβOγ transparent ceramics were
fabricated using a spark plasma sintering method. This technique is comparatively simple and consumes lesstime than other methods such as vacuum hot pressing. The scintillation properties and transmittance spectra of
the as-produced ceramics were studied in both the visible and infrared regions. Radioluminescence spectra were
measured in the range 800-1,β00 nm. Ndγ+ emission lines were observed in the transparency window of humanbody. Thus, these ceramic materials could be a candidate for medical imaging applications.

E-mail Address:

kurosawa@imr.tohoku.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/abstractAuthors.jsp?arnumber=6704851

90

OPTICAL MATERIALS 36, 568, Published: DEC2014

Luminescence and scintillation characteristics of Gd3Al2Ga3O12:Ce3+ scintillators
O. Sakthong1, W. Chewpraditkul1, C. Wanarak1, J. Pejchalβ,5, K. Kamadaγ, A. Yoshikawaβ,γ, G. P. Pazzi4, M.
Nikl5

Abstract:

1. Department of Physics, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand
β. Institute for Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
γ. NICHe, Tohoku University 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan
4. Institute of Applied Physics “N.Carrara” of CNR, 50019 Sesto Fiorentino, (Firenze), Italy
5. Institute of Physics, AS CR, Cukrovarnicka 10, Prague 16β5γ, Czech Republic

Cerium-doped GdγAlβGaγO1β single crystals were grown by the Czochralski method with 1 at.% cerium.
Absorption, luminescence and scintillation characteristics were investigated. The light yield and energy
resolution were measured under 66β keV -ray excitation. The characteristic emission band of Ceγ+ 5d–4ftransition peaking around 5β5 nm was observed in the photoluminescence of GdγAlβGaγO1β:Ce. The light yieldof 56,100 ph/MeV and energy resolution of 6.8% were obtained for a 5 × 5 × 1 mmγ Gd γAlβGaγO1β:Ce sample.
The light yield dependence on the sample height and on the shaping time was also studied and compared withLuγAl5O1β:Ce crystal.

E-mail Address:

weerapong.che@kmutt.ac.th

Site Address:

http://www.sciencedirect.com/science/article/pii/S09β5γ4671γ00565X#

91

OPTICAL MATERIALS 36, 769, Published: FEB2014

Perovskite fluoride crystals as light emitting materials in vacuum ultraviolet region
K. Yamanoi1, R. Nishi1, K. Takeda1, Y. Shinzato1, M. Tsuboi1, M. V. Luong1, T. Nakazato1, T. Shimizu1,
N. Sarukura1, M. Cadatal-Radubanβ, M. H. Pham1,γ, H. D. Nguyenγ, S. Kurosawa4, Y. Yokota4, A. Yoshikawa4,
T. Togashi5, M. Nagasono6, T. Ishikawa6

Abstract:

1. Institute of Laser Engineering, Osaka University, β–6 Yamadaoka, Suita, Osaka 565-0871, Japan
β. Centre for Theoretical Chemistry and Physics, Institute of Natural and Mathematical Sciences, Massey
University, Albany, Auckland 06γβ, New Zealandγ. Institute of Physics, Viet Nam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi, Viet Nam
4. Institute for Materials Research, Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577
Japan
5. JASRI/SPring-8, Sayo, Hyogo 679-5148, Japan
6. RIKEN/SPring-8, Sayo, Hyogo 679-5148, Japan

Vacuum-ultraviolet (VUV) fluorescence from KMgFγ and BaLiFγ crystals excited by an extreme ultraviolet freeelectron laser (EUV-FEL) with 61-nm emission wavelength is studied. Cross-luminescence (CL) peaks at 8.5
eV and 7.5 eV, due to an electron from the valence band recombining with a hole in the Fβp core band edge areobserved in KMgFγ. On the other hand, BaLiFγ exhibited a fluorescence peak at 7.75 eV. The band gap energyof BaLiFγ is estimated from its absorption spectrum to be around 8.41 eV. Results suggest the possibility ofdeveloping VUV solid-state devices including light emitting diodes.

E-mail Address:

yamanoi-k@ile.osaka-u.ac.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S09β5γ4671γ006198

92

RADIATION MEASUREMENTS 62, 6, Published: MAR2014

Optical and scintillating properties of Ce:Li(Y,Lu)F4 single crystals
Y. Yokota1, S. Kurosawa1,β, V. Chaniβ, K. Kamada1, A. Yoshikawa1,β1. New Industry Creation Hatchery Center, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 9808579, Japan
β. Institute for Materials Research, Tohoku University, β-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan

Abstract:

We have investigated the optical and scintillating properties of Lu co-doped Ce:LiYF4 single crystals withvarious Lu content. In the transmittance and absorption spectra, the absorption peaks at β4γ nm get
systematically red shifted in contrast to the peaks at 197 and β00 nm which get blue shifted with the increase in
Lu content. At the same time, emission peaks at γ06 nm and β00 nm under β95 nm excitation also get red
shifted. The decay time of Ce:Li(Y,Lu)F4 crystals under β95 nm excitation is found to be faster than that of
Ce:LiYF4 and Ce:LiLuF4 crystals. The alpha-peak positions in the pulse-height spectra and decay times ofcrystals under alpha-ray irradiation are found to vary with the Lu content.

E-mail Address:

yokota@imr.tohoku.ac.jp

Site Address:

http://www.sciencedirect.com/science/article/pii/S1γ5044871γ00γ84γ

93IEEE TRANSACTIONS ON NUCLEAR SCIENCE, 60, 959, Published: APR2013

Temperature Dependence of Neutron-Gamma Discrimination Based on Pulse ShapeDiscrimination Technique in a Ce:LiCaAlF6 Scintillator
K. Watanabe1, Y. Kondo1, A. Yamazaki1, A. Uritani1, T. Iguchi1, N. Kawaguchiβ, K. Fukudaβ, S. Ishiduβ,
T. Yanagidaγ, Y. Fujimotoγ, A. Yoshikawaγ
1. Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-860γ, Japan
β. Tokuyama Corporation, Shunan City, Yamaguchi 745-8648, Japan
γ. Tohoku University, β-1-1 Katahira, Aoba-ku, Sendai 980-081β, Japan

Abstract:

LiCaAlF6 scintillators are one of the attractive scintillators for neutron detection. To reduce the effect on
gamma-rays, the Ce doped LiCaAlF6 scintillators can discriminate the neutron and gamma-ray events based on
the pulse shape discrimination technique. To apply the scintillators for the oil logging, the high temperature
characteristics must be investigated. In this paper, the temperature dependence of the neutron-gamma
discrimination based on pulse shape discrimination technique in the Ce:LiCaAlF 6 scintillator is investigated as
one of the high temperature characteristics. The property of pulse shape discrimination in the Ce:LiCaAlF 6 hassmall temperature dependence ranging from β5°C to 150°C. We concluded that the Ce:LiCaAlF 6 scintillators
can discriminate neutron and gamma-ray events under high temperature condition up to 150°C .

E-mail Address:

k-watanabe@nucl.nagoya-u.ac.jp

Site Address:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=641β759

94EPJ WEB OF CONFERENCES 59, 13011, Published: NOV2013

Multichannel down-scattered neutron detector for areal density measurement
Y. Arikawa1, H. Hosoda1, T. Nagai1, K. Watanabe1, K. Yamanoi1, M. Cadatal-Raduban1, T. Shimizu1, N.
Sarukura1, M. Nakai1, T. Norimatsu1, H. Azechi1, N. Izumiβ, T. Murata1,γ, T. Suyama4, A. Yoshikawa5, K.
Kamada6, Y. Usuki6, N. Satoh7, H. Kan7
1. Institute of Laser Engineering, Osaka University, β-6 Yamadaoka, Suita, Osaka 565-0871, Japan
β. Lawerence Livermore National Laboratory, Livermore, California 94550, USA
γ. Kumamoto University, β-40-1 Kurokami, Kumamoto 860-8555, Japan
4. Tokuyama Corporation, γ–β-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-898γ, Japan
5. Tohoku University, β–1–1 Katahira, Aoyou, Sendai, Miyagi 980–8577, Japan
6. Furukawa Co., Ltd., 1–β5–1γ, Kannondai, Tsukuba, Ibaraki γ05-0856, Japan
7. Hamamatsu Photonics k.k., 18β0, Kurematsu, Nishi-ku, Hamamatsu-City 4γ1-1β0β, Japan

Abstract:

A down-scattered neutron detector operating in the multichannel counting mode was developed for areal density(ρR) measurement. Equipped with a newly developed 6Li glass scintillator (APLF80), the detector was tested ina fusion experiment at the GEKKO XII facility, Osaka University, Osaka, Japan. For a low-ρR fusion shot, thedetector clearly discriminated the -rays, primary neutrons, -rays produced via (n, ) reactions from the target
chamber, and neutrons scattered by the target chamber. Furthermore, the observed signal was in good agreementwith predictions made by Monte Carlo simulation.

E-mail Address:
N/A
Site Address:

http://www.epjconferences.org/articles/epjconf/abs/β01γ/β0/epjconf_ifsaβ011_1γ011/epjconf_ifsaβ011_1γ011.html

95IEEE TRANSACTIONS ON NUCLEAR SCIENCES 60, 988, Published: APR2013

First Performance Results of Ce:GAGG Scintillation Crystals With Silicon
Photomultipliers
J. Y. Yeom1, S. Yamamotoβ, S. E. Derenzoγ, V. Ch. Spanoudaki1,4, K. Kamada5, T. Endo5, C. S. Levin6
1. Molecular Imaging Program at Stanford and Department of Radiology, Stanford University, Stanford, CA
94γ05, USA
β. Department of Radiological and Medical Laboratory Sciences, Nagoya University, Nagoya 461-867γ, Japan
γ. Department of Radiotracer Development and Imaging Technology, Lawrence Berkeley National
Laboratory, Berkeley, CA 947β0, USA
4. Koch Institute for Integrative Cancer Research, MIT, MA 0β1γ9, USA
5. Materials Research Laboratory, Furukawa Co. Ltd., Tsukuba γ05-0856, Japan
6. Departments of Radiology, Physics and Electrical Engineering, Stanford University, Stanford, CA 94γ05,
USA

Abstract:

A new single-crystal Cerium doped GdγAlβGaγO1β (GAGG) scintillation crystal with high luminosity, highdensity and relatively fast decay time has successfully been grown. We report on the first performance results of
the new GAGG scintillation crystal read out with silicon photomultipliers (SiPM) from Hamamatsu (MPPC)
and FBK. The best energy resolution (511 keV peak of Ge-68) of 7.9% was attained with GAGG coupled to
MPPC and 9.0% with the FBK SiPM after correcting for non-linearity. On the other hand, the best coincidence
resolving time (FWHM) of polished γ × γ × 5 mmγ and γ × γ × β0mmγcrystals were 464 ±1β ps and 577 ±ββ psfor GAGG crystals compared to 179 ±8 ps and β14 ±6 ps for LYSO crystals respectively with MPPCs. The risetime of GAGG was measured to be β00 ps (75%) and 6 ns (β5%) while the decay time was 140 ns (9β%), 500
ns (7.7%) 6000 ns (0.γ%).

E-mail Address:
yeomjy@stanford.edu
Site Address:

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=64β8666

96IEEE TRANSACTIONS ON NUCLEAR SCIENCES 60, 4582, Published: APR2013

Development of an Ultrahigh Resolution Block Detector Based on 0.4 mm Pixel
Ce:GAGG Scintillators and a Silicon Photomultiplier Array
S. Yamamoto1, J. Y. Yeomβ,γ, K. Kamada4, T. Endo5, C. S. Levin6
1. Department of Radiological and Medical Laboratory Sciences, Nagoya University, Nagoya 461-867γ, Japan
β. Molecular Imaging Program at Stanford and Department of Radiology, Stanford University, Stanford, CA
94γ05, USA
γ. Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi,
South Korea
4. New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8577, Japan
5. Materials Research Laboratory, Furukawa Co. Ltd., Tsukuba γ05-0856, Japan
6. Departments of Radiology, Physics and Electrical Engineering, Stanford University, Stanford, CA 94γ05,
USA

Abstract:

Ce doped GdγAlβGaγO1β (Ce:GAGG) is a newly developed single-crystal scintillator which has a large light
output and longer emission light wavelength. The longer wavelength of the scintillation photons will produce alarger signal when coupled to typical silicon photomultiplier (Si-PM) as the quantum efficiency ofsemiconductor based photodetector is generally higher for light with longer wavelength. A block detector withhigher spatial resolution may thus be realized by combining Ce:GAGG with Si-PM arrays. To achieve thehighest possible spatial resolution for PET and SPECT detectors, we developed an ultrahigh resolution blockdetector using 0.4 mm × 0.4 mm × 5 mm Ce:GAGG pixels assembled to form a β4 × β4 matrix that is coupled
to an Si-PM array and evaluated the performance. All Ce:GAGG pixels were separated in the β-dimensional
position histograms for Cs-1γ7 (66β keV) gamma photons with an average peak-to-valley (P/V) ratio of β.4.
The energy resolution was β1.6% FWHM for Cs-1γ7 (66β keV) and βγ.8% for Co-57 (1ββ keV) gamma
photons. Since Ce:GAGG does not contain naturally occurring radioisotope (Lu), beta-gamma true coincidences
can be avoided and randoms are reduced when used for PET detectors. Furthermore, this property, together with
its high light output and good intrinsic energy resolution, make the scintillator suited for SPECT detectors. An
ultrahigh resolution PET/SPECT hybrid system might be an interesting application using Ce:GAGG/Si-PM
block detectors.

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

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=66517β5

97IEEE TRANSACTIONS ON NUCLEAR SCIENCES 60, 4582, Published: APR2013

Development of an Ultrahigh Resolution Block Detector Based on 0.4 mm Pixel
Ce:GAGG Scintillators and a Silicon Photomultiplier Array
S. Yamamoto1, J. Y. Yeomβ,γ, K. Kamada4, T. Endo5, C. S. Levin6
1. Department of Radiological and Medical Laboratory Sciences, Nagoya University, Nagoya 461-867γ, Japan
β. Molecular Imaging Program at Stanford and Department of Radiology, Stanford University, Stanford, CA
94γ05, USA
γ. Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi,
South Korea
4. New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8577, Japan
5. Materials Research Laboratory, Furukawa Co. Ltd., Tsukuba γ05-0856, Japan
6. Departments of Radiology, Physics and Electrical Engineering, Stanford University, Stanford, CA 94γ05,
USA

Abstract:

Ce doped GdγAlβGaγO1β (Ce:GAGG) is a newly developed single-crystal scintillator which has a large light
output and longer emission light wavelength. The longer wavelength of the scintillation photons will produce alarger signal when coupled to typical silicon photomultiplier (Si-PM) as the quantum efficiency ofsemiconductor based photodetector is generally higher for light with longer wavelength. A block detector withhigher spatial resolution may thus be realized by combining Ce:GAGG with Si-PM arrays. To achieve thehighest possible spatial resolution for PET and SPECT detectors, we developed an ultrahigh resolution blockdetector using 0.4 mm × 0.4 mm × 5 mm Ce:GAGG pixels assembled to form a β4 × β4 matrix that is coupled
to an Si-PM array and evaluated the performance. All Ce:GAGG pixels were separated in the β-dimensional
position histograms for Cs-1γ7 (66β keV) gamma photons with an average peak-to-valley (P/V) ratio of β.4.
The energy resolution was β1.6% FWHM for Cs-1γ7 (66β keV) and βγ.8% for Co-57 (1ββ keV) gamma
photons. Since Ce:GAGG does not contain naturally occurring radioisotope (Lu), beta-gamma true coincidences
can be avoided and randoms are reduced when used for PET detectors. Furthermore, this property, together with
its high light output and good intrinsic energy resolution, make the scintillator suited for SPECT detectors. An
ultrahigh resolution PET/SPECT hybrid system might be an interesting application using Ce:GAGG/Si-PM
block detectors.

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

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=66517β5

98

99

TV, journal and newspaper items

100

学工業日報
吉川彰 東

年 月
日朝刊
面
大学教授に報公賞

101

電波新聞
年
月
日

102

金

List of events1062013年度 吉川研究室 行事
月 吉川研究室内行事
生 来日
4
新人
チ・
研究室内花見
金研花見大会
5
工学
・開発系プ
見学会

博士

6
来日

学会
T

上

研究会・講演会
学振
委員会

海
T
ワフ
金研

強誘電体応用会議
京都市

学振
委員会
金研・
春季講演会
学内次世代自動車プ
新 学技術推進協会

招待講演

客員教授 6/9-18 3CG
6/24-28 iWoRID2013

客員教授 来日
6/4 Welcome party
参加
7
戸口氏 産休復帰
新 装置の火入れ式・祝賀会
横田 生 准教授昇進祝賀会
金研ビ
参加
武田氏 加入8
長門氏 早坂氏 加入
8/1 Welcom party
歓迎会
9

7/21-25 IEEE-UFFC
プ

学振
学振

委員会
委員会

学振

委員会

学振

委員会

幌

コ
・キ
ワ
ワ
日

協会

秋季
応用物理学会秋季
学術講演会
9/21-29 SSD17

10

開参加
11
博士 来日

キ
9/24-27 SSDM2013
生来日
日 結晶成長学会・取材
成長分科会
片 まつり きん ん一般公上海
10/27-11/2 IEEE
共融会フ サ 大会
T生
日 結晶成長学会

学振委員会
第 回材料科学若手学校

生 来日
－
T
11/8 Pre welcome party
次世代自動車国際
芋煮会
第 回放射線 ニタ
ワ
お疲れ様会 歓迎会および
ョ プ
修論激励会
12
博士および
日 フ
成長学
博士来日
会
両博士歓迎会
物性研究会
忘 会
納会
1
放射線検出器とそ
圧電材料・の応用
次世代自動車のための産学官連携ベ
ョ 成果報告発表会
学術委員会・学術委員会 同委員会
2
修論発表会・修論打ち上
3 ISFM 2013 in Tazawa-ko
応用物理学会春季
学術講演会 相模原

4/11 _ Cherry blossom party

5/23_Jan san promotion / Birth day party)

7/12 _Fire ceremony (30Cz)

7/12 _Yokota Sensei Promotion party

8/1 _Welcome party

8/11-15 _ICCGE-17

9/15_In Kyoto

10/28-29_IEEE (in Korea)

10/11_IMR opening to the public11/8 welcome party

Yoshikawa Sensei Birth day

2/8 Oral presentation of Master thesis

One dayYoshikawa Lab.
Research Report
Published on June 1, 2014

ANNUAL REPORT 2013
編集・発行
東 大学 金属材料研究所
吉川研究室
吉川彰
Edited and published by
A. Yoshikawa
Yoshikawa Laboratory
Institute for Materials Research,
Tohoku University