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Halide ScintillatorHalide Scintillator Growth & Characterization Growth & Characterization
for Rare Decay Searchfor Rare Decay Search
Presented byPresented by
Gul RoohGul Rooh
Kyungpook National UniversityKyungpook National University
Republic of KoreaRepublic of Korea
OutlineOutline
• Crystal growing and characterizationCrystal growing and characterization• IntroductionIntroduction• Properties of an ideal scintillation crystalProperties of an ideal scintillation crystal• Crystal growth system by CzochralskiCrystal growth system by Czochralski• γ-ray spectroscopy systemγ-ray spectroscopy system• Grown crystals using Czochralski method at KNUGrown crystals using Czochralski method at KNU• New Czochralski for oxide scintillatorsNew Czochralski for oxide scintillators• Bridgman MethodBridgman Method• CeBrCeBr33 crystal grown by Bridgman method crystal grown by Bridgman method • CeBrCeBr33 crystal for 2 crystal for 2ββ+, +, KKββ+ + andand 2K2K decay searchdecay search
Crystal growing & characterizationCrystal growing & characterization
Kyungpook National Univ. Kyungpook National Univ.
Pukyong National Univ.Pukyong National Univ.
Dague Health CollegeDague Health College
• Application for radiation detector & medical Application for radiation detector & medical imagingimaging
• Application for the rare decay experimentApplication for the rare decay experiment1.1.Double beta decayDouble beta decay2.2.Dark matter searchDark matter search
IntroductionIntroductionTo develop new scintillation detectors To develop new scintillation detectors • • Determine optimum crystal growing conditions for Determine optimum crystal growing conditions for the single crystalsthe single crystals • • Confirmation of the crystal structures using XRDConfirmation of the crystal structures using XRD • • Measurement of the emission spectraMeasurement of the emission spectra • • Measurement of the scintillation propertiesMeasurement of the scintillation properties
Pulse height spectra for different radioisotopesPulse height spectra for different radioisotopes Light yieldLight yield Proportionality curve Proportionality curve Energy resolution Energy resolution Fluorescence decay timeFluorescence decay time αα//ββ ratio ratio
Important properties of an Important properties of an ideal scintillation crystalideal scintillation crystal
• High Density and atomic number (Z)High Density and atomic number (Z)
• High Light output ->good energy resolutionHigh Light output ->good energy resolution
• Decay time Decay time (duration of the scintillation light pulse)(duration of the scintillation light pulse)
• Mechanical and optical propertiesMechanical and optical properties
• Radiation damage hardnessRadiation damage hardness
• CostCost
Crystal growth system by Crystal growth system by CzochralskiCzochralski
Pt BAR & Pt WIRE
SEED
ALUMINA TUBE
WINDOW
CRYSTAL
R.F. COIL
THERMO COUPLE
Pt CRUCIBLE
FIRE-BRICK
Outside Inside
Czochralski crystal growth Czochralski crystal growth processprocess
WeighingWeighing
CuttingCutting
GrowingGrowing3 mm/hr 25 rpm in Ar3 mm/hr 25 rpm in Ar
PolishingPolishing10 10 10 mmⅹ ⅹ10 10 10 mmⅹ ⅹ 33
Grown crystals using Grown crystals using Czochralski & Bridgman Czochralski & Bridgman
method at KNUmethod at KNU
PbClPbCl22:Eu:Eu
CsICsI PbClPbCl22
CsSrClCsSrCl33
CsClCsCl33:Ce:Ce
LaClLaCl33:Ce:Ce
SrClSrCl22:Eu:Eu
BaBaxxSrSr1-x1-xClCl22
γ-ray spectroscopy γ-ray spectroscopy systemsystem
Crystal PMT
400 MHzFADC
High VoltageComputer
RootRoot Dark BoxDark Box
FADCFADC
Pre-AmpPre-Amp
OscilloscopeOscilloscope
CsClCsCl33:Ce:Ce with with 137137Cs Cs γγ-- rays rays
By Jinho MoonBy Jinho Moon
LaClLaCl33:Ce:Ce3+ 3+ with with 137137CsCs γγ-- rays rays
By Jinho MoonBy Jinho Moon
Energy resolution & light yield of Energy resolution & light yield of the SrClthe SrCl22:Eu:Eu2+2+ depending on Eu depending on Eu2+2+
concentrationsconcentrations
By Jinho Moon By Jinho Moon
0.1 0.2 0.3 0.4 0.5 0.6 0.7
6
8
10
12
14
En
erg
y R
eso
luti
on
( %
)
Concentrations of Eu2+ ( mol% )
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70.0
0.5
1.0
1.5
2.0
Lig
ht
Yie
ld /
Lig
ht
Yie
ld o
f C
sI(T
l)
Concentrations of Eu2+ (mol%)
New Czochralski for Oxide New Czochralski for Oxide scintillatorsscintillators
• Today we have new czochralski for bigger crystals and Today we have new czochralski for bigger crystals and high melting point powders i.e. Oxides.high melting point powders i.e. Oxides.
• It is under observation for the temperature controlling.It is under observation for the temperature controlling.
10 times bigger
Bridgman Method
CeBrCeBr33 by Bridgman Method by Bridgman Method
• Short decay time <20nsShort decay time <20ns• Good energy resolution (5% FWHM)Good energy resolution (5% FWHM)
By Sejin RaBy Sejin Ra
Relative light yield of CeBrRelative light yield of CeBr33 single crystal with Bialkali PMTsingle crystal with Bialkali PMT
CeBrCeBr33 for 2 for 2ββ++,, KKββ+ + and 2K decayand 2K decay searchsearch
• 136136Ce has Q-value = 2400keV Ce has Q-value = 2400keV • Natural abundance =0.185%Natural abundance =0.185%• Exp: calculated half life for 0Exp: calculated half life for 0vv
6.9x106.9x1017 17 yrs (2yrs (2ββ++) ) (By Bernabei e(By Bernabei et.alt.al)) 3.8x103.8x1016 16 yrs (Kyrs (Kββ+ + ) ) (By Danevich e(By Danevich et.alt.al)) 6.0x106.0x1015 15 yrsyrs (2K) (2K) (By Danevich (By Danevich et.alet.al))
• Under investigation for rareUnder investigation for rare decaydecay search at Y2L lab.search at Y2L lab.
• SrClSrCl22(Pure) single crystal for EC/(Pure) single crystal for EC/ββ+ + (Presented by J.H.So)(Presented by J.H.So)
SummarySummary
• To develop new halide scintillators for nuclear & To develop new halide scintillators for nuclear & high energy physics experiments & medical high energy physics experiments & medical imaging.imaging.
• Crystal growth system by CzochralskiCrystal growth system by Czochralski• γ-ray spectroscopy systemγ-ray spectroscopy system• Some developed crystals by CZ technique at KNUSome developed crystals by CZ technique at KNU• New CZ for Oxides and bigger crystals growthNew CZ for Oxides and bigger crystals growth• Bridgman MethodBridgman Method
• CeBrCeBr33 crystal scintillation properties and for the crystal scintillation properties and for the
study of rarestudy of rare decay searchdecay search
• Number of nuclei of Ce in GSO:Ce =4.1 × 1019
• Emission wavelength of CsI:Tl =540nm
CeBr3
200 250 300 350 400 450 500 550
0.0
0.2
0.4
0.6
0.8
1.0
Excitation
em : 235 nm
Emission ex
: 368 nm
Inte
nsit
y (
Arb
.Un
it)
Wavelength (nm)