1. Halide Scintillator Growth & Characterization for Rare Decay Search Presented by Gul Rooh Kyungpook National University Republic of Korea

2. Outline 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 CeBr 3 crystal grown by Bridgman methodCeBr 3 crystal grown by Bridgman method CeBr 3 crystal for 2β +, Kβ + and 2K decay searchCeBr 3 crystal for 2β +, Kβ + and 2K decay search

3. Crystal growing & characterization Kyungpook National Univ. Pukyong National Univ. Dague Health College Application for radiation detector & medical imagingApplication for radiation detector & medical imaging Application for the rare decay experimentApplication for the rare decay experiment 1.Double beta decay 2.Dark matter search

4. Introduction To develop new scintillation detectors Determine optimum crystal growing conditions for Determine optimum crystal growing conditions for the single crystals the single crystals Confirmation of the crystal structures using XRD Confirmation of the crystal structures using XRD Measurement of the emission spectra Measurement of the emission spectra Measurement of the scintillation properties Measurement of the scintillation properties  Pulse height spectra for different radioisotopes  Light yield  Proportionality curve  Energy resolution  Fluorescence decay time  α/β ratio

5. Important properties of an ideal 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 (duration of the scintillation light pulse)Decay time (duration of the scintillation light pulse) Mechanical and optical propertiesMechanical and optical properties Radiation damage hardnessRadiation damage hardness CostCost

6. Crystal growth system by Czochralski Pt BAR & Pt WIRE SEED ALUMINA TUBE WINDOW CRYSTAL R.F. COIL THERMO COUPLE Pt CRUCIBLE FIRE-BRICK OutsideInside

7. Czochralski crystal growth process Weighing Cutting Growing 3 mm/hr 25 rpm in Ar Polishing 10 ⅹ 10 ⅹ 10 mm 3

8. Grown crystals using Czochralski & Bridgman method at KNU PbCl 2 :Eu CsI PbCl 2 CsSrCl 3 CsCl 3 :Ce LaCl 3 :Ce SrCl 2 :Eu Ba x Sr 1-x Cl 2

9. γ-ray spectroscopy system Crystal PMT 400 MHz FADC High Voltage Computer Root Dark Box FADC Pre-Amp Oscilloscope

10. CsCl 3 :Ce with 137 Cs γ- rays By Jinho Moon

11. LaCl 3 :Ce 3+ with 137 Cs γ- rays By Jinho Moon

12. Energy resolution & light yield of the SrCl 2 :Eu 2+ depending on Eu 2+ concentrations By Jinho Moon

13. New Czochralski for Oxide scintillators Today we have new czochralski for bigger crystals and high melting point powders i.e. Oxides.Today we have new czochralski for bigger crystals and 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

14. Bridgman Method

15. CeBr 3 by Bridgman Method Short decay time <20nsShort decay time <20ns Good energy resolution (5% FWHM)Good energy resolution (5% FWHM) By Sejin Ra

16. Relative light yield of CeBr 3 single crystal with Bialkali PMT

17. CeBr 3 for 2β +, Kβ + and 2K decaysearch CeBr 3 for 2β +, Kβ + and 2K decay search 136 Ce has Q-value = 2400keV 136 Ce has Q-value = 2400keV Natural abundance =0.185%Natural abundance =0.185% Exp: calculated half life for 0vExp: calculated half life for 0v  6.9x10 17 yrs (2β + ) (By Bernabei et.al)  3.8x10 16 yrs (Kβ + ) (By Danevich et.al)  6.0x10 15 yrs (2K) (By Danevich et.al) Under investigation for rare decaysearch at Y2L lab.Under investigation for rare decay search at Y2L lab. SrCl 2 (Pure) single crystal for EC/ β + (Presented by J.H.So)SrCl 2 (Pure) single crystal for EC/ β + (Presented by J.H.So)

18. Summary To develop new halide scintillators for nuclear & high energy physics experiments & medical imaging.To develop new halide scintillators for nuclear & high energy physics experiments & medical 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 CeBr 3 crystal scintillation properties and for the study of rare decay searchCeBr 3 crystal scintillation properties and for the study of rare decay search

19. Number of nuclei of Ce in GSO:Ce =4.1 × 10 19 Emission wavelength of CsI:Tl =540nm

20. CeBr3