Halide Scintillator Growth & Characterization for Rare Decay Search

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

2. Outline • Crystal growing and characterization • Introduction • Properties of an ideal scintillation crystal • Crystal growth system by Czochralski • γ-ray spectroscopy system • Grown crystals using Czochralski method at KNU • New Czochralski for oxide scintillators • Bridgman Method • CeBr3 crystal grown by Bridgman method • CeBr3 crystal for 2β+, Kβ+ and2Kdecay search

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

4. Introduction • To develop new scintillation detectors • • Determine optimum crystal growing conditions for • the single crystals • • Confirmation of the crystal structures using XRD • • Measurement of the emission spectra • • 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 Light output ->good energy resolution • Decay time (duration of the scintillation light pulse) • Mechanical and optical properties • Radiation damage hardness • Cost

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

7. Growing 3 mm/hr 25 rpm in Ar Weighing 10ⅹ10ⅹ10 mm3 Polishing Cutting Czochralski crystal growth process

8. CsI SrCl2:Eu CsCl3:Ce PbCl2 PbCl2:Eu LaCl3:Ce CsSrCl3 BaxSr1-xCl2 Grown crystals using Czochralski & Bridgman method at KNU

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

10. CsCl3:Cewith 137Cs γ- rays By Jinho Moon

11. LaCl3:Ce3+ with 137Csγ- rays By Jinho Moon

12. Energy resolution & light yield of the SrCl2:Eu2+ depending on Eu2+ concentrations By Jinho Moon

13. New Czochralski for Oxide scintillators 10 times bigger • Today we have new czochralski for bigger crystals and high melting point powders i.e. Oxides. • It is under observation for the temperature controlling.

14. Bridgman Method

15. CeBr3 by Bridgman Method • Short decay time <20ns • Good energy resolution (5% FWHM) By Sejin Ra

16. Relative light yield of CeBr3 single crystal with Bialkali PMT

17. CeBr3 for 2β+,Kβ+ and 2K decaysearch • 136Ce has Q-value = 2400keV • Natural abundance =0.185% • Exp: calculated half life for 0v • 6.9x1017 yrs (2β+) (By Bernabei et.al) • 3.8x1016 yrs (Kβ+ ) (By Danevich et.al) • 6.0x1015 yrs(2K) (By Danevich et.al) • Under investigation for raredecaysearch at Y2L lab. • SrCl2(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. • Crystal growth system by Czochralski • γ-ray spectroscopy system • Some developed crystals by CZ technique at KNU • New CZ for Oxides and bigger crystals growth • Bridgman Method • CeBr3 crystal scintillation properties and for the study of raredecay search

19. Number of nuclei of Ce in GSO:Ce =4.1 × 1019 • Emission wavelength of CsI:Tl =540nm

20. CeBr3