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Scintillator Studies

Scintillator Studies. Andrea Wilms Ruhr-Universität Bochum. CsI(Tl) measurements with different readouts CeF 3 measurements with PMT readout Tests of PbWO 4 with PMT readout Irradiation tests BGO tests with different readouts Timing studies Matthias Steinke

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Scintillator Studies

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  1. Scintillator Studies Andrea Wilms Ruhr-Universität Bochum Andrea Wilms

  2. CsI(Tl) measurements with different readouts CeF3 measurements with PMT readout Tests of PbWO4 with PMT readout Irradiation tests BGO tests with different readouts Timing studies Matthias Steinke Conclusion and Outlook Overview Andrea Wilms

  3. CsI(Tl): Standard, high LY, slow CeF3: fast & high LY PWO: fast & compact BGO: compact & high LY, slower Available crystals Andrea Wilms

  4. 60 mm 60 mm 50 mm 50 mm CsI(Tl) measurements 137Cs @ T = 0 °C APD (Hamamatsu) readout active area: (5 x 5) mm2 PMT ( R1635 ) readout active area: Ø 10 mm 662 keV Entries Entries 662 keV ADC channel ADC channel Andrea Wilms

  5. CeF3 measurements (1) Readout: PMT @ T = RT 137Cs Entries 662 keV ADC channel Andrea Wilms

  6. BGO CsI(Tl) PWO CeF3 CeF3 measurements (2) Readout with APD: not possible because of wavelength of emission peak Andrea Wilms

  7. Available xtals: PWO (first generation) Length 15 cm, not tapered PWO II Russia Length 12 cm, tapered PWO China Length 12 cm, tapered PWO Andrea Wilms

  8. PWO measurements (1) Noise spectra at different temperatures (Readout with PMT) T = 21.5 °C T = 0 °C Entries Entries self -activity self -activity ADC channel ADC channel to increase LY: PWO should be cooled to 0 °C Andrea Wilms

  9. PWO measurements (2) Readout: PMT @ T = 0 °C 137Cs (BG subtracted ) Entries 662 keV ADC channel Andrea Wilms

  10. PWO measurements (3) Light yield measurements • Comparison between LY of PWO and CsI(Tl): • usage of 60Co source @ T = RT • readout with PMT measured value: LY( CsI(Tl) ) / LY( PWO ) ≈ 43 PDG value: 40 Andrea Wilms

  11. PWO II : Russian crystal (1) Readout: PMT @ T = 0 °C 137Cs 662 keV Entries ADC channel Andrea Wilms

  12. PWO II : Russian crystal (2) Readout: PMT @ T = 0 °C Andrea Wilms

  13. PWO : Chinese crystal (1) Readout: PMT @ T = 0 °C 137Cs 662 keV Entries ADC channel Andrea Wilms

  14. PWO : Chinese crystal (2) Readout: PMT @ T = 0 °C Andrea Wilms

  15. Comparison of PWO types Readout: PMT @ T = 0 °C • „New generation“ of PWO: • increase of energy resolution • increase of S / N Effect of tapering??? Andrea Wilms

  16. Irradiation @ COSY (1) positioning of the crystals @ YESSICA @ COSY Andrea Wilms

  17. Irradiation @ COSY (2) • Irradiation @YESSICA: • pulsed beam • proton energy: 2.1 GeV • 108 protons / s • irradiation time: 15 min • integrated rate for one irradiation: 1011 protons • dose for each crystal: 200 – 300 rad 1 hour after excitation: activity of each crystal: ~ 20 kBq • storage of the crystals @ COSY after 2 days: no residual activity • measurements of LY: 1 week after irradiation Andrea Wilms

  18. Irradiation results (1) Readout: PWO#2 PMT R2059 @ T = 0 °C 1250 keV 60Co Entries Entries 1250 keV channel: 77 channel: 410 ADC channel ADC channel LY decreased by a factor of ~ 5 Andrea Wilms

  19. Irradiation results (2) Readout: PWO#4 PMT R2059 @ T = 0 °C 1250 keV 60Co Entries Entries 1250 keV channel: 79 channel: 335 ADC channel ADC channel LY decreased by a factor of ~ 4 Andrea Wilms

  20. Irradiation results (3) Readout: PWO/Russia PMT R2059 @ T = 0 °C 1250 keV 60Co 1250 keV Entries Entries channel: 78 channel: 320 ADC channel ADC channel LY decreased by a factor of ~ 4 Andrea Wilms

  21. Irradiation results (4) Readout: PWO/China PMT R2059 @ T = 0 °C 1250 keV 60Co Entries Entries channel: 97 1250 keV channel: 465 ADC channel ADC channel LY decreased by a factor of ~ 5 Andrea Wilms

  22. Inorganic scintillators Andrea Wilms

  23. Why BGO : Similar radiation length as PWO LY x 15 Decay time: 300 ns Borrowed from L3: Length: 23 cm, tapered BGO Andrea Wilms

  24. BGO: PMT-readout (1) Readout: PMT @ T = RT 137Cs Entries 662 keV ADC channel Andrea Wilms

  25. BGO: PMT-readout (2) Readout: PMT @ T = RT Andrea Wilms

  26. BGO: APD-readout (1) Readout: APD @ T = RT 60Co 137Cs Entries Entries 662 keV 1250 keV ADC channel ADC channel Andrea Wilms

  27. BGO: APD-readout (2) Readout: APD @ T = RT 22Na • How can S / N be increased ? • Decrease temperature : Increase LY! • Increase UB : Increase APD internal gain! Entries 1275 keV ADC channel Andrea Wilms

  28. BGO measurements Readout: APD @ T = 0 °C and UB = 374 V Readout: PMT R1635 @ T = 0 °C 22Na 22Na Entries Entries 511 keV 25 mm 25 mm 511 keV 25 mm 25 mm 1275 keV 1275 keV ADC channel ADC channel Andrea Wilms

  29. Summary & Outlook: PWO • Test with radioactive sources: • large crystals: PWO II has improved energy resolution, • but still: • LY too low for APD readout • new crystals later this year • contact Hamamatsu for larger APDs • next step: tests with small PWO crystals (1 cm3) • First irradiation tests: • 200 - 300 rad from protons: decrease of LY by factor 4 - 5 • question for simulation: • expected dose from protons @ experiment? • irradiation tests with π, γ and e- ? Andrea Wilms

  30. Summary & Outlook: BGO • Tests with radioactive sources: • readout with APDs ok • contact Hamamatsu for larger APDs • More to do: • check availability of BGO • timing studies  Matthias Steinke • Irradiation tests Andrea Wilms

  31. Lots of work ahead !! Future activities for EMC Rainer Novotny to be continued… Outlook Andrea Wilms

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