Absolute light output determination of crystal scintillators

1
Absolute light output determination of crystal
scintillators

• Presented by Min Jeong Kim

2
Contents

• Large Area Avalanche Photodiode
• Experimental Setup
• APD Optimization Test
• CsI(Tl) and newly developed crystal test
• Conclusion

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Large Area Avalanche photodiode
ltWindowless LAAPDgt

• The quantum efficiency close to the 80 in the
  visible and near infra-red. (PMT 20)
• Gain of up to several hundred in the total
  collected charge is possible.
• (Photodiode doesnt have internal gain)

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CsI(Tl) Experimental setup
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APD optimization test

• Energy resolution from different gain by changing
  high voltage.
• The best resolution is obtained between 1780V
  and 1820V.

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APD optimization test

• Energy resolution from different shaping time.
• The best resolution is obtained with 34µs
  shaping time.

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Energy resolution of CsI(Tl)

• Energy resolution (FWHM)
• 4.7
• If we use PMT, energy resolution is about 7

662 keV
ltHV1800, gain20 and shaping time4us in
amplifiergt
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Calibration
ltHV1800, gain100 and shaping time4us in
amplifiergt

• The number of e-h pairs 37,000 e-h/MeV
• The absolute light output 52,000 ph/MeV

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CsI(Tl) from Yangyang
47,000 ph/MeV
73,000 ph/MeV
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SrCl2 crystal test

• Energy resolution (FWHM) 9.6
• The number of e-h pair 14,000 e-h/MeV
• The absolute light output 20,000 ph/MeV

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Ba0.20Sr0.80Cl2 crystal test
662 keV

• Energy resolution (FWHM) 5.4
• The number of e-h pair 16,500 e-h/MeV
• The absolute light output 23,000 ph/MeV

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Conclusion

• The best resolution of CsI(Tl) is obtained with
  34 µs shaping time, and with 1800V high voltage
  of LAAPD.
• We can measure the number of e-h pairs and the
  absolute light yield of scintillation crystals
  with LAAPD.
• The number of e-h pair of CsI(Tl) is obtained to
  be about 37,000 e-h/MeV and the absolute light
  output is obtained to be about 52,000 ph/MeV for
  662 keV 137Cs ?-ray source.
• We estimate the relative light output of newly
  developed SrCl2 crystal to be about 40 of
  CsI(Tl) and Ba0.20Sr0.80Cl2 crystal to be about
  45 of that.
• We measured the absolute light yield of ZnSe(O),
  CeBr3 and other scintillation crystals.