A Study of CsI(Tl) Scintillator with Optimized Condition
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Transcript A Study of CsI(Tl) Scintillator with Optimized Condition
Absolute light output determination of
crystal scintillators
Presented by Min Jeong Kim
Contents
Large Area Avalanche Photodiode
Experimental Setup
APD Optimization Test
CsI(Tl) and newly developed crystal test
Conclusion
Large Area Avalanche photodiode
<Windowless LAAPD>
Model
630-70-73-510
Diameter
16mm
window
Windowless
Enhancement
UV
Gain
130 at 2600 V
Dark current
110 nA
Capacitance
110 pF
The quantum efficiency close to the 80% in the visible and near infrared. (PMT ~20%)
Gain of up to several hundred in the total collected charge is possible.
(Photodiode doesn’t have internal gain)
CsI(Tl) & Experimental setup
property
value
Light output (Photons/MeV)
40000~60000
Density (g/cm3)
4.53
Decay Time (ns)
~1050
Peak Emission (nm)
550
Hygroscopicity
slight
<Properties of CsI(Tl) made by Bicron>
crystal APD
APD
PreAmp
Amplifier
FADC
FADC
25MHz
25MHz
HV
(1800V)
PC
PC
APD optimization test
Energy resolution
from different gain by
changing high
voltage.
The best resolution
is obtained between
1780V and 1820V.
APD optimization test
Energy resolution
from different
shaping time.
The best resolution
is obtained with
3~4μs shaping time.
Energy resolution of CsI(Tl)
662 keV
<HV:1800, gain:20 and shaping time:4us in amplifier>
Energy resolution
(FWHM)
:4.7%
If we use PMT,
energy resolution
is about 7%
Calibration
Ppeak E X ray 1
Yeh
PX ray Eion E
Yeh 1
Yph , APD
RPTFE Q.E
<HV:1800, gain:100 and shaping time:4us in amplifier>
The number of e-h pairs : 37,000 e-h/MeV
The absolute light output : 52,000 ph/MeV
CsI(Tl) from Yangyang
CsI(Tl)_1
CsI(Tl)_2
47,000 ph/MeV
73,000 ph/MeV
SrCl2 crystal test
662 keV
Energy resolution (FWHM) : 9.6%
The number of e-h pair : 14,000 e-h/MeV
The absolute light output : 20,000 ph/MeV
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
Conclusion
The best resolution of CsI(Tl) is obtained with 3~4 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 γ-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.