energy resolution of several scintillating crystals using different readout systems
TRANSCRIPT
Energy resolution of several scintillating crystalsusing differents readout systems
Measurements performed during Jul-Sept 2007 at the GSI
Martın Gascon
Particle Physics DepartamentUniversity of Santiago de Compostela
5th. October, 2007
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 1
Contents
Tests performed
1 Energy resolution calibration using 1 cm3 CsI(Tl)
2 Energy resolution of CsI(Na) and BGO using APDs
3 Comparison between APDs and PIN Diodes
4 Energy resolution of LaBr3 using PMTs
5 Energy resolution of LaCl3 using PMTs
6 Non-Uniformities measurements
7 Best values obtained for energy resolution
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 2
1. Energy resolution calibrationusing 1 cm3 CsI(Tl)
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDExperimental setup
The detector is electrically isolated by a grounded Faraday box
The detector and Preamplifier are placed in a metalic box with a humidity control system
The system is temperature monitorized
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDBias Voltage Optimization
Bias Voltage Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.300 937.3 ± 0.3 4.87 ± 0.08 937.1 ± 0.4 4.90 ± 0.08320 1254 ± 0.5 5.12 ± 0.09 1258 ± 0.5 5.16 ± 0.10340 1698 ± 0.7 5.37 ± 0.10 1705 ± 0.6 4.83 ± 0.09360 2357 ± 0.9 5.23 ± 0.09 2366 ± 0.9 4.79 ± 0.09380 3255 ± 1.3 5.14 ± 0.09 3266 ± 1.2 4.75 ± 0.08400 4517 ± 1.8 4.97 ± 0.08 4527 ± 1.6 4.57 ± 0.08420 6211 ± 2.3 4.62 ± 0.08 6222 ± 2.2 4.54 ± 0.08430 7275 ± 2.7 4.74 ± 0.09 7285 ± 2.7 4.71 ± 0.08
Table: Photopeak position vs Bias Voltage
Spectra for each Bias Voltage are taken twice,in order to check stability and to reduceuncertainties
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDBias Voltage Optimization
Not saturated between 300 V and 420 V
There is no minimum in the energy resolution
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDBias Voltage Optimization
Bias Voltage Amp. gain Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.360 135 6307 ± 2.3 4.51 ± 0.08 6304 ± 2.3 4.81 ± 0.09370 113 6330 ± 2.3 4.71 ± 0.08 6332 ± 2.3 4.59 ± 0.08380 96 6330 ± 2.2 4.61 ± 0.08 6326 ± 2.4 4.62 ± 0.08390 81 6335 ± 2.4 4.85 ± 0.09 6340 ± 2.3 4.74 ± 0.08400 69 6296 ± 2.4 4.92 ± 0.09 6302 ± 2.3 4.74 ± 0.09410 59 6333 ± 2.3 4.71 ± 0.09 6333 ± 2.3 4.83 ± 0.09
Table: Photopeak position vs Bias Voltage
Varying Bias Voltage and Amplifier gain to keepconstant the photopeak channel
There is minimum of energy resolution around380 V
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDAmplifier Gain
Linear along the whole dynamic range
the higher the Amplifier gain, the better the energy resolution
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDAcquisition Time
There is a statistical deficit below 40 seconds
60 seconds give us a good energy resolution
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDShaping Time
3 µs and 6 µs are a good trade-off
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDFinal energy resolution
Temp. oC Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.24.3 ± 0.1 6156 ± 2.3 4.96 ± 0.09 6154 ± 2.4 4.87 ± 0.0924.3 ± 0.1 6159 ± 2.4 5.08 ± 0.09 6156 ± 2.4 5.04 ± 0.0924.3 ± 0.1 6159 ± 2.3 4.75 ± 0.09 6152 ± 2.3 4.65 ± 0.0924.3 ± 0.1 6157 ± 2.5 4.97 ± 0.09 6155 ± 2.4 4.93 ± 0.0924.3 ± 0.1 6151 ± 2.3 4.81 ± 0.09 6155 ± 2.4 4.86 ± 0.09
Table: Ten spectra acquired for st = 3µs, t = 50s, HV = 380V and G = 105
Temp. oC Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.24.3 ± 0.1 6220 ± 2.2 4.59 ± 0.08 6221 ± 2.3 4.68 ± 0.0824.3 ± 0.1 6219 ± 2.3 4.74 ± 0.09 6219 ± 2.2 4.68 ± 0.0824.3 ± 0.1 6219 ± 2.2 4.60 ± 0.08 6222 ± 2.2 4.59 ± 0.0824.3 ± 0.1 6220 ± 2.3 4.65 ± 0.08 6221 ± 2.2 4.63 ± 0.0824.3 ± 0.1 6216 ± 2.2 4.55 ± 0.08 6219 ± 2.3 4.73 ± 0.09
Table: Ten spectra acquired for st = 6µs, t = 50s, HV = 380V and G = 96
3 µs: Mean value: 4.89± 0.09 - Best value: 4.65± 0.09
6 µs: Mean value: 4.64± 0.09 - Best value: 4.55± 0.08
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDEnergy resolution vs Energy
1170 keV is part of Comptom edge of 1332 keV of 60Co
The energy resolution is function of the square root of the incident energy photon
We used a 60Co, 137Cs and 152Eu sources
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Energy resolution calibration using 1 cubic cm CsI(Tl) + APDEnergy resolution
The reported energy resolution obtained is 4.55 % is similar to the obtained in”Optimization of energy resolution obtained with CsI(Tl) crystals for the R3BCalorimeter” M. Gascon et al., Submited to IEEE Transactions on NuclearScience.
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Albert Einstein
A theory issomething nobodybelieves, except theperson who made it.An experiment issomething everybodybelieves, except theperson who made it.
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2. Energy resolution ofCsI(Na) and BGO using APDs
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Energy resolution of CsI(Na) and BGO using APDsExperimental setup
Frustum shape crystals (170 mm length)
All are encapsulated into aluminium shielding
9x9 and 15x15 windows (1mm thick) (Face A and B)
Delivered by Scionix Holland.
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Energy resolution of CsI(Na) and BGO using APDsExperimental setup
The detector is electrically isolated by a grounded Faraday box
The detector and Preamplifier are placed in a metalic box with a humidity control system
The system is temperature monitorized
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Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Shaping Time - Face A
between 1 and 3 µs the energy resolution is approximately constant
3 µs requires the lowest amplifier gain
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Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Acquisition Time - Face A
80 seconds is a good trade-off
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Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Amplifier Gain - Face A
Linear along the whole amplifier dynamic range
500 is the situable one
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Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Amplifier Gain - Face A and B
Face B provides more light collection
The higher the light collection, the better the energy resolution
300 is selected for Face B
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Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Acquisition Time - Face A and B
The higher the light collection, the better the energy resolution
80 seconds is a good trade-off
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Energy resolution of CsI(Na) and BGO using APDsBGO - Shaping Time - Face B
between 1 and 2 µs the energy resolution is approximately constant
1 µs requires lower amplifier gain
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Energy resolution of CsI(Na) and BGO using APDsBGO - Amplifier Gain - Face B
Linear along the whole dynamic range
500 is selected, above this value noise is amplified.
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Energy resolution of CsI(Na) and BGO using APDsBGO - Acquisition Time - Face B
60 seconds is a good trade-off
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 25
African Proverb
Not to knowis bad. Not towish to know isworse.
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 26
3. Comparison betweenAPDs and PIN Diodes
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Comparison between APDs and PIN DiodesExperimental setup
Filter + Preamp made by GSI
No chance of varying Bias Voltage
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Comparison between APDs and PIN DiodesAmplifier Gain
Bad energy resolution
PINs Don’t need High Voltage
Faster stabilization
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 29
Comparison between APDs and PIN DiodesAcquisition Time
similar behavior to Hamamatsu
70 seconds is appropriated
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 30
Comparison between APDs and PIN DiodesShaping Time
1 µs and 6 µs are minima
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 31
Comparison between APDs and PIN DiodesExperimental setup
Canberra 2001A Preamplifier
PIN Diode S3590-08 from Hamamatsu
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Comparison between APDs and PIN DiodesBias Voltage
PINs require much lower Bias Voltage
Faster stabilization (stable between 40 V and 80 V)
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Comparison between APDs and PIN DiodesBias Voltage
60 V is selected
Energy resolution is 2 % worse for PIN diode
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Comparison between APDs and PIN DiodesAmplifier Gain
Linear along the whole dynamic range
750 is selected
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 35
Comparison between APDs and PIN DiodesAcquisition Time
Similar behavior to Hamamatsu
60 seconds is adecuated
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Comparison between APDs and PIN DiodesShaping Time
3 µs and 6 µs are good trade off for both
Pin Diode are too noisy, so that they can not resolve energies below 400 keV
Pin Diode has worse energy resolution, but similar trend for energies above 500keV
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4. Energy resolution of LaBr3
using PMTs
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Energy resolution of LaBr3 using PMTsR329 - Experimental setup
Brillance 380 (Saint Gobain)
R329 Hamamatsu PMT
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Energy resolution of LaBr3 using PMTsR329 - Bias Voltage
Last point is out of the curve
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Energy resolution of LaBr3 using PMTsR329 - Bias Voltage
Varying Bias Voltage and Amplifier gain to keep constant the photopeak channel
1050 V is selected
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Energy resolution of LaBr3 using PMTsR329 - Amplifier Gain
Not linear for gain higher than 40
36 is selected
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Energy resolution of LaBr3 using PMTsR329 - Acquisition Time
120 seconds is selected
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Energy resolution of LaBr3 using PMTsR329 - Shaping Time
1 µs and 2 µs are good trade off
after 2 µs saturates
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Energy resolution of LaBr3 using PMTsXP1918 - Experimental setup
Brillance 380 (Saint Gobain)
XP1918 Photonis
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Energy resolution of LaBr3 using PMTsXP1918 - Bias Voltage
After 1100 V is saturated
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 46
Energy resolution of LaBr3 using PMTsXP1918 - Amplifier Gain
Not linear from 40
36 is adecuated
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Energy resolution of LaBr3 using PMTsXP1918 - Acquisition Time
80 seconds is selected
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Energy resolution of LaBr3 using PMTsXP1918 - Shaping Time
1 or 2 µs are selected
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Energy resolution of LaBr3 using PMTsXP1918 - Energy resolution
4.11 % is the lowest energy resolution without saturation.
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Energy resolution of LaBr3 using PMTsXP1918 - Energy resolution
The presented by Saint Gobain resolutions could be saturated
The relation between Photopeak channel/Compton is higher
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5. Energy resolution of LaCl3using PMTs
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Energy resolution of LaCl3 using PMTsExperimental setup
R329 PMT from Hamamatsu
Brillance 350 - 10 cm LaCl3 (1 and 2 windows)
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Energy resolution of LaCl3 using PMTsR329 - Bias Voltage
After 1200 V is saturated
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Energy resolution of LaCl3 using PMTsR329 - Bias Voltage
Varying the gain and Bias Voltage
1050 V is adecuated
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Energy resolution of LaCl3 using PMTsR329 - Amplifier Gain
linear
40 is selected
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 56
Energy resolution of LaCl3 using PMTsR329 - Acquisition Time
120 seconds is selected
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Energy resolution of LaCl3 using PMTsR329 - Shaping Time
1 or 2 µs are selected
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Energy resolution of LaCl3 using PMTsR329 - Amplifier Gain
Covering the window with aluminized mylar
linear
60 is selected
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Energy resolution of LaCl3 using PMTsR329 -Energy resolution
5.78 % is the best energy resolution achieved.
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6. Non-Uniformities measurements
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Non-Uniformities measurementsExperimental setup
To collimate the source, we use Lead blocks of 5 cm length
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Non-Uniformities measurementsNon-Uniformity definitions
Non Uniformity in the Ligth Output
is one of the factors worsening the energy resolution
at least, 2 methods are used to define it: G and δ
Definition of G
G =LOmax − LOmin
LOmed(1)
Definition of δ
LOLOmed
= 1 + δ(x − xmed
xmed) (2)
Notes
δ-value is independent of the number of measuring points, but G does not
infinite number of measuring points means G = 2 · δExample:
For a 10 cm lenght crystal, if we measure 9 points every 1 cm, we get:G = 1.6 · δ
(1) D.M. Beylin, et al., Nucl. Inst. and Meth., vol. A541, pp 501-515, 2005.(2) G. Ren, X et al.,Nucl. Inst. and Meth., vol. A564, pp 364-369, 2006.
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 63
Non-Uniformities measurementsNon-Uniformity definitions
Non Uniformity in the Ligth Output
is one of the factors worsening the energy resolution
at least, 2 methods are used to define it: G and δ
Definition of G
G =LOmax − LOmin
LOmed(1)
Definition of δ
LOLOmed
= 1 + δ(x − xmed
xmed) (2)
Notes
δ-value is independent of the number of measuring points, but G does not
infinite number of measuring points means G = 2 · δExample:
For a 10 cm lenght crystal, if we measure 9 points every 1 cm, we get:G = 1.6 · δ
(1) D.M. Beylin, et al., Nucl. Inst. and Meth., vol. A541, pp 501-515, 2005.(2) G. Ren, X et al.,Nucl. Inst. and Meth., vol. A564, pp 364-369, 2006.
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 63
Non-Uniformities measurements10 cm CsI(Tl) + APD + PMT
Spectra were taken using Cs-137 and Co-60 sources
Fitting the photopeak channel from the 1332 MeV gamma of a Co-60 source
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Non-Uniformities measurements10 cm CsI(Tl) + APD + PMT
G = 16.7 %; δ = 9.28% for 10 cm CsI(Tl) + HAMA
G = 9.6 %; δ = 5.33% for 10 cm CsI(Tl) + XP1918
Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 65
Non-Uniformities measurements10 cm CsI(Tl) + APD + PMT
Increasing the PMT gain and plotting as a function of distance to APD
Using a 1332 keV of Cobaltum 60 source (5 min/point)
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Non-Uniformities measurements10 cm CsI(Tl) + APD + PMT
Doing the sum of the photopeak channel for both
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Non-Uniformities measurementsCsI(Na) - Non Uniformity in light collection - Face B
Collimated source of 60Co by 5 cm of Lead
Face A produced few light to perform this test
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7. Best values obtainedfor energy resolution
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Best values obtained for energy resolutionEnergy resolution
Crystal lenght Readout Premplifiera Shaping Bias Volt. Energy Resolutionb
CsI(Tl) 1 cm APDc Canb. 2001 6 µs e-m 4.50%
CsI(Tl) 1 cm Pin GSI-Preamp 6 µs - 18.7%
CsI(Tl) 1 cm Pin Canb. 2001 6 µs e-m 6.45%
CsI(Tl) 10 cm APD Canb. 2001 6 µs e-m 5.36%
LaBr3 3 cm R329 - 2 µs Wenzel 4.54%
LaBr3 3 cm XP1918 - 2 µs Wenzel 4.11%
CsI(Na) 17 cm APD Canb. 2001 3 µs e-m 17.1%
BGO 17 cm APD Canb. 2001 1 µs e-m 23.7%
LaCl3 10 cm R329 - 1 µs Wenzel 5.70%
LaCl3 (2w) 10 cm R329 - 1 µs Wenzel 8.35%
aThe Amplifier used was Ortec 572bEnergy Resolution for the 662 keV photon of a Cs-137 sourcecAPD is S8664-1010 from Hamamatsu
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Conclusions
The calibration showed that the energy resolution value of 4.5 % is repeated with different electronicchains
The enery resolution of CsI(Na) and BGO are bad because its bad quality
The used window for the frustum like crystals produced an energy resolution worsening
There is difference of aproximately 4 % in the energy resolution between Face A and B in frustum likecrystals
The Filter and Preamplifier made by GSI for Pin Diodes don’t offer an energy resolution comparable toCanberra Preamplifier
Pin Diodes don’t need High Voltage, are stable between 40 and 80 V, have an energy resolution of 6.5% for 662 keV photons
Pin Diodes has worse energy resolution for low shaping times and for incident energies below 400 keVthan APDs.
LaBr3 produces so many light in a so short time that saturates common PMT working at tipical voltagevalues
Working at linear gain, the best energy resolution obtained for LaBr3 was 4.11 % for XP1918 PMT fromPhotonis
The best energy resolution for LaCl3 was 5.78 % for the R329 PMT from Hamamatsu
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Bibliography
Technical Proposal for the Design, Construction, Commissioning and Operation of R3B.http://www-land.gsi.de/r3b/
H. Alvarez−Pol et al. A first proposal for the geometry of the Total Absorption Calorimeterdesign at R3B. Internal Note: R3B CAL 01/05. http://www.usc.es/genp/
C.W.E. van Eijk, P. Dorenbos, E.V.D. van Loef, K. Kramer, H. Gudel ”Energy resolution ofsome new inorganic-scintillator in gamma-ray detectors” Radiation Measurements, vol. 33, pp521-525, 2001.
Hamamatsu Photonics: Photomultiplier Tubes and Related Products
D.M. Beylin, A.I. Korchagin, A.S. Kuzmin, L.M. Kurdadze, S.B. Oreshkin, S.E. Petrov, B.A.Shwartz, ”Study of the radiation hardness of CsI(Tl) scintillation crystals,”Nucl. Inst. and Meth., vol. A541, pp 501-515, 2005.
G. Ren, X. Chen, S. Lu, Z.Li, X. Xue, D. Shen, ”Non-uniformity of light output in large-sizedCsI(Tl) crystals grown by non-vacuum Bridgman method”,Nucl. Inst. and Meth., vol. A564, pp 364-369, 2006.
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