![SrI2(Eu) crystals anisotropy
CapeSym, Inc. SPIE 2018: Optics + Photonics 25
Canberra 2005 preamplifier, and 2025 AFT research amplifier (coarse gain 20, shaping mode 12us) were used to shape
the signal and send it to Pocket MCA 8000A digitizer from AmpTek. Data analyzed in OriginPro2018
A
B A
B
“Side A”
850 900 950 1000 1050
0.0
5.0x10-1
1.0x100
SubtractedData
Baseline X
Peak Analysis
Fitting Results
BaseLine:Exponential
Adj. R-Square=9.87820E-001 # of Data Points=163
Degrees of Freedom=160SS=1.75327E-001
Chi^2=1.09580E-003
Date:8/14/2018Data Set:[Book1]Sheet1!C
Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP
1 Gaussian 31.40339 31.15829 0.94683 940.80504 100
600 620 640 660 680 700 720
0.0
5.0x10-1
1.0x100
SubtractedData
Baseline X
Peak Analysis
Fitting Results
BaseLine:Exponential
Adj. R-Square=9.98494E-001 # of Data Points=174
Degrees of Freedom=171SS=2.69077E-002
Chi^2=1.57355E-004
Date:8/14/2018Data Set:[Book1]Sheet1!B
Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP
1 Gaussian 20.11298 19.38761 0.97459 661.96755 100
“Side B”
Gaussian fit
2.9%
Same 2.9%
but with
shoulder
“Side A” “Side B”
137Cs
137Cs](https://image.slidesharecdn.com/performanceoptimizationoflargediametersri2eudetectorassemblies-180914213030/85/Performance-optimization-of-large-diameter-SrI-Eu-detector-assemblies-25-320.jpg)
![SrI2(Eu) crystals anisotropy
CapeSym, Inc. SPIE 2018: Optics + Photonics 26
“Side A”
850 900 950 1000 1050
0.0
5.0x10-1
1.0x100
SubtractedData
Baseline X
Peak Analysis
Fitting Results
BaseLine:Exponential
Adj. R-Square=9.87820E-001 # of Data Points=163
Degrees of Freedom=160SS=1.75327E-001
Chi^2=1.09580E-003
Date:8/14/2018Data Set:[Book1]Sheet1!C
Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP
1 Gaussian 31.40339 31.15829 0.94683 940.80504 100
600 620 640 660 680 700 720
0.0
5.0x10-1
1.0x100
SubtractedData
Baseline X
Peak Analysis
Fitting Results
BaseLine:Exponential
Adj. R-Square=9.98494E-001 # of Data Points=174
Degrees of Freedom=171SS=2.69077E-002
Chi^2=1.57355E-004
Date:8/14/2018Data Set:[Book1]Sheet1!B
Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP
1 Gaussian 20.11298 19.38761 0.97459 661.96755 100
“Side B”
High energy shoulder is caused by impurities or crystal
inhomogeneities but not necessarily self absorption.
Gaussian fit
2.9%
Same 2.9%
but with
shoulder
0 20 40 60 80 100 120 140
0
20
40
60
80
100
Absorption(%)
Thickness (mm)
at 662keV
at 1332keV
Gamma attenuation is anisotropic by definition
ScintiClear™ is a new high-performance SrI2(Eu)-based scintillator manufactured using proprietary purification and
crystal growth process that improves its inherently excellent performance.](https://image.slidesharecdn.com/performanceoptimizationoflargediametersri2eudetectorassemblies-180914213030/85/Performance-optimization-of-large-diameter-SrI-Eu-detector-assemblies-26-320.jpg)
Performance optimization of large diameter SrI(Eu) detector assemblies
- 1. Performance optimization of large diameter SrI2(Eu) detector assemblies (manufacturing notes) Ivan Khodyuk, Stacy Swider, Amlan Datta, Maria Hackett, Stephanie Lam, and Shariar Motakef CapeSym, Inc., MA, USA Presented at SPIE Optics + Photonics: Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XX August 20, 2018 at the San Diego Convention Center
- 2. MEETING YOUR NEEDS CapeSym partners with its customers to match the specifications and form factors required for each sensor module. CapeSym company overview CapeSym, Inc. SPIE 2018: Optics + Photonics 2 TEAM CapeSym’s R&D team includes physicists, chemists, electrical engineers, mechanical engineers, and software engineers. BACKGROUND Founded in 1992 as Cape Simulations, CapeSym, Inc. is now a multi-faceted company offering novel technical crystals for nuclear detection, including ScintiClear™ and elpasolite scintillators, and TlBr and CdZnTe semiconductors. FACILITY Our 12,000 sq. ft. facility in Natick, MA, USA
- 3. Outline and definitions CapeSym, Inc. SPIE 2018: Optics + Photonics 3 1- Overview of SrI2(Eu) properties 2- Scintillation detectors design and optimization a) General considerations b) Read-out selection c) Crystal optimization d) Encapsulation e) Signal acquisition Performance – energy resolution Large diameter – 38.1 mm and larger SrI2(Eu) – high performance scintillator material ScintiClear™ – SrI2(Eu)-based scintillator manufactured by CapeSym using proprietary crystal growth and purification methods
- 4. Light Yield 80,000 ph/MeV Energy Resolution @ 662keV ~3% Decay Time 1-3 µs Emission Range 400-480 nm Max Emission 430 nm Density 4.59 g/cm3 Zeffective 50 Intrinsic activity <0.05 Bq/cm3 Moisture Sensitivity Hygroscopic (similar to NaI(Tl)) Refractive Index 1.85 Thermal shock up to 10 ˚C/min SrI2(Eu) was originally proposed as a radiation detector by R. Hofstadter in 1968. In 2008 scientists from Lawrence Livermore National Laboratory (USA) spearheaded the development of SrI2(Eu) into a leading edge radiation detector. SrI2(Eu) high performance scintillator CapeSym, Inc. SPIE 2018: Optics + Photonics 4 Linear attenuation coefficient, 1/cm
- 5. CapeSym, Inc. SPIE 2018: Optics + Photonics 5 • Sr has naturally stable isotopic composition. • Intrinsic activity of SrI2(Eu) is up to forty times smaller compare to LaBr3(Ce). • Sr is the 15th most abundant element on Earth. • Although Strontium Iodide salt becomes corrosive when exposed to air, Strontium is fundamentally non toxic. SrI2(Eu) has low to no internal activity Internal activity spectrum of a standard 1.5” SrI2(Eu) in comparison with LaBr3(Ce), as measured inside a Pb castle with 2 inch thick walls.
- 6. High energy resolution in the entire energy range CapeSym, Inc. SPIE 2018: Optics + Photonics 6 Energy resolution can be as good as 2.8% at 662keV and about 2.2% at 1332keV.
- 7. CapeSym, Inc. SPIE 2018: Optics + Photonics 7 Unambiguous Identification Clear detection of both WGPu (414 keV) and HEU (186 keV) and separation between 214Bi and 137Cs (609 and 662 keV). High energy resolution in the MeV range, and no internal activity.
- 8. How to achieve high scintillation performance? High performance crystal
- 9. How to achieve high scintillation performance? High performance crystal Matching readout
- 10. How to achieve high scintillation performance? High performance crystal Matching readout Appropriate encapsulation
- 11. How to achieve high scintillation performance? High performance crystal Matching readout Appropriate encapsulation Optimized electronics
- 12. How to achieve high scintillation performance? High performance crystal Matching readout Appropriate encapsulation Optimized electronics High performance radiation spectrometer + + + =
- 13. How to achieve high scintillation performance? High performance crystal Matching readout Appropriate encapsulation Optimized electronics High performance radiation spectrometer + + + = Start design here
- 14. Readout selection - PMTs CapeSym, Inc. SPIE 2018: Optics + Photonics 14 Spectral sensitivity and Quantum efficiency Size and form-factor Ø2” Ø3” Ø5” Other shapes are available:
- 15. Readout selection – PMTs (sensitivity and QE) CapeSym, Inc. SPIE 2018: Optics + Photonics 15 0 10000 20000 30000 40000 SrI2_Eu(0,1mol%)_Exc=290nm_T=300K SrI2_Eu(0,1mol%)_Exc=300nm_T=10K SrI2(Eu)emission BA SBA UBA EGBA BA – bialkali SBA – super-bialkali UBA – ultra-bialkali EGBA – extended green bialkali
- 16. Readout selection –PMTs (sensitivity and QE) CapeSym, Inc. SPIE 2018: Optics + Photonics 16 Photochathode Material Curve code Peak QE, nm Typical ER, % at 662keV BA 400K 420 4% SBA 440K 380 3% UBA 441K 400 3% EGBA 444K 420 3% SrI2(Eu) emission max 430nm High quantum efficiency is more important than spectral match! 0 10000 20000 30000 40000 SrI2_Eu(0,1mol%)_Exc=290nm_T=300K SrI2_Eu(0,1mol%)_Exc=300nm_T=10K SrI2(Eu)emission BA SBA UBA EGBA
- 17. Readout selection – PMTs (size and form) CapeSym, Inc. SPIE 2018: Optics + Photonics 17 d46mm d70mm d111mm Ø PMT ≠ Ø Photocathode
- 18. Readout selection – PMTs (photocathode) CapeSym, Inc. SPIE 2018: Optics + Photonics 18 6 255.54 0.95 KEY Channel No. (proportional to LY) Relative Light Yield (normalized to response at position 3)Location # 0 1 2 3 4 5 0 1 2 3 4 5 Y(cm) X (cm) 244.4 249.3 254.2 259.1 264.0 268.9 273.8 278.7 283.6 Channel No.
- 19. Readout selection – PMTs (photocathode) CapeSym, Inc. SPIE 2018: Optics + Photonics 19 6 255.54 0.95 KEY Channel No. (proportional to LY) Relative Light Yield (normalized to response at position 3)Location # 0 1 2 3 4 5 0 1 2 3 4 5 Y(cm) X (cm) 244.4 249.3 254.2 259.1 264.0 268.9 273.8 278.7 283.6 Channel No. 16%
- 20. Readout selection – SiPMs CapeSym, Inc. SPIE 2018: Optics + Photonics 20 J-series C-series 300 350 400 450 500 550 600 0 10000 20000 30000 40000 SrI2_Eu(0,1mol%)_Exc=290nm_T=300K SrI2_Eu(0,1mol%)_Exc=300nm_T=10K 300 350 400 450 500 550 600 0 10000 20000 30000 40000 50000 SrI2_Eu(0,1mol%)_Exc=290nm_T=300K SrI2_Eu(0,1mol%)_Exc=300nm_T=10K emissionspectra 50% 40% Important factors: 1) Photon detection efficiency; 2) Active area vs total area ratio
- 21. Standard readout limitations • PMTs – SBA • SiPMs CapeSym, Inc. SPIE 2018: Optics + Photonics 21 ArrayJ-60035-64P-PCB Very promising, but: 1) Expensive (economy of scale applies) 2) Pad to pad variations 3) Performance deterioration above 40 degC 4) Square + dead space in between Very reliable, but: 1) Economy of scale doesn’t apply 2) Performance variation 3) Bulky and fragile 4) Limited choice 5) Sensitive to magnetic field
- 22. Crystal size vs scintillation performance Let’s compare performance of Ø38.1mm vs Ø46mm, and Ø50.8mm ScintiClear crystals on 2” (R6231-100) and 3” (R6233-100) SBA PMTs. CapeSym, Inc. SPIE 2018: Optics + Photonics 22 ScintiClear diameter, mm R6231-100 – 2” PMT ER at 662keV, % R6233-100 – 3” PMT ER at 662keV, % 38.1 2.9% 3.0% 46.0 2.9% 3.1% 50.8 4.3% 3.1% Insensitive area on the photocathode perimeter is detrimental to ScintiClear scintillation performance. Photocathode sensitive area must be ≥ than crystal front face.
- 23. Surface treatment CapeSym, Inc. SPIE 2018: Optics + Photonics 23 Optically polished surface is important for optimal performance Rough After shaping Additional polishing
- 24. SrI2(Eu) crystals anisotropy CapeSym, Inc. SPIE 2018: Optics + Photonics 24 0 500 1000 0.0 0.5 1.0 1.5 Normcounts MCA channel Æ38.1 x 38.1 mm3 SrI2(Eu) Side A Side B Canberra 2005 preamplifier, and 2025 AFT research amplifier (coarse gain 20, shaping mode 12us) were used to shape the signal and send it to Pocket MCA 8000A digitizer from AmpTek. Data analyzed in OriginPro2018 “Side A” “Side B” A B A B Side B has high energy shoulder! 662keV 137Cs 137Cs
- 25. SrI2(Eu) crystals anisotropy CapeSym, Inc. SPIE 2018: Optics + Photonics 25 Canberra 2005 preamplifier, and 2025 AFT research amplifier (coarse gain 20, shaping mode 12us) were used to shape the signal and send it to Pocket MCA 8000A digitizer from AmpTek. Data analyzed in OriginPro2018 A B A B “Side A” 850 900 950 1000 1050 0.0 5.0x10-1 1.0x100 SubtractedData Baseline X Peak Analysis Fitting Results BaseLine:Exponential Adj. R-Square=9.87820E-001 # of Data Points=163 Degrees of Freedom=160SS=1.75327E-001 Chi^2=1.09580E-003 Date:8/14/2018Data Set:[Book1]Sheet1!C Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP 1 Gaussian 31.40339 31.15829 0.94683 940.80504 100 600 620 640 660 680 700 720 0.0 5.0x10-1 1.0x100 SubtractedData Baseline X Peak Analysis Fitting Results BaseLine:Exponential Adj. R-Square=9.98494E-001 # of Data Points=174 Degrees of Freedom=171SS=2.69077E-002 Chi^2=1.57355E-004 Date:8/14/2018Data Set:[Book1]Sheet1!B Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP 1 Gaussian 20.11298 19.38761 0.97459 661.96755 100 “Side B” Gaussian fit 2.9% Same 2.9% but with shoulder “Side A” “Side B” 137Cs 137Cs
- 26. SrI2(Eu) crystals anisotropy CapeSym, Inc. SPIE 2018: Optics + Photonics 26 “Side A” 850 900 950 1000 1050 0.0 5.0x10-1 1.0x100 SubtractedData Baseline X Peak Analysis Fitting Results BaseLine:Exponential Adj. R-Square=9.87820E-001 # of Data Points=163 Degrees of Freedom=160SS=1.75327E-001 Chi^2=1.09580E-003 Date:8/14/2018Data Set:[Book1]Sheet1!C Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP 1 Gaussian 31.40339 31.15829 0.94683 940.80504 100 600 620 640 660 680 700 720 0.0 5.0x10-1 1.0x100 SubtractedData Baseline X Peak Analysis Fitting Results BaseLine:Exponential Adj. R-Square=9.98494E-001 # of Data Points=174 Degrees of Freedom=171SS=2.69077E-002 Chi^2=1.57355E-004 Date:8/14/2018Data Set:[Book1]Sheet1!B Peak Index Peak Type Area Intg FWHM Max Height Center Grvty Area IntgP 1 Gaussian 20.11298 19.38761 0.97459 661.96755 100 “Side B” High energy shoulder is caused by impurities or crystal inhomogeneities but not necessarily self absorption. Gaussian fit 2.9% Same 2.9% but with shoulder 0 20 40 60 80 100 120 140 0 20 40 60 80 100 Absorption(%) Thickness (mm) at 662keV at 1332keV Gamma attenuation is anisotropic by definition ScintiClear™ is a new high-performance SrI2(Eu)-based scintillator manufactured using proprietary purification and crystal growth process that improves its inherently excellent performance.
- 27. Self-absorption? CapeSym, Inc. SPIE 2018: Optics + Photonics 27 137Cs 101.6mm 50.8mm Length of the crystal versus performance
- 28. Self-absorption? CapeSym, Inc. SPIE 2018: Optics + Photonics 28 137Cs 101.6mm 50.8mm Length of the crystal versus performance Step 1 – Measurement 101.6 mm long crystal 0 500 1000 1500 2000 -200 0 200 400 600 800 1000 1200 1400 1600 Counts MCA channel ScintiClear ER = 3.2% Peak max = 1034 Canberra 2005 preamplifier, and 2025 AFT research amplifier (coarse gain 20, shaping mode 12us) were used to shape the signal and send it to Pocket MCA 8000A digitizer from AmpTek. Data analyzed in OriginPro2018
- 29. Self-absorption? CapeSym, Inc. SPIE 2018: Optics + Photonics 29 137Cs 76.2mm 50.8mm Length of the crystal versus performance Step 2 – Cut the crystal Line of cut 25mm
- 30. Self-absorption? CapeSym, Inc. SPIE 2018: Optics + Photonics 30 137Cs 76.2mm 50.8mm Length of the crystal versus performance Step 3 – Measurement 76.2 mm long crystal 0 500 1000 1500 2000 -200 0 200 400 600 800 1000 1200 1400 1600 Counts MCA channel ScintiClear ER = 3.2% Peak max = 1245 Canberra 2005 preamplifier, and 2025 AFT research amplifier (coarse gain 20, shaping mode 12us) were used to shape the signal and send it to Pocket MCA 8000A digitizer from AmpTek. Data analyzed in OriginPro2018 0 500 1000 1500 2000 0 2000 4000 6000 8000 Counts MCA channel ScintiClear and so on…
- 31. Self-absorption? CapeSym, Inc. SPIE 2018: Optics + Photonics 31 137Cs Length of the crystal versus performance 100 80 60 40 20 3.00 3.05 3.10 3.15 3.20 Energyresolution,% Crystal length, mm ScintiClear 100 80 60 40 20 1000 1050 1100 1150 1200 1250 1300 Peakposition Crystal length, mm ScintiClear Performance is governed by the volume where gamma radiation is absorbed. Self-absorption doesn’t influence energy resolution.
- 32. Effects of encapsulation – Ø25.4mm+ CapeSym, Inc. SPIE 2018: Optics + Photonics 32 Larger size crystals Ø25.4mm and up – minor deterioration -14% Light Output Comparable resolution 0 500 1000 0.0 0.5 1.0 Normalizedcounts MCA channel ScintiClear Æ51x102mm3 Bare Packed Peak = 1002 ER = 3.2% 662keV Peak = 860 ER = 3.2%
- 33. CapeSym, Inc. SPIE 2018: Optics + Photonics 33 Effects of encapsulation – smaller crystals 0 500 1000 1500 0.00 0.05 0.10 0.15 0.20 0.25 0.30 Peak = 1294 ER = 3.1% Normalizedcounts MCA channel ScintiClear 12.7mm cube Bare Packed Peak = 1507 ER = 2.9% Smaller size crystals are more challenging to pack. We always observe performance deterioration for packed crystals. Solution : direct coupling to a readout
- 34. Detector encapsulation CapeSym, Inc. SPIE 2018: Optics + Photonics 34 ScintiClear™ RIID detector cores comply with ANSI N42.34 environmental standards for temperature and thermal shock.
- 35. ScintiClear benefits from long shaping/integration time Standard Spectroscopic Scintillation electronics: 1) Canberra 2005 preamplifier 2) Ortec 672 - 10μs /Canberra 2025 - 12μs 3) MCA CapeSym, Inc. SPIE 2018: Optics + Photonics 35 Shaping and integration time - analog No special signal processing is required to achieve high energy resolution
- 36. Insufficient integration time = poor ER Decay time of ScintiClear crystals is size and shape dependent, and ranges from 1 to 3μs on average. Optimal ER achieved with ~15-25μs digital integration time. ScintiClear benefits from long shaping/integration time Time, us Signal,mV CapeSym, Inc. SPIE 2018: Optics + Photonics 36 Shaping and integration time - digital Other digital DAQ systems:
- 37. Developer’s kit – performance guaranteed CapeSym, Inc. SPIE 2018: Optics + Photonics 37 Key features: • Integrated PMT and DAQ • USB-powered and controlled • Web-browser base GUI • Open source API in Python and C++ • Energy resolution <3.3% at 662keV • -30˚C to +55˚C operation temperature • Digital pulse-shape acquisition capabilities ScintiClear kit – plug and measure Benefits: • Ready to use in 30 minutes • Parameters optimized for ScintiClear • OEM ready
- 38. Thank you for your attention. SPIE 2018: Optics + Photonics