Skip to main content
Main Menu
  • Products
    Back
    Products
    • Radiation Detection Products
      Back
      Radiation Detection Products
      • Crystal Scintillators
        Back
        Crystal Scintillators
        • Crystal Scintillation Materials
          Back
          Crystal Scintillation Materials
          • Standard Detector Assemblies
          • DUAL Gamma Neutron Detection
          • Pixellated Arrays
          • Nuclear Imaging
          • Rugged Extreme Environment
          • SiPM Integrated Detectors
        • Standard Design Product List
        • Electronics
          Back
          Electronics
          • Plug-on Bases
          • Sensor Kit (Detector with MCA)
        • Organic Scintillators
          Back
          Organic Scintillators
          • Organic Scintillation Materials
            Back
            Organic Scintillation Materials
            • Cast Sheet and Detectors
            • Cells for Liquid Scintillators
            • Scintillating Fiber
            • Extended Life Plastic
            • Neutron Detection NeuPort NeuTruck
            • Fast or Thermal Neutron Detectors
            • Plastic Optical Components
            • Assembly Materials
          • Efficiency Calculator
          • Materials Selector
        • Photonic Products
          Back
          Photonic Products
          • SYNTHETIC SAPPHIRE
            Back
            SYNTHETIC SAPPHIRE
            • Sapphire Materials
            • Large Sapphire Windows
            • Tubes & Rods
            • Bonding for Complex Shapes
            • Curved Sapphire
            • Protective Transparent Window
          • X-RAY MONOCHROMATORS
          • GARNET SUBSTRATES
      • Application
        Back
        Application
        • Portable Detection
        • Nuclear Research
        • Imaging
      • Markets
        Back
        Markets
        • MEDICAL
          Back
          MEDICAL
          • PET
          • SPECT
          • Blood Measurement & other applications
          • Bone Mineral Densitometry
          • Sapphire for Intraoperative Imaging
        • SECURITY
          Back
          SECURITY
          • First Responders
          • Border Inspection
          • Baggage Scanners
        • PHYSICS
        • OIL & GAS
          Back
          OIL & GAS
          • Wireline
          • MWD & LWD
          • Aerial Survey
          • Surface Measurements
        • INDUSTRIAL-RADIATION
          Back
          INDUSTRIAL-RADIATION
          • Environmental Monitoring
          • Health Physics
          • Nuclear Fuel & Safeguards
          • Scrap Steel Monitoring
          • Process Monitoring and Gauging
        • PROTECTION & AEROSPACE
          Back
          PROTECTION & AEROSPACE
          • Transparent Protective Window
          • Infra-Red Countermeasures
          • Optical Vision System
        • INDUSTRIAL-SPECIALTY MATERIALS
          Back
          INDUSTRIAL-SPECIALTY MATERIALS
          • Semiconductor Manufacturing
          • Microwave - RF
          • Excimer Laser
          • Optical Isolator Wafers
          • X-Ray elemental analysis
      • Contact Us
        Back
        Contact Us
        • Contact & Site Locator
        • Request a Contact
        • Request a quote
      • Media Center
        Back
        Media Center
        • Resource library
        • News & Events
      • FAQs
      world SAINT-GOBAIN
      Logo Saint-Gobain Crystals
      • Products
        • Radiation Detection Products
          • Crystal Scintillators
            • Crystal Scintillation Materials
            • Standard Detector Assemblies
            • DUAL Gamma Neutron Detection
            • Pixellated Arrays
            • Nuclear Imaging
            • Rugged Extreme Environment
            • SiPM Integrated Detectors
          • Standard Design Product List
          • Electronics
            • Plug-on Bases
            • Sensor Kit (Detector with MCA)
          • Organic Scintillators
            • Organic Scintillation Materials
            • Cast Sheet and Detectors
            • Cells for Liquid Scintillators
            • Scintillating Fiber
            • Extended Life Plastic
            • Neutron Detection NeuPort NeuTruck
            • Fast or Thermal Neutron Detectors
            • Plastic Optical Components
            • Assembly Materials
          • Efficiency Calculator
          • Materials Selector
        • Photonic Products
          • SYNTHETIC SAPPHIRE
            • Sapphire Materials
            • Large Sapphire Windows
            • Tubes & Rods
            • Bonding for Complex Shapes
            • Curved Sapphire
            • Protective Transparent Window
          • X-RAY MONOCHROMATORS
          • GARNET SUBSTRATES
      • Application
        • Portable Detection
        • Nuclear Research
        • Imaging
      • Markets
        • MEDICAL
          • PET
          • SPECT
          • Blood Measurement & other applications
          • Bone Mineral Densitometry
          • Sapphire for Intraoperative Imaging
        • SECURITY
          • First Responders
          • Border Inspection
          • Baggage Scanners
        • PHYSICS
        • OIL & GAS
          • Wireline
          • MWD & LWD
          • Aerial Survey
          • Surface Measurements
        • INDUSTRIAL-RADIATION
          • Environmental Monitoring
          • Health Physics
          • Nuclear Fuel & Safeguards
          • Scrap Steel Monitoring
          • Process Monitoring and Gauging
        • PROTECTION & AEROSPACE
          • Transparent Protective Window
          • Infra-Red Countermeasures
          • Optical Vision System
        • INDUSTRIAL-SPECIALTY MATERIALS
          • Semiconductor Manufacturing
          • Microwave - RF
          • Excimer Laser
          • Optical Isolator Wafers
          • X-Ray elemental analysis
      • Contact Us
        • Contact & Site Locator
        • Request a Contact
        • Request a quote
      • Media Center
        • Resource library
        • News & Events
      • FAQs

      You are here

      1. Home
      2. Products
      3. Radiation Detection
      4. Crystal Scintillation
      5. Pixellated Arrays

      Pixellated Arrays

      Offering pixellated array assemblies that include crystals such as CdW04, CsI(Tl), BGO, and LYSO or other materials such as scintillating plastic. Saint-Gobain can also produce crystal arrays made from other materials not grown by Saint-Gobain.  We offer a variety of design options and reflector materials to optimize array performance for your application. Our manufacturing process ensures high light output as well as excellent pixel to pixel uniformity with minimal crosstalk.

      The type of material depends on the application, and the information being sought.

      Applications Well-suited for Scintillation Array Materials
      Material CsI(TL) CdWO4 BGO LYSO
      Gamma Cameras X      
      CT Imaging X X    
      Positron Emission Tomography X   X X
      Line Scanning X X    
      Industrial Imaging X X X  
      Flash Radiography     X X
      Digital Radiography X   X  

       

      The optimal material choice involves a combination of factors including the application, the photo readout device to be used, etc. For example, if the application calls for rapid detection of radiation pulses, then the decay time and afterglow drive the choice (BGO, LYSO, CdWO4). If high efficiency and low cost are paramount, then NaI(Tl) with a PMT readout or CsI(Tl) with a photodiode readout are the first detectors to consider. The physical properties of each material must be considered as well. For example, the natural cleavage plane in CdWO4 restricts the minimum size of 2D pixels. Saint-Gobain’s technical experts can help guide your decision. Talk to us about your application or request a quotation.

       

      Features/Benefits

      • Minimal pixel separation
      • Reduced optical crosstalk
      • Excellent pixel to pixel uniformity
      • Array to array (batch to batch) uniformity.
      • Offers a fully integrated design with several choices of readout devices including photodiodes, PSPMTs, or SiPMs, or any customer-supplied devices.   
       

      Design Options

      There are many design options in terms of pixel size, the number of pixels, pixel separator materials (reflective and/or radiation barrier) and crystal surface finishes.

      Linear Array Assemblies (single row of pixels) – Linear array assemblies are typically used with pixelated photodiodes and used quite often in security type applications, most common are baggage scanners, cargo inspection, and other non-destructive testing.   When used in a medical application, crystals such as LYSO are used in Bone Mineral Densitometry machines.

      2D Array Assemblies (pixels arranged in an X-Y matrix) – 2D arrays are typically used with pixelated photodiodes, position-sensitive photomultiplier tubes (PSPMT) and silicon photomultipliers (SiPM) and most common use is in medical imaging scanners (PET, SPECT, CT), and non-destructive testing and inspection.

       

      Properties of Materials used in Arrays

      Material

      CsI(Tl)

      CdWO4

      BGO

      LYSO

      Density, g/cm3 4.51 8.0 7.13 7.10
      Solubility in H2O, g/100g@25oC 85.5 0.5 – –
      Hygroscopic slightly no no no
      Relative Light Output [photons/keV] 54 13 9 32
      Relative Rad Hardness Medium High High High
      Wavelength of Maximum Emission [nm] 550 475 480 420
      Primary Decay Time 1μs 14μs 300μs 41μs
      Afterglow 0.5-5% @6ms 0.1% @3ms 0.005% @3ms <0.1% @6ms

      CdWO4 high light output and low afterglow make it ideal for use with silicon photodiodes in detectors for medical and industrial CT scanners. CdWO4 has very good radiation resistance, and its temperature dependence is small in the 0 to 60oC range. Its high density makes it a good choice for 300+ keV imaging for container and vehicle scanning.

      CsI(Tl) has the highest light output of these scintillators, and its emission matches well with silicon photodiodes. However, its long afterglow limits its use to applications for which intervals between sampling are long or some residual signal can be tolerated. CsI(Tl) is a rugged, malleable material that can be easily fabricated into a variety of geometries. It is slightly hygroscopic but is packaged in a manner to minimize exposure to moisture. CsI(Tl) is regularly fabricated into both linear and 2-dimensional (2D) arrays with pixel sizes as small as 500 microns square.

      LYSO is a Cerium doped lutetium based scintillation crystal that offers high density and a short decay time. It has an improved light output and energy resolution compared to BGO, which has a similar density. Applications that require higher throughput, better timing and better energy resolution will benefit from using LYSO material.

      Saint-Gobain Crystals fabricates arrays from a variety of other scintillation materials including BGO and ceramics.

      Array Design Parameters

      There are choices of scintillator materials and separator / reflectors to optimize performance to a specific application. The listing of parameters addresses the elements that must be considered in the design of a linear or 2D array.

      The table below shows the materials and the associated pixel sizes that are regularly produced today. The pixel sizes are controlled primarily by mechanical properties of the crystals, e.g. hardness, cleavage, ease of machining. For example, CdWO4 has a cleavage plane in one crystallographic direction. For that reason, it is not possible, with current techniques, to achieve 0.3 x 0.3 mm2 pixels because of fractures along the cleavage planes that occur during cutting and grinding in manufacture. However, 0.3 x 1.0 mm2 pixels can be produced.

       

      Design Parameters

       

      • Material: Type of scintillation crystal or material desired.
      • Pixel or Element Size: The “X” and “Y” dimensions of each scintillator pixel.
      • Separator Type and Thickness: The type of reflector between the crystal pixels and its overall thickness, “Gap X(A)” or “Gap Y(B)”.  Note: this may be a composite or laminate of white reflector and metal materials. The geometry of the pixel, the thickness of the reflector, the scintillator material used and other factors influence the reflectivity obtained in each array design. Array reflector materials are listed in the order of decreasing reflectivity.
      • Pitch: This is the distance between the center of one element to the center of an adjacent element, “X” + “Gap X(A)” or “Y” + “Gap Y(B)” Note: In 2D arrays with rectangular pixels, the pitches in the “X” and “Y” directions will be different.
      • Radiation Thickness: This is the “Z” dimension and specifies the thickness of the array in the direction of the incoming radiation.
      • Back Reflector Thickness: Usually a white reflector is applied to the radiation entrance side of the array to reflect the light back into the pixel so it can be directed to the light sensor.
      • Material adjacent to the end pixels or elements: The end crystals may need a special reflector thickness or other treatment, e.g., to keep a constant pitch from array to array if they will be joined together in use.

       

       

      1D and 2D Configurations

       

       

      Minimum Discrete Pixel Sizes Available
      in Crystal Scintillators
      Material Minimum Pixel Sizes * Comments
      Linear (mm) 2D (mm)
      CsI(Tl) 0.3 0.5  
      CdWO4 0.3 1.0 Cleavage Plane
      BGO 0.3 0.3  
      LYSO 0.8 0.8 Min. Untested
      * Guidelines, not hard numbers
      Separator Types and Thicknesses in Order of Decreasing Reflectivity
      Material Thickness Range Approximate Relative
      Reflectivity *
      White Powder (e.g. TiO2, MgO) ** 0.25 mm and up 100%
      Teflon Sheet ** 0.15 mm - 0.50 mm 98%
      White Reflector Paint 0.04 mm - 0.10 mm 96%
      White Plastic 0.05 mm and up 95%
      White Epoxy 0.10 mm - 0.75 mm 94%
      Composites *** 0.10 mm and up 94%
      Aluminum/Epoxy 0.05 mm - 0-.1 mm 75%
      Metals (Pb, Ta) / Epoxy 0.05 mm and up 65%
      * These are guidelines only and are based on optimum, not minimum, thickness.
         Values will vary with pixel geometry, surface finish and other specific design parameters.
      ** These are used as reflector materials in large scintillation crystal packaging.
      *** Composite separators are clear epoxy-paint-clear epoxy, white epoxy- metal-white epoxy.

      Understanding Array Model Numbers

          1D Array 2D Array

       

      Example Model Numbers 82.58X4.2A30/16/5.2CsI(Tl) 82.58X4.2A30/16x4/5.2x4CsI(Tl)

      1

      Active area length 82.58 82.58
      2 Active area height 4.175 4.175
      3 X-ray crystal depth (Z) 30 30
      4 Number of pixels
      If the array is 2D, this is in the format [Pixels X] x [Pixels Y]
      16 16x4
      5 Pitch [X + Gap X(A)]
      If the array is 2D AND the pitch is different in X and Y, this is in the format [X+GapX(A)]x[Y+GapY(B)].
      5.2 5.2x4
      6 Scintillator CsI(Tl) CsI(Tl)

              

       

      Low Afterglow Linear Arrays

      Linear CsI(Tl) Segmented Arrays

      Recent advances in CsI(Tl) array manufacturing have resulted in afterglow reduction, improved light output, and afterglow uniformity. Single energy, dual-energy, fixed frame, rotating gantry, CsI(Tl) based arrays can be used in almost any high-quality X-Ray imaging application in a multitude of industries (Security Baggage Scanning, Cargo Scanning, Medical, Non-Destructive Industrial Inspection).  To download the product performance sheet, click here.

       

      Array Performance (Typical)

      X-Ray Test Parameter

      Light output uniformity ±10% within an array
      (requires matching photodiode)
      X-Ray Power 120KV @ 1mA
      Light output array to array ±10% Irradiation Time 2.5 Seconds
      Afterglow 5000ppm @100ms (initial test)
      ≤2500ppm (after burn in)
      Afterglow Measurements 100ms
      Afterglow uniformity ±10% within an array Distance Crystal to X-Ray Source 60 cm

      Array Design Capabilities

      Typical Sampling Rate 1 ms
      Number of channels (typical) 8-64

      Afterglow in PPM (parts-per-million) is calculated by dividing the output at 100 ms by the reference output with the X-Ray beam on, times 1 million to convert it to PPM:

      V100 (1E6)
      Vref
      Minimum pitch 0.5mm Light output calculation:
      -% uniformity = (Min-Avg)/Avg
      +% uniformity = (Max-Avg)/Avg
      X-Ray thickness 50mm max    

      Linear CsI(Tl) Segmented Arrays Afterglow calculations 

      Related Resources

       Scintillation Array Brochure
       LYSO Material Data Sheet
       Low Afterglow linear CsI(Tl) Segmented Arrays
       Cadmium Tungstate Material Data Sheet
       BGO Material Data Sheet
       Interpreting Model Numbers

       Contact us to learn more!

      Saint-Gobain Crystals is a business of
      Saint-Gobain Ceramic Materials

       

      Hear what we do from a few of the Crystals' team. Click here

       

       

       

      FOLLOW US

      LinkedIn        Youtube

      • Radiation Detection
      • Synthetic Sapphire
      • X-Ray Monochromators
      • Garnets
      • About Us
      • Faqs
      • News & Events
      • ISO Certificates
      • Conditions of Sale
      • Legal
      • CATSCA
      • Site Map

       

       Contact Us

       Request a Quote

       Phone and Email

       

      © Copyright Saint-Gobain 2020. All rights reserved.