Standard Detector Assemblies

Designs for Radiation Counting Applications

The proper detector packaging and integration of scintillation crystals is a science combining advanced design and engineering skills with proven assembly techniques and materials to produce stable, high-resolution radiation detectors.

Scintillation Detector Configurations

Offering a variety of standard detector designs to fulfill most radiation counting applications.

  • Solid detectors are commonly used for gamma-ray spectroscopy, material assay, activation analysis, radon canister counting, thyroid uptake measurements, and health physics applications for energies greater than 15 keV.
  • End well and through-side well-configured detectors are highly efficient for measuring activity of small-sized sources and in higher energy emitting isotope measurements. End well detectors are the most efficient (typically greater than 80%) because the scintillator surrounds the sample. Through-side well detectors are ideal when space is limited and is the second most efficient configuration, and are ideal for radioimmunoassay and fuel rod monitoring applications.
  • Square or Rectangular Cross-Section provides a 27% increase in volume over a cylindrical scintillator of the same diameter and length. This increases detector efficiency while keeping package size and shielding requirements down. They are easily stacked in arrays for increased efficiency for applications such as aerial survey, whole-body counting, security portal monitoring and medium and high energy physics.
  • Thin radiation entrance window designs are used for low-energy and X-ray detection applications. A thin entrance window allows measurements down to 3 keV while a thin crystal reduces sensitivity to background radiation. 

Light sensor options included PMT, position-sensitive PMT and SiPM selected for low-background, premium resolution, fixed high voltage use, or gain matching.

Each of those standard detector configurations can be designed with:

  • Added Electronics
    • integrated or plug-on voltage divider, preamplifier, high voltage power supply and multi-channel analyzer.
  • Custom designs options
    • such as special flanges, mounting fixtures, low background packaging options, harsh environments to operate outside a standard laboratory environment (extreme cold, vacuum, elevated temperatures, underwater, severe mechanical shock and vibration) or other modifications can be requested.
Integrated
In this configuration, an integrally mounted light sensing device, such as a photomultiplier tube (PMT) and silicon photomultiplier (SiPM), is optically coupled directly to the scintillator. The scintillator and light sensor are assembled in a light-tight, compact and hermetic package for optimal performance.
This design usually yields better and more consistent energy resolution than others. Therefore, these are detectors of choice for spectroscopy and radioisotope assay.

Features

  • Direct light sensor-to-crystal mounting
  • Compact package
  • Light sensor is matched and tested with scintillator
  • Consistent, superior energy resolution

Design Notes

  • Design suitable for NaI(Tl), CsI, LaBr3(Ce), CLLB, BGO and other scintillation materials
  • The detector package is hermetically sealed when the scintillator is hygroscopic such as NaI(Tl).
  • The maximum scintillator size is 127mm (5") in diameter or on the diagonal.
Integrated scintillation detectors for radiation detection
 
Typical design examples  
Scintillator Model Scintillator Size PMT dia. pins Stages PHR @ Cs-137 Sales Drawing
NaI(Tl) 2M2/2 2" dia. x 2" thick 2" 14 -pin 8 < 8.0%
NaI(Tl) 3M3/3 3" dia. x 3" thick 3" 14-pin 10 ≤ 7.5%
NaI(Tl) 3M3/3 3" dia. x 3" thick 3" 14-pin 8 ≤ 7.5%
LaBr3(Ce) 25S25/1.5 1" dia. x 1" thick 1.5" 12-pin 8 ≤ 3.5%
LaBr3(Ce) 51S51/2 2" dia. x 2" thick 2" 14-pin 8 ≤ 3.5%
LaBr3(Ce) 51S51/3 2" dia. x 2" thick 3" 14-pin 8 ≤ 3.0%

 

Demountable
The demountable designs are made with hermetic seals to optical windows that allow the removal of the light sensor(s) without disturbing the scintillator hermetic package. This configuration is well-suited for applications requiring the use of a crystal larger than 4” diameter or multiple light sensors.

Features

  • Light sensor may be removed without disturbing the scintillation crystal's hermetic package
  • Large scintillator volumes can be accommodated
  • Detector performance can be guaranteed for energy and/or timing resolutions

Design Notes

  • Large detectors may require multiple PMTs
  • For a multiple PMT assembly, the PMTs are matched for gain and balanced. This makes it possible to sum the output of all PMTs and obtain one uniform signal with optimum energy resolution. Records for each detector in our database allow us to supply replacement PMTs.
  • Scintillator areas not viewed by PMTs are covered with a reflector for optimum light collection.
Detector with demountable PMT assembly
 
Typical design examples
Scintillator Model Scintillator Size PMT dia. pins Stages PHR @ Cs-137 Drawing
NaI(Tl) 5H5/5 5" dia. x 5" thick 5" 14-pin 10 ≤ 8.5%
NaI(Tl) 6H6/5 6" dia. x 6" thick 5" 14-pin 10 ≤ 8.5%
NaI(Tl) 4X4H16/3.5A 4" x 4" x 16" long 3.5" 14-pin 10 ≤ 8.0%

 

Rectangular
Scintillation detectors with square or rectangular cross-sections are a cost-effective alternative to the standard right circular cylinder. Various lengths are available, depending on the scintillator choice, with 16” being a common size. Excellent uniformity can be achieved for long square or rectangular detectors. Up to 1m lengths have been designed and assembled. The stopping power is sufficient for high-energy gammas. Common applications include aerial survey, whole-body scanning, pulse gamma neutron activation analysis (PGNAA) and portal monitors.

Features

  • Increased crystal volume
  • Reduced number of light sensors for large coverage area
  • Only one PMT needed for a large crystal volume
  • Easily stacked in arrays for increased efficiency
  • Excellent energy resolution and uniformity

The most common sizes are 2"x4"x16", 3"x5"x16" and 4"x4"x16" assemblies. PMT sizes include 2", 3" and 3.5". Aluminum or stainless steel housings are common.
Applications include aerial survey, whole body counting, security portal monitoring and medium and high energy physics.

Rectangular NaI Detector
 
Typical design examples
Scintillator Model Scintillator Size PMT dia. pins Stages PHR @ Cs-137 Drawing
NaI(Tl) 2X4H16/3A 2" x 4" x 16" long 3" 14-pin 8 ≤ 8.0%
NaI(Tl) 3X5H16/3SS 3" x 5" x 16" long 3" 14-pin 10 ≤ 9.0%
NaI(Tl) 4X4HG16/3.5SS 4" x 4" x 16" long 3.5" 14-pin 10 ≤ 8.5%

 

Packaged
Text The scintillation crystal is hermetically packaged with a metal container, an optical window incorporated on one end, and reflector material between the scintillator and the container walls. A wide variety of shapes (including rectangular) and sizes can be produced. These detectors require user-supplied, externally-coupled light sensors.

Features

  • Reliable hermetically package
  • Stable reflector systems
  • Flexible configurations

Design Notes

  • Detectors made with non-hygroscopic scintillators can be assembled without the optical window, e.g., BGO, CdWO4.
  • Detectors are hermetically sealed when hygroscopic scintillators, e.g., NaI(Tl) are used.
  • You can temporarily mount a PMT by using an optical coupling compound and black tape to make a light seal. Optical coupling materials are available.
Packaged Scintillation Crystals
 
Typical design examples
Model Scintillator Size PHR @ Cs-137 Drawing
2R2 2" dia. x 2" thick ≤ 8.0%
3R3 3" dia. x 3" thick ≤ 8.5%

 

Thin window
Our X-ray detectors and probes are used in various low-energy and X-ray detection applications. These detectors come in three types of assemblies:
  • Packaged X-ray crystals used in X-ray diffraction, X-ray fluorescence, Mossbauer studies and gauging.
  • Integral X-ray detectors are used in health physics applications
  • X-ray probe with fixed collimator is ideal when a constant area of exposure is needed.
All use a thin 1mm or 2mm NaI(Tl) crystal — usually 25mm (1"), 38mm (1.5") or 51mm (2") in diameter — and a radiation entrance window selected to provide the appropriate transmission for the energy of interest. The typical energy range for an assembly with a beryllium entrance window is 3 to 100 keV and 10 to 200 keV for an assembly with an aluminum entrance window

Features

  • Thin entrance window allows measurements down to 3 keV
  • Thin crystal reduces sensitivity to background radiation

Popular Configurations

  • X-ray packaged crystals with 1mm thick NaI(Tl) crystal mounted in an aluminum container with a radiation entrance window and an optical window hermetically sealed.
  • X-ray integral assemblies with 1mm thick NaI(Tl) crystal mounted in an aluminum container with a radiation entrance window, and optically coupled directly to a photomultiplier tube with an external light shield. The PMT terminates in a 12- or 14-pin phenolic base, depending on whether a 1.5" or 2" PMT is used. The scintillator container and light shield form a continuous, hermetically sealed, light-tight housing for the detector.
  • X-ray probe consists of a packaged crystal (model 1XR.040/B) mounted in an aluminum container with a removable brass collimator, and optically coupled to a photomultiplier tube with a mu-metal magnetic light shield. The PMT is connected to a built-in, low-noise voltage divider that terminates with cables for signal and high voltage. The scintillator container and light shield form a continuous, light-tight housing for the detector.
Scintillation Detector with thin entrance window for low energy
Some typical designs  
Scintillator Model Scintillator Size PMT dia. pins Note PHR @ Fe-55 Drawing
NaI(Tl) 1XR .040 B 1" dia. x 0.040" None Packaged ≤ 55%
NaI(Tl) 1XM .040/1.5B 1" dia. x 0.040" 1.5" 12-pin Integral ≤ 50%
NaI(Tl) 1XMP .040 B 1" dia. x 0.040" 1" integrated Probe with voltage divider preamp ≤ 55%

 

Brochures
Scintillation-Materials-and-Assemblies.pdf

basic properties of our radiation detection products and the mechanical features of various standard and specialty designs

PDF | 6.27 MB
Scintillation-Materials-and-Assemblies