This knowledge base answers some of the most common questions about our products and services.  Please contact us if you don't find the answer you seek. 

Scintillation Detector Related Questions

What is the expected service life of a detector?

Our standard warranty is two years for workmanship issues and we pass on the one year warranty from the photomultiplier tube vendor.  The expected lifetime is approximately 5-10 years.  This time frame is based upon limited data from non-warranty returns provided to Saint-Gobain for scrap or refurbishment.  Many of the detectors have been in the field for more than ten years without any issues.  NaI(Tl) crystals and photomultiplier tubes are thermally and mechanically shock sensitive.  Overexposure to either can cause premature failures.  Care should be taken when handling the detectors.  Photomultiplier tubes should function for many thousands of hours, and particularly long life is commonplace in scintillation counting experiments where incident light levels and output current demands are fairly low.  Factors shortening the life of the tube include high current operation, excessive voltage operation, high light levels and increased temperature.  If the detector is exposed to high levels of gamma radiation, the lifetime of the photomultiplier can be reduced.

Do you sell bare or un-encapsulated scintillation crystals or scintillation crystals without a photosensor (PMT or SIPM)?

In most cases, Saint-Gobain can offer a packaged scintillator + photosensor solution optimized for performance and cost. Exceptions to the policy are reviewed on a case by case basis.

What is the difference between 8 stage and 10 stage detectors?

This is related to the number of dynodes the PMT has.  Your electronics should match with the dynode structure.

What are the typical energy resolution values between Enhanced Lanthanum Bromide, Lanthanum Bromide and CLLB scintillation crystals?

It is important to mention that we have 2 categories of designs for these high resolving materials: Premium designs and Compact designs.

The premium designs are full oriented for the best spectroscopy performances (the best energy resolution) and usually use a larger PMT compared to the cross section of the crystal.

The Compact designs use a smaller PMT and provide the best compromise between energy resolution and outer mechanical dimensions.

If we compared equivalent Premium designs for these different materials (with standard dimensions from 1.5”x1.5” to 3”x3” for example), a product with a Lanthanum Bromide scintillation crystal will provide a guaranteed PHR @ 662keV <3.0% (with average values around 2.7%); when an Enhanced Lanthanum Bromide scintillation crystal will provide a guaranteed PHR @ 662keV <2.5% (with typical values at 2.2-2.3%).

For equivalent design, the CLLB scintillation product will have a guaranteed PHR @ 662keV <4,5%. To illustrate this last value, we can refer to a 2019 production of more than 100 units with 2” diameter X 4” long CLLB scintillation crystal: all products have been delivered with a PHR @ 662keV <4.5% and the average value for these units was at 4.03%.

Is there a different background level in Enhanced Lanthanum Bromide compared to standard Lanthanum Bromide scintillation crystals?

Currently, there is the same 227Ac background for both Lanthanum Bromide [LaBr3(Ce)], and Enhanced Lanthanum Bromide [LaBr3(Ce+Sr)]. This background has a maximum level around 0.2 – 0.15 Bq/cc for these alpha emitters (227Ac).

But, it’s important to note that the position of this background is not at the same location in the spectrum for Enhanced Lanthanum Bromide compared to standard Lanthanum Bromide: For Lanthanum Bromide, the 227Ac background is between 1.6MeV et 2.7MeV, and the same background is between 2.5MeV to 3.8MeV for Enhanced Lanthanum Bromide: Depending on the application, the background may be outside the interest range.

What are the available dimensions for Enhanced Lanthanum Bromide and Lanthanum Bromide crystals?

We have been manufacturing Lanthanum Bromide products since 2006. Today, our largest standard dimension is 3” diameter x 3” thick, but upon specific request we can supply a larger diameter (up to 5”) and a longer length (up to 8”).

For Enhanced Lanthanum Bromide material, we use our knowledge and competencies that have been developed with our standard Lanthanum Bromide. Then, today we are able to provide scintillation products with large Enhanced Lanthanum Bromide crystals: 3” diameter x 3” thick standard dimensions and we can provide, upon request, scintillation product with crystal up to 3” diameter x 4” thick.

SiPM Related Questions

Is the performance of an integrated SiPM detector assembly comparable to a PMT?

The difference between Saint Gobain’s SiPM based Nal Detectors over PMT based detectors is discussed in this document 

Does the SiPM signal output read the same as PMT?

No – the SiPM units have a preamp that produces a positive pulse on the analog output pin.

At what point does the noise due to temp overwhelm the low energy signal from SiPM detector?

We currently offer a solution that is low noise up to 50°C, and are developing one to even higher temps

What are the power in and signal out requirements for SiPM detector readout?

Power in 5 volts at 15 milliamps

Is a Scintillation detector integrated with SiPM more robust than a detector with PMT?

No, the scintillator package has the same conditions. However, SiPM detectors are immune to magnetic fields, where PMTs are not.

Plastic and Liquid Scintillator Related Questions

Can plastic scintillator be bent?

Plastic scintillator can be bent to hold a shape. Typically, the temperature would need to be in the 80 – 90 °C range, and the surface being bent should be one of the polished surfaces.  Cool the plastic completely before removing from the bending fixture. If done correctly, the performance properties of the plastic should not be affected.

What is the minimum thickness for plastic scintillators?

Plastic scintillator thickness is dependent on the surface area.  0.5 mm is the minimum if the width and length is under 30 x 60 cm.  Click here to see a list of standard Cast Sheet Sizes.    Thin Film BC-400B is available in three thicknesses; 0.15, 0.20 and 0.25mm x largest size 150 x 350 mm. 

What is the attenuation length of plastic scintillator?

Bulk attenuation length (click here) is for material as cast before any machining.  Attenuation length for finished parts is dependent on thickness, final machining and reflector.

How is light output defined for organic scintillators?

The light output of organic scintillators is traditionally given as a percentage of the light output of Anthracene.  Anthracene is an organic crystal that is not commercially available.  On this scale, the light output of NaI(Tl) is about 210%.  A better number for PVT based plastic scintillators is 104 scintillation photons per MeV deposited into the scintillator.  That number is good for Minimum Ionizing Particles (MIPs) such as fast electron and cosmic ray muons.  Heavier and/or more ionizing particles such as protons and alpha particles produce few photons per unit energy deposited.  The relative light yield by particle type is shown in a chart in the 

.  The energy deposition rate for MIPs in plastic scintillators is 2 MeV/cm.

How was pulse width determined for the plastic scintillators?

The pulse width is typically measured with a small scintillator (1” dia x 1”) coupled to a very fast PMT (XP2020).  The anode pulse from the PMT is viewed on an oscilloscope that is terminated 50 Ohms.  The width is the FWHM of the pulse.

What is the operating temperature of plastic scintillator

Plastic scintillator is good from -40°C to about +65°C, at 70°C it will be start to soften, so to be safe, we recommend 65°C as a max working temperature. For higher temperatures, please consider BC-440 series.

Can all 4 or 6 sides of plastic scintillator be as cast?

No, only the thickness, the remaining 4 sides can be rough cut, or diamond milled. For round parts, depending on dimensions, most of the time the thickness is as cast, and the outside diameter is diamond turned.  For parts that are closer to a rod than a disc, both the out diamter and the length would be diamond turned.

How do you diamond mill plastic?

The tool is a diamond tipped tool, but the actual parameters and methods are considered proprietary.

Can plastic scintillator be cleaned?

PVT will not tolerate any organic solvents or solvent vapors.  For example, Acetone and Xylene are very bad.  Water is ok for short periods of time so a brief cleaning is not a problem.  Avoid long time exposure as water will eventurally penetrate the plastic.

Can plastic be used outdoors?

Plastic will eventually absorb liquid and condensation must be avoided.  We offer product packaging solution that will extend the life of your plastic scintillation detector.  Click here for details.  

Can you make special mixtures for BC-521 and BC-525 (liquid scintillators) other than what is in your literature?

Yes, this is a case by case basis and needs to be reviewed by the Application Technology manager.

Fiber Related Questions

Are fibers sensitive to Neutrons?

All scintillating fibers are sensitive to fast neutrons through proton recoil.

How is fiber light output defined?

We define the light output as # of photons per MeV for minimum ionizing Particle, which is approximately 8000 for BCF-12.  The more densely ionizing particles emits less light than per unit energy.

What is the fiber spool size?

Fiber is wound on a spool that measures 30" (762mm) outer diameter x 27.4" (698.5mm) core x 2.25" (57mm) with 1" (50.8mm) center hole. It will fit 1000 meters of 1mm fiber.

What is the lower temperature limit of Scintillating Fiber?

The lower limit on operating temperature has not been set, but research experiments have used fiber in temperatures down to about 4 degrees K.  Fiber will lose their flexibility at low temperatures.

What is the typical bend radius of a scintillating fiber

The typical bend radius is 30-40 times the diameter of the fiber.

General Support

Is there a minimum order?

Minimum Order Value Charge will be applied for all orders less than €1500 (or 1500 USD for orders processed in USD).  The exception is detector assembly materials, which are €500 (or 500 USD for orders processed in USD).

Where can Safety Data Sheets be found?

SDS are available in our Document Center.