WAVELENGTH SHIFTING PLASTICS
EJ-280, EJ-282, EJ-284, EJ-286
Four wavelength shifting (WLS) plastics are available. All are normally based on PVT but can also be provided based on PVT variants providing higher temperature characteristics. These products are also available in custom formulations. Please contact us regarding your specific requirements.
EJ-280 is a green-emitting WLS plastic ideal for shifting the emission spectra of common blue scintillators. It is commonly used in the form of long narrow bars air-coupled to blue scintillators arrayed either in flat planes or in stacks. The bars provide a compact means of light collection. The green light is effectively turned 90° as a result of the isotropic re-emission and is transmitted by total internal reflection to photomultiplier tubes at both ends of the bar to achieve highly uniform light collection. While there is a typical 75% loss of signal amplitude in these systems, they can provide advantages over conventional light collection methods. Although not indicated in the spectrum below, EJ-280 has also been shown to be particularly good for shifitng wavelengths below 200 nm.
EJ-282 is a green-emitting WLS plastic similar to EJ-280 but with a slightly shorter maximum emission wavelength making it suitable for use with blue-sensitive photomultiplier tubes.
EJ-284 is a red-emitting WLS plastic ideal for shifting green-emitting scintillators such as CsI(Tl) into the red. There is also a useful absorption maximum in the blue, as indicated in the spectrum below.
EJ-286 is a blue-emitting WLS plastic with strong broad absorbance in the near-UV and formerly known as EJ-299-27. It is formulated to reduce the scintillation response by a factor exceeding 100x.
|Wavelength of Maximum Emission (nm)
|Wavelength of Maximum Absorption (nm)
|Decay Time (ns)||8.5||1.9||13||~1.2|
|Quantum Efficiency (%)||86||93||95||92|
|Coefficient of Linear Expansion||7.8 x 10-5 below 67°C|
Attacked by: Aromatic solvents, Chlorinated solvents, Ketones, Solvent bonding cements, etc.
Stable in: Water, Dilute acids and alkalis, Lower alcohols, and Silicone greases.
It is safe to use most epoxies with these scintillators.