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EJ-232, EJ-232Q




EJ-232 plastic scintillator is intended for very fast timing applications or when very high pulse pair resolution is required. Due to the small emission wavelength, the optical mean free path of this scintillator is approximately 10 cm. Therefore, to achieve the best light collection and to optimize the timing performance, EJ-232 should be used in a small size with the largest scintillator dimension less than 10 cm to minimize photon scattering effects.  The use of light guides is best avoided.

EJ-232Q plastic scintillator is a quenched variant of EJ-232 specifically formulated for ultra-fast counting applications. The introduction of small amounts of benzophenone to EJ-232 significantly shortens the timing properties for purposes of achieving very high counting rates or improved coincidence timing. The quenching does not affect the emission spectrum but does reduce the scintillation efficiency (see table below). While it is recommended to keep the scintillator size and shape small in order to achieve the best timing performance, it is not recommended to use EJ-232Q in thin films (thicknesses ≤ 3 mm) due to the vapor pressure of benzophenone.


PROPERTIES EJ-232 EJ-232Q (% Benzophenone)
0.5 1.0 2.0 3.0 5.0
Light Output (% Anthracene) 55 19 11 5 4 3
Scintillation Efficiency (photons/1 MeV e-)
8,400 2,900 1,700 770 610 460
Wavelength of Maximum Emission (nm) 370 370 370 370 370 370
Rise Time (ps) 350 110 105 100 100 100
Decay Time (ps) 1600 700 700 700 700 700
Pulse Width, FWHM (ps) 1300 360 290 260 240 220
No. of H Atoms per cm3 (x1022) 5.13 5.12 5.12 5.12 5.12 5.12
No. of C Atoms per cm3 (x1022) 4.66 4.66 4.66 4.66 4.66 4.66
No. of Electrons per cm3 (x1023) 3.30 3.38 3.38 3.38 3.38 3.38
Density (g/cm3) 1.023 1.023 1.023 1.023 1.023 1.023
Polymer Base Polyvinyltoluene
Refractive Index 1.58
Softening Point 75°C
Vapor Pressure Vacuum-compatible
Coefficient of Linear Expansion 7.8 x 10-5 below 67°C
Light Output vs. Temperature At 60°C, L.O. = 95% of that at 20°C.
No change from 20°C to -60°C.
Temperature Range -20°C to 60°C


Chemical Compatibility
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 this scintillator.


EJ-232 & EJ-232Q Emission Spectrum


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