ELJEN Products List EJ-240 plastic Scintillator distributed by
This plastic scintillator has an unusually long principal decay time, 285 ns.   Its primary application is to be used in combination with standard organic scintillators having typical decay times near 2 ns.  Such phoswich detectors are usually constructed with the fast and slow scintillators combined to form one optical element viewed by a single photomultiplier with pulse shape discrimination electronics employed to identify the different pulses.  The fast front scintillator is usually relatively thin providing dE/dX information while the slow rear scintillator is slow relatively thick to provide the full energy signal.  The PMT is mounted on the slow scintillator, and the fast pulse is easily identified since it undergoes little degradation while passing through the slow one.  
A green emitting variant, EJ-240G, is also available with emission maximum at 490nm.  

Physical and Scintillation Constants:
Light output, % Anthracene 41% EJ-240 emission spectrum
Scintllation efficiency, photons/1MeV e¯ 6,300
Wavelength of max emission, nm 435
Decay Time, nSec. 285
No. of H atoms per cm3 x 1022 5. 19
No. of C atoms per cm3 x 1022 4. 68
No. of electrons per cm3 x 1023 3. 33
Density, g / cc 1. 02
Polymer Base: Polyvinyltoluene
Refractive Index: 1. 58
Vapor Pressure: Is vacuum-compatible
Expansion Coefficient: 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
Chemical Compatability: Is attacked by aromatic solvents, chlorinated solvents, ketones, solvent bonding cements, etc.  It is stable in water, dilute acids and alkalis, lower alcohols and silicone greases.  It is safe to use most epoxies and super glues with EJ-240. 

EJ-240 emission decay timing trace compared to NaI(Tl) and standard PVT base plastic scintillator ( ELJEN  type EJ-212 )   ( all 3 oscilloscope traces are normalized to identical time scale )
 EJ-240
 		 EJ-212
 		 NaI(Tl)
exhibited date are supplied by the courtesy of Hamamatsu Photonics, Electron Tube Division.  
G-tech, Corp.    local representative in Japan
365-1, Sayamagahara, Iruma-shi, Saitama 358-0032
Phone# 04-2935-2777 Fax# 04-2935-2778  
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