PULSE SHAPE DISCRIMINATION

EJ-276D & EJ-276G

(Formerly EJ-299-33A, EJ-299-34)

EJ-276 EJ-276G

EJ-276D pulse-shape discriminating (PSD) plastic scintillator enables the separation of gamma and fast neutron signals on the basis of their timing characteristics. This scintillator replaces all versions of EJ-276, EJ-299-33, and EJ-299-34 PSD scintillators and embodies the following improvements:

Non-hygroscopic
Excellent physical hardness, equal to or superior to that of standard plastic scintillators
Long-term stability of scintillation and optical characteristics
Basic PSD properties increased to being comparable to the best liquid scintillators

EJ-276G with green fluorescence is also available for use with solid-state sensors.

PROPERTIES		EJ-276D	EJ-276G
Light Output (% Anthracene)		56	52
Scintillation Efficiency (photons/1 MeV e^-)		8,600	8,000
Wavelength of Maximum Emission (nm)		425	490
No. of H Atoms per cm³ (x10²²)		4.647	4.647
No. of C Atoms per cm³ (x10²²)		4.944	4.944
No. of Electrons per cm³ (x10²³)		3.545	3.545
Density (g/cm³)		1.099	1.099
Approx. Mean Decay Times of First 3 Components (ns)	Gamma Excitation	13, 35, 270	—
Approx. Mean Decay Times of First 3 Components (ns)	Neutron Excitation	13, 59, 460	—

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 these scintillators.

ULTRA-THIN FILM

EJ-214

Formerly known as EJ-299-07, this special plastic scintillator has been formulated specifically for use in ultra-thin films employed for heavy ion studies and beam monitors. The formula contains a very high concentration of the waveshifting dopant to efficiently absorb and shift the primary scintillation light, which is in the UV range. The plastic base is PVT, and the films are suitable for use in high vacuum. They may be mounted to light guides with optical epoxies or silicone greases. Cleaning is best done with isopropyl alcohol.

PROPERTIES	EJ-214
Scintillation Efficiency (photons/1 MeV e^-)	9,000
Wavelength of Maximum Emission (nm)	435
Decay Time (ns)	2
No. of H Atoms per cm³ (x10²²)	5.18
No. of C Atoms per cm³ (x10²²)	4.67
No. of N Atoms per cm³ (x10¹⁹)	4.89
No. of O Atoms per cm³ (x10¹⁹)	2.59
No. of Electrons per cm³ (x10²³)	3.27
Density (g/cm³)	1.02
Softening Point (°C)	60

EJ-214 Emission Spectrum

PLASTIC SCINTILLATOR PAINT

EJ-296

EJ-296 is a solution of plastic scintillator materials dissolved in a xylene solvent to form a paint for fabricating ultra-thin films or for applying directly to a customer's support surface. Scintillator films as thin as 0.1 micrometer can be made by forming the films on a water surface. Spin casting techniques have also been used successfully to form films of well controlled thickness. EJ-296 is a moderately viscous solution which may be applied as received. For making thinner films, the paint can be thinned with additional solvent.

The fluor system of EJ-296 has been formulated specifically for the fabrication of thin films with two specific considerations in mind: (1) Vacuum compatibility and (2) maximum shifting of the primary scintillation light in thin films. Because the base solvent is xylene, care should be taken in handling and storing EJ-296 with regard to potential flammability. Always work in a well ventilated area.

PROPERTIES	EJ-296
Light Output (% Anthracene)	60
Scintillation Efficiency (photons/1 MeV e^-)	9,000
Wavelength of Maximum Emission (nm)	435
Rise Time (ns)	~ 1.0
Decay Time (ns)	~ 2.5
Pulse Width, FWHM (ns)	~ 3.5
No. of H Atoms per cm³ (x10²²)	5.17
No. of C Atoms per cm³ (x10²²)	4.69
No. of Electrons per cm³ (x10²³)	3.33
Density (g/cm³)	1.02

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 -60°C to 20°C
Temperature Range	-60°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.

CASTING RESIN

EJ-290

EJ-290 is a partially-polymerized plastic scintillator formulated for final curing in the user's facilities at a relatively low temperature. It is supplied in a kit form consisting primarily of the scintillator resin and a polymerization initiator. Upon combining the ingredients in accordance with the provided instructions, a solid plastic scintillator can be made at a relatively low polymerization temperature. The final scintillation and physical properties are quite similar to those of the conventional blue-emitting plastic scintillator EJ-212.

Click the link in the side-menu for instructions on how to use EJ-290. Typical shelf life for this product is approximately 3 months when tightly sealed and stored in a cool place, preferably in a refrigerator.

PROPERTIES	EJ-290
Light Output (% Anthracene)	58
Scintillation Efficiency (photons/1 MeV e^-)	9,000
Wavelength of Maximum Emission (nm)	423
Decay Time (ns)	~ 3
No. of H Atoms per cm³ (x10²²)	5.17
No. of C Atoms per cm³ (x10²²)	4.67
No. of Electrons per cm³ (x10²³)	3.33
Density (g/cm³)	1.02

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

EJ-290 Emission Spectrum

GREEN EMITTING

EJ-260, EJ-262

EJ-260 & EJ-262

These plastic scintillators have been formulated for use where longer wavelengths are needed for efficient optical coupling to solid-state photosensors. Because of their longer emission wavelengths, they will exhibit somewhat greater radiation hardness than conventional blue plastic scintillators. Both scintillators can be used to detect the same kinds of radiation commonly measured with blue scintillators.

EJ-260 is a green emitting plastic scintillator that has been formulated for use where longer wavelengths are advantageous for purposes of light piping. The green fluorescence is of short enough wavelength and the scintillation efficiency is high enough for successful use with conventional blue sensitive photomultiplier tubes. The light output data presented in the table were determined with a flat response photodetector and would be approximately one half that level for a typical bialkali photomultiplier tube.

EJ-262 is also a green emitting scintillator, but has a faster decay time and a shorter maximum emission wavelength than those of EJ-260. The shorter emission wavelength makes EJ-262 suitable for use with blue sensitive photomultiplier tubes.

PROPERTIES	EJ-260	EJ-262
Light Output (% Anthracene)	60	57
Scintillation Efficiency (photons/1 MeV e^-)	9,200	8,700
Wavelength of Maximum Emission (nm)	490	481
Light Attenuation Length (cm)	350	250
Rise Time (ns)	~1.5	0.9
Decay Time (ns)	9.2	2.1
No. of H Atoms per cm³ (x10²²)	5.21	5.20
No. of C Atoms per cm³ (x10²²)	4.70	4.69
No. of Electrons per cm³ (x10²³)	3.35	3.33
Density (g/cm³)	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 -60°C to 20°C
Temperature Range	-60°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 these scintillators.

EJ-260 Emission Spectrum

EJ-262 Emission Spectrum

LEAD LOADED

EJ-256

EJ-256 is a homogeneous, clear plastic scintillator in which lead has been incorporated by means of organometallic chemistry. Typical lead loading ranges from 1% to 5% by weight. Loadings up to 10% have been made but are not recommended. With increasing lead loading, there are corresponding losses in scintillation efficiency and optical clarity of the final plastic.

EJ-256 is best used for gamma detection at energies below 100 keV where there is a significant impact of the lead on attenuation coefficients. This is most strongly evident at 60 keV and lower where the photoelectric cross section is notably enhanced. At these energies, signal amplitudes from EJ-256 are commonly greater than those from an intrinsically brighter plastic scintillator that has no loading with heavy atoms as a result of the photoelectric contribution in the detection process. Detection efficiencies are also notably increased.

EJ-256 is also excellent for dosimetric detection applications. Lead concentrations in the 1-2% range impart a flatness in response down to at least 20 keV.

PROPERTIES	EJ-256-5%	EJ-254-1.5%
Light Output (% Anthracene)	34	50
Scintillation Efficiency (photons/1 MeV e^-)	5,200	7,700
Wavelength of Maximum Emission (nm)	425	425
Decay Time (ns)	2.1	2.1
No. of H Atoms per cm³ (x10²²)	5.20	5.21
No. of C Atoms per cm³ (x10²²)	4.62	4.68
No. of Electrons per cm³ (x10²³)	3.48	3.39
Density (g/cm³)	1.081	1.037
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
Temperature Range	-60°C to 60°C
Light Output vs. Temperature	At 60°C, L.O. = 95% of that at 20°C No change from -60°C to 20°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-256 Emission Spectrum

BORON LOADED

EJ-254

This blue-emitting plastic scintillator contains natural boron at concentrations up to 5% by weight. It is a clear, stable plastic with physical properties similar to those of the standard Eljen plastic scintillators. Its principal applications are fast neutron spectrometry and thermal neutron detection. The primary function of the boron is to provide a unique scintillation signal for low energy neutrons. The standard formulation contains 5% boron, and practical boron concentrations down to 1% are available.

The isotopic fraction of ¹⁰B in natural boron is 19.9%, meaning that the 5% loaded plastic contains nearly 1% of ¹⁰B. The neutron capture reaction on the boron ¹⁰B(n,αγ)⁷Li has a Q value of 2.78 MeV of which 2.34 MeV is shared by the alpha and lithium particles. This energy is fully captured in the plastic to produce a scintillation signal approximately equivalent in amplitude to that of a 76 keV electron. For delayed coincidence timing of the capture of fast neutrons, the time delay from the prompt recoil-proton pulse is typically 2.7 µs for 5% B-nat plastics. This delay is inversely proportional to the boron loading.

Reference: D.M. Drake et al., Nucl. Instr. & Meth., A247, 576-582 (1986)

PROPERTIES	EJ-254-5%	EJ-254-2.5%	EJ-254-1%
Light Output (% Anthracene)	48	56	60
Scintillation Efficiency (photons/1 MeV e^-)	7,500	8,600	9,200
Wavelength of Maximum Emission (nm)	425	425	425
Rise Time (ns)	0.85	0.85	0.85
Decay Time (ns)	1.51	1.51	1.51
Pulse Width, FWHM (ns)	2.24	2.24	2.24
No. of H Atoms per cm³ (x10²²)	5.18	5.17	5.16
No. of C Atoms per cm³ (x10²²)	4.44	4.55	4.62
No. of ¹⁰B Atoms per cm³ (x10²⁰)	5.68	2.83	1.14
No. of Electrons per cm³ (x10²³)	3.33	3.33	3.33
Density (g/cc)	1.026	1.023	1.021
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 -60°C to 20°C
Temperature Range	-60°C to 60°C