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LIQUID SCINTILLATOR CELLS AND DETECTOR ASSEMBLIES

 

Liquid Scintillator Cells

 

Our liquid scintillators are available encapsulated within either aluminum or glass cells with a clear window for coupling to a photomultiplier tube. The most common model is a cylindrical aluminum cell with one window and a mounting flange. Both cells with an expansion void bubble and bubble-free cells are offered. Standard sizes are 51 mm (2”) dia., 76 mm (3”) dia., and 127 mm (5”) dia. regular cylinders. Custom sizes are also available.

Aluminum liquid scintillator cells can also be supplied with a photomultiplier tube as a complete detector assembly. Assemblies include a photomultiplier tube, voltage divider, Mu-shielding and light-tight housing.

For more information, please contact us regarding your specific requirements.

 

Expansion Void Cell with Flange

VMF-DxH Liquid Scintillator Cell

VMF-DxH

 

Bubble-Free Cell with Flange

BFF-DxH Liquid Scintillator Cell

BFF-DxH

 

M510-30x30 (3" Dia.) Liquid Scintillator Detector Assembly

M510-30x30

AQUEOUS SAMPLES

EJ-351

 

EJ-351

 

EJ-351 is a scintillation cocktail based on highly purified dioxane and is identical to the original NE-220. It is intended primarily for alpha and beta detection in counting water-based solutions of sugars and salts as well as body fluids such as urine and blood serum. It can also be used to assay tritiated water. Since it is dioxane-based, it offers very high light output and is relatively resistant to quenching.  Water can be added to EJ-351 in quantities up to 10% of the final solution mixture.

 

PROPERTIES EJ-351
Light Output (% Anthracene) 65
Scintillation Efficiency (photons/1 MeV e-)
 10,000
Wavelength of Maximum Emission (nm) 425
Decay Time, Short Component (ns) 3.8
Specific Gravity 1.036
Refractive Index 1.442
Flash Point (°C) 12
Boiling Point (°C at 1 atm) 104
No. of H Atoms per cm3 (x1022) 5.32
No. of C Atoms per cm3 (x1022) 3.23
No. of O Atoms per cm3 (x1022) 1.14
No. of Electrons per cm3 (x1023) 2.47

 

EJ-351 Emission Spectrum
 

GADOLINIUM LOADED

EJ-331, EJ-335

 EJ-331EJ-335

The principal applications of these liquid scintillators are neutron spectrometry and neutrino studies. The neutron capture reaction in gadolinium produces a multiplicity of gamma rays with a total energy of about 8 MeV. Delayed coincidence and pulse shape discrimination techniques are commonly employed with these liquids. Also, because they are often employed in large volumes, both are formulated with high flash point solvents.

EJ-331, based on a fully aromatic solvent, provides the maximum light output consistent with long-term stability. The standard gadolinium loading is 0.5% by weight, but it is also available with gadolinium loadings from 0.1% to 1.5%.

EJ-335 contains mineral oil substituted for some of the aromatic solvent for purposes of higher hydrogen content and higher flash point for use in very large tanks. The maximum gadolinium content is 0.5%, and loadings down to 0.1% are used in very large volume detectors.

 

PROPERTIES EJ-331-0.5%
 EJ-335-0.25%
Gadolinium Content (% w/w) 0.5 0.25
Light Output (% Anthracene) 68 55
Wavelength of Maximum Emission (nm)
 424 424
Bulk Light Attenuation Length (m) >4 >4.5
Specific Gravity 0.90 0.89
Refractive Index 1.50 1.49
Flash Point (°C) 44 64
No. of H Atoms per cm3 (x1022) 5.27 6.16
No. of C Atoms per cm3 (x1022) 4.00 3.93
No. of Electrons per cm3 (x1023) 2.98 3.06

 

EJ-331 & EJ-335 Emission Spectrum

MINERAL OIL BASED

EJ-321L, EJ-321H, EJ-321P, EJ-321S

 

EJ-321

 

This is a family of four different formulations, EJ-321L, EJ-321H, EJ-321P, and EJ-321S, all based on mineral oil. The main difference between them is light output which varies primarily by the percentage of mineral oil in the various solutions. Other properties which vary with the light output are optical mean free path, flash point and hydrogen-to-carbon ratio. They are recommended for use in large tanks, including acrylic tanks, where lower costs are important.

The tendency for chemical action on container components runs in parallel with the light output. In the construction of acrylic tanks, it is strongly recommended that only cell cast sheet stock, not extruded materials, be employed. Glue joints should be made with solvent action cements and should be annealed afterward. Extruded tubing has been successfully used but only when the inside walls of the cells have been passivated with a thin coating of polyvinyl alcohol. EJ-321P may also be used in tanks fabricated with gray PVC plastic.

 

PROPERTIES EJ-321L
 EJ-321H
 EJ-321P
 EJ-321S
Light Output (% Anthracene)
Saturated with Nitrogen
Saturated with Air
 
39
30
 
52
40
 
28
21
 
66
51
Mean Free Path (400-500nm, in m) >5 >5 >6 >4
Wavelength of Maximum Emission (nm)
 425 425 425 425
Decay Time, Short Component (ns) 2.0 2.0 2.2 2.0
Specific Gravity 0.86 0.86 0.85 0.87
Refractive Index 1.47 1.48 1.47 1.49
Flash Point (°C) 102 81 115 74
No. of H Atoms per cm3 (x1022) 7.37 7.03 7.47 6.48
No. of C Atoms per cm3 (x1022) 3.66 3.72 3.63 3.83
No. of Electrons per cm3 (x1023) 2.93 2.94 2.93 2.94

 

EJ-321 Emission Spectrum
 

MINERAL OIL BASED WITH PSD

EJ-325A

 

EJ-325A

 

EJ-325A is a mineral oil based liquid scintillator having pulse shape discrimination (PSD) properties for the separation of fast neutrons and gammas. EJ-325A replaces the original EJ-325. The new formula exhibits slightly improved scintillation efficiency and PSD properties and, importantly, has a very high flash point for safety and ease of shipping. With the mineral oil as a major solvent component, EJ-235A possesses greater optical clarity for use in large tanks.

EJ-325A exhibits considerably low solvent properties making it ideal for incorporation in containers fabricated with cast acrylic and PVC.

 

PROPERTIES EJ-25A
Light Output (% Anthracene) 62
Scintillation Efficiency (photons/1 MeV e-) 
9,500
Wavelength of Maximum Emission (nm) 425
Decay Time, Short Component (ns) ~ 3.5
Bulk Light Attenuation Length (m) >1
Specific Gravity 0.954
Refractive Index 1.55
Flash Point (°C) 146
Boiling Point (°C)
 290-300
Vapor Pressure (mm Hg, at 20°C)
 0.002
No. of H Atoms per cm3 (x1022) 6.73
No. of C Atoms per cm3 (x1022) 3.92
H:C Atomic Ratio 1.72
No. of Electrons per cm3 (x1023) 3.02

 

EJ-325A Emission Spectrum

DEUTERATED

EJ-315

 

EJ-315

 

EJ-315 is based on highly purified deuterated benzene and is useful for fast neutron research. A particularly highly enriched deuterated benzene is employed to achieve the very high D:H ratio of 141:1. A non-deuterated version, EJ-315H, is also available for comparison studies. EJ-315H is based on normal standard benzene, but otherwise the formulae of the two scintillators are identical. The properties of each are presented below.

Because of the toxic nature of benzene, it is strongly recommended that the liquids be ordered in the encapsulated form so you need only to mount your phototubes in order to put the scintillator into service.

 

PROPERTIES EJ-315
 EJ-315H
Light Output (% Anthracene) 60 60
Scintillation Efficiency (photons/1 MeV e-)
 9,200 9,200
Wavelength of Maximum Emission (nm) 425 425
Decay Time, Short Component (ns) 3.5 3.5
Bulk Light Attenuation Length (m) >3 >3
Specific Gravity 0.954 0.878
Refractive Index 1.498 1.501
Flash Point (°C) -11 -11
Boiling Point (°C at 1 atm) 79 80
No. of D Atoms per cm3 (x1022)
 4.06 -
No. of H Atoms per cm3 (x1020) 0.0287 4.04
No. of C Atoms per cm3 (x1022) 4.10 4.06
No. of Electrons per cm3 (x1023) 2.87 2.84

 

EJ-315 Emission Spectrum
 

HYDROGEN FREE

EJ-313

 

EJ-313

 

EJ-313 is based on highly purified hexafluorobenzene. Because it is almost free from hydrogen, it is relatively insensitive to fast neutrons, making EJ-313 useful for gamma ray detection in a fast neutron flux.1 According to Jupiter and Parez2 the ratio of the relative gamma ray response to neutron responses for EJ-313 compared to a xylene-based liquid scintillator is 14.5 for 2.6 MeV neutrons and 8.5 for 1 MeV neutrons. Ewen and Gonsior3 found that the gamma ray and neutron efficiencies of this hydrogen-free scintillator to be 25% and 0.4% respectively, relative to those of a NaI(Tl) detector.

 

PROPERTIES EJ-313
Light Output (% Anthracene) 20
Scintillation Efficiency (photons/1 MeV e-)
 3,060
Wavelength of Maximum Emission (nm) 425
Decay Time, Short Component (ns) ~ 3
Bulk Light Attenuation Length (m) >1
Specific Gravity 1.619
Refractive Index 1.38
Flash Point (°C) 10
Boiling Point (°C at 1 atm) 80
No. of F Atoms per cm3 (x1022)
 3.14
No. of H Atoms per cm3 (x1020) 1.02
No. of C Atoms per cm3 (x1022) 3.15
No. of Electrons per cm3 (x1023) 4.72

 

EJ-313 Emission Spectrum

 

References:
1. S. Homma & S. Takemoto, Rev. Sci. Instr. 32, No. 9, 1055 (Sept. 1961).
2. C. P. Jupiter & J. Parez, IEEE Trans. Nucl. Sci., NS-13, (1) 692-703 (1966).
3. K. Ewen & B. Gonsior, Nucl. Instr. & Meth., 99, 573-578 (1972).

 

More Articles ...

  1. EJ-309B
  2. EJ-301, EJ-309
  3. Liquid Scintillators

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