SCINTILLATION AND WAVELENGTH SHIFTING PLASTIC FIBERS

Eljen Technology is proud to introduce our own brand of plastic fiber optics that are designed for applications needing fiber optics and flexibility. In ongoing collaboration with our clients and our extensive experience in the production of plastics, we are embarking on bringing the best in plastic fiber optics to our customers. These new plastic fibers are based on many years of manufacturing the highest quality Organic Scintillators and Wavelength Shifting Plastics for commercial, scientific and government communities.

Eljen's plastic fibers are available in single and double clad, round or square, canes, spools, and bundles, with diameters ranging from 0.3 mm to 5.0 mm. Our cutting-edge fiber draw systems can also create unclad for filament 3D printing of wavelength shifting and scintillating detector systems.

The fibers can be supplied in plastic matrix bases of polyvinyl toluene (PVT) or polystyrene (PS) and are available in a number of formulations based on our standard Scintillation and Wavelength Shifting plastics. All fibers are drawn and cut to customer specified dimensions and tested to meet specifications.

Please contact us regarding your specific needs and requirements.

Square green emitting fibers — Square Fibers

Blue emitting fiber bundle — Fiber Bundle

COMMON PROPERTIES

PROPERTIES	FIBER SPECIFICATIONS
Core Material	PS	PVT
Core Material Light Output (% Anthracene)	58	64
Working Temperature (°C)	100	75
Density (g/cm³)	1.05	1.03
Core Refractive Index	1.59
Cladding Material	PMMA
Cladding Refractive Index	1.49
Cladding Thickness	3% of fiber diameter
H Atoms per cm³ (core) (x10²²)	5.16
C Atoms per cm³ (core) (x10²²)	4.68
Electrons per cm³ (core) (x10²³)	3.33
Operating Temperature	-60°C to 60°C
Vacuum Compatible	Yes

FIBER TYPES & SPECIFICATIONS

Scintillating Fibers

Material	Emission Color	Emission Peak (nm)	Decay Time (ns)	Attenuation Length (m)	Photons per MeV
EJ-100	Blue	425	2.1	2+	10,000
EJ-104	Blue	408	1.8	2+	10,400
EJ-108	Blue	435	3.3	2+	9,200
EJ-160	Green	490	9.2	2+	9,200
EJ-162	Green	481	2.1	2+	8,700

Wavelength Shifting Fibers

Material	Emission Color	Absorbance Peak (nm)	Emission Peak (nm)	Decay Time (ns)	Attenuation Length (m)
EJ-180	Green	427	490	8.5	2+
EJ-182	Blue/Green	390	481	1.9	2+
EJ-184	Red	574	608	13	2+
EJ-186	Blue	355	425	∼ 1.2	2+

Light Attenuation Graph of EJ-182 PVT and PS Fibers (µA vs. Distance from SiPM [m])

Loss of Signal Graph in 1 mm PS and PVT Fibers (Bending Loss [%] vs. Bending Diameter D [mm])

LIGHT GUIDES AND ACRYLIC PLASTIC

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Light Guides

Numerous light guides have been fabricated by Eljen Technology to meet a wide variety of light collection applications for scintillators. Light guides are always custom made for each customer's needs. One general rule to remember when considering using light guides: they usually improve the uniformity of light collection but often reduce the average signal amplitude. Light guide types fabricated by Eljen include, but are not limited to, the following general types:

Adiabatic Light Guides: Consists of an array of strips adapting the edges of scintillator plates to a single phototube. These generally apply best on wide scintillators and are the most expensive.
Fishtail Light Guides: Consists of a single solid element providing a smooth adaption of a rectangular cross section to a round PMT face.
Flat Trapezoid Light Guides: Consists of a flat triangular PMMA sheet terminated at the PMT end by a cylindrical rod or disc for effective PMT mounting.

Light guides are fabricated from cast acrylic materials. Cast acrylic generally has good optical clarity, good mechanical properties, and very little natural scintillation response to ionizing radiation.

Cast acrylic is also known as PMMA (polymethylmethacrylate) and is often referred to in a generic sense by the many commercial product names under which it is manufactured. Some of these names include: Lucite®, Plexiglas®, Perspex®, and Rohaglas®. It is normally made as cast sheet stock with UV absorbing additives for general purpose commercial applications. When the UV absorbers are omitted to obtain optical transmission into the ultraviolet regions, the product is often referred to as UVT. Sheet stock up to about 6 mm (0.25”) thick are also made by extrusion processes. However, the best optical properties are obtained with the cast material. Acrylic sheets are occasionally used in fabricating tanks for selected liquid scintillators. In this case, the cast materials provide superior resistance to chemical attack.

The plot below demonstrates typical properties of these two classes of plastics.

ACRYLIC PLASTIC MATERIALS

Material	Description/Application	Commercial Equivalents
Material	Description/Application	NE	S-G
PMMA	Clear acrylic plastic, Light guides	-	BC-802
UVT	UV transmitting acrylic plastic, Light guides	-	BC-800

PROPERTIES	CAST PMMA
Specific Gravity at 20°C	1.190
Refractive Index, n_D (589nm)	1.492
Refractive Index (436nm)	1.502
No. of H Atoms per cm³ (x10²²)	5.73
No. of C Atoms per cm³ (x10²²)	3.58
No. of O Atoms per cm³ (x10²²)	1.43