Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Reexamination Certificate
1999-01-29
2001-04-17
Font, Frank G. (Department: 2877)
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
C250S487100
Reexamination Certificate
active
06218670
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to plastic scintillators, and in particular to a crystalline polymeric scintillator having a thin layer of the same polymer mixed with a white pigment that is laminated or coextruded to the exterior surface of the scintillator.
BACKGROUND OF THE INVENTION
Scintillators are materials that emit flashes or pulses of light when they interact with ionizing radiation such as gamma rays. Plastic scintillators formed from crystalline polystyrene are particularly well suited for radiation detection applications. Crystalline polystyrene is readily melt processible and capable of being extruded into a variety shapes and sizes to meet the spatial requirements of the detector involved.
When crystalline polystyrene scintillators are employed in radiation detection applications, conventional practice is to paint the scintillator white or wrap the exterior surface of the scintillator with a white sheet material such as, for example, TYVEK brand polymeric sheet material. The scintillator is generally painted or wrapped such that the exterior surface has a white coating thereon. The white coating improves that light yield from the scintillator and simplifies the handling of the scintillator by providing a protective exterior surface. The process of painting or wrapping a white coating on the exterior surface of a scintillator is labor intensive, however, thereby increasing the cost to manufacture the scintillator.
SUMMARY OF THE INVENTION
A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder comprises polymeric material from which the scintillator is formed.
In one embodiment of the polymeric scintillator, the polymeric material is crystalline polystyrene. The polymeric material can also be formed from other polymeric scintillator materials generally.
In one embodiment, the reflective pigment is a white pigment, preferably titanium dioxide. In another embodiment, the reflective pigment is a white pigment comprising magnesium oxide. Other pigments can be employed depending upon the spectral distribution of light to be collected.
In one embodiment of the polymeric scintillator, the proportion of titanium dioxide in the reflective layer is about 10% by weight.
In a method of forming a polymeric scintillator having a reflective layer adhered to the exterior surface thereof, the method comprises:
(a) extruding an inner core member from a first amount of polymeric scintillator material;
(b) coextruding an outer reflective layer on the exterior surface of the inner core member, the outer reflective layer comprising a reflective pigment and a second amount of the polymeric scintillator material.
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patent: 4631409 (1986-12-01), Sparacia et al.
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patent: 4720426 (1988-01-01), Englert et al.
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patent: 5663005 (1997-09-01), Dooms et al.
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“Plastics Materials and Processes (excerpt)”, Van Nostrad Reinhold Co., p. 597, Schwartz et al, 1982.
Para Adam
Yun Jae-Chul
Font Frank G.
McAndrews Held & Malloy Ltd.
Smith Zandra V.
Universities Research Association Inc.
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