General Electric Company

Pacific Bell

Dominic A Cusano

Charles D Greskovich

Frank A DiBianca

Philip J White

Robert K Swank

Harold F Webster

James A Loughran

Robert J Riedner

Jerome S Prener

Yen Sheng Sun

Gary William Yeager

George E Possin

Dale M Brown

Fred F Holub

Svante Prochazka

Robert Joseph Lyons

Gerald J Michon

Marvin Garfinkel

Stanley Joseph Lubowski

Erdogan O Gurmen

Jean-Pierre J Georges

Frank A Di Bianca

Frank A DeBianca

A polycrystalline ceramic scintillator exhibiting reduced afterglow includes between about 5 and 50 mole percent Gd.sub.2 O.sub.3, between about 0.02 and 12 mole percent of either Eu.sub.2 O.sub.3 or Nd.sub.2 O.sub.3 as a rare earth activator oxide, and between about 0.003 and 0.5 mole percent of either Pr.sub.2 O.sub.3 and Tb.sub.2 O.sub.3 as an afterglow reducer. The remainder of the scintillator composition is Y.sub.2 O.sub.3. The resulting scintillator is especially useful for a radiation detector of the type having a plurality of radiation receiving channels. A scintillator body is disposed in each channel so that radiation being received therein is incident on the scintillator body and causes the body to convert the incident radiation to light energy of a predetermined wavelength. The radiation detector also includes means for converting the light energy from the scintillator into electrical signals which are proportional to the amount of radiation incident on the scintillator body. Methods for preparing the scintillator of the present invention include sintering, sintering combined with gas hot isostatic pressing, and vacuum hot pressing.

Radiation detector employing solid-state scintillator material and

A low capacitance radiation detector comprises a monocrystalline silicon substrate heavily doped to N type conductivity with a more lightly doped N type conductivity epitaxial layer formed on the substrate. A plurality of heavily doped N type upper surface layer segments are formed in the epitaxial layer. A patterned region of the epitaxial layer, heavily doped to P type conductivity and in the shape of parallel stripes joined at each end by a respective stripe perpendicular to the parallel stripes, is formed in the epitaxial layer and situated between adjacent ones of the upper surface layer segments, with each stripe extending into the epitaxial layer deeper than, and separated from, the upper surface layer segments so as to form a minority charge carrier-collecting PN junction with the epitaxial layer. The parallel stripes are spaced apart from each other by a distance smaller than or comparable to the minority charge carrier recombination diffusion length for the epitaxial layer, and the epitaxial layer thickness is smaller than or comparable to the minority charge carrier recombination diffusion length. In a second embodiment, the epitaxial layer has beveled edges and the heavily doped N type upper surface layer segments formed in the epitaxial layer extend over the beveled edges.

Low capacitance X-ray radiation detector

An elastomeric light valve has a substrate with a principal surface on which is formed a multiplicity of pixels; each pixel includes a first set of pixel electrodes interdigitated with a second set of pixel electrodes. A silicone elastomer gel is disposed over both the principal substrate surface and the two sets of pixel electrodes. At least one silicone/polycarbonate self-supporting pellicle is disposed substantially completely over the gel layer; the pellicle and elastomer gel layer are heat cured to improve the response of the layers to electrostatic forces induced in the light valve by control voltages applied during operation of the light valve. A layer of gold is disposed over the at least one pellicle and a layer of silver is disposed over the gold layer to provide an exposed specular surface which is easily deformed and resilient to transverse stresses. Address-lines are provided for applying control voltages to the first and second sets of pixel electrodes responsive to a video signal; a bias voltage is applied to the gold and silver layers to provide optimum light valve sensitivity at lower control voltages.

Transferrable, self-supporting pellicle for elastomer light valve

A method of producing a photostimulable x-ray converter for digital radiographic applications including forming a solid mixture of europium activated barium fluorohalide phosphor and a chemical compound containing an impurity ion, heating the mixture to cause the impurity ion to diffuse into the phosphor matrix, combining the treated phosphor crystals with a thermoplastic synthetic organic polymer, subjecting the second mixture to elevated pressure and temperature conditions to obtain a void free suspension and cooling the mixture to obtain a solid storage member.

Method of producing a photostimulable x-ray image convertor

A system and method for improved conductive circuit patterning utilizing laser ablation is disclosed. In an embodiment, a substrate, which has an electroless conductive layer plated thereon, is heated to a predetermined temperature for a predetermined time to form an oxide layer upon the conductive layer. The oxide layer, due to its non-absorptive properties, is more easily ablated than the conductive layer. Hence, the overall processing time for circuit patterning is significantly reduced.

System and method for providing a conductive circuit pattern utilizing

A method for providing a circuit pattern on an insulated substrate that has improved adherence thereto. By providing an electroless conductive layer of a predetermined thickness on the substrate and thereafter exposing the substrate to an ablative laser beam, the resultant conductive lines are stronger than those provided by previously known techniques.

Method for providing a strengthened conductive circuit pattern

A digital radiographic imaging system which employs co-operative means for converting the x-rays to an optical image having enhanced quality and detecting said optical image. The x-ray conversion medium employed in the improved radiographic system is positioned physically contiguous to a bi-directional array of electrical charge transfer devices which convert the optical image to an electronic analog representation thereof. Digital information processing means are further included in the improved radiographic system to convert the electronic analog representation of the optical image to a recorded digital representation thereof. The x-ray conversion medium being employed in the improved radiographic system is a high efficiency scintillator body which moves co-operatively with the photo detection means being employed in a further synchronious relationship with a moving fan beam of X radiation being employed to generate the desired optical image after passage through a stationary object.

Digital radiographic imaging system and method therefor

A polycrystalline ceramic scintillator is disclosed for radiographic applications which has received a controlled oxidation anneal to reduce radiation damage otherwise occuring when said scintillator is exposed to X radiation during conversion of said X radiation to the display image. The particular ceramic material treated in said manner comprises a densely sintered rare earth doped gadolinia containing metal oxide having a cubic crystal structure which has been annealed after sintering in a controlled oxygen containing atmosphere. A preferred ceramic composition comprises from about 5 mole percent up to about 50 mole percent Gd.sub.2 O.sub.3, between about 0.5 mole percent and 12 mole percent of a rare earth activator oxide selected from the group consisting of Eu.sub.2 O.sub.3 and Nd.sub.2 O.sub.3, and between about 0.0001 and 0.5 mole percent of at least one afterglow reducer selected from the group consisting of Pr.sub.2 O.sub.3 and Tb.sub.2 O.sub.3, and the remainder of said composition being Y.sub.2 O.sub.3. A treatment to produce said improved x-ray conversion medium is also disclosed along with radiographic imaging systems and methods employing said improved x-ray image conversion medium.

Solid state scintillator and treatment therefor

Rare-earth-doped, polycrystalline yttria-gadolinia ceramic scintillators with high density, optical clarity, uniformity, cubic structure and which are useful in the detection of x-rays, include one or more of the oxides of rare earth elements Eu, Nd, Yb, Dy, Tb, and Pr as activators. The ceramic scintillator may also include CaO, SrO, and Yb.sub.2 O.sub.3 as afterglow reducers. Sintering, sintering combined with gas hot isostatic pressing, and hot pressing methods for preparing the ceramic scintillators are also described.

Rare-earth-doped yttria-gadolina ceramic scintillators

Sintering and gas hot isostatic pressing are used to prepare polycrystalline yttria-gadolinia ceramic scintillator bodies. Multicomponent powder compacts, formed by cold pressing and cold isostatic pressing, are sintered to the closed porosity stage. The density of the sintered compacts is then increased by gas hot isostatic pressing. The finished scintillator includes Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, and one or more of Eu.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Pr.sub.2 O.sub.3, and Tb.sub.2 O.sub.3 rare-earth activator oxides. At least one of the oxides of elements Zr, Th, and Ta is included as a transparency promoting densifying agent. At least one of CaO and SrO may be included as a light output restorer.

Preparation of yttria-gadolinia ceramic scintillators by sintering and

An improved scintillator for a solid state radiation detector useful in CT (computed tomography), DR (digital radiography), and related technologies. The scintillator, rather than being grown as a single crystal, is formed by means of hot pressing or sintering, as a polycrystalline ceramic. Rare earth oxides doped with rare earth activators are selected to yield a cubic crystal structure of high density and transmittance, which satisfies radiation detector requirements better than crystals utilized heretofore.

Rare earth ceramic scintillator

A method for preparing high density yttria-gadolinia ceramic scintillators by cold-pressing multicomponent powder to form powder compacts and then sintering the compacts to form transparent-to-translucent ceramic scintillator bodies. The powder compacts are formed by either die pressing or die pressing followed by isostatic pressing to further increase green density. The powder compacts are sintered in vacuum or a reducing atmosphere at a temperatue of between 1800.degree. C. and 2100.degree. C. The preferred heating sequence includes a holding period at a temperature lower than the final sintering temperature. The finished scintillator includes Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, and one or more of Eu.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Pr.sub.2 O.sub.3, and Tb.sub.2 O.sub.3 rare earth activator oxides. At least one of the oxides of elements Zr, Th, and Ta is included as a transparency promoting densifying agent. At least one of CaO and SrO may be included as a light output restorer.

Method for sintering high density yttria-gadolinia ceramic scintillators

Sintering and gas hot isostatic pressing are used to prepare polycrystalline yttria-gadolinia ceramic scintillator bodies. Multi-component powder compacts, formed by cold pressing cold isostatic pressing, are sintered to the closed porosity stage. The density of the sintered compacts is then increased by gas hot isostatic pressing. The finished scintillator includes Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, and one or more of Eu.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Pr.sub.2 O.sub.3, and Tb.sub.2 O.sub.3 rare earth activator oxides. The finished scintillator may also include at least one of SrO and CaO as afterglow reducers.

A method for preparing high density yttria-gadolinia ceramic scintillators includes cold-pressing a multicomponent powder to form powder compacts and then sintering the compacts to form transparent-to-translucent ceramic scintillator bodies. The powder compacts are formed by either die pressing or die pressing followed by isostatic pressing to further increase green density. The powder compacts are sintered in vacuum or a reducing atmosphere at a temperature of between 1800.degree. C. and 2100.degree. C. The preferred heating sequence includes a holding period at a temperature lower than the final sintering temperature. The finished scintillator includes Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, and one or more of Eu.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Pr.sub.2 O.sub.3, Dy.sub.2 O.sub.3, and Tb.sub.2 O.sub.3 rare earth activator oxides. The finished scintillator may also include at least one of SrO and CaO as afterglow reducers.

Polycrystalline ceramic scintillators are prepared by a vacuum hot-pressing method. The process includes pressing a multi-component powder at high temperature under vacuum. Following a holding period, the pressure and temperature are increased and maintained for a predetermined length of time. The finished scintillator includes Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, and one or more of Eu.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Yb.sub.2 O.sub.3, DY.sub.2 O.sub.3, Pr.sub.2 O.sub.3, and Tb.sub.2 O.sub.3 rare earth activator oxides. The finished scintillator may also include at least one of SrO and CaO as afterglow reducers.

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Schenectady, NY, United States of America

Dominic A Cusano