Westinghouse Electric Corporation

John Bartko

Thomas V Congedo

Krishan S Tarneja

Edward Jean Lahoda

David C Grant

Earl S Schlegel

Patrick E Felice

Chang K Chu

Karl F Schoch, Jr

Steven H Peterson

Michael C Skriba

Joseph E Johnson

Edward F Sverdrup

Arthur L Wolfe

Robert E Witkowski

William D Partlow

David F McLaughlin

John G Seidel

Arnold H Fero

Francis H Ruddy

Maurice H Hanes

James W Wonn

Frank H Ruddy

Prosenjit Rai-Choudhury

Richard C Smith

Stanwood L Anderson

Joseph L Gonzalez

J Richard Hansen

Phillip D Blais

Stanwood L Anderson, Jr

Kuan H Sun

Francis H Ruddgy

A system for determining depth profiles of concentrations of hazardous elements in soils comprises a neutron source for generating neutrons of a first energy level and irradiating a volume of soil with the neutrons. Nuclear reactions are effected within the soil and gamma radiation is emitted from the soil. The system also includes an array of gamma detectors for detecting gamma radiation emitted from the soil; source electronics for controlling the width of regularly repeated pulses of neutrons generated by the neutron source; detector electronics associated with the gamma detectors for amplifying and digitalizing signals generated by the gamma detectors and storing data representing the digitalized signals; spectral analysis software for analyzing the data and determining the concentrations of selected target elements in the soil; and an acquisition interface module (AIM). The AIM controls the timing of the source and detector electronics such that the neutron source generates neutrons in regularly repeated bursts of a prescribed pulse width and the detectors and detector electronics detect gamma rays during a plurality of time intervals associated with the burst and acquire groups of data. Each group is indicative of a number of gamma rays emitted and their energy levels during a corresponding time interval. The system also includes a mobile platform carrying the neutron source, array of gamma ray detectors and software for determining a depth profile of a target element. Trace elements can also be detected with the disclosed system.

Prompt gamma neutron activation analysis system

The concentrations of residual heavy metal contaminants in the particulate material in a slurry produced in a particulate material washing process are monitored on-line and can be used to control the washing process. In alternative embodiments of the invention, x-rays, thermal neutrons or laser beams are directed at the slurry as it flows through a flow cell to induce emission of secondary x-rays, gamma rays or light, respectively, characteristic of the heavy metal contaminants and constituents representative of the solids contents of the slurry. These characteristic energies are measured and used to determine the concentration in ppm of the residual heavy metal contaminants in the particulate material within the slurry.

System and method for on-line monitoring and control of heavy metal

Processes for producing stable, radiation hard, highly conductive polymers by a combination of chemical doping and ion irradiation and microelectronics are described. The highly conductive polymers formed by these processes may contain regions of different kinds of conductivity on the same polymer. Resist coatings and masks are used in conjunction with chemical doping and ion irradiation to create specific predetermined n and p conductivity patterns and insulation areas on polymeric films of selected thicknesses for electronic circuitry applications. The resulting circuitry, besides having a conductivity approaching that of metal, is extremely light in weight, flexible, and conductively stable. Several different configurations of microelectronic junction devices fabricated from single type or multiple type conductivity polymer films used either alone or with a polymer of opposite conductivity and a suitable metal or metals are disclosed.

Production of highly conductive polymers for electronic circuits

High resolution scintillation counters comprise a flat-faced photomultiplier tube 10 optically coupled to a long scintillator rod 30 having reduced internal light reflectance 45 and a medium 55 between the photomultiplier tube and the scintillator, said medium having both an index of refraction less than that of the scintillator and the capacity to attenuate light traveling from the scintillator to the photomultiplier on the basis of the light's point of origin within the scintillator. In preferred embodiments, the medium comprises air. The scintillation counters disclosed are useful in the detection of electromagnetic radiation, especially gamma rays.

High resolution scintillation counters

Disclosed is a method and apparatus for measuring the burnup of nuclear fuel. A curve giving the calculated relationship between the fast neutron emission rate and the burnup of fuel is prepared. The fast neutron counting rate from a sample of nuclear fuel of known burnup is measured and the proportionality ratio between that measurement and the fast neutron emission given by the curve for the same burnup is determined. The fast neutron counting rate of nuclear fuel of unknown burnup is then measured and multiplied by the proportionality ratio to determine the fast neutron emission rate, from which the unknown burnup is then determined by means of the curve.

Measuring nuclear fuel burnup

A neutron dosimeter and a method for neutron dosimetry involving a two-layer structure, one layer being a fissile material, and the other being a material which changes its conductivity in accordance with a density of implanted ions. Neutrons striking the fissile material result in the production of energetic ions, a determinable number of which implant themselves in the second layer and so alter its conductivity. Measurements of the conductivity of the second layer provide information from which neutron dose may be inferred.

Neutron dosimeter

A method and apparatus for measuring a neutron flux in which the neutrons induce fission reactions in the layer of fissile material, the fission reactions in turn inducing light pulses in a scintillator material. A photomultiplier tube detects the light pulses and emits an electrical pulse in response. The electrical pulses are summed, checked for coincidence, stored, and otherwise manipulated in order to detect and measure neutron flux. In one advantageous embodiment of the invention, several different fissile materials or coated and uncoated fissile materials are used in order to obtain a spectral distribution of the incident neutron flux. At another embodiment, opposed detectors are used in order to discriminate between actual neutron-induced fission events and background events.

Method and apparatus for neutron dosimetry

A method of lithographically forming a pattern on a surface is disclosed. The surface on which the pattern is to be formed is first coated with a resist layer. A mask preferably consisting of a beryllium of foil and a pattern gold layer affixed thereto is then positioned in overlying relationship to the resist layer. The thickness of the beryllium foil is selected such that it is transparent to high energy particles of a preselected energy while the combination of the pattern gold areas and the beryllium foil is impervious to these particles. A flood beam of high energy particles is directed such that it impinges on the beryllium foil thereby exposing the resist in areas not protected by the combination of the beryllium foil and the gold. The resist layer is processed to produce a patterned layer.

High resolution lithography using protons or alpha particles

A method for eliminating the latch-up effect in integrated circuits having parasitic pnpn structures has been described comprising the step of irradiating the circuit with high energy particulate ions to provide low lifetime regions in the circuit to lower parasitic transistor gain. The invention overcomes the problem of latch-up effect in integrated circuits where parasitic pnpn structures act as thyristors or silicon-controlled rectifiers which provide a low impedance path across the pnpn structure when the thyristor or silicon-controlled rectifier is turned on such as by transient ionizing radiation or by transient circuit voltages which forward bias the external junctions of the pnpn structure.

Method for radiation hardening semiconductor devices and integrated

A method of reducing the reverse recovery charge of thyristors without substantially increasing forward voltage drop by first determining the depth of the anode PN junction from a major surface adjoining a cathode emitter region. The depth of maximum defect generation in thyristor on irradiation through the major surface with a given radiation source radiating particles with molecular weight greater than one, preferably proton or alpha particles, and adjusting the energy level at the major surface of the thyristor from the radiation source to provide the depth of maximum defect generation adjacent the anode PN junction and preferably in the anode base region within 20 micrometers of the anode PN junction or in the anode emitter region within 15 micrometers of the anode PN junction. Thereafter the thyristor is irradiated through said major surface with the adjusted energy level from the radiation source to a given dosage to reduce the reverse recovery stored charge of the thyristor without substantially increasing the forward voltage drop.

Reducing the reverse recovery charge of thyristors by nuclear irradiation

Irradiated regions are formed in materials such as semiconductor bodies by nuclear radiation where the irradiated regions are of a desired thickness, dosage and dosage gradient, a desired distance from a selected surface of the material. A nuclear radiation beam from a given radiation source radiating particles with molecular weight of at least one (1) is provided that can penetrate the material through a selected surface to a depth greater than the maximum depth of the irradiated region from the selected surface. A beam modifier is formed of a given material and non-uniform shape to modify the energy of the radiation beam on transmission therethrough to form a transmitted radiation beam capable of forming an irradiated region of a desired thickness and dosage gradient in the material a given distance from the selected surface on irradiation of the material through the selected surface with the transmitted radiation beam. The material in which the desired irradiated region is to be formed is positioned with the selected surface thereof to be exposed to the radiation beam from the radiation source on transmission through the beam modifier. The material is thereafter irradiated through the beam modifier and through the selected surface with the radiation beam, preferably while the beam modifier and material are moved relative to each other through a predetermined motion, to form in the material an irradiated region of desired thickness, dosage and dosage gradient, a desired distance from the selected surface. The irradiated region thus formed in semiconductor bodies are particularly of value in changing the electrical characteristics without substantial change of other electrical characteristics.

Forming of contoured irradiated regions in materials such as

A method for making a pnpn semiconductor reverse conducting thyristor comprises the steps of forming n-type semiconductor layers on both sides of a p-type semiconductor substrate for forming an n-type emitter layer and an n-type anode-base layer. A p-type semiconductor impurity region is formed in the n-type anode-base layer for forming a p-type anode layer. A p.sup.+ -type semiconductor layer is ion implanted in the p-type substrate adjacent to the n-type cathode emitter layer by irradiating it with boron atoms.

Method of making ion implanted reverse-conducting thyristor

The switching time of certain semiconductor devices is decreased while maintaining other electrical characteristics of the devices by irradiating them with a neutron radiation source of greater than 1.0 Mev. to a dosage between 1.times.10.sup.11 and 1.times.10.sup.15 neutrons per square centimeter. The irradiation is preferably to a dosage between 1.times.10.sup.1 and 1.times.10.sup.14 neutrons per square centimeter and preferably has substantial energy greater than 14 Mev. The devices are also annealed during and/or subsequent to the irradiation at a temperature higher than the highest specified temperature and preferably at least 50.degree. C. higher than the highest specified temperature.

Reducing the switching time of semiconductor devices by neutron

The turn-off time of a reverse blocking diode thyristor is decreased without significantly effecting other electrical characteristics by irradiating with a radiation source to a dosage corresponding to between about 4 .times. 10.sup.13 and about 2 .times. 10.sup.14 electrons/cm.sup.2 and preferably to between about 6 .times. 10.sup.13 and about 2 .times. 10.sup.14 electrons/cm.sup.2 with 2 MeV electron radiation source. Preferably the radiation source is electron radiation with an energy greater than 1 MeV.

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Monroeville, PA, United States of America

John Bartko