Abstract: Disclosed is a means for reducing leakage current associated with a path used to couple a high impedance sensor to a detector as, for example, in coupling a smoke-sensitive ionization chamber to an integrated circuit smoke detector chip. A unity gain amplifier is provided which receives a detection voltage signal from the sensor and generates an output guard voltage which tracks the detection voltage signal. The output guard voltage is used to bias the voltage of the areas surrounding the path used to conduct the detection voltage signal. The effect of undesirable leakage paths that may exist between the detection voltage signal conduction path and surrounding areas is reduced by minimizing the voltage across the leakage paths, thus maintaining a high impedance value associated with the detector input.

Abstract: PCT No. PCT/FR 78/00046 Sec. 371 Date Aug. 2, 1979 Sec. 102(e) Date Aug. 2, 1979 PCT Filed Dec. 7, 1978 PCT Pub. No. W079/00353 PCT Pub. Date June 28, 1979A device for detecting and localizing soft gamma and X radiations, comprising an enclosure 10 provided with a window 11 opaque to light and transparent to incident radiations, occupied by a noble gas and provided with electrodes for causing the electrons to drift towards a secondary photon creation space.In said space there reigns an electric field having sufficient value to cause the formation of secondary photons by excitation then de-excitation of the atoms of the noble gas. The secondary photons pass through a transparent window 12 and are converted into photons in the close UV or visible spectrum. The scintillations are localized by PM tubes 23 and 24.

Abstract: A combined dose rate meter and charger unit therefor which does not require he use of batteries but on the other hand produces a charging potential by means of a piezoelectric cylinder which is struck by a manually triggered hammer mechanism. A tubular type electrometer is mounted in a portable housing which additionally includes a Geiger-Muller (GM) counter tube and electronic circuitry coupled to the electrometer for providing multi-mode operation. In one mode of operation, an RC circuit of predetermined time constant is connected to a storage capacitor which serves as a timed power source for the GM tube, providing a measurement in terms of dose rate which is indicated by the electrometer. In another mode, the electrometer indicates individual counts.

Abstract: An ionization chamber has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionize the gas.

Abstract: An alpha particle monitor is disclosed which includes a flow-through linear ionization chamber with means to pass therethrough gas-borne radioactive matter exhibiting alpha decay, such as, radon gas, air-borne plutonium or uranium dust, etc., and an amplifier sensitive to charges on the order of 10.sup.-14 coulombs associated with an alpha emission event. In a preferred form, the amplifier includes a solid state operational amplifier having a stray feedback capacitance sufficiently low to provide, in response to an alpha decay event, an output pulse with a measurable voltage amplitude, e.g., 0.1-1.0 volts, and a feedback resistance sufficiently high to provide the amplifier with a time constant such that the output pulse produced in response to an alpha emission event has a width sufficient to facilitate detection in the presence of noise.

Abstract: When subjected to radiation overload existing Geiger-Mueller counters may give an erroneously low reading, resulting in possible hazard to personnel. The instant invention discloses simple and inexpensive apparatus to remedy this dangerous shortcoming. Depending on the geometry of the detector tube, two possible failure modes have been identified, and circuitry is disclosed to detect the existence of these respective failure modes. The disclosed apparatus indicates the absence of an overload condition, in addition to signaling, by both visible and audible means, the existence of excessive radiation that might result in erroneously low reading of the Geiger-Mueller counter.

Abstract: A radiation detection device comprising a housing which comprises an entrance window and in which at least one ionization chamber detector is arranged. The detector comprises a flat high-voltage electrode which is directed transversely transverse the entrance window and a flat collector electrode which is arranged to be at least substantially parallel to the high-voltage electrode. The end faces of these electrodes which face the entrance window are in electrical contact with a flat auxiliary electrode which extends parallel to the entrance window. As a result, a small direct current flows in a direction transverse to the other electrodes during operation, because the auxiliary electrode has a low electrical conductivity. Consequently, the electrical field in the ionization chamber detector is very homogeneous, with the result that the measuring speed can be optimized.

Abstract: A resistor of a specific resistance value is inserted between a signal line for transmitting ionization chamber current and a logarithmic amplifier. The specific resistance value is selected to be a proper value so that the value of a negative feedback capacitance of the logarithmic amplifier can be made zero or extremely small without instability phenomena such as an overshoot, ringing or oscillation. Accordingly, it is possible that the response time of a logarithmic measuring apparatus is extremely reduced in a small input-current region.

Abstract: A monitoring system transparent to ionizing radiation, designed for measuring the position, intensity, uniformity and directivity of a radiation beam, comprises two or three superimposed ionization chambers respectively provided with respective disk electrodes. One electrode is of smaller area than the other electrode or electrodes, the latter being substantially equal to the cross-sectional area of the radiation beam. Circuits for processing the signals furnished by the different electrodes are associated with comparators and with a safety system which readjusts the beam or deactivates the radiation source in the event that certain "threshold" values are exceeded, indicating a deviation of the beam from a centered position.

Abstract: Improved binary and tertiary gas mixtures for gas-filled particle detectors are provided. The components are chosen on the basis of the principle that the first component is one gas or mixture of two gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a gas (Ar) having a very small cross section at and below aout 0.5 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electron field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

Abstract: A position-sensitive proportional counter circuit is provided which allows the use of a conventional (low-resistance, metal-wire anode) proportional counter for spatial resolution of an ionizing event along the anode of the counter. A pair of specially designed active-capacitance preamplifiers are used to terminate the anode ends wherein the anode is treated as an RC line. The preamplifiers act as stabilized active capacitance loads and each is composed of a series-feedback, low-noise amplifier, a unity-gain, shunt-feedback amplifier whose output is connected through a feedback capacitor to the series-feedback amplifier input. The stabilized capacitance loading of the anode allows distributed RC-line position encoding and subsequent time difference decoding by sensing the difference in rise times of pulses at the anode ends where the difference is primarily in response to the distributed capacitance along the anode.

Abstract: An improved sealed proportional counter window for an X-ray spectrometer includes a metallic foil having high X-ray transmission characteristics and having an ultra thin plastic coating thereon for sealing the inherent porosity of the metallic foil. The plastic coated foil is suitably supported by an arrangement which provides a relatively high percentage of unobstructed counter window area.

Abstract: Measuring channels with ionization detectors as primary input are supervised by monitoring any imbalance between AC and DC components of the measuring currents, primarily to detect insulation failure of the connecting cable on account of heavy radiation and thermal losses. Detection of the imbalance is independent from radiation changes to be measured.

Abstract: A radiation detection ionization chamber comprising an elongated cylindrical pencil-shaped tubing forming an outer wall of the chamber and a center electrode disposed along the major axis of the tubing is disclosed. The length of the chamber is substantially greater than the diameter. A cable connecting portion at one end of the chamber is provided for connecting the chamber to a triaxial cable. An end support portion is connected at the other end of the chamber for supporting and tensioning the center electrode.

Abstract: An array of electrode plates are arranged in parallel and spaced apart relationship to define ionization cells in a channel within a housing that is occupied by high pressured gas. A broad beam of x-ray photons penetrates a window in the housing and produces ionization events that result in analog signals corresponding with photon energies and intensities. Conduction of the signals from the interior to the exterior of the detector housing is accomplished with a printed circuit board assembly that is sealed between the housing and its cover.

Abstract: A radiation detector of the gas-filled counter tube type which has a reduced count rate drift. An electrically conductive coating is applied to the interior insulating surfaces in proximity to the anode wire of a gas-filled counter tube structure having an axially disposed wire anode. The electrically conductive coating is maintained at the same electrical potential as the anode and accumulated charges in proximity to the anode are thereby eliminated. Alternately, the electrically conductive coating applied to the interior insulating surfaces in proximity to the anode may be maintained at the same electrical potential as the outer conducting cylinder in order to eliminate accumulated charges. The elimination of accumulated charges in proximity to the anode significantly reduces count rate drift and hence improves detector performance.

Abstract: A circuit improvement is disclosed for use in an electron capture detector of the type including an electron capture cell, means for applying polarization pulses to the cell to derive a cell current, means for varying the pulse rate to maintain the cell current constant, and means for converting the pulse frequency to an analog signal indicative of the concentration of an electron-capturing component.

Abstract: A portable gamma radiation dose rate meter suitable for use over 3 or 4 decades over the dose rate range 0.1 mR/hr and 1000 R/hr which incorporates an ion chamber or other radiation detector and a null deflection readout system using a calibrated potentiometer and two single light emitting diodes as high and low indicators.

Abstract: In an illustrated embodiment a radiation detector is to be arranged in front of a xeroradiographic cassette and yet to avoid adverse effects on the xerographic image. To achieve this the shielding layer for the cassette is a graphite layer and the electrode layer consists of a vacuum-deposited electrically conductive material having a low atomic number. Desirably the electrode layer has marginal zones which continuously decrease in thickness so that no sharp absorption contours are present which would be over-accentuated in xerographic image production. Because of the utilization of a graphite layer as a protective shield, the absorption of the radiation detector can be kept very small. Electrical contact with the vacuum deposited electrode layer may be by means of a graphite layer which is in electrical contact with the electrode layer.

Abstract: In a proportional counter comprising a detector for detecting radiation pulses, an energy channel for receiving detected pulses, preferably as pre-amplified, from the detector, and a pulse height analyzer for the analysis of pulses received from the energy channel, the background effect is reduced by measuring the detector charge pulse collection time caused by electron diffusion and the time interval between the detector pulses, comparing the measured times with predetermined limit values and, thereupon, discriminating all pulses which have collection times longer than the predetermined rise time that is have too long a rise time, or which appear at shorter intervals than the predetermined limit interval, that is are too close to an adjacent pulse be it a preceding or following pulse. In order to produce signals proportional to said rise time and said time interval, the pulses are preferably transformed in electronic circuits, for example, in two derivation circuits and one integration circuit.

Abstract: Xonics chambers can normally be used only with comparatively low electrode voltages in the Townsend-plateau region of the discharge where no charge carrier multiplication occurs. The sensitivity is then comparatively low. The sensitivity can be increased by increasing the electrode voltage, but this gives rise to a high electrode voltage for a reasonable charge carrier multiplication. According to the invention a gas is added whose ionization energy is smaller than the energy of the lowest metastable levels of the rare gas in the chamber. The charge carrier multiplication, and hence the sensitivity is thus improved without the electrode voltage being substantially increased. For example, when 0.2% by volume trimethylamine is added, an electrode voltage of 13 kV already suffices.

Abstract: A gamma camera within a signal generating system encompassing a stage converting an image which is to be photographed into an electron image, following which there is a locating or position-finding system from which signals emanate which facilitate the pictorial reproduction of the incident radiation.

Abstract: An x-ray exposure device comprising a flat and plane rectangular chamber containing an ionizable gas and having walls provided with electrode structures which generate a potential distribution corresponding to that of two concentric spherical electrodes, an insulating foil on which charge carriers resulting from ionization of the gas by the x-radiation and displaceable in the longitudinal direction of the chamber being arranged therewithin.

Abstract: A shock-, vibrations- and tampering-proof attachment means of an object, h as a signal producing insert of an ionization alarm system coaxially and non-rotatably to a support, such as for land-, marine- and air vehicles provides a spring assembly with a spring and biased coaxial protrusion in the bottom of the object with a helically wound canal running through the protrusion having end orifices in its surface. The support is provided with a U-shaped fork fixed with its yoke in it. A connecting means equipped with a rod traverses the protrusion perpendicularly to its axis. The rod is fastened to both free ends of the yoke. Optimum shapes and dimensions of the respective parts are established, also with the view of maintaining a minimum size of the object itself. The object with the fixed protrusion is mounted by rotation thereof to the support, thus hiding the attachment means and making them vibration proof and inaccessible from the outside.

Abstract: An ionization chamber array, useful in computerized X-ray tomography apparatus comprises a plurality of substantially parallel, rod-like cathodes disposed equi-distant between parallel planar anodes in a high pressure detector gas. X-ray energy enters the array in the plane of the cathodes in a direction substantially parallel to their long dimensions.

Abstract: A two-dimensional array of ionization chamber x-ray detector cells comprises a plurality of planar anode assemblies disposed equi-distant between parallel cathode plates in a gas of high atomic number. Each anode assembly comprises a plurality of conductive strips disposed on a thin dielectric sheet in a direction substantially parallel to the incident x-ray energy.

Abstract: An electrical cable is described wherein an inner conductor having one or more layers of radiation resistant organic insulation extends through a metal sleeve which is larger than the insulation to leave a space capable of accommodating thermal expansion of the insulation layer or layers and which may be filled with a non-reacting gas. Also described are a method for connecting such a cable, and a radiation sensor and cable assembly incorporating such a cable.

Abstract: An ionization chamber for use in determining the spatial distribution of x-ray photons in tomography systems comprises a plurality of substantially parallel, planar anodes separated by parallel, planar cathodes and enclosed in a gas of high atomic weight at a pressure from approximately 10 atmospheres to approximately 50 atmospheres. The cathode and anode structures comprise metals which are substantially opaque to x-ray radiation and thereby tend to reduce the resolution limiting effects of x-ray fluoresence in the gas.In another embodiment of the invention the anodes comprise parallel conductive bars disposed between two planar cathodes.Guard rings eliminate surface leakage currents between adjacent electrodes.

Abstract: A method and apparatus designed for the purpose of determining quickly and with high resolution the spatial distribution of radioactivity within an object emitting radioactive particles, especially those of low energy. A gas-filled position sensitive detector is used having an elongated electrode wire enclosed inside of and running the length of the detector. The object is placed inside the detector in close proximity to the wire. An electric circuit means is operably connected to the wire to determine the point along the wire at which an emitted particle is sensed. A two-or three-dimensional spatial distribution can be obtained by using a plurality of such wires.

Abstract: A system for detecting ultraviolet (UV) radiations and particularly adapted for the detection of fire. Electrical pulses are produced at a rate proportional to the intensity of UV energy received by a UV detector tube. An alarm and/or control function is actuated only when the tube pulse rate and pulse rate duration correspond to predetermined values. In addition, the alarm and/or control function is inhibited when the detector tube is exposed to non-fire created UV energy.

Abstract: An electrode arrangement for the detection of species ionized by radiant energy from a radiation source, comprising: an annular cathode; a shield, opaque to the radiant energy, extending across the cathode and having an aperture smaller than and coaxial with the annulus formed by the cathode; and an elongated anode having its distal end coaxially of the cathode and the shield aperture, the cathode being shielded from and the anode being exposed to the radiant energy from the radiation source.

Abstract: A parallel-plate variable-gap diode is described which is used to detect X nd gamma radiation pulses. The collector of the diode is comprised of an interior circular portion and a concentric external annular portion, the collecting surfaces of which are coplanar and noncontiguous. A shielded low-inductance resistor-ring shunts the bulk of the sampled current back through the annular portion of the collector to the emitter thereby reducing self-bias effects. The central location and relatively small size of the current sampler minimize the perturbing influence of the walls at the periphery of the cavity. A one-dimensional electron transport analysis can therefore provide the link between the incident radiation and the observed current response of the diode. The cylindrical walls of the cavity are interchangeable spacers which permit the variation of separation between emitter and collector.

Abstract: An improved system of circuitry for use in combination with an ionizing-radiation detector over a wide range of radiation levels includes a current-to-frequency converter together with a digital data processor for respectively producing and measuring a pulse repetition frequency which is proportional to the output current of the ionizing-radiation detector, a dc-to-dc converter for providing closely regulated operating voltages from a rechargeable battery and a bias supply for providing high voltage to the ionization chamber. The ionizing-radiation detector operating as a part of this system produces a signal responsive to the level of ionizing radiation in the vicinity of the detector, and this signal is converted into a pulse frequency which will vary in direct proportion to such level of ionizing-radiation.

Abstract: A sheet beam x-ray source having energy components greater than 1.02 Mev is passed through an object under study. The emitted gamma rays due to pair production are measured using a positron-sensitive coincidence counting system on either side of the excited section. The location of each detected event is made using the positron information of each detector and the location of the excited section. An image is rapidly formed which is sensitive to the atomic number and density of materials in the cross section of the object.

Abstract: A method and apparatus for taking x-ray pictures by ionography wherein the object to be studied is radiated by x-rays which fall on an ionization chamber. The ionization chamber includes a pair of electrodes at least one of which is in the form of a flexible sheet which includes a conductive layer and an insulating layer for collecting on the surface thereof ions generated in the chamber. Both of the electrodes have substantially spherically curved surfaces with their respective centers of curvatures located at the source of ionizing radiation. The flexible sheet is formed into a spherically curved shape by establishing a differential gas pressure across the sheet.

Abstract: A radiation measuring instrument including a fast charge digitizer and a digital data acquisition system has been developed. The fast charge digitizer includes a charge integrator connected to a conventional ionization chamber which generates an output current in proportion to ionizing radiation exposure rate. The charge integrator has an output connected to a comparator which is switched from a high state to a low state when the output of the integrator goes above the comparator threshold. The comparator output is connected to a bistable multivibrator consisting of two non-retriggerable one shot multivibrators connected in a feedback configuration. As long as the comparator output is in the low state, the bistable multivibrator generates a train of pluses which are fed back through an analog switch and a high megohm resistance to the input of the integrator.

Abstract: Logic elements are provided for a reactor period meter trip circuit. For one element, first and second inputs are applied to first and second chopper comparators, respectively. The output of each comparator is O if the input applied to it is greater than or equal to a trip level associated with each input and each output is a square wave of frequency f if the input applied to it is less than the associated trip level. The outputs of the comparators are algebraically summed and applied to a bandpass filter tuned to f. For another element, the output of each comparator is applied to a bandpass filter which is tuned to f to give a sine wave of frequency f. The outputs of the filters are multiplied by an analog multiplier whose output is 0 if either input is 0 and a sine wave of frequency 2f if both inputs are a frequency f.

Abstract: An improved gas-filled proportional counter which includes a resistor netk connected between the anode and cathode at the ends of the counter in order to eliminate "end effects".