Abstract: A new design for a cylindrical ionization detector, featuring a resistive cathode, and external pickup wires that sense both the azimuthal and radial coordinates of interaction vertices. Combined with measurement of the longitudinal coordinate (using resistive anode wire charge division or other technique), the proposed design can provide an accurate 3-dimensional imaging detector and offer improved spectroscopic response.

Abstract: The invention provides apparatus and methods which facilitate movement of an instrument relative to an item or location being monitored and/or the item or location relative to the instrument, whilst successfully excluding extraneous ions from the detection location. Thus, ions generated by emissions from the item or location can successfully be monitored during movement. The technique employs sealing to exclude such ions, for instance, through an electro-field which attracts and discharges the ions prior to their entering the detecting location and/or using a magnetic field configured to repel the ions away from the detecting location.

Abstract: A radiation detector comprises two electrode arrangements, each including a dielectric substrate and an electrically conducting layer formed on a first surface of respective dielectric substrate, wherein the electrodes are oriented such that the conducting layers are facing each other. A dielectric spacer is provided to hold the electrodes at a distance from each other to thereby define an inter-electrode space, which, during use, is filled with an ionizable gas. The electrodes are held at respective electric potentials to drift electrons released during ionization of the ionizable gas by external radiation towards one of the electrodes for detection.

Abstract: The present invention concerns an ionization chamber cylindrical in shape comprising an anode (35) formed by a central rod in current-carrying material and a cathode (38) in current-carrying material around the said anode, both connected to two elements of a mechanical base of the said chamber in which two cylindrical end shields (36, 37) in non-magnetic and insulating material are centred on the anode (35) and arranged at right angles to this at both ends, the cathode (38) being made up of a spooled wire on the outer rim of these two end shields (36, 37).

Abstract: An integrated CMOS semiconductor circuit comprises: an internal circuit composed of CMOS transistors including P3- and N-channel transistors each having a gate electrode and source/drain regions formed on a semiconductor substrate, the internal circuit functioning in at least two states including an active state in which data is input and output, and a standby state in which a state of the internal circuit is maintained; an external circuit composed of any electrical element and provided with a power source; and a switch portion which is enable to apply, in the standby state in the internal circuit, a reverse bias between the source and the substrate of either one of the P- and N-channel transistors of the internal circuit by the power source of the external circuit.

Abstract: The present invention describes an apparatus for detection of ionizing radiation, wherein the incident radiation ionizes a substance, and the electrons released as a result thereof are accelerated in a dual parallel plate electrode arrangement. These electrons will interact with a scintillating substance to emit light, which is detected by a position sensitive light detector. Since the light is emitted isotropically in such scintillator measures are taken to achieve a good spatial resolution. Thus, the scintillating substance is either arranged in an array of separately located scintillating elements, wherein each scintillating element is separated from the other ones by means of a light impermeable wall, or has an extension in the direction of the accelerated electrons shorter than the absorption length of the light photons emitted in the scintillating substance.

Abstract: Apparatus and methods for measuring activity of radioactivity at a source location within an environment provided. The method in particular includes measuring emissions using an instrument as a measurement location, which instrument includes a detector, the instrument considering a detector field of view of the environment, which field of view includes a source location and providing an indication of detected emissions for that field of view, correcting the detected emissions to give emitted emissions in respect of that field of view, the correction being achieved by using a correction factor specific for that field of view, the correction factor accounting for one or more field of view format and/or the attenuation between the source location and the detector and/or the distance between the source location and the detector, the emitted emissions being indicative of the activity.

Abstract: In order to obtain suitable absorption of the radiation to be detected in the detector gas of a radiation detector, in particular an X-ray detector, the detector is constructed in such a way that the radiation enters the detector parallel to the counting wire, thus offering an absorption path having any desired length. According to the invention, a number of avalanche chambers 50 is arranged adjacent the absorption chamber 46, said avalanche chambers having a comparatively small cross-section. The avalanche chambers are provided with grids 54 in such a way that charge multiplication by the grid voltage can occur only in the avalanche chamber. Due to the comparatively small cross-section of the avalanche chambers, broadening of the current impulses to be detected is prevented. Moreover, the comparatively long absorption chamber offers good radiation absorption and the presence of several avalanche chambers enables a favourable detection rate.

Abstract: A detector (64) for detection of ionizing radiation, an apparatus for use in planar beam radiography, comprising such a detector, and a method for detecting ionizing radiation. The detector comprises: a chamber filled with an ionizable gas; first and second electrode arrangements (2, 1, 18, 19) provided in said chamber with a space between them, said space including a conversion volume (13); means for electron avalanche amplification (17) arranged in said chamber; and, at least one arrangement of read-out elements (15) for detection of electron avalanches. A radiation entrance is provided so that radiation enters the conversion volume between the first and second electrode arrangements. In order to achieve well-defined avalanches the means for electron avalanche amplification includes a plurality of avalanche regions.

Abstract: A low cost and simple technique for measurement of radioactive contaminants in the air, soil, or in buildings is provided. The alpha, beta gamma radiation monitor comprises a thin window and two more removable radiation windows on top of a pancake-shaped conductive plastic chamber, with a microscope and a carbon fiber electrometer within the chamber protruding through the chamber's side wall, and the microscope and electrometer opposing each other. Within the chamber the microscope is optically focused on the electrometer fiber. Three radiation windows are provided: one admits alpha particles, beta particles and gamma radiation to the chamber, another admits beta particles and gamma radiation, and a third one admits only gamma radiation. Thus one can measure or observe alpha, beta, and gamma radiation, beta and gamma radiation, or only gamma radiation. The present invention's configuration allows the concentration of each type of radiation to be independently determined.

Abstract: An optical sensor for detecting a document moving along a document path. The invention provides at least two light paths across the document path, so that the document breaks at least one of the light paths as it moves along the document path, and this broken light path indicates the presence of the document. In an exemplary embodiment, the optical sensor comprises a photo-emitter that emits light across the document path to provide the first light path. A first reflector is optically coupled to the photo-emitter, and receives and reflects the light emitted by the photo-emitter. At least a second reflector is optically coupled to the first reflector to receive the light from the first reflector and to reflect that light across the document path to provide the second data path. A photo-detector is disposed across the light path from the second reflector and is optically coupled to the second reflector.

Abstract: The application of gas-detection principles on both dual-energy detection, such as for chest radiography and mammorgraphy, and quantitative autoradiography enhances dramatically the image quality of the digital dual-energy detector with great implications in general-purpose digital radiography, computer assisted tomography (CT), microtomography and x-ray microscopy, and offers notable advantages over film autoradiography with a higher sensitivity, much lower exposure times, as well as imaging access at the cellular level. A gas microstrip detector receives incident radiation through a subject to generate an image. The detector includes a substrate having on a first surface a plurality of alternating anodes and cathodes, a detector cathode spaced apart from and opposing the substrate, and a zone for dispensing a gaseous medium between the substrate and the detector cathode and for receiving incident radiation imparted through the subject.

Abstract: This is a method of generating a plurality of images of a substrate from radioactive radiation coming from a plurality of radioactive tracers contained in the substrate. To this end, data representing the different detection signals generated by a detector are memorised, individually for each radioactive emission detected during a certain observation period, then statistical processing of these data is carried out in such a way as to estimate the images of the different tracers which correspond best to the set of memorised data.

Abstract: A monitor for measuring the activity of a surface contaminated with a radioactive material, such as tritium, is disclosed. The monitor comprises: (a) a collector spaced from the surface; (b) a potential generators for generating a potential difference between the surface and the collector sufficient to induce particle migration; and (c) an electrometer or other current measuring device for measuring the current generated by impingement of charged particles on the collector.

Abstract: A radiation beam scanner system employs a peak detection methodology to measure the intensity and distribution of radiation produced by a medical linear accelerator. The scanner system combines the capability to perform scanning measurements with the capability to perform high accuracy calibrations of the linear accelerator. The system employs two ion chamber detectors, signal and reference, with the signal detector positioned within a tank of water (phantom tank). As the water is irradiated by the linear accelerator, the signal detector is continuously moved within the water by means of electrical stepper motors as the reference detector remains stationary at some point within the radiation beam. The reference detector output is compared to a predetermined threshold and, when the threshold is reached, a peak detector circuit monitors the signal detector output for a radiation pulse peak.

Abstract: An apparatus for determining the characteristics of a particular ionization chamber by measuring the capacitance of the chamber and using that capacitance to identify the particular type of chamber being used to measure the ionizing radiation.

Abstract: An apparatus for detecting the area and concentration of radioactive contamination on surfaces, objects and personnel is disclosed. The apparatus is capable of automatic adjustment without intervention by an operator, providing for self-calibration and avoiding the need for periodic calibration, source checking and maintenance by personnel. The apparatus is comprised of one or more position sensitive proportional counters coupled together to act as a single counter. A computer based acquisition system is used to collect the time, energy and position of an ionization event that is caused by the contamination. Collimated radiation sources are located inside of each position sensitive proportional counter. These sources act as stable artifacts in the position and energy spectra that the device acquires as a function of time.

Abstract: An improved ECD employing an ECD cell having a third electrode, i.e. guard positioned between the ECD cell field electrodes. The guard electrode is physically interposed between said field electrodes to divert all leakage current in the support insulators which flow between the field electrodes. The guard electrode ECD cell provides improved linear dynamic range as well as avoiding deterioration from handling during manufacture or repair.

Abstract: An apparatus for detecting the area and concentration of radioactive contamination on surfaces, objects and personnel is capable of automatic adjustment without intervention by an operator, providing for self-calibration and avoiding the need for periodic calibration, source checking and maintenance by personnel. The apparatus is comprised of one or more position sensitive proportional counters coupled together to act as a single counter. A computer based acquisition system is used to collect the time, energy and position of an ionization event that is caused by the contamination. Collimated radiation sources are located inside of each position sensitive proportional counter. These sources act as stable artifacts in the position and energy spectra that the device acquires as a function of time. The computer continuously adjusts parameters such as detector high voltage, amplifier gain and discrimination to keep the count rate, energy and position that the system measures for these check sources constant.

Abstract: A laser spectrometer suitable for detecting gas components in a test sample in the ultraviolet range. The measuring laser radiation (2) is sent to a nonlinear crystal (20, 40, 41), which increases the nominal laser frequency to the frequency that corresponds to the absorption wavelength of the measured gas. Tripling of the frequency takes place either after passage of the radiation through a single nonlinear crystal (20), or by mixing a frequency-doubled laser beam with the measuring laser radiation (2) in a common, second nonlinear crystal (41).

Abstract: An optical ionization detector wherein a beam of light is split so that one arm passes through a fiber optics and the other arm passes through a gas-filled region, and uses interferometry to detect density changes in a gas when charged particles pass through it. The gas-filled region of the detector is subjected to a high electric field and as a charged particle traverses this gas region electrons are freed from the cathode and accelerated so as to generate an electron avalanche which is collected on the anode. The gas density is effected by the electron avalanche formation and if the index or refraction is proportional to the gas density the index will change accordingly. The detector uses this index change by modulating the one arm of the split light beam passing through the gas, with respect to the other arm that is passed through the fiber optic.

Abstract: Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species.

Abstract: A radiation measurement apparatus and method extends the measurement range of a single Geiger Mueller tube (GMT). The apparatus may operate in a either a conventional mode, used to measure low radiation levels, e.g. background radiation, or an extended range geiger (ERG) mode, used to measure high radiation levels. Both modes utilize the same GMT and basic operating circuitry, including a power supply for generating a GMT anode voltage, a GMT anode voltage control circuit, a GMT trigger circuit, a clock circuit, and a GMT pulse counter circuit. In the conventional mode, the radiation rate is determined as a function of the number of GMT pulses counted over a prescribed time period. In the ERG mode, an additional counter is employed to count trial intervals of a prescribed duration.

Abstract: Alpha particle detectors capable of detecting alpha radiation from distant sources. In one embodiment, a voltage is generated in a single electrically conductive grid while a fan draws air containing air molecules ionized by alpha particles through an air passage and across the conductive grid. The current in the conductive grid can be detected and used for measurement or alarm. Another embodiment builds on this concept and provides an additional grid so that air ions of both polarities can be detected. The detector can be used in many applications, such as for pipe or duct, tank, or soil sample monitoring.

Abstract: A detecting system capable of simultaneously detecting radioactive emissions from a multiplicity of samples uses a sample holder containing a multiplicity of receiving zones and a multiplicity of drift chambers corresponding respectively to each receiving zone and also having one or more apertures. An array of cathodes is disposed transversely to an array of anodes and the crossing points corresponds to the apertures. There is also a structure that eliminates cross talk between the chambers. This structure is arranged so that a potential difference can be applied across the sample holder which in turn creates a field within the drift chambers in order to improve the detection gain of the detector head assembly.

Abstract: An X-ray gas detector for analyzing a material by studying X-ray diffraction. In order to minimize the parallax error without resorting to auxiliary electrodes, difficult to manufacture, a radial field in the whole gas space (40) is generated only by means of input electrodes (36) set to appropriate voltages and by means of lateral electrodes (44) also individually set to appropriate voltages. By modifying the voltages, it is also possible to move the center of the spheric equipotentials for permitting the analysis without parallax error of samples (20) placed at variable distances (D) from mthe input window (32) of the detector.

Abstract: A system for detecting ultra-violet radiation has a cold cathode discharge tube which produces a pulse each time it avalanches. A logic arrangement steers these pulses successively to separate timers in that order. In response to each pulse, each timer sends its own output line HIGH for a preset period, the same for all the timers. An AND gate receives all the timer outputs and produces an alarm signal when all these are HIGH at the same time.

Abstract: A laser beam focussed on a moving surface, e.g. of a rolling mill, is modulated by means of a rotating disk with through-orifices. The radial lateral faces of the orifices have, relative to the axis of the laser beam, angles of inclination which are different from each other; this difference in inclination is such that the laser beam deviated by one of the radial lateral faces is then reflected by the opposite radial lateral face towards the zone of the surface which is struck by the laser beam passing, without being deviated, through the orifice. The difference in inclination may be between 15.degree. and 30.degree.. The lateral faces of the through-orifices may be lined with a reflective material.

Abstract: In an ionization type detector for high energy radiation wherein the energy of incident radiation is absorbed through the ionization of a liquid noble gas and resulting free charge is collected to form a signal indicative of the energy of the incident radiation, an improvement comprising doping the liquid noble gas with photosensitive molecules to convert scintillation light due to recombination of ions, to additional free charge.

Abstract: To enable an ionization chamber used for measuring the intensity of a beam of ionizing radiation, for example an electron beam produced by a linear accelerator and used for radiotherapy, both to give an output signal which is independent of ambient pressure and temperature and to present a low weight of scattering material per unit area to the beam, the chamber is of flexible construction so that the volume of gas in it adapts to ambient pressure and temperature, and such that the weight of gas in the active region between the electrodes per unit area remains substantially constant. Suitably, the electrodes are conductive layers on flexible plastics sheets, an outer annular portion of one sheet providing a flexible connection between two opposed chamber wall portions which remain substantially planar and parallel; the proportional change (.DELTA.V.sub.1 /V.sub.1) in a volume bounded by the opposed wall portions and including the active region equals the proportional change (.DELTA.V.sub.2 /V.sub.

Abstract: Apparatus and method for electronically reading planar two dimensional .beta.-ray emitter-labeled gel electrophoretograms. A single, flat rectangular multiwire proportional chamber is placed in close proximity to the gel and the assembly placed in an intense uniform magnetic field disposed in a perpendicular manner to the rectangular face of the proportional chamber. Beta rays emitted in the direction of the proportional chamber are caused to execute helical motions which substantially preserve knowledge of the coordinates of their origin in the gel. Perpendicularly oriented, parallel wire, parallel plane cathodes electronically sense the location of the .beta.-rays from ionization generated thereby in a detection gas coupled with an electron avalanche effect resulting from the action of a parallel wire anode located therebetween. A scintillator permits the present apparatus to be rendered insensitive when signals are generated from cosmic rays incident on the proportional chamber.

Abstract: A Geiger-Mueller tube includes a tubular, stainless steel cathode (A) which defines a chamber (B) therein. An anode (C) extends axially through the chamber in a spaced relationship with the cathode. A thin layer of rhenium (20) is plated on an interior surface (12) of the cathode. End caps (32, 36) and ceramic fittings (34, 38) hermetically seal the ends of the cathode tube. The cathode chamber is charged with a gaseous mixture including in primary part noble gases, such as neon and argon, and about 1-3% bromine or other halogen gases. The Geiger-Mueller tube with a rhenium plated cathode is relatively inexpensive to manufacture, provides excellent bromine and halogen degradation resistance at elevated temperatures, and provides superior, linear operating characteristics over a wide range of temperatures.

Abstract: The invention substantially eliminates measurement errors in radiation field strength due to circuit propagation time delays and slow drift conditions, Geiger-Mueller tube turn-on time and response curve variations, and the need to manually calibrate the measurement apparatus in high radiation fields to compensate for time errors. The exponential probability function has the property that the expected value for the arithmetic mean of any right hand segment of the curve is always the same provided that the axis is adjusted so that the starting point of the selected segment is zero. The curve is trimmed dynamically each time a new rate is calculated. An individual count of strike events is kept for N separate but consecutive time units, and the counts for the later occurring events are lumped together as the Main Event. After the data collection period ends, a total accumulated time and accumulated count are constructed. This construction begins by examining the Main Event data.

Abstract: This invention describes apparatus for and a method of measuring radiation field strength which uses a pulse enabled detector (e.g. G-M tube) and is based on the equation R=K/t, where R is the radiation field strength, t is the time till first strike, and K is a proportionality constant for the given apparatus. The G-M detector is enabled by pulsing the bias voltage across the detector up into its active region and then measuring the elapsed time interval to the incident of first strike. Since the reciprocal of this time is proportional to the radiation field strength, all information necessary to determine the field strength has been obtained. A constant wait time is employed after each strike to assure that the G-M tube full recovery time has expired, and the G-M tube is then enabled and the process repeated. Because of the random nature of radiation phenomena the confidence level that any given measurement is an accurate representation of the true average field strength is low.

Abstract: A method of improving the radiation resistant characteristic of a BF.sub.3 proportional counter, comprising a tube having electrodes provided thereon and BF.sub.3 gas filled therein, by subjecting the counter before use to any one of 10.sup.4 -2.times.10.sup.5 R gamma ray, 10.sup.4 -2.times.10.sup.5 R X-ray, or 10.sup.10 -10.sup.11 nvt thermal neutron with a direct current high voltage applied between the above stated electrodes. The counter thus adapted exhibits little deterioration even in the surroundings of strong gamma ray, X-ray, and thermal neutron flux, and can maintain a stable operation. In particular, since the upper limit of the radiation amount in the process of improving the radiation resistant characteristic is set at a low value, the remaining life of the BF.sub.3 proportional counter is not shortened unduely.

Abstract: A radiation level measuring system having a Geiger-Muller gas ionizing tube as a detector. The inherent dead-time of the Geiger-Muller tube that follows a discharge pulse is compensated by the pulse counting electronic measuring circuit. A signal pulse of varying duration is formed from the detector output pulses in a manner that corrects for this dead-time. Measurement of this generated signal pulse duration give the actual radiation level that would be measured if the detector dead-time did not exist.

Abstract: The device comprises, on the one hand, a cassette containing an electret between two electrodes and, on the other hand, a fixed reader adapted to receive the cassette in a pocket, to identify it, to measure the charge of its electret and to display data relating to this charge. This reader comprises also a head adapted to record the data on an area (or strip) of the cassette and there are provided readers independent of the aforesaid reader adapted to subsequently receive the cassette, to measure the charge of its electret, to read the data and, by difference between the measured value and that read, to display the radiation dose received by the cassette since its recording.

Abstract: An ionization detector unit innovatively adapted to provide mobility to the nit and to render it especially suitable for convenient "field-use" in point-source sampling and monitoring of the compositional characteristics of a gaseous medium such as, for example, the ambient atmosphere, and in emitting a discernible electrical signal which in response to a perceptible change in the compositional characteristics in the medium being monitored by the detector will be altered sufficiently to activate, or trigger, a suitable alarm or warning mechanism.

Abstract: A radiation detector is fabricated by the insertion into an arcuate support structure, a plurality of modules comprised of ceramic members with electrode plates disposed therebetween. Securing of the ceramic members to the support structure is accommodated by threaded fasteners which pass through the support section into inserts which are bonded into cavities formed in the ceramic members. Before installation of the module into the support structure, the modules can be tested and the better performing modules can then be installed in the central portion of the support structure.

Abstract: A method and apparatus for monitoring the output of an ion chamber type in-core neutron detector is disclosed. Neutron detectors of this type are known to produce both alternating current and direct current signals which are used as measures of the neutron flux in the chamber. The monitor employs a ratio of the alternating current and direct current signals to detect ion chamber leaks, to correct the output of the detector after a leak, to predict the end-of-life of the detector and to determine the non-linearity of the detector at different power levels.

Abstract: An improved system of circuitry for operating an electronic counter connected to a Geiger-Mueller (GM) tube or to a similar source of random pulses with an associated dead time making the system response linear at increased counting rates, includes an electronic one-shot device, an and-gate connected to a pulse counter, a second and-gate connected to an interval counter, and a frequency source for producing periodic clock pulses. When a GM tube is operated as a part of this system, it detects ionizing radiation by producing pulses at a rate proportional to the amount of radiation present. The one-shot inhibits further GM-tube pulses from entering the pulse counter for a fixed time selected to be somewhat longer than the maximum GM-tube dead time, and at the same time it inhibits further periodic clock pulses from entering the interval counter, automatically correcting the measured and displayed pulse count for dead time without regard to the precise value of the dead time of the GM tube or other pulse source.

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: 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: Radon is directly measured by a portable device which is attached to the l of a mine or other area from which the gas may be emanating. The radon is collected and directed to an instrument having a gas proportional counter. To prevent build up of radon daughters on the gas proportional counter, with consequent high alpha particle background, a moving film surrounds the counter and carries away the radon daughters.

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.