Abstract: A detector (64) for detection of ionizing radiation, and an apparatus for use in planar beam radiography, including the detector (64). The detector (64) includes a chamber filled with an ionizable gas; first and second electrode arrangements (2, 1, 18, 19) provided in the chamber with a space between them, the space including a conversion volume (13); an electron avalanche amplification unit (17) arranged in the chamber; and, at least one arrangement of read-out elements (15) for detecting 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 detectors which are simple to stack with each other, the first and second electrode arrangements exhibit a first and a second main plane, said planes being non-parallel. This permits stacked detectors to be manufactured simply and cost effectively.

Abstract: The present invention may provide a particle or radiation detector or imager which may be used for accurate recording of medical (2-D) X-ray images. The imager includes at least one detector panel. The detector panel includes a microgap detector with an array of pixel electrodes of a novel form. Each pixel electrode is insulated from a planar cathode by means of an insulating layer. Each pixel electrode is connected to an underlying contact by means of a via hole in the insulating layer. The insulating layer is preferably conformal with the electrodes. The underlying contact is connected to an electronic measuring element which preferably lies underneath the electrode and is about the same size as the electrode. The measuring element may be a storage device, a digital counter or similar. A switching transistor is connected to the measuring device. The switching transistor may be a thin film transistor. Alternatively, both measuring element and transistor may be formed in a single crystal semiconductor, e.g.

Abstract: A detection apparatus for detecting an electron cloud includes a resistive anode layer with a detection plane upon which the electron cloud is incident. The resistive layer is capacitively coupled to a readout structure having a conductive grid parallel to the detection plane. Charge on the resistive layer induces a charge on the readout structure, and currents in the grid. The location of the induced charge on the readout structure corresponds to the location on the detection plane at which the electron cloud is incident. Typically, the detection apparatus is part of a detector, such as a gas avalanche detector, in which the electron cloud is formed by conversion of a high-energy photon or particle to electrons that undergo avalanche multiplication. The spacing between the anode layer and the readout structure is selected so that the width of the charge distribution matches the pitch between conductive segments of the grid.

Abstract: Spectrally resolved detection of ionizing radiation in a detector comprising a chamber (13) filled with an ionizable substance, a radiation entrance (33), an electron avalanche amplification means, and a read-out arrangement (29), comprises introducing a broadband radiation beam (1) into the chamber between and in parallel first and second electrode arrangements for ionization of the ionizable substance and avalanche amplifying said electrons. By means of the read-out arrangement (29) electron avalanches (SX1, SX2, . . . SXN), derivable mainly from ionization in sections (X1, H2, . . . , XN) of the chamber that are separated in the direction of the introduced radiation beam, are separately detected. From spectrally resolved absorption data, weighting factors (W11, W21, . . . , WM1, W12, W22, . . . , WM2, . . . , W1N, W2N, . . . , WMN) for different spectral components (E1, E2, . . . , EM) of the radiation (1) and for different sections (X1, X2, . . .

Abstract: The apparatus and method provide a technique for improving detection of alpha and/or beta emitting sources on items or in locations using indirect means. The emission forms generate ions in a medium surrounding the item or location and the medium is then moved to a detecting location where the ions are discharged to give a measure of the emission levels. To increase the level of ions generated and render the system particularly applicable for narrow pipes and other forms of conduits, the medium pressure is increased above atmospheric pressure.

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 method and apparatus for radiography and also a detector for detecting incident radiation. In the method and the apparatus X-rays (9) are emitted from an X-ray source (60). The X-rays which have interfered with an object to be imaged are detected (62) in a detector (64). The detector (64), which detects incident radiation includes a gaseous avalanche chamber, including electrode arrangements between which a voltage is applied for creating an electrical field, which causes electron-ion avalanches of primary and secondary ionization electrons released by incident radiation.

Abstract: A microstrip gas chamber comprises a gas volume, an electrically insulating substrate having a surface exposed to the gas volume, a set of alternating cathode strips and anode strips on the surface of substrate, a high voltage source for establishing a potential difference between the anode and cathode strips to thereby produce an electric field sufficient for avalanche multiplication in said gas medium in a region near the anode strips, and grid electrodes provided on the surface at each gap between the cathode strip and anode strip. The multi-grid type MSGC can offer very narrow gap between neighboring electrodes that might reduce a surface charge effect considerably. The present MSGC may be applied to the field where both the high gain and the stable operation are required.

Abstract: An apparatus for photographing a radiographic image, has an image sensing system for obtaining a radiographic image; an image process system for correcting the radiographic image obtained by the image sensing system using input/output characteristics in units of pixels of the image sensing system, and outputting the corrected radiographic image; and a predetermined factor detecting unit for monitoring a predetermined factor value that ultimately influences the output from the image process system.

Abstract: A magnetic field generator includes a movable magnetic pole pair within a stationary return yoke, modifying a magnetic field at a high speed with high precision. The magnetic field generator includes a first return yoke having a first internal volume, a magnetic pole pair with magnetic poles disposed opposite each other, disposed in the first internal volume, and movable relative to the first return yoke, and a driver for moving the magnetic pole pair within the first internal volume.

Abstract: A photo-ionization detector (PID) includes an ultraviolet (UV) lamp that transmits UV light into an ionization chamber to ionize volatile gases. An ion detector in the ionization chamber includes interdigital electrodes that collect resulting ions using an electrical field perpendicular to the UV light propagation. A pump in the PID circulates gases through the ionization chamber in a direction perpendicular to the electrical field and to the UV light propagation. The PID additionally provides a UV monitor having interdigital electrodes that release electrons when struck by the UV light. The size of a monitor current in the UV monitor indicates the intensity of the UV light. The UV monitor is in a UV monitor chamber that protects the UV monitor from exposure to the ionized gases and improves the accuracy of UV intensity measurements.

Abstract: The present invention is a dynamic radiation scanning system for detecting radiation dosimetry of a beam emitted along an axis from a radiotherapy treatment machine and a method for its use. The system contains a dosimetry probe to sense photons and electrons, a dynamic phantom body formed from a material having a density approximating that of the human body, a gantry mounting assembly rigidly attached to the radiotherapy machine for positioning of the phantom body, and a lead screw assembly rigidly affixed to the gantry for providing coplanar movement of the dynamic phantom within a plane perpendicular to the axis of radiation emission. Movement of the dynamic phantom through a series of locations is carried out at varying depths and angles so as to provide sufficient data to determine variations in beam uniformity, thereby providing for simple and reliable testing and calibration of the machine.

Abstract: A system and method is disclosed for optically locating a microchannel position. A laser source generates a primary laser beam which is directed at a microchannel plate. The microchannel plates include microchannels at various locations. A back-reflectance beam detector receives a back-reflected beam from the plate. The back-reflected beam is generated when the primary beam reflects off of the plate. A photodiode circuit generates a trigger signal when the back-reflected beam exceeds a predetermined threshold, indicating a presence of the microchannel. The method of the present invention includes the steps of generating a primary beam, directing the primary beam to a plate containing a microchannel, receiving from the plate a back-reflected beam generated in response to the primary beam, and generating a trigger signal when the back-reflected beam exceeds a predetermined threshold which corresponds to a presence of the microchannel.

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: A device for testing flat materials during production of material webs has a radiation source from which radiation passes through the material under investigation, residual radiation on another side of the material being detected by a gas-filled ionization detector. The detector arrangement has a plurality of interconnected measurement chambers provided with collector electrodes and arranged inside a common housing. The measurement chambers can together be evacuated and filled with an ionizable gas. Each of the measurement chambers is allocated its own radiation inlet window. The radiation source is allocated to the measurement chamber and has a linear radiation distribution.

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: The present invention relates to a device for measuring an absorbed dose in an ionizing radiation field, and to a sensitive medium for use in an ionization chamber. The device includes a detector body (11) which is of the ionization chamber type and comprises two mutually spaced electrode elements (20, 30) and means (50) which together with the electrode elements delimit in the detector body a measuring first chamber (40) for a sensitive medium. A second chamber (60) is disposed in spaced relationship with the measuring chamber, and a flow channel (61) extends through one of the electrode elements such as to connect the measuring chamber with the second chamber. The sensitive medium is a liquid. According to the invention, the sensitive medium is a mixture of isooctane (C8H18) and tetramethylsilane (Si(CH3)4).

Abstract: A resonant absorption cell filled with a gas, selected in accordance with the wavelength of the laser radiation of interest, such as DF. The gas within the cell is maintained at substantially atmospheric pressure. The energy state of the gas within the cell is raised by either external resistance heating or optical pumping. In an increased energy state, gas molecules resonate with the incoming laser radiation causing the molecules to absorb incident photons before the gas molecules have a chance to re-radiate the captured photons, collisions with other gas molecules within the cell transfer the excitation energy into heat in order to filter out laser radiation but past all other wavelengths.

Abstract: Linearization of an ionization detector is obtained by processing the output signal derived from the ionization detector so as to compensate for the naturally-occurring logarithmic decay of the detector response at high sample concentrations. Linearization is accomplished according to a linearizing formula:I.sub.(lin) =I[1+(I/I.sub.(dec))].sup.pwrwhere:I.sub.(lin) =linearized output signal current of the detectorI=non-linearized output signal current of the detectorI.sub.

Abstract: This detector comprises a gas chamber (2) containing plane electrodes (4, 6, 8) delimiting conversion (C) and amplification (A) gaps. One of the electrodes is perforated with holes (18) and forms the detector cathode (6). The distance between the detector cathode and the anode (8) is less than 500 .mu.m. The intensity of the electric field in the amplification gap is ten times higher than the intensity of the electric field in the conversion gap. Application in particle physics, medicine, biology.

Abstract: The present invention may provide a particle detector or imager which may be used for accurate recording of medical (2-D) X-ray images. The imager includes at least one detector panel. The detector panel includes a microgap detector with an array of pixel electrodes of a novel form. Each pixel electrode is insulated from a planar cathode by means of an insulating layer. Each pixel electrode is connected to an underlying contact by means of a via hole in the insulating layer. The insulating layer is preferable conformal with the electrodes. The underlying contact is connected to an electronic measuring element which preferably lies underneath the electrode and is about the same size as the electrode. The measuring element may be a storage device, a digital counter or similar. A switching transistor is connected to the measuring device. The switching transistor may be a thin film transistor. Alternatively, both measuring element and transistor may be formed in a single crystal semiconductor, e.g.

Abstract: An ultraviolet detector comprises a metal tubular member which hermetically encloses an anode and a cathode therein and is filled with a discharged gas introduced therein from a metal exhaust tube. After the anode and the cathode are enclosed within the tubular member, the ultraviolet detector can be made without being subjected to any glass fusing process. Accordingly, the inside of the sealed vessel V1 can be prevented from being contaminated with fluorine, whereby the ultraviolet detector with stable characteristics can be provided.

Abstract: A method and apparatus for radiography, and especially for planar beam radiography, and also a detector for detecting incident radiation. In the method and the apparatus, wherein X-rays are emitted from an X-ray source, the X-rays are formed into a planar beam and are transmitted through an object to be imaged, and the X-rays transmitted through said object are detected in a detector. The detector, which detects incident radiation is a gaseous parallel plate avalanche chamber, including electrode arrangements between which a voltage is applied for creating an electrical field, which causes electron-ion avalanches of primary and secondary ionization electrons released by incident radiation. The detector is oriented, in relation to the incident radiation, so that the radiation enters sideways between a first and a second parallel plate, between which the electrical field is created.

Abstract: A gamma ray detector for determining the position of gamma ray interactions has at least one module. Each module has a converter for converting gamma rays to charged particles, a scintillator for emitting light in response to charged particles produced by the converter, a photodetector to determine when light has been emitted from the scintillator, a two-coordinate position detector for determining the X and Y coordinates of charged particles interacting with the position detector, and a signal device for signaling the presence of emitted light in the photodetector and for activating the position detector.

Abstract: An imaging microstrip gas chamber (MSGC) high-speed data acquisition system capable of processing at high speed a large number of output signals of an imaging microstrip gas chamber.

Abstract: A structure for detecting radiation, useful in an imaging camera for nuclear medicine, comprising a plurality of tubes, each of said tubes having (1) an electrically conductive wall structure defining a tube internal radius and a proximal and a distal end, (2) a pressure retaining and electrically insulative tube end closure means at each tube end, (3) a coaxial electrically conductive element located between said insulative tube end closure means; said tubes containing xenon at a pressure sufficient to provide for a photoelectron range there within of or less than that distance existing between the proximal and distal ends thereof and a maximum ionization collection distance of or less than the tube internal radius; said tubes positioned in a honeycomb-like array such that each proximal and distal tube end is in a common plane one with another, respectively.

Abstract: A multi-detector system receives incident radiation through a subject includes a gaseous microstrip detector, which has alternating anodes and cathodes on a substrate opposite a voltage source, is positioned adjacent a semiconductor detector. In a dual energy environment, electric fields are applied to both detectors as the incident radiation is directed therethrough. Accordingly, the detectors generate corresponding signals which are compared to generate a contrasted signal of the subject. These signals may be generated for imaging, radiation monitoring, radiation measuring and the like. The direction of incident radiation and the orientation of the electric fields may be adjusted according to the particular application. Additionally, the system can be utilized in a single-energy environment where two images of the same incident radiation energy will be formed from the different detector media. By utilizing various processing techniques enhanced contrast between the images can be obtained.

Abstract: Streak camera whereof the pulse converter for converting a photon pulse for detecting into an electron stream comprises a gaseous medium. A streak camera for a photon pulse in the far-infrared region is provided with a laser source to bring particles in the medium into a Rydberg state, in a streak camera for an X-ray pulse the medium contains particles for bringing into an Auger state, and additional deflection plates are provided for separating a primary electron stream from a secondary electron stream.

Abstract: A radiation detector in which primary electrons are released into a gas by ionizing radiations and drifted through an electric field to a collecting electrode for detection. It further includes a gas electron multiplier formed by one or several matrices of electric field condensing areas which are distributed within a solid surface perpendicular to the electric field. Each electric field condensing area consists of a tiny hole passing through the solid surface that forms a dipole adapted to produce a local electric field amplitude enhancement proper to generate an electron avalanche from one primary electron. The gas electron multiplier operates thus as an amplifier or a preamplifier within a host radiation detector.

Abstract: A high resolution radiographic imaging device for medical or industrial radiography includes at least one ionizing particles detector equipped with at least one gas chamber provided with a window for the lateral or frontal inlet of the illumination beam. A first, a second and a third flat electrode are placed in parallel with one another in order to form a conversion space and a amplification space with the distance separating the second and third electrodes being less than 200 .mu.m and the amplitude ratio of the electrical fields created between the second and third electrodes and the first and second electrodes being greater than 10.

Abstract: The ultraviolet detector in accordance with the present invention comprises a sealed vessel enclosing a discharged gas therein, and a metal anode and a metal cathode which are disposed close to each other within the sealed vessel so as to generate therebetween discharge in response to ultraviolet radiation entering the sealed vessel. The anode and cathode are independently secured to the sealed vessel with a plurality (at least three pieces each) of anode pins and cathode pins, respectively. An electrically-insulating spacer is disposed between the anode and cathode so as to fix their relative positions with respect to each other, thereby defining a discharging gap, by which discharge is stably generated between these electrodes. The current resulting from the discharge is observed so as to detect the incidence of ultraviolet radiation.

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 monitor for use with liquids that utilizes air ions created by alpha radiation emitted by the liquids as its detectable element. A signal plane, held at an electrical potential with respect to ground, collects these air ions. A guard plane or guard rings is used to limit leakage currents. In one embodiment, the monitor is used for monitoring liquids retained in a tank. Other embodiments monitor liquids flowing through a tank, and bodies of liquids, such as ponds, lakes, rivers and oceans.

Abstract: A spectrometric gas measurement apparatus for the determination of the presence and/or concentration of gases in a spatial region has a spectrometric measurement head which transmits into the spatial region measurement radiation having the spectral ranges necessary for the determination of the gases. Furthermore, a reflector is provided at the spatial region which reflects the light which is passed through at least a part of the spatial region back to the measurement head where it is split up spectrally in an analyzer and then supplied to a photoreceiver arrangement. A measurement tube extending in the direction of light propagation is provided in the spatial region through which the measurement light passes.

Abstract: The object of the invention is a method for determining the size and shape of the radiation field (11) of an X-ray machine automatically by means of a multielectrode ionization chamber (5). By means of the method relating to the invention both the dose and the size and shape of the radiation field can be measured separately so that the ratios of the currents of the electrodes (2, 3) located in different directions in the ionization chamber (5) to the current of the reference electrode (1) provide information on the size and shape of the field, and the sum of the currents is proportional to the dose.

Abstract: An ionizing radiation detector having an enclosure filled with a rare gas within which is located a proportional counter. An absorption zone is formed between the counter and the upper wall of the enclosure in which radiation is ionized. The counter has at least one anode and at least one cathode which are parallel to one another and separated by an insulating material layer. The cathode and the insulating material layer have at least one opening in which there is a substantially uniform electric field and which constitutes a multiplication zone for electrons which result from the ionization of the radiation.

Abstract: A method for detecting ionizing radiation by allowing the radiation to affect the surface of the floating gate of a MOSFET transistor through an air or gas space. For this purpose, an uncovered area is formed on the surface of the floating gate of the MOSFET transistor forming the detector. The MOSFET transistor is used so that a charge is formed on its floating gate, the charge changing as a result of the ionizing radiation the transistor is exposed to. The radiation dose is determined by the change which takes place in the charge on the gate.

Abstract: A microgap sensor, and manufacturing method therefor, which includes a cathode and at least one strip anode parallel to the cathode, in which the strip anode is separated and insulated from the cathode by an insulation layer made from a polymeric material. The microgap sensor further includes a cathodic drift electrode substantially parallel to the cathode, the cathode and drift electrode being separated by a gap fillable with an ionizable gas. The gap is considerably greater than the thickness of the insulating layer, and the strip anode is located in the gap between the cathode and the drift electrode.

Abstract: A beta radiation detector which is capable of reliably detecting beta radiation emitted from a surface. An electrically conductive signal collector is adjustably mounted inside an electrically conductive enclosure which may define a single large opening for placing against a surface. The adjustable mounting of the electrically conductive signal collector can be based on the distance from the surface or on the expected beta energy range. A voltage source is connected to the signal collector through an electrometer or other display means for creating an electric field between the signal collector and the enclosure. Air ions created by the beta radiation are collected and the current produced is indicated on the electrometer or other display means.

Abstract: A radiation sensor and/or imager is formed by sandwiching two materials having different atomic numbers (Z) around a radiation detector, such as scintilator or Geiger-Mueller type radiation counters, or solid state radiation detectors, such as those made of silicon). In one embodiment of the present invention, a thin layer of lead (Pb) is placed on one side of a Geiger-Mueller radiation counter and a layer of Lucite.TM. is disposed on the opposite side. One example, of a preferred Geiger-Mueller counter which may be used in the present invention is a modified pancake Geiger-Mueller counter with thin ruby mica windows, approximately 2.8 mg/cm.sup.2 thick on both sides.

Abstract: An electrostatic alpha radiation detector for measuring alpha radiation emitted from inside an enclosure comprising an electrically conductive expandable electrode for insertion into the enclosure. After insertion, the electrically conductive expandable electrode is insulated from the enclosure and defines a decay cavity between the electrically conductive expandable electrode and the enclosure so that air ions generated in the decay cavity are electrostatically captured by the electrically conductive expandable electrode and the enclosure when an electric potential is applied between the electrically conductive expandable electrode and the enclosure. Indicator means are attached to the electrically conductive expandable electrode for indicating an electrical current produced by generation of the air ions generated in the decay cavity by collisions between air molecules and the alpha particles emitted from the enclosure.

Abstract: A penetrometer sensor probe and system with a detachable sleeve section which performs radiation measurements in subsurface formations. The penetrometer sensor probe measures radiation particularly gamma radiation in real time as the sensor probe is retrieved from a subsurface formation following an initial penetrometer push operation. A sacrificial sleeve surrounding the sensor probe's radiation detector is separated from the penetrometer after an initial push operation at a particular subsurface depth. During a retraction process, a sleeve section containing the radiation detector is detached from the sacrificial sleeve of the penetrometer. The sleeve provides both strength to the penetrometer and protects the probe's radiation detector from damage. Additionally, the detachable sleeve results in significantly reduced bremsstrauling scattering radiation attributed to gamma radiation that otherwise would strike a steel casing adjacent to the radiation detector.

Abstract: The present invention provides electrode assemblies for LIC imagers that maximize ion collection and the electric field for the minimum bias voltage. To achieve this optimization the ion collection is confined to small regions. Due to this limited ion collection region, high neutralization efficiencies and fast sweep-out times can be obtained. Furthermore, with an electrode separation of approximately 0.1 millimeters, pulse voltages of less than 100 volts can be used. Low voltages result in improved reliability, longer system life, and lower safety risks.

Abstract: A radiation detector includes a substrate having a cavity defined therein, an anode surface positioned in the bottom of the cavity and a cathode positioned adjacent the cavity opening. A drift electrode is juxtaposed over the substrate opposite the cavity and defines a region containing a gaseous medium. As ionized charge pairs are established in the gaseous medium due to radiation provided by an external radiation source, electrons drift toward the anode under the influence of a first electric field established between the anode and drift electrode. Thereafter, the electron undergoes avalanche multiplication with the gaseous medium in an avalanche region defined by a second intense electric field established between the anode and cathode. The structure of the present invention provides an electric field gradient geometry which permits optimal design of the avalanche region geometry, and which further minimizes photon feedback from the cathode.

Abstract: An optical imaging system includes an array of optical imaging devices each comprising a device for providing charge amplification in a gaseous medium. A preferred embodiment of such a charge amplification device includes a substrate having a cavity defined therein, an anode surface positioned in the bottom of the cavity and a cathode positioned adjacent the cavity opening. A drift electrode is juxtaposed over the substrate opposite the cavity and defines a region containing a gaseous medium. As ionized charge pairs are established in the gaseous medium due to radiation provided by an external radiation source, electrons are attracted toward the anode where they undergo avalanche multiplication with the gaseous medium under the influence of an intense electric field established between the anode and cathode.

Abstract: A device for forming images of ionizing particles through single-dimensional electrophoresis provided with a multi-wire proportional chamber. The chamber filled with a gas is of asymmetric structure and is formed successively by an entry window for the particles, taken to a negative potential, a multi-wire anode electrode, taken to a potential positive with respect to a reference potential, and a cathode electrode which is placed in the vicinity of the anode electrode. The cathode electrode, which is taken to the reference potential, is formed by a network of parallel electrically conducting strips. Detection of the position of impact of the ionizing particle along the pitch of the network is performed by induction of a delayed electric pulse caused by an avalanche of the ionization electrons issuing from the ionizing particle in the region of the strip situated in line with the impact by the particle in the chamber, the reference time being that of the ionization electrons close to the wires.

Abstract: An electrostatic detector for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure.

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: A surface radiation detector for sensing low energy ionizing radiation on the surface of an object includes a open window gas proportional counter provided with a compressible skirt surrounding the window in a detection chamber. The compressible skirt is preferably of open cell plastic foam, but may be made from a gas impermeable sheet formed in the shape of an accordion bellows. An open screen of electrically conductive material, attached to said skirt and covering the window, may be placed in direct contact with the surface of an object to be tested. Counter gas flows at a rate into the chamber sufficient to maintain a positive pressure in the chamber relative to the ambient atmosphere. A momentarily actuated valve supplies additional counter gas at a flow rate sufficient to fill said chamber within a short period of time.

Abstract: An ionization detector electrode and signal subtraction apparatus and method provides at least one first conductive trace formed onto the first surface of an ionization detector. The first surface opposes a second surface of the ionization detector. At least one second conductive trace is also formed on the first surface of the ionization detector in a substantially interlaced and symmetrical pattern with the at least one first conductive trace. Both of the traces are held at a voltage potential of a first polarity type. By forming the traces in a substantially interlaced and symmetric pattern, signals generated by a charge carrier are substantially of equal strength with respect to both of the traces. The only significant difference in measured signal strength occurs when the charge carrier moves to within close proximity of the traces and is received at the collecting trace.