Abstract: The present invention provides a wireless communication device and a subscriber identity module card in a wireless communication device. The subscriber identity module card comprises a flat plate carrier, a subscriber identity module circuit and a gas sensing chip. The flat plate carrier comprises a first surface where the subscriber identity module circuit is disposed, a second surface where the gas sensing chip is disposed, a through hole, and an electrical contact portion passing through the through hole and extending to reach the first surface and the second surface. The electrical contact portion is electrically connected to the subscriber identity module circuit and the gas sensing chip. The gas sensing chip is disposed on a portion of the subscriber identity module card where not occupied by the subscriber identity module circuit. Thus, the wireless communication device provides gas sensing function without additionally equipping with an external gas sensing element.

Abstract: A method of measuring a radon concentration or a radon exposure level comprising: placing a plurality of individual radon measurement instruments at locations, each instrument being capable of data output; receiving radon measurement data from each of said plurality of instruments; combining said data from said plurality of instruments into a single data set; and calculating a radon concentration or radon exposure value from said single data set. Using a plurality of individual detectors and combining their data provides a much better overall analysis of radon concentration or radon exposure level. The calculated value may include producing an average of the radon concentrations across the multiple instruments. The average may be weighted with weights determined according to different locations such as proximity to ventilation devices or based on the time that an average user spends in each location.

Abstract: A method of detecting a leak source within a tank includes coupling a first seal member to an external surface of the tank around an external leak location and coupling a second seal member to the external surface around a perimeter of the first seal member to define a gap between the first seal member and the second seal member. The method also includes coupling a sealing membrane to the first and second seal members such that a first cavity is at least partially defined within the perimeter of the first seal member and such that a second cavity is at least partially defined between the first seal member and the second seal member. The gap at least partially defines the second cavity. The method further includes applying a vacuum to the second cavity and injecting a detectable gas into the first cavity.

Abstract: A tritium-in-air measuring apparatus for measuring a concentration of tritium in air, the measuring apparatus comprising a sensing apparatus for sensing the concentration of tritium in the air and producing at least one signal representing the concentration; a signal processing apparatus, operatively connected to the sensing apparatus, for receiving the signal, processing the signal, and outputting an indication of the concentration of tritium; the sensing apparatus comprising four equal-dimensioned ion chambers, the four chambers being formed in a single block of metal, the four chambers comprising a first measurement chamber, a second measurement chamber, a first compensation chamber and a second compensation chamber.

Abstract: Alpha particle detecting devices are disclosed that have a chamber that can hold a fluid in a tensioned metastable state. The chamber is tuned with a suitable fluid and tension such that alpha emitting materials such as radon and one or more of its decay products can be detected. The devices can be portable and can be placed in areas, such as rooms in dwellings or laboratories and used to measure radon in these areas, in situ and in real time. The disclosed detectors can detect radon at and below 4 pCi/L in air; also, at and below 4,000 pCi/L or 300 pCi/L in water.

Abstract: A hand-held radiation detector that produces a voltage as a function of the amount of ionizing radiation is described. The hand-held radiation detector may be configured for measuring low levels of ionizing radiation including alpha radiation. A light alert feature may blink and/or a sound alert feature may produce a bird chirping sound at a frequency relative to the amount of radiation detected. The ionizing radiation detector may have an ion chamber comprising a first electrode chamber and a second electrode configured inside the first electrode chamber, and it may be an open type ion chamber allowing ambient air to enter the ion chamber. A sensitivity range selector may be used to increase or decrease the voltage range for detection. An input selector may be used to select the type of detection a user desires, such as consumables or radon gas for example.

Abstract: A beam scheduler adds the maximum allowable waiting time until a beam is allocated to an irradiation chamber corresponding to an irradiation request when the irradiation request is received from one irradiation chamber of a plurality of irradiation chambers A to D; adds the irradiation request to the end of the order of a waiting list; determines whether or not the predicted waiting time until the beam is allocated to the one irradiation chamber exceeds the maximum allowable waiting time; and advances the order of the irradiation request on the waiting list, thereby allocating the beam to the irradiation chamber corresponding to the top irradiation request in the order of the waiting list, if it is determined that the predicted waiting time exceeds the maximum allowable waiting time.

Abstract: Provided is an apparatus for measuring radioactivity without loss of radioactive particles. The apparatus includes a sampler that collects a radioactive sample from an exhaust pipe, a sample detector that is provided adjacent to the exhaust pipe and includes a particle collecting filter and a first radioactivity detector, sample transporting pipe that extends from the sample detector and transports the radioactive sample from which the radioactive particles have been removed, a sample transporting pump that is provided at the sample transporting pipe, and a gaseous radioactivity detector that is provided at the sample transporting pipe and detects a radioactivity of the radioactive sample from which the radioactive particles have been removed. The particle collecting filter filters out the radioactive particles from the radioactive sample and the first radioactivity detector detects a radioactivity of the radioactive particles filtered out by the particle collecting filter.

Abstract: In the field of protection from ionising alpha particle radiation there is a need for a low cost, reliable, maintenance free, and self-contained detector that can monitor continuously over a plurality of time periods the levels of airborne alpha particle radiation. The detector operates by measuring the charge created by alpha particle decay between electrodes in an enclosure. Detectors may be linked together to monitor several parts of a building or a large area for applications such as civil emergencies and earthquake warning.

Abstract: A novel method for measuring airborne radon and thoron capable of separately measuring radon and thoron with high sensitivity, having a small-sized device structure, and free of the influence from its measurement environment. In the method, by measuring Cherenkov light generated when airborne radon and thoron are adsorbed to an absorbent and then ? rays emitted in process of disintegrations of radon and thoron pass through the absorbent, radon and thoron are measured. Based on a decay time of the Cherenkov light, a mixture ratio between radon and thoron is measured. As the absorbent, porous glass is preferably employed which is provided with fine pores of 0.3 to 30 nm in diameter.

Abstract: The present invention relates to the method and equipment for inspecting nuclear experimental locales, and particularly relates to the method and system for separating and measuring 37Ar quickly. The method of the invention comprises the steps of sampling, eliminating impurities, separating, purifying, measuring the sum of Ar, collecting Ar, measuring the activity of 37Ar, etc. The control unit in the system of the invention connects respectively to a sampling unit, a separating-purifying unit, and a radioactivity measuring unit which are connected in turn, and a computer and the software of the control unit are in charge of the automatic operation, measurement and data-collection of the whole system. The method and system for quickly separating and measuring 37Ar of the patent can meet the requirements of locales inspection for Comprehensive Test Ban Treaty (CTBT), the sensitivity of measuring 37Ar is high, so do the production and purity of Ar.

Abstract: The invention relates to a method for the continuous determination of the damage to at least one system (7) used for the post-treatment of exhaust gases from an internal combustion engine (2), caused by the lubricating oil, the fuel and/or at least one lubricating oil additive and/or fuel additive used.

Abstract: A method of utilizing existing fire panel infrastructure to fight terrorism. The fire alarm systems ionization type smoke detectors, in addition to detecting the presence of smoke, would also detect the presence of airborne radioactive particles by effecting only a minor software modification. This enhanced detection ability will enable existing fire panels, as well as standalone residential smoke detectors, to detect the presence of radioactive particles such as those that would be indicative of a deliberate terrorist attack from a “Dirty Bomb” or “Dirty Aerosol” release, or an non-intentional release of radioactive particles due to an accident or natural disaster.

Abstract: A system is presented for remotely measuring a concentration of a target material (e.g., radioactive gas, suspended aerosols or non-radioactive gaseous chemistries). The system includes a data processing system and a monitoring device. The device includes a detector having a chamber, collector in the chamber and a sensor. The target material enters the chamber. The collector collects ions generated by decay of the material. In one embodiment, the sensor measures changes in an electrostatic potential of the collector in response to the ions. In another embodiment, the sensor includes a scintillation counter that measures alpha or beta particles and provides an energy spectrum. In another embodiment, the sensor includes a material whose optical properties vary according to fields formed within the sensor. The device includes a transmitter for transmitting the potential, the spectrum or the field strength to the processing system for determining the concentration of the target material.

Abstract: A system is presented for remotely measuring a concentration of a target material (e.g., radioactive gas, suspended aerosols or non-radioactive gaseous chemistries). The system includes a data processing system and a monitoring device. The device includes a detector having a chamber, collector in the chamber and a sensor. The target material enters the chamber. The collector collects ions generated by decay of the material. In one embodiment, the sensor measures changes in an electrostatic potential of the collector in response to the ions. In another embodiment, the sensor includes a scintillation counter that measures alpha or beta particles and provides an energy spectrum. In another embodiment, the sensor includes a material whose optical properties vary according to fields formed within the sensor. The device includes a transmitter for transmitting the potential, the spectrum or the field strength to the processing system for determining the concentration of the target material.

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: In the field of protection from ionising alpha particle radiation there is a need for a low cost, reliable, maintenance free, and self contained detector that con monitor continuously over a plurality of time periods the levels of airborne alpha particle radiation. The detector operates by measuring the charge created by alpha particle decay between electrodes in an enclosure. Detectors may be linked together to monitor several parts of a building or a large area of applications such as civil emergencies and earthquake warning.

Abstract: The apparatus and method provide techniques for monitoring the position on alpha contamination in or on items or locations. The technique is particularly applicable to pipes, conduits and other locations to which access is difficult. The technique uses indirect monitoring of alpha emissions by detecting ions generated by the alpha emissions. The medium containing the ions is moved in a controlled manner frog in proximity with the item or location to the detecting unit and the signals achieved over time are used to generate alpha source position information.

Abstract: The apparatus and method provide a technique for significantly reducing capacitance effects in detector electrodes arising due to movement of the instrument relative to the item/location being monitored in ion detection based techniques. The capacitance variations are rendered less significant by placing an electrically conducting element between the detector electrodes and the monitored location/item. Improved sensitivity and reduced noise signals arise as a result. The technique also provides apparatus and method suitable for monitoring elongate items which are unsuited to complete enclosure in one go within a chamber. The items are monitored part by part as the pass through the instrument, so increasing the range of items or locations which can be successfully monitored.

Abstract: The apparatus and method provide a technique for more simply measuring alpha and/or beta emissions arising from items or locations. The technique uses indirect monitoring of the emissions by detecting ions generated by the emissions, the ions being attracted electrostatically to electrodes for discharge of collection. The apparatus and method employ a chamber which is sealed around the item or location during monitoring with no air being drawn into or expelled from the chamber during the monitoring process. A simplified structure and operations arises as a result, but without impairing the efficiency and accuracy of the detection technique.

Abstract: The radometer is a portable instrument for the measurement of the concentration of atmospheric radon/thoron in a test area. A constant velocity pump pulls the air from the outside at a constant flow rate. If the air is too moist, some or all of the sample is passed through a desiccant filter prior to encountering an electrostatic filter. The electrostatic filter prevents any charged particles from entering the sampling chamber. Once the sample has entered the chamber, the progeny of the decay of radon/thoron are collected on a detector and measured. The measured data is compiled by a computer and displayed.

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: A background canceling long range alpha detector which is capable of providing output proportional to both the alpha radiation emitted from a surface and to radioactive gas emanating from the surface. The detector operates by using an electrical field between first and second signal planes, an enclosure and the surface or substance to be monitored for alpha radiation. The first and second signal planes are maintained at the same voltage with respect to the electrically conductive enclosure, reducing leakage currents. In the presence of alpha radiation and radioactive gas decay, the signal from the first signal plane is proportional to both the surface alpha radiation and to the airborne radioactive gas, while the signal from the second signal plane is proportional only to the airborne radioactive gas. The difference between these two signals is proportional to the surface alpha radiation alone.

Abstract: An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors.

Abstract: A radon gas detector comprises a housing having an air inlet port leading to an interior, a radiation detection (e.g. alpha particle measurement) chamber and an air exhaust port leading from the interior chamber to the exterior of the housing. The chamber is closed to the entry of ambient light by a pair of light-obstructing baffles that respectively couple the air inlet and air exhaust ports to the interior chamber. Coupled with the air inlet port is a first removable, electrically conductive mesh filter. Coupled with the air exhaust port is a second, fixed electrically conductive mesh filter. Since each mesh filter is electrically conductive, it readily traps radon daughter products before they can enter into the interior chamber. Also, because of its mesh configuration, each filter readily permits substantial air flow. To measure radon concentration in the air being circulated through detector, a radiation (e.g.

Abstract: A fan-less long range alpha detector which operates by using an electrical field between a signal plane and the surface or substance to be monitored for air ions created by collisions with alpha radiation. Without a fan, the detector can operate without the possibility of spreading dust and potential contamination into the atmosphere. A guard plane between the signal plane and the electrically conductive enclosure and maintained at the same voltage as the signal plane, reduces leakage currents. The detector can easily monitor soil, or other solid or liquid surfaces.

Abstract: A detector for atmospheric radon using a long range alpha detector as its sensing element. An electrostatic filter removes ions from ambient air, while allowing radon atoms to pass into a decay cavity. Here, radon atoms are allowed to decay, creating air ions. These air ions are drawn by a fan through a second electrostatic filter which can be activated or deactivated, and into the long range alpha detector. With the second electrostatic filter activated, no air ions are allowed to pass, and the signal output from the long range alpha detector consists of only the electronic background. With the second electrostatic filter deactivated, air ions and cosmic rays will be detected. The cosmic ray contribution can be minimized by shielding.

Abstract: A proportional-type detector for the detection of low levels of radioactivity, such as alpha and beta particles generated by radioactive materials. In the preferred embodiment, this detector has a pancake-shaped cavity with a disk-shaped base and a cylindrical wall, with at least one anode member traversing the cavity. This anode member is maintained at an elevated potential so as to multiply and collect electrons formed within a counting gas within the cavity as a result of interaction between the radioactivity and a counter gas cavity. A perforated grid member, in one embodiment being a spiral coil, is substantially concentric with the anode member to provided a uniform electric field around the anode member. In the preferred embodiment, spacing between turns of the spiral grid is equal to or less than twice the radial distance between the anode member and the inside diameter of the grid.

Abstract: An alpha particle detector, utilizing alternating currents, whcih is capable of detecting alpha particles from distinct sources. The use of alternating currents allows use of simpler ac circuits which, in turn, are not susceptible to dc error components. It also allows the benefit of gas gain, if desired. In the invention, a voltage source creates an electric field between two conductive grids, and between the grids and a conductive enclosure. Air containing air ions created by collision with alpha particles is drawn into the enclosure and detected. In some embodiments, the air flow into the enclosure is interrupted, creating an alternating flow of ions. In another embodiment, a modulated voltage is applied to the grid, also modulating the detection of ions.

Abstract: An alpha particle detector capable of detecting alpha radiation from distant sources. In one embodiment, a high voltage is generated in a first electrically conductive mesh while a fan draws air containing air molecules ionized by alpha particles through an air passage and across a second electrically conductive mesh. The current in the second electrically conductive mesh can be detected and used for measurement or alarm. The detector can be used for area, personnel and equipment monitoring.

Abstract: An electret ion chamber based radon monitor is employed as a method of measuring radium-226 and dissolved radon-222 concentrations in water. The procedure consists of taking a known volume of water and placing it in a container of known volume and determining the equilibrium radon concentration in the air phase above the water using an electret ion chamber radon. The radon concentration in the original water sample is calculated from the radon concentration of the air phase. A detailed theory is proposed and experimental results reported. Given a 200 ml water sample, it is typically possible to measure radon concentration of 160 pCi/l with an accuracy of 10% in a one day measurement. One pCi/l of Ra-226 can be also determined with an accuracy of 10% over a 10 day period.

Abstract: The Alpha Energy Range Discrimination (AERD) method employs first and second proportional counter tubes separated by a foil and an electronic evaluation system, and comprises the following steps:(a) a filter is disposed in the stream of air flow and is thereby covered with dust, no artificial aerosol alpha activity being present;(b) the radiation of natural nuclides is measured by means of the first and second counter tubes in pulses per second, and respective count rates alpha.sub.1 and alpha.sub.2 are determined;(c) the ratio alpha.sub.1 /alpha.sub.2 is plotted graphically against alpha.sub.2 and corresponding constant values a.sub.1 and a.sub.2 are determined for each counter tube in accordance with the least square fit method;(d) the counter tubes are arranged with the second counter tube above the first counter tube, separated by the separating foil, so that the lower counter tube measures the radiation of both natural and artificial nuclides (count rate alpha.sub.

Abstract: A sensitive alpha radiation detector, not responsive to beta or gamma radiation, is provided in an air contamination system to respond to small levels of radon such as 4 picocuries per liter of air. Thus a substantially instantaneous detector for radon in dwellings is provided. The detector comprises a vessel having a housing outer electrode with an air passage screen leading into a first interior compartment confronting a detector electrode. Another interior compartment has therein a calibrated alpha source for ionizing that compartment which is separated from the first compartment by the detector electrode. Thus a small amount of alpha radiation is detectable when presented near the air passage screen. For providing direct radon readings consistent with the Environmental Protection Agency standard of 4 picocuries per liter of air, accumulation of dust and radon daughters from a measured amount of air passed through a filter for a minute or so are processed.

Abstract: A nuclear radiation level detector includes an ionization chamber. Within the ionization chamber are spaced electrodes. The space between the electrodes communicates with the atmosphere so as to expose the electrodes to the atmosphere. A voltage source applies a potential across the electrodes. When the atmosphere is not contaminated with nuclear radiation above a reference level, the current flow between the electrodes is nil or substantially so. In the event the atmosphere is contaminated with nuclear radiation above a reference level, a measurable current flows between the electrodes. A measurement and alarm circuit operates an alarm in response to the current flow between the electrodes of a measurable magnitude.

Abstract: A smoke detector is provided having an ionization chamber (1). For counterbalancing the removal of ions (5.sub.1), taken out of the chamber by the violent air currents (C) passing through this chamber, these air currents are previously enriched with ions (7.sub.

Abstract: A housing assembly for use with a room air monitor for simultaneous collection and counting of suspended particles includes a casing containing a combination detector-preamplifier system at one end, a filter system at the other end, and an air flow system consisting of an air inlet formed in the casing between the detector-preamplifier system and the filter system and an air passageway extending from the air inlet through the casing and out the end opposite the detector-preamplifier combination. The filter system collects suspended particles transported directly through the housing by means of the air flow system, and these particles are detected and examined for radioactivity by the detector-preThe U.S. Government has rights in this invention pursuant to Contract No. DE-AC04-76DP03533 between the Department of Energy and Rockwell International Corporation.

Abstract: A method is provided for contamination and irradiation measurement and a universal sensor for implementing said process. The individual portable sensor of the invention includes an electret a first face of which is at least partially in contact with the fluid which it is desired to monitor and electrodes disposed opposite the second face. An electronic circuit measures the field variation of the electret in the zone opposite said electrodes. An aerolic circuit ensures a constant flow of fluid over the electret.

Abstract: Apparatus for checking atmospheric pollution by alpha particle-emitting aerosols includes a filter, a detector positioned facing the filter and a unique grid positioned between the filter and the detector. The grid is constituted by radial plates perpendicular to the filter and the detector extending over the entire distance between the latter and defining cells, each of which is open towards the outside of the space between the filter and the detector.

Abstract: An apparatus for detecting iodine isotopes in the exhaust gas of a nuclear installation includes a duct for a partial exhaust gas stream, which duct includes an absorption chamber which is disposed in a radiation shielding structure and through which the exhaust gas flows and which has associated therewith means for admitting absorption material and for removing it therefrom. Radiation detectors are supported in the radiation shielding structure at opposite sides of the absorption chamber for monitoring radiation of iodine isotopes collected therein, the cavity in the shielding structure in which the absorption chamber is disposed being larger than the absorption chamber and the absorption chamber being supported so as to be movable in the cavity relative to said detectors to permit calibrating the apparatus.

Abstract: Process for the detection of atmospheric contamination by alpha particle aerosols eliminating the background noise due to radon daughter nuclei, of the type consisting of collecting, by circulation of the atmospheric air, the alpha particles to be detected on a filter placed in front of a detection and counting system, wherein there is discrimination between the alpha particles present in the atmosphere coming from a polluting source and which it is wished to detect and count and the alpha particles constituting the background noise and which are normally present in the atmosphere, on the basis of their different grain sizes. The invention also relates to a portable detector for performing the aforementioned process. Application to monitoring the ambient air of laboratories, etc.

Abstract: Measuring arrangement for determining the concentration of gaseous radioiodine in a carrier gas, composed of a mass of sorption agent for separating the gaseous radioiodine from the carrier gas and for accumulating the separated radioiodine, with a part of the mass of sorption agent being located in a measuring region, a conduit for conducting the carrier gas to the sorption agent and provided with at least one outlet via which carrier gas can flow into the measuring region containing sorption agent, and a radiation detector disposed for detecting radiation emanating from the measuring region, with the sorption agent being movable relative to the conduit for bringing different portions of the mass of sorption material into the measuring region.

Abstract: A system for monitoring potentially hazardous conditions in an area. The monitor system provides a continuous check of the atmosphere in a given area for nuclear radiation hazard and for combustion hazard. When a predetermined radiation level or combustion condition occurs in the area an alarm is activated which indicates the particular kind of danger existing. A small bomb calorimeter housing or vessel supports and houses a radiation sensor and a combustion sensor. Detection circuitry responds to the radiation and combustion sensors to provide an output signal when a predetermined, dangerous threshold condition exists in the area. A screen capacitor, electroscope, and a periodic charging circuit comprise the radiation hazard detection circuitry. A reflex surge generator comprised of a sparking circuit and a spark gap in conjunction with a resistance thermometer detector provide the fire hazard circuitry. Indicator or annunciator circuitry coupled to the detectors disclose the status of the two circuits.

Abstract: The present invention relates to a pressure reducing device and to an apparatus for detecting aerosols and particularly aerosols of solid particles emitting .alpha. rays. This apparatus comprises a measuring chamber equipped with a sampling filter and a radiation detector and linked with the outside by an inlet pipe and an outlet pipe. The inlet pipe is equipped with a venturi tube making it possible to produce a pressure reduction in the measuring chamber and exert on the solid particles of the aerosol fluid flow forces exceeding the forces tending to make these particles adhere to the walls. Application to the detection of .alpha. radiation emitting aerosols.

Abstract: A conventional Kanne tritium monitor has been redesigned to reduce its sensitivity to such contaminants as tritiated water vapor and tritiated oil. The high voltage electrode has been replaced by a wire cylinder and the collector electrode has been reduced in diameter. The area sensitive to contamination has thereby been reduced by about a factor of forty while the overall apparatus sensitivity and operation has not been affected. The design allows for in situ decontamination of the chambers, if necessary.

Abstract: A wide range radioactive gas concentration detector and monitor which is capable of measuring radioactive gas concentrations over a range of eight orders of magnitude. The device of the present invention is designed to have an ionization chamber which is sufficiently small to give a fast response time for measuring radioactive gases but sufficiently large to provide accurate readings at low concentration levels. Closely spaced parallel plate grids provide a uniform electric field in the active region to improve the accuracy of measurements and reduce ion migration time so as to virtually eliminate errors due to ion recombination. The parallel plate grids are fabricated with a minimal surface area to reduce the effects of contamination resulting from absorption of contaminating materials on the surface of the grids. Additionally, the ionization chamber wall is spaced a sufficient distance from the active region of the ionization chamber to minimize contamination effects.

Abstract: A measuring head 1 which contains in a shielding housing 3 a measuring chamber 5 with a surface barrier-layer detector 9 is provided for measuring the noble gas activity concentration and the aerosol activity concentration. The gas whose activity concentration is to be measured is compressed and introduced into the measuring chamber 5. Due to the pressure increase of the gas, the volume of the measuring chamber 5 and, therefore, the weight of the shielding housing 3 can be reduced.

Abstract: A portable radiation dosimeter unit for continuously measuring exposure to radioactive decay products in ambient air. The unit is constructed as a unitary assembly suitable for mounting on a portable battery casing, the assembly housing a constant flow air pump for maintaining a constant flow of air through a filter, a detection unit and electronic circuitry connected to the detection unit for processing, counting and storing pulses generated by the detection of radioactive particles from decay products entrapped by the filter. The filter is readily replaceable, and in use is clamped in position by a clamp assembly pivotally mounted on a front wall of the unit, the clamp assembly providing an internal air passage forming part of the air flow path and positioned to receive the air which is drawn through the filter.

Abstract: The background counting rate of a plutonium measuring channel which is caused by the partial transition of .alpha.-ray energy spectrum of the daughter nuclides of the radon and the thoron to low energy side has relationship with the counting rate due to the daughter nuclide of the radon and the thoron which have energy exceeding 5.5 MeV. The background counting rate of the plutonium measuring channel is erased digitally by using the above mentioned relationship in a plutonium air monitor.

Abstract: A radioactive gas monitor that is adapted to measure total airborne radiation activity over an extended period of time and provide a readout in units that can be directly correlated to the maximum permissible exposure standards established by the federal government. The instrument also includes automatic background count rate subtraction, as well as means for measuring the actual background radiation level and adjusting the subtracted count rate accordingly.

Abstract: Device for analyzing the activity of a radioactive aerosol as a function of the grain size distribution of its particles of the type comprising a tight enclosure, means for circulating the aerosol through said enclosure and within the latter, a plurality of stages for collecting aerosol particles with a given grain size, each of the stages comprising an aerosol injection plate perforated by at least one calibrated opening and a collection plate for particles of a given grain size, wherein it comprises means for establishing an electric field between the injection and collection plates of each of the stages with a view to establishing an ionization current through a stage during the disintegration of the particles collected in the latter and means for measuring the ionization current of one of the said stages.