Abstract: An amplifier-discriminator is tailored to output a very short pulse upon an above-threshold input from a detector which may be a .sup.3 He detector. The short pulse output is stretched and energizes a light emitting diode (LED) to provide a visual output of operation and pulse detection. The short pulse is further fed to a digital section for processing and possible ORing with other like generated pulses. Finally, the output (or ORed output ) is fed to a derandomizing buffer which converts the rapidly and randomly occurring pulses into synchronized and periodically spaced-apart pulses for the accurate counting thereof. Provision is also made for the internal and external disabling of each individual channel of amplifier-discriminators in an ORed plurality of same.

Abstract: Disclosed is a neutron detector, provided with a sealed chamber having two spaced apart electrodes, hermetically sealed in the chamber with a seal which is located in an environment of at least two decades less neutron flux than that experienced by the detector. An ionizable gas is placed within the space between the electrodes, and pressurized to a pressure above one atmosphere. A layer of a mixture of an active material and a breeding material are positioned within the chamber, the active material and breeding material being respectively U-235 and U-234, which layer has a thickness of at least 0.2 milligrams per square centimeter.

Abstract: A detector apparatus for differentiating between gamma and neutron radiation is provided. The detector includes a pair of differentially shielded Geiger-Mueller tubes. The first tube is wrapped in silver foil and the second tube is wrapped in lead foil. Both the silver and lead foils allow the passage of gamma rays at a constant rate in a gamma ray only field. When neutrons are present, however, the silver activates and emits beta radiation that is also detected by the silver wrapped Geiger-Mueller tube while the radiation detected by the lead wrapped Geiger-Mueller tube remains constant. The amount of radiation impinging on the separate Geiger-Mueller tubes is then correlated in order to distinguish between the neutron and gamma radiations.

Abstract: A method for fabricating a thermocouple unit for service in and about nuclear reactors and other radioactive environments. The method provides a thermocouple encapsulated within a sphere of fissile material.

Abstract: A neutron detector system is disclosed wherein a neutron charge amplifier discriminator circuit is used in conjunction with a neutron detector enabling detection of nuclear events, amplification of extremely small signals, conditioning of the signals, further amplification of the signal, discrimination of the signals, conversion into digital form and counting for a predetermined time period.

Abstract: An electronic circuit provides various accurate counts of detected neutrons to enable the assaying of fissile material in a neutron emitting radioactive source. The circuit develops a time correlated window associated with each detected neutron, and delays these windows to develop uncorrelated windows. These windows are used to develop separate detected neutron counts which distinguish between time correlated fission neutron detections and time uncorrelated singular neutron detections. The circuit also develops a count of all detected neutrons.

Abstract: In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

Abstract: The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

Abstract: A system for gamma-ray interference-free fast-neutron radiography is provd. The system comprises a radiation detector adapted to distinguish between neutron and gamma radiation, an imaging device transducing object-point related signals generated by the object-modified neutron and gamma radiation in the radiation detector. The system also includes a pulse-shaped discrimination and gating device for passing only neutron-induced image-producing pulses so as to filter out the gamma-ray induced, interfering signals.

Abstract: A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

Abstract: An apparatus for measuring neutrons and gamma rays is disclosed in which after pulses generated by neutrons are discriminated from pulses generated by gamma rays, two different counted values are obtained for either the pulses generated by neutrons or the pulses generated by gamma rays to control a discriminating circuit between the pulses by neutrons and the pulses by gamma rays so that a ratio between the different counted values is kept constant, and further two different counted values are obtained for either the pulses by neutrons or the pulses by gamma rays in a manner the same as the above-mentioned to control the output of a detector so that a ratio between the counted values is kept constant.

Abstract: A method for improving the accuracy of neutron detectors is disclosed wherein a predetermined threshold level, by analysis of a neutron and gamma relative distribution curve, is set and all amplitudes below this predetermined minimum are removed from a neutron detector total count.

Abstract: A neutron detector is disclosed which uses the moderating material as the structural support for the neutron detector element. A thin metal liner is affixed to the inside of the plastic moderating material encasement for containing a neutron detecting gas. A high voltage supply is connected to an electrical conductor which extends between the ends of the encasement and serves to furnish output pulses to a pulse counter upon the occurrence of ionization of the counting gas in response to neutron flux through the volume of the detector.

Abstract: Measurement of the level of materials in bins, hoppers, and the like is effected by a neutron monitoring technique. A sensor is located to move substantially vertically in a guide located in or near the bin or hopper. The sensor contains a fast neutron source, a detector of thermal neutrons, and a moderator-containing material in the vicinity of the detector. In a preferred form of the sensor, the neutron source and thermal neutron detector are separated by lead and cadmium screening, and the moderator-containing material is a sheath of polyethylene around the detector. With sensors of this type, material levels may be sensed whether the material contains a neutron moderator or not.

Abstract: In a neutron detector of the type comprising an ionization chamber provided with anode and cathode electrodes for detecting neutron flux injected into the ionization chamber, and a cable including a central conductor connected to the anode or cathode electrode and the outer conductor connected to the cathode or anode electrode there are provided an intermediate insulated annular conductor arranged between the inner and outer conductors of the cable, and upper and lower insulated annular conductors disposed between the anode and cathode electrodes for supporting one of them. The upper and lower insulated annular conductors are electrically interconnected and the upper insulated annular conductor is connected to the intermediate annular conductor of the cable.

Abstract: According to the present invention there is provided a neutron dosimeter sensitive in the region of from 1 eV to about 14 MeV which comprises a .sup.10 B miniature spectrometer for the region of 1 eV to 30 KeV, a .sup.10 B albedo detector for the range of 30 KeV to 1 MeV and a suitable polymer foil selected from polycarbonate foil and a plastic made from a diester of a carbonic acid, such as the product sold under the trade name of CR-39 with a thin proton radiator for the region of 1 MeV to 14 MeV.

Abstract: A sample fluid stream passes through a molecular sieve in which moisture is adsorbed in direct proportion to the moisture in the fluid stream. Fast neutrons beamed through the sieve interact with the hydrogen nuclei in the accumulated water. The resulting slow neutrons are detected to produce an output indicative of the percentage of moisture in the fluid stream.

Abstract: A method is disclosed for rapidly and accurately generating an output signal corresponding to the power of a nuclear reactor core. The method comprises generating out of core neutron flux signals at different time intervals and utilizing predetermined relationships therebetween to adjust a more accurate thermal power signal which has a slow response to transient power conditions.

Abstract: A nondestructive method for uniqely distinguishing among and quantifying the mass of individual fuel plates in situ in fuel drawers utilized in nuclear reactors is described. The method is both rapid and passive, eliminating the personnel hazard of the commonly used irradiation techniques which require that the analysis be performed in proximity to an intense neutron source such as a reactor. In the present technique, only normally decaying nuclei are observed. This allows the analysis to be performed anywhere. This feature, combined with rapid scanning of a given fuel drawer (in approximately 30 s), and the computer data analysis allows the processing of large numbers of fuel drawers efficiently in the event of a loss alert.

Abstract: A device for gauging the thickness of refractory lining, comprising an electric pulse measuring unit connected to a lining thickness pulse transducer. The latter is mounted on that portion of the lining which is subjected to thickness measurements, and comprises a fast neutron source, a protective shield, and a thermal and epithermal neutron detector; these are successively arranged in a sealed housing. The thermal and epithermal neutron detector contains a plurality of thermal neutron counters with the number thereof being determined by the activity of the fast neutron source, and a neutron moderator intended to expand the energy interval of neutrons counted by the thermal neutron counters.

Abstract: A nuclear method and apparatus determines the temperature of a medium by injecting fast neutrons into the medium and detecting returning slow neutrons in three first energy ranges by producing three respective detection signals. The detection signals are combined to produce three derived indicia each systematically related to the population of slow neutrons returning from the medium in a respective one of three second energy ranges, specifically exclusively epithermal neutrons, exclusively substantially all thermal neutrons and exclusively a portion of the thermal neutron spectrum. The derived indicia are compared with calibration indicia similarly systematically related to the population of slow neutrons in the same three second energy ranges returning from similarly irradiated calibration media for which the relationships temperature, neutron absorption cross section and neutron moderating power to such calibration indicia are known.

Abstract: An apparatus and method for measuring the neutron moderating or absorbing properties of objects or materials in which a fast neutron source cooperates with a neutron absorbing material which reduces the energy of the fast neutrons by inelastic scattering so that they can be readily thermalized by a moderator. A thermal neutron detector is disposed adjacent the material and serves to detect thermal neutrons emitted by a moderator placed to receive and thermalize the reduced energy neutrons. A material whose absorption is to be measured is placed between a moderator and the detector.

Abstract: A radioactivity well logging tool employs an epithermal neutron detector having a thermal neutron counter surrounded by a thermal neutron shield. Located between the counter and the shield is a neutron moderating material for slowing down epithermal neutrons penetrating the thermal neutron shield to enable their counting by the thermal neutron counter.

Abstract: A portable high-speed neutron spectrometer consisting of an organic scintillator, a true zero-crossing pulse shape discriminator, a 1 MHz conversion-rate multichannel analyzer, an 8-bit microcomputer, and appropriate displays. The device can be used to measure neutron energy spectra and kerma rate in intense n-.gamma. radiation fields in which the neutron energy is from 0.5 to 15 MeV.

Abstract: A portable neutron spectrometer/kerma-rate meter for the measurement of the fast neutron component of mixed n-.gamma. fields in the 1 to 15 MeV neutron energy range. The system includes an organic scintillation detector, pulse shape discrimination circuitry, a 1.4 .mu.sec multichannel analyzer, an 8-bit microcomputer, and appropriate displays. The instrument is capable of both gathering and processing recoil-proton pulse-height data in the field.

Abstract: A scintillator for neutron time-of-flight measurements is positioned at a desired angle with respect to the neutron beam, and as a function of the energy thereof, such that the sum of the transit times of the neutrons and photons in the scintillator are substantially independent of the points of scintillations within the scintillator. Extrapolated zero timing is employed rather than the usual constant fraction timing. As a result, a substantially larger scintillator can be employed that substantially increases the data rate and shortens the experiment time.

Abstract: Cold neutron radiation of energy less that 0.025 eV having a flux greater than 1.times.10.sup.3 neutrons/square centimeter/second is used to diagnose temporal information about the spatial distribution of hydrocarbon fuel and lubrication oils in internal combustion engines, gas turbine engines and fuel systems.Images of the movement of fuel or oil are recorded by directing a beam of neutrons through an engine and using an image intensifier responsive to low light levels to intensify an image formed by neutrons which have been directed through the engine onto a fluorescent screen. The output image from the intensifier is recorded by a video or cine camera.

Abstract: An improved cold neutron radiographic apparatus and method are disclosed wherein neutron temperature is matched to the specific material to be examined. This can be done, in one embodiment, by placing a radioactive source of neutrons, such as californium 252, in a moderator such as solid methane and using a cryogenic refrigeration system to cool the moderator to any pre-selected cryogenic temperature.

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: A composite transducer for the measurement of a physical condition such as, but not limited to, temperature, pressure, liquid level, rate of flow, concentration of a constituent gas in a mixture of gases, or neutron flux density; wherein the output signal of a prompt responding but relatively inaccurate sensor is combined with the output signal of a slow responding but relatively accurate sensor to generate a composite transducer output signal having a response time comparable to that of the fast responding sensor and an accuracy equal to that of the slow responding sensor.

Abstract: The fast neutron hodoscope, a device that produces neutron radiographs with coarse space resolution in a short time, is modified to produce neutron or gamma radiographs of relatively thick samples and with high space resolution. The modification comprises motorizing a neutron and gamma collimator to permit a controlled scanning pattern, simultaneous collection of data in a number of hodoscope channels over a period of time, and computerized image reconstruction of the data thus gathered.

Abstract: An apparatus for determining the dose equivalent and dose rate equivalent neutrons, which includes a detector for absorbing neutrons and emitting voltage pulses. The detector is surrounded by a mantle for moderating purposes and for absorbing neutrons. The detector is followed by amplifying means for amplifying the voltage pulses emitted by the detector while a voltage discriminator receives the amplified voltage pulses. The voltage discriminator is followed by recording means for registering the time average number of the voltage pulses emitted by the voltage discriminator while the detector for neutrons with energies up to at least 10.sup.6 eV emits voltage pulses, the height of which, depends both on the energy freed by the nuclear reaction initiated by the absorbed neutrons and on the kinetic energy of the absorbed neutrons. The number of these voltage pulses shows a maximum.

Abstract: A fission chamber neutron detector which is both gamma and alpha compensated. The alpha compensation is provided by inclusion of a low neutron cross section, alpha particle emissive isotope within the gamma compensation portion of the fission chamber.

Abstract: Pulses from a particle detector and a reference-pulse generator are fed to multichannel analyzer converting the pulse amplitudes into binary signals appearing on its stage outputs, certain of these stage outputs being connected to a pair of decoders in such a way that one decoder responds to pulse amplitudes in a first group of n channels whereas the other decoder registers amplitudes in a second n-channel group divided into two halves which bracket the first group. The reference pulses are of such amplitude as to fall in the middle of the first channel group; if a measuring pulse in the detector output coincides with a reference pulse, the amplitude of the latter is either increased or decreased so as to fall mainly in one or the other half of the second group.

Abstract: A method of determining a depth of an accumulation of snow in which the water-equivalent depth of an accumulation of snow is determined from the count of survival neutrons of cosmic rays after passing through an accumulation of snow.

Abstract: An improved, self-powered, gamma compensated, neutron detector having two electrically conductive concentric cylindrical electrodes and a central rod emitter formed from a material which emits beta particles when bombarded by neutrons. The outer electrode and emitter are maintained at a common potential and the neutron representative current is furnished at the inner cylindrical electrode which serves as a collector. The two concentric cylindrical electrodes are designed to exhibit substantially equal electron emission induced by Compton scattering under neutron bombardment to supply the desired gamma compensation.

Abstract: A flux of neutrons is measured by disposing a detector in the flux and applying electronic correlation techniques to discriminate between the electrical signals generated by the neutron detector and the unwanted interfering electrical signals generated by the incidence of a neutron flux upon the cables connecting the detector to the electronic measuring equipment at a remote location.

Abstract: A radiation flux measuring device is described which employs a differential pair of transistors, the output of which is maintained constant, connected to a radiation detector. Means connected to the differential pair produce a signal representing the log of the a-c component of the radiation detector, thereby providing a signal representing the true root mean square logarithmic output.

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

Abstract: A method of automatically monitoring the power distribution of a nuclear reactor during normal power operation employing in-core detectors maintained within the thermal environment of the reactor at a prearranged storage location, normally outside the core reactivity region. The detectors are intermittently inserted into the core region according to a periodic predetermined time program. Upon insertion, the detectors are moved along corresponding preselected linear paths which terminate at the detector storage locations. Detector output vs. position is continuously recorded during travel to provide a partial core flux map.Four detectors, arranged in two electronically redundant groups, are alternately inserted into the core at staggered intervals dictated by the time program to obtain the desired flux information.

Abstract: An improved log N amplifier type nuclear reactor period meter with reduced probability for noise-induced scrams is provided. With the reactor at low power levels a sampling circuit is provided to determine the reactor period by measuring the finite change in the amplitude of the log N amplifier output signal for a predetermined time period, while at high power levels, differentiation of the log N amplifier output signal provides an additional measure of the reactor period.