Abstract: A self-powered in-core detector arrangement for measuring flux in a nuclear reactor core includes a first in-core detector and a second in-core detector. The first in-core detector includes a first flux detecting material, a first lead wire extending longitudinally from a first axial end of the first flux detecting material, a first insulating material surrounding outer diameters of the first flux detecting material and the first lead wire and a first sheath surrounding the first insulating material. The first sheath includes a first section surrounding the first flux detecting material and a second section surrounding the first lead wire. The first section of the first sheath has a greater outer diameter than the second section of the first sheath.

Abstract: A temperature measurement sensor for use in a nuclear reactor is described. The sensor includes a first neutron detector member and a second neutron detector member. The first neutron detector includes an outer shield material with an effective neutron capture cross section that is temperature dependent. The first neutron detector member outputs a first current signal and the second neutron detector member outputs a second current signal. An electrical connection between the first and second neutron detector members produces a net current that is the difference in current between the first and second signals. The difference is proportional to changes in temperature.

Abstract: A neutron proportional counter is provided. The proportional counter can include a chamber and a gas mixture. The chamber includes an anode and a cathode. The gas mixture is contained within the chamber and includes at least one neutron sensitive fill gas and a quench gas including BF3. In certain embodiments, the neutron sensitive fill gas can be configured for detection of thermal neutrons (e.g., He-3), fast neutrons (e.g., He-4, H2), or both (e.g., UF6).

Abstract: A subcritical reactivity monitor that utilizes one or more primarily gamma sensitive (prompt responding) self-powered detector style radiation measurement devices located within the core of a nuclear reactor to determine the amount that the reactor multiplication factor (Keff) is below the reactivity required to achieve or maintain a self-sustaining nuclear chain reaction. This invention utilizes measured changes in the self-powered detectors' current(s) to allow a reactor operator to measure the value of Keff at essentially any desired interval while the reactor is shutdown with a Keff value less than the critical value of 1.0. This invention will enable integration of the output of the value of Keff directly into the Reactor Protection System, which will enable the elimination of the operational and core design analysis constraint costs associated with the current Boron Dilution Accident prevention methodology and enable automatic control of the Chemical Volume Control System.

Abstract: Embodiments described herein provide for smart configuration of audio settings for a playback device. According to an embodiment, while a playback device is a part of a first zone group that includes the playback device and at least one first playback device, the playback device applies a first audio setting. The embodiment also includes the playback device joining a second zone group that includes the playback device and at least one second playback device. The embodiment further includes the playback device applying a second audio setting based on an audio content profile corresponding to the second zone group.

Abstract: Systems and methods for neutron detection using tensioned metastable fluid detectors, using multi-atom spectroscopy approach.

Abstract: A process signal control and monitoring system, includes: a signal processing device which is installed on an outside of a nuclear reactor containment vessel, an internal electrical power source, an analog-digital conversion part, an internal communication part which transmits the digital signal to the signal processing device, an internal repeater, and an external repeater which transmits the received signal to a communication satellite. When electric power supply from the signal processing device is disconnected, the internal electrical power source supplies electric power which is charged in the rechargeable battery, to the analog-digital conversion part and the internal communication part; and the internal communication part judges whether communication with the signal processing device is continued or disconnected; and when the communication is judged to be continued, the internal communication part continues transmitting the digital signal to the signal processing device.

Abstract: Methods and systems for non-intrusively detecting existence of fissile materials by measuring energetic prompt neutrons. The unique nature of the prompt neutron energy spectrum from photo-fission arising from emission of neutrons from almost fully accelerated fragments is used to unambiguously identify fissile material. Angular distribution of prompt neutrons from photo-fission and energy distribution correlated to neutron angle relative to the photon beam are used to distinguish odd-even from even-even nuclei undergoing photo-fission. Independence of the neutron yield curve (yield as a function of electron beam energy or photon energy) on neutron energy is used to distinguish photo-fission from other processes such as (?, n). Different beam geometries detect localized samples of fissile material and fissile materials dispersed as small fragments or thin sheets over broad regions.

Abstract: Systems and methods for neutron detection using tensioned metastable fluid detectors, using a single atom spectroscopy approach.

Abstract: Tensioned metastable fluid detectors are disclosed that minimize false positive detection events. The methods involve the use of new fluids that provide improved neutron-alpha fission detection at reduced tension states. The rate of spin is also increased using a new protocol that avoids the creation of liquid imbalances in the arms of a CTMFD (centrifugally tensioned metastable fluid detector). The disclosed CTMFD radiation detection system includes a detector assembly containing a detection fluid, a base, a safety enclosure, a motor and motor mounting bracket, speed sensors, a cooling system that includes an air inlet and outlet and a safety enclosure. The CTMFD radiation detection system can include a plurality of independent detector arms having fluids with distinct Pneg requirements such that the range of detectable radiation is increased. Also disclosed are methods for detecting radiation using the disclosed CTMFD radiation detection system. Motor speed calibration procedures are also disclosed.

Abstract: Compositions and methods for monitoring the quantity of actinides present in a test sample are disclosed. Compositions and methods for monitoring the motion of special nuclear materials through space are also described. Compositions and methods for monitoring the quantity of a fissile special nuclear material present in a test sample are disclosed. Compositions and methods for monitoring actinides during reprocessing of spent nuclear fuel after 30-year cool down are disclosed. Compositions and methods for monitoring actinides during reprocessing of spent nuclear fuel after 180 day cool down are also disclosed.

Abstract: To provide an X-ray detector facilitating the installing and replacement work of a module while reducing the possibility of breakage. An X-ray detector 50 detecting X-ray image data for each detection module includes: a detection module 7 provided with a protruding frame on a back side of a detection device detecting X-rays; and a guide frame 12 fitting into the protruding frame and removably supporting the detection device, wherein the guide frame 12 fixes the position of the detection device relative to the guide frame 12 by fitting. Therefore, fitting the protruding frame 8 into the guide frame 12 enables precise and easy installation/removal of the detection module. That is a detection module can be newly installed onto the guide frame without interfering each other with adjacent detection modules already installed while minimizing a space therebetween.

Abstract: A single crystal yttrium aluminum perovskite scintillator has a minimum thickness of at least 5 mm and a transmittance of at least 50% at a wavelength of 370 nm. A method for fabricating the yttrium aluminum perovskite scintillator includes acquiring a yttrium aluminum perovskite single crystal boule, annealing the yttrium aluminum perovskite single crystal boule in an oxygen containing environment to obtain a partially annealed crystal, and annealing the partially annealed crystal in an inert environment or a reducing environment to obtain the yttrium aluminum perovskite single crystal scintillator.

Abstract: A device for detecting neutrons includes at least one common module, where a number of solid state sensors are assembled. The sensors are configured in the module side by side and/or stacked in a layered structure. At least one of the sensors includes neutron reactive material as a neutron converter for interacting with neutrons incident thereon to be detected and to release ionizing radiation reaction products responsive to interactions with the incident neutrons. The neutron converters are coupled with corresponding semiconductor elements so that the semiconductor elements interact with the ionizing radiation reaction products for providing electrical charges in proportion to the energy of the ionizing radiation reaction products. The semiconductor elements are configured with electrodes for providing charge collection areas for collecting the electrical charges and to provide electrically readable signals proportional to the collected electrical charges.

Abstract: A method and system for detecting special nuclear materials are disclosed. Said method and system detect the special nuclear materials by making use of the photofission characteristic and thermal neutron induced fission characteristic thereof. In one preferred embodiment, the high density and/or high atomic number region in the object to be detected is also detected first as a suspicious region.

Abstract: Apparatus and method for detecting radiation-of-interest, such as neutron radiation, employs a gas chamber, a gas that responds to ionizing particles by producing electrons and ions, a cathode that attracts ions, and a supporting layer with a conductive pathway. The conductive pathway collects electrons and responds to electrons that drift towards the conductive pathway by inducing production of further electrons and ions within the gas. The electrons that are collected at the conductive pathway and/or the ions that drift away from the conductive pathway will induce an electrical signal, which can be used to detect the radiation-of-interest.

Abstract: A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

Abstract: A reactor state monitoring apparatus including: a first gamma ray-dose measurement device that detects and measures an atmospheric radiation dose caused by radioactive substances on a containment vessel side respective to a biological shielding wall surrounding a pressure vessel and outside the pressure vessel; a second gamma ray-dose measurement device that detects and measures a radiation dose on the pressure vessel side respective to the biological shielding wall; a fuel radiation measuring device that detects and measures a radiation dose of fuel in the pressure vessel; and a water amount evaluation device that calculates a difference between radiation doses measured by the fuel radiation measuring device and the first gamma ray-dose measurement device as a corrected fuel radiation dose, and acquires a cooling water level as a water level evaluation value, based on the radiation dose measured by the second gamma ray-dose measurement device and the corrected fuel radiation dose.

Abstract: A method for detecting particles is presented. The method comprises generating a reaction to a plurality of particles using a converter material, wherein the converter material is operable to interact with the plurality of particles, and wherein a subset of the plurality of particles comprises neutrons. Further, the method comprises converting a response to the reaction to a readable electrical signal using a sensor, wherein the sensor comprises an array of pixels. Also, the method comprises processing the readable electrical signal from the sensor to generate information for each pixel on the array of pixels and transmitting the information to a processing unit. Also, the method comprises executing a discrimination procedure using the information for distinguishing between instances of impingement of neutrons and non-neutron particles on the array of pixels. Further, the method comprises determining the radionuclide or non-radionuclide source of origin of the neutron and non-neutron particles.

Abstract: Methods for detecting and identifying carbon- and/or nitrogen-containing materials are disclosed. The methods may comprise detection of photo-nuclear reaction products of nitrogen and carbon to detect and identify the carbon- and/or nitrogen-containing materials.

Abstract: A method for providing a boron-lined neutron detector. The method includes providing a boron-containing material and providing water. The method includes mixing the boron-containing material into the water to create a water-based liquid mixture and providing a substrate of a cathode of the neutron detector. The method includes applying the water-based liquid mixture to the substrate of the cathode and removing water from the water-based liquid applied to the substrate to leave a boron-containing layer upon the substrate that is sensitive to neutron impingement. The step of providing a boron-containing material may be to provide the material to include B-10.

Abstract: A method and apparatus for identifying and tagging a target, such an individual or an item, are described that provide an improved mechanism for identifying the target without alerting the target. In this regard, a method and apparatus can irradiate the target so as to create a radioisotope signature for the target. By thereafter monitoring the radioisotope signature, the target can be identified and tracked in a covert manner.

Abstract: A self-powered integral in-core instrument thimble assembly for monitoring the temperature and radiation levels surrounding a nuclear fuel assembly, that transmits output signals wirelessly to a remote location. The in-core instrument thimble assembly is activated by a short exposure within a reactor core and remains active after the fuel assembly is removed from the reactor core to continuously provide a remote monitoring capability for the fuel assembly as it is transported or stored at a remote location, without an external power source.

Abstract: An activation detector for fast-neutrons has a yttrium target exposed to a neutron source. Fast-neutrons which have energy in excess of 1 MeV (above a threshold energy level) generate gamma rays from a nuclear reaction with the yttrium, the gamma rays having an energy level of 908.96 keV, and the resultant gamma rays are coupled to a scintillator which generates an optical response, the optical response of the scintillator is coupled to a photomultiplier tube which generates an electrical response. The number of counts from the photomultiplier tube provides an accurate indication of the fast-neutron flux, and the detector is exclusively sensitive to fast-neutrons with an energy level over 1 MeV, thereby providing a fast-neutron detector which does not require calibration or the setting of a threshold.

Abstract: Systems and methods for detecting clandestine fissile or radioactive material on the basis of emitted radiation and particles (such as neutrons and alpha particles) arising from within the material. Emission by the fissile or radioactive material is detected in conjunction with a conventional x-ray imaging system that includes an external source of illuminating penetrating radiation, at least one detector configured to detect at least the penetrating radiation and to generate a detector signal, and a processor configured as a detector signal discriminator to generate an output indicating whether the detector signal is triggered by an origin other than illuminating penetrating radiation. Active and passive modes of detection are described by some embodiments. Other embodiments are directed toward neutron detection, gamma ray detection with energy resolution, and designs of detectors to enhance the detection of clandestine nuclear material.

Abstract: A first pulsed beam of charged particles from a particle accelerator is accelerated toward a first target that is configured to emit a fast neutron beam in response to being struck by an accelerated particle such that the fast neutron beam is directed toward a physical region. The last neutron beam includes a neutron having an energy sufficient to cause fission in a fissionable material. Data from a sensor configured to detect radiation of a fission product is accessed, and before accelerating a second pulsed beam of charged particles, whether the physical region includes a fissionable material based on the data from the sensor is determined.

Abstract: The Cherenkov effect is used to detect neutrons emitted by man-made radioactive materials. Water or other liquid or gas may be used as a detection medium. The water may include a dispersed or dissolved dopant having a high neutron capture cross-section, which renders the dopant able to absorb and react with neutron radiation effectively. When the dopant absorbs, or reacts with, a neutron particle, the result of the reaction may be the generation of beta particles which can be detected via the accompanying emission of light, dispersed or dissolved, according to the Cherenkov effect.

Abstract: Systems and methods for detecting clandestine fissile or radioactive material on the basis of emitted radiation and particles (such as neutrons and alpha particles) arising from within the material. Emission by the fissile or radioactive material is detected in conjunction with a conventional x-ray imaging system that includes an external source of illuminating penetrating radiation, at least one detector configured to detect at least the penetrating radiation and to generate a detector signal, and a processor configured as a detector signal discriminator to generate an output indicating whether the detector signal is triggered by an origin other than illuminating penetrating radiation. Active and passive modes of detection are described by some embodiments. Other embodiments are directed toward neutron detection, gamma ray detection with energy resolution, and designs of detectors to enhance the detection of clandestine nuclear material.

Abstract: A method for measuring high-energy radiation includes applying a voltage pulse to electrodes in an ion chamber filled with a gas capable of forming charged ions by the high-energy radiation; measuring an ion current signal related to ion currents induced by the voltage pulse; and determining a magnitude of the high-energy radiation based on the ion current signal.

Abstract: A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

Abstract: A neutron detector system for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. The system includes a graphing component that displays the plot of the neutron distribution from the unknown source over a Poisson distribution and a plot of neutrons due to background or environmental sources. The system further includes a known neutron source placed in proximity to the unknown source to actively interrogate the unknown source in order to accentuate differences in neutron emission from the unknown source from Poisson distributions and/or environmental sources.

Abstract: A neutron detector that includes an anode and a cathode. The cathode includes at least one portion that has a porous substrate with surface segments that define open pores and a layer of neutron sensitive material on the surface segments of the porous substrate.

Abstract: A system to detect ionizing particles includes an enclosure which holds a fluid in a tensioned metastable state. The interaction of a particle with the liquid creates a respective vapor pocket that can be seen and recorded, and also results in a shock wave that can be heard and recorded. The level of tension metastability in combination with agents, such as Be and B atoms, and surfactants that minimize evaporation losses is associated with a particular type of particle.

Abstract: A method of collecting data on radioactive material includes: positioning a detector unit at a first position relative to the environment; collecting at least a part of a first set of data from a first position using a detector unit; and collecting at least a part of one or more subsequent sets of data on the environment from one or more subsequent positions using the detector unit; wherein one or more of the subsequent positions is determined, at least in part, by considering at least a part of the data of one or more of the sets of data previously collected. The subsequent positions are determined so as to improve the information on the radioactive material provided as a result of the data collected from that position.

Abstract: Systems and methods for detecting clandestine fissile or radioactive material on the basis of emitted radiation and particles (such as neutrons and alpha particles) arising from within the material. Emission by the fissile or radioactive material is detected in conjunction with a conventional x-ray imaging system that includes an external source of illuminating penetrating radiation, at least one detector configured to detect at least the penetrating radiation and to generate a detector signal, and a processor configured as a detector signal discriminator to generate an output indicating whether the detector signal is triggered by an origin other than illuminating penetrating radiation. Active and passive modes of detection are described by some embodiments. Other embodiments are directed toward neutron detection, gamma ray detection with energy resolution, and designs of detectors to enhance the detection of clandestine nuclear material.

Abstract: A system for detecting and classifying small amounts of explosives and other controlled substances while rejecting confounders, including a source/detector array formed of a plurality of sources and a plurality of detectors, a signal processor coupled to the source/detector array for processing data received from the detectors, a classifier coupled to the signal processor for classifying data received from the signal processor according to a plurality of algorithms, a maximal rejection classifier coupled to the classifier; and a declarative decision module coupled to the maximal rejection classifier for rendering an accurate decision regarding the contents of the object is provided. The apparatus includes an enclosure, a shield layer disposed within the enclosure, a cavity disposed within the shield layer, a plurality of neutron sources and a detection array disposed within the cavity, and a transport mechanism for moving objects through the cavity past the sources and detection array.

Abstract: A nuclear reactor plant protection system printed circuit card comprises a first logic device having a number of basic logic circuits, and a second logic device operatively connected with the first logic device for testing the number of basic logic circuits without taking the printed circuit card out of service. A nuclear reactor plant protection system printed circuit card comprises a first logic device producing a first output signal in response to a test signal, a second logic device producing a second output signal in response to the test signal, and a comparator for comparing the first output signal and the second output signal, wherein the test signal has a pulse duration that is less than a latching period associated with the printed circuit card. A method of testing and a nuclear reactor control system incorporating the nuclear reactor plant protection system printed circuit card is also provided.

Abstract: A method for measuring high-energy radiation flux includes applying a positive voltage to electrodes in an ion chamber filled with a gas capable of forming charged ions by a high-energy radiation, measuring a positive ion current signal related to ion currents induced by the positive voltage, applying a negative voltage to the electrodes, measuring a negative signal related to ion currents induced by the negative voltage, and determining a magnitude of the high-energy radiation flux based on the ion current signal.

Abstract: A device for detecting photonuclear-induced neutrons is described herein. One embodiment of the device may comprise a neutron detector and a detection circuit. The neutron detector may comprise a detector output. The detection circuit may be operatively connected to the detector output and may comprise an amplifier, a low-pass filter, and a high pass filter. The amplifier may comprise an amplifier input and an amplifier output. The amplifier input may be being operatively connected to the detector output. The low-pass filter may comprise a low-pass filter input and a low-pass filter output. The low-pass filter input may be operatively connected to the amplifier output. The high-pass filter may comprise a high-pass filter input and a high-pass filter output. The high-pass filter input may be operatively connected to the amplifier output.

Abstract: A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron spectrometer for aircraft is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The preferred dodecahedron embodiment of the neutron spectrometer is a solid, polyethylene dodecahedron assembly with 12 surface facets covered by a solid-state detector stacked on an absorbing layer composed of tantalum. Each absorbing layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron detector utilizing a sol-gel absorber incorporating a fissionable material and an activation disk. Preferably utilizing Li-6 and B-10 as fissionable material and Ag-109 as activation disk material for increased sensitivity and better differentiation of thermal versus prompt neutrons and neutrons versus other radiation fragments.

Abstract: A boron carbide solid state neutron detector and method of using the detector is disclosed, wherein the detector includes a layer of boron carbide wherein the boron carbide layer is an electrically active part of the detection device, a sensing mechanism inherent to said boron carbide layer, wherein the sensing mechanism detects changes in the boron carbide layer caused by the interception of neutrons and a monitoring device coupled to the sensing mechanics.

Abstract: A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The preferred dodecahedron embodiment of the neutron spectrometer is a solid, polyethylene dodecahedron assembly with 12 surface facets covered by a solid-state detector stacked on an absorbing layer composed of titanium. Each absorbing layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.

Abstract: A neutron spectrometer for aircraft is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The preferred dodecahedron embodiment of the neutron spectrometer is a solid, polyethylene dodecahedron assembly with 12 surface facets covered by a solid-state detector stacked on an absorbing layer composed of aluminum. Each absorbing layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum.