Abstract: A remmeter includes two or more different-sized hydrogenous moderators, each incorporating a hydrogenous spectroscopic fast neutron detector and a thermal neutron detector to provide more accurate neutron dosimetry across a wide range of neutron energies (thermal neutrons to >15 MeV) in a form factor that is lighter than conventional remmeters. The remmeter utilizes the principle of spectral dosimetry, where the energy or energy distribution of the incident neutrons is first measured and then this energy information (along with the measured fluence) is used to establish the dosimetric quantity using the various fluence-to-dose conversion curves (e.g. H*(10) (ICRP(1997)), NCRP-38(1971)). Using the method of spectral dosimetry, the large variation in response in these curves as a function of neutron energy (especially over the region 1 keV to 1 MeV) is largely mitigated through the use of the energy and fluence information, and the appropriate fluence-to-dose conversion curve to calculate the dose.

Abstract: This invention describes a remmeter that is based on the use of an assembly comprising two or more different-sized hydrogenous moderators, each hydrogenous moderator incorporating a hydrogenous spectroscopic fast neutron detector and a thermal neutron detector in order to provide more accurate neutron dosimetry across a wide range of neutron energies (thermal neutrons to >15 MeV) in a form factor that is lighter than conventional remmeters. The new remmeter utilizes the principle of spectral dosimetry, where the energy or energy distribution of the incident neutrons is first measured and then this energy information (along with the measured fluence) is used to establish the dosimetric quantity using the various fluence-to-dose conversion curves (e.g. H*(10) (ICRP (1997)), NCRP-38 (1971)).

Abstract: Described is a system and method for detecting contaminants using a flexible Surface Enhanced Raman Spectroscopy (SERS) substrate. The contaminant is collected on a flexible SERS substrate and directly interrogated with a Raman Spectrometer to obtaining a SERS emission spectrum for the contaminant. The obtained spectrum can be compared to a library of SERS signatures to identify the contaminant.

Abstract: A gas avalanche neutron detector (GAND) filled with counting gas for detecting thermal neutrons or neutron radiation without the use of a conventional proportional counter is provided. The GAND may include a layer of thermalization material, a cathode having a face with a layer of material, exhibiting neutron capture followed by charged particle emission such as Boron-10, a microstructure amplifier, and an anode. Thermal neutrons may enter the detector and interact with the material on the face of the cathode producing alpha particles. The alpha particles may ionize the counting gas inside the detector and produce ionization electrons. The cathode, microstructure amplifier and anode may have voltages applied that create electric fields that cause the ionization electrons to drift toward the microstructure amplifier. The microstructure then accelerates the electrons causing an avalanche effect within the gas and provides an amplification of the signal dramatically increasing neutron detection sensitivity.

Abstract: The invention provides a method of performing fast neutron detection or spectroscopy comprising selecting at least one isotope which exhibits fast neutron-induced charged particle reactions, selecting a host medium capable of performing radiation energy spectroscopy, combining the isotope and host medium into an interactive spectroscopic combination, exposing the combination structure to radiation comprising fast neutrons to provide a spectroscopic output, which includes at least one peak in the pulse-height spectrum whose height and amplitude correlate to the energy and intensity respectively of the incident neutrons; and processing the output to detect or to provide measurements of the energy and intensity of incident fast neutron radiation. The invention also provides a fast neutron spectrometer for use with the method.

Abstract: The Microstructure Photomultiplier Assembly (MPA) enables the effective conversion of light signals (received at the front of the assembly) into readily-detectable electrical signals. The MPA comprises a photocathode, followed by an electron-multiplying plate(s) made from an insulating substrate which does not emit sufficient contaminants to poison the photocathode. Each plate is coated with a conductive layer. The front face of each plate is further coated with a layer of secondary electron-emissive material which, when struck by an incoming electron, can produce secondary electrons. Each plate is perforated with channels. The channels are designed to promote the efficient transfer and acceleration of electrons through the channels, under an applied voltage differential across the plate(s). An anode (pixelated or non-pixelated) at the end of the last plate collects the electrons and generates an electrical signal. The MPA is contained within a vacuum enclosure.

Abstract: A detector for fast neutrons has been developed which includes 1) selected open structure of solid hydrogen-containing material which converts impinging neutrons into recoil protons; 2) a surrounding gas which interacts with the protons to release electrons; 3) an electric field able to drift the electrons through and away from the open-structure material; and 4) an electron detector which monitors the drifted electrons thereby sensing the original impinging neutrons. This type of detector is advantageous for many applications, including efficient fast neutron detection; large area imaging of fast neutrons for fast neutron radiography; or fast neutron beam profiling.

Abstract: The invention provides a method of performing fast neutron detection or spectroscopy comprising selecting at least one isotope which exhibits fast neutron-induced charged particle reactions, selecting a host medium capable of performing radiation energy spectroscopy, combining the isotope and host medium into an interactive spectroscopic combination, exposing the combination structure to radiation comprising fast neutrons to provide a spectroscopic output, which includes at least one peak in the pulse-height spectrum whose height and amplitude correlate to the energy and intensity respectively of the incident neutrons; and processing the output to detect or to provide measurements of the energy and intensity of incident fast neutron radiation. The invention also provides a fast neutron spectrometer for use with the method.

Abstract: The subject invention provides for a novel photomultiplier assembly, termed the Microstructure Photomultiplier Assembly (MPA), which enables the effective conversion of light signals (received at the front of the assembly) into readily-detectable electrical signals. The MPA comprises a photocathode (which converts light into electrons and which is located in front of or on the front surface of the assembly), followed by an electron-multiplying plate, or series of plates, each made from an insulating substrate which does not emit sufficient contaminants to poison the photocathode. Each plate is coated on the front and rear faces with a conductive layer. In addition, the front face of each plate is further coated with a layer of secondary electron-emissive material which, when struck by an incoming electron, can produce secondary electrons.

Abstract: A detector for fast neutrons has been developed which includes 1) selected open structure of solid hydrogen-containing material which converts impinging neutrons into recoil protons; 2) a surrounding gas which interacts with the protons to release electrons; 3) an electric field able to drift the electrons through and away from the open-structure material; and 4) an electron detector which monitors the drifted electrons thereby sensing the original impinging neutrons. This type of detector is advantageous for many applications, including efficient fast neutron detection; large area imaging of fast neutrons for fast neutron radiography; or fast neutron beam profiling.

Abstract: According to one embodiment, generating image data includes receiving coded aperture imaging sensor data collected according to coded aperture imaging and receiving Compton imaging sensor data collected according to Compton imaging. The coded aperture imaging sensor data and the Compton imaging sensor data are generated by a sensor system sensing radiation from a radiation source. A coded aperture imaging pixel value and a Compton imaging pixel value are determined for each pixel of an image. A combining function comprising addition is applied to the coded aperture imaging pixel value and the Compton imaging pixel value to yield a combined pixel value for each pixel. Combined image data is generated from the combined pixel values. The combined image data is configured to yield a combined image of the radiation source.

Abstract: A portable directional gamma ray radiation detector having a plurality of gamma ray radiation detectors separated by lead shielding arranged in an enclosure. Outputs from the detectors are applied to a signal processor to determine the location of a gamma ray emitter, and the signal processor is connected to a display device on the detector that indicates the direction to the gamma ray emitter.

Abstract: A portable directional gamma ray radiation detector having a plurality of gamma ray radiation detectors separated by lead shielding arranged in an enclosure. Outputs from the detectors are applied to a signal processor to determine the location of a gamma ray emitter, and the signal processor is connected to a display device on the detector that indicates the direction to the gamma ray emitter.

Abstract: A sensor for detecting the radio-luminescence created by radioactive sources includes a telescope, a plurality of UV sensitive cameras, and an optical system in the optical path of the telescope for directing images to the cameras. The cameras simultaneously obtain images from a plurality of spectral bands covering strong transitions of N2 molecule created by the radioactive source and at least one spectral band containing very little transition strength (a background band). The background image is used to assess the background level for the other spectral bands. The images are then fused digitally to create one image of the radio-luminescence.

Abstract: An apparatus and method for the detection of fissionable materials (e.g. uranium and plutonium) in cargo, vehicles, soil, waste, etc. utilizing a penetrating photon beam causing emission of neutrons from such materials. The neutrons are detected by selected detectors able to function throughout an appropriate test and emission period. Suitable detectors are of the super-heated droplet type. The photon energy, beam intensity and direction, number of beams, emission period and detector arrangement are chosen to give the desired sensitivity for the fissionable elements of concern.

Abstract: In the present invention there is a provided an array of radiation detectors comprising at least one detector capable of detecting both low and high energy gamma radiation and adapted to provide spectrometric identification of the gamma source; at least one detector capable of detecting and providing spectrometric identification of fast neutrons and low resolution gamma spectra; at least one detector adapted to detect thermal neutrons; and, at least one plastic scintillator to give enhanced gamma ray sensitivity.

Abstract: A process for identifying and rejecting pile-up pulses in a system is provided. Preferably, the process is applied to mine detection where time is at a premium. A thermal neutron activator sensor (TNA) trails a mine-detecting vehicle and is dwells over the coordinates of a target of interest for a short a time as possible. The TNA interrogates the object with slow neutrons, the required time being brief due to the use of a strong source coupled with a the process for analyzing the resultant high number and rate of pulses and rejecting piled-up pulses. Specifically, low energy pulses are removed and the remaining pulse is analyzed for its shape in comparison to the known shape of a non-piled-up pulse. The pulse is integrated using a gated integrator between a designated portion the pulse and for the whole pulse. For a normal pulse, the difference between the two integrations produces a repeatable baseline which is zeroed out to a null difference.

Abstract: A multisensor vehicle-mounted mine detector having one or more sensors leading the vehicle for detecting objects in the ground while moving. A navigational system tracks the coordinates of the detected objects, performs data fusion, declares whether the object is a target worthy of interest and if so, stops the vehicle with a trailing thermal neutron activator sensor (TNA) over the coordinates of the object and interrogating the object with slow neutrons to confirm whether it contains sufficient nitrogen to indeed be a mine. The TNA confirmation is kept brief due to the use of a strong source coupled with means for analysing the resultant pulses and rejecting piled-up pulses. The difference between an integration of the entire pulse and a portion of the pulse is compared against a predetermined difference for a normal pulse wherein variations therebetween are indicative of a piled-up pulse which is then rejected.

Abstract: Radiation detectors and dosimeters having superheated droplets of detector liquid as the radiation-sensitive component have been found to have significant variation in sensitivity with changes in operating temperature. In order to provide a more constant sensitivity, a self-regulating pressure control has been developed which will alter the pressure on the droplet-containing medium to compensate for changes in operating temperature. The pressure control is for instance a mechanical system selected from a pressure-multiplying piston or bellows assembly pressurized by a volatile liquid, and a spring-loaded elastic diaphragm assembly. This pressure control is designed to maintain a constant degree of superheat of the detector liquid in activated detectors.

Abstract: A direct reading, self-powered detector and dosimeter for gamma rays, and other low LET radiation, and optionally microwaves, is described. A transparent elastic solid medium contains uniformly dispersed droplets of a very high vapor pressure detector liquid substantially immiscible with the elastic solid. It has been found possible to form stable droplets having a sufficiently high degree of superheat for their vaporization to be sensitive to lightly ionizing radiation such as gamma rays and even to microwave radiation. The droplets can be made stable to spontaneous vaporization, yet their explosive vaporization will be triggered by gamma or in some cases microwave radiation. The solid medium will retain a record of each droplet vaporized, the number being proportional to the dose of radiation. If desired the detector liquid vapors can be condensed or compressed into droplets again and the detector/dosimeter re-used.