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: 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.