Disclosed are systems and methods for detecting fissile material. The systems and methods include devices and operations for measuring background neutron detection events using a plurality of fast neutron detectors arranged around a stimulation neutron source, measuring sample neutron detection events using the plurality of fast neutron detectors arranged around a small volume of sample material, measuring stimulated neutron detection events using the plurality of fast neutron detectors when the sample material is irradiated by the stimulation neutron source, (which in various implementations, includes determining a number of single neutron detection events), and determining a presence of fissile material in the sample material based upon the background neutron detection events, sample neutron detection events and the stimulated neutron detection events.

Disclosed are systems and methods for detecting fissile material. The systems and methods include devices and operations for measuring background neutron detection events using a plurality of fast neutron detectors arranged around a stimulation neutron source, measuring sample neutron detection events using the plurality of fast neutron detectors arranged around a small volume of sample material, measuring stimulated neutron detection events using the plurality of fast neutron detectors when the sample material is irradiated by the stimulation neutron source, (which in various implementations, includes determining a number of single neutron detection events), and determining a presence of fissile material in the sample material based upon the background neutron detection events, sample neutron detection events and the stimulated neutron detection events.

A radiation detector to monitor the neutron flux of a nuclear reactor or other high-radiation environment, that can withstand the high temperatures and radiation fields of such environment, is provided. A small dielectric substrate with a low neutron-activation cross section is provided. The substrate is coated with a neutron conversion material, such as uranium oxide or thorium oxide. One or more substrates form a micro-sized detection cavity that is filled with a detection gas. A voltage is provided across anode and cathode wires in the detection cavity. A neutron absorbed in the conversion material may release reaction products into the gas, causing ionization of the gas which then produces a current or voltage signal. The small detector volume minimizes energy deposition into the detection gas by competing particles such as gamma rays, fast electrons, and beta particles, and therefore minimizes false counts while retaining large signals from neutron interactions.

A neutron scintillator is formed of a resin-based composite. The resin-based composite includes a phosphor part (A) formed of a resin composition including inorganic phosphor particles containing at least one kind of neutron-capturing isotope that is selected from lithium 6 and boron 10 such as Eu:LiCaAlF.sub.6 and a resin, and at least one wavelength converting part (B) comprising a wavelength converting fiber or a wavelength converting sheet. In the neutron scintillator, it is preferred that the wavelength converting part (B) is enclosed in the phosphor part (A).

A .sup.3Helium gas counter comprising polyethylene slabs, a rectangular gas tube within the polyethylene slabs, and a mixture of .sup.3Helium and Xenon. A .sup.3Helium gas counter comprising polyethylene slabs, a rectangular gas tube within the polyethylene slabs, and a mixture of .sup.3Helium and Krypton. A method of making a .sup.3Helium gas counter comprising providing polyethylene slabs, placing a rectangular gas tube within the polyethylene slabs, and depositing a mixture of .sup.3Helium and Xenon into the rectangular gas tube.

A method of verifying the operational status of a neutron detecting device includes at least partially enclosing a neutron detecting device including a neutron detector in a container having outer walls comprising a thermal neutron absorber material, and determining an attenuated neutron count rate of the neutron detecting device. The method then includes removing the neutron detecting device from the container, exposing the neutron detecting device to neutron radiation originating from cosmic ray background, determining an operational neutron count rate of the neutron detecting device, determining a ratio between the operational neutron count rate and the attenuated neutron count rate, and verifying the operational status of the neutron detecting device if the operational neutron count rate is higher than the attenuated neutron count rate by at least a predetermined amount and the ratio is in a predetermined range.

A method of verifying the operational status of a neutron detecting device includes at least partially enclosing a neutron detecting device including a neutron detector in a container having outer walls comprising a thermal neutron absorber material, and determining an attenuated neutron count rate of the neutron detecting device. The method then includes removing the neutron detecting device from the container, exposing the neutron detecting device to neutron radiation originating from cosmic ray background, determining an operational neutron count rate of the neutron detecting device, determining a ratio between the operational neutron count rate and the attenuated neutron count rate, and verifying the operational status of the neutron detecting device if the operational neutron count rate is higher than the attenuated neutron count rate by at least a predetermined amount and the ratio is in a predetermined range.

An optoelectronic neutron detector and method for detecting nuclear material having a neutron capture and scatter medium receiving neutrons and producing secondary charged particles, a photodetector detecting emitted light from the secondary charged particles and outputting a detector signal, and a controller receiving the detector signal and providing an alert or quantitative indication of detected nuclear material in response to the detector signal.

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

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