A method of determining a quantity of a first radioisotope in a source term, disintegrating into a second radioisotope, the radioisotopes respectively emitting first and second gamma rays screened by the source term, the method comprising the steps: a) determining the theoretical ratio of counts between the first and second rays emitted in the absence of screening; b) measuring the net counts associated with the first and second rays emitted by the first and second radioisotopes; c) determining the screening rates of the first and second rays by the source term based on the ratio obtained in step a) and the counts obtained in step b); d) determining the quantity of the first radioisotope based on the screening rate of either the first or the second ray determined in step c).

A method of determining a quantity of a first radioisotope in a source term, disintegrating into a second radioisotope, the radioisotopes respectively emitting first and second gamma rays screened by the source term, the method comprising the steps: a) determining the theoretical ratio of counts between the first and second rays emitted in the absence of screening; b) measuring the net counts associated with the first and second rays emitted by the first and second radioisotopes; c) determining the screening rates of the first and second rays by the source term based on the ratio obtained in step a) and the counts obtained in step b); d) determining the quantity of the first radioisotope based on the screening rate of either the first or the second ray determined in step c).

A coded mask apparatus is provided for gamma rays. The apparatus uses nested masks, at least one of which rotates relative to the other.

A coded mask apparatus is provided for gamma rays. The apparatus uses nested masks, at least one of which rotates relative to the other.

A system of particle detectors can determine the location of a source without rotations or iterations. Embodiments of the system may comprise a middle detector flanked by two shield plates, with two side detector panels exterior to the shields. The middle detector may be positioned toward the front and orthogonal to the side detectors. By comparing a ratio of the detector data to a predetermined angular correlation function, the system can determine both the sign and magnitude of the source angle in real-time. Embodiments of the system can rapidly and automatically localize sources including nuclear and radiological weapons materials, whether in vehicles or cargo containers, and can provide improved sensitivity in walk-through personnel portal applications, enable enhanced detection of hidden weapons by a mobile area scanner, and enable a hand-held survey meter that indicates the radiation level as well as the location of the source of radiation.

A system of particle detectors can determine the location of a source without rotations or iterations. Embodiments of the system may comprise a middle detector flanked by two shield plates, with two side detector panels exterior to the shields. The middle detector may be positioned toward the front and orthogonal to the side detectors. By comparing a ratio of the detector data to a predetermined angular correlation function, the system can determine both the sign and magnitude of the source angle in real-time. Embodiments of the system can rapidly and automatically localize sources including nuclear and radiological weapons materials, whether in vehicles or cargo containers, and can provide improved sensitivity in walk-through personnel portal applications, enable enhanced detection of hidden weapons by a mobile area scanner, and enable a hand-held survey meter that indicates the radiation level as well as the location of the source of radiation.

A method of detecting radon may include starting a first timer at a radon detection device in response to a first triggering action. A seal of the radon detection device may transition to a seal position from an open position in response to the first timer being equal to a measurement interval. The open position may facilitate the introduction of ambient air to a vent of the radon detection device. The seal position may discourage introduction of the ambient air to the vent. The vent may be in fluid communication with a test material. The test material may collect radon from the ambient air introduced to the radon detection device. A second timer may be started in response to the seal transitioning from the open position to the seal position. The seal remains in the sealed position following the transition from the open position to the sealed position.

Techniques for determining the suitability of a subterranean formation as a hazardous waste repository include determining a concentration of at least one noble gas isotope of a plurality of noble gas isotopes in fluid sample from a subterranean formation below a terranean surface; determining a produced amount of the at least one noble gas isotope in the subterranean formation based on a production rate of the at least one noble gas isotope and a minimum residence time; calculating a ratio of the determined concentration of the at least one noble gas isotope in the fluid sample to the determined produced amount of the at least one noble gas isotope; and based on the calculated ratio being at or near a threshold value, determining that the subterranean formation is suitable as a hazardous waste repository.

Techniques for determining the suitability of a subterranean formation as a hazardous waste repository include determining a concentration of at least one noble gas isotope of a plurality of noble gas isotopes in fluid sample from a subterranean formation below a terranean surface; determining a produced amount of the at least one noble gas isotope in the subterranean formation based on a production rate of the at least one noble gas isotope and a minimum residence time; calculating a ratio of the determined concentration of the at least one noble gas isotope in the fluid sample to the determined produced amount of the at least one noble gas isotope; and based on the calculated ratio being at or near a threshold value, determining that the subterranean formation is suitable as a hazardous waste repository.

A slow neutron detection device is disclosed, comprising: a first slow neutron converter and a second slow neutron converter, and a readout electrode wire set and cathode wire sets arranged between the first slow neutron converter and the second slow neutron converter. By arranging a readout circuit between the two slow neutron converters, an electron drift distance is reduced by half without changing a dimension of the detection device, and an average over-threshold probability of a signal is increased.