Abstract: Methods and apparatuses for rejecting radioactive interference in a radiation monitoring station. Techniques typically include two radiation detectors positioned to acquire first and second radiation measurements from a moving radiological source in substantially distinct fields of view. A transition zone is established between the fields of view. A function yielding a dependent variable is defined at least in part by the first radiation level measurement and the second radiation level measurement. A detection alert is generated when the dependent variable reaches the first threshold value. In some embodiments a determination is mage as to whether the monitoring station is occupied as a condition for generating a detection alert, and in some embodiments a determination is made as to whether the detected radiological source is likely innocuous or offensive prior to generating a detection alert.

Abstract: A system for interrogating a package, container, vehicle, or similar examination article for the presence of nuclear material. The system typically includes a source of photo-fission energy configured to irradiate the examination article and trigger fission of a fissile or a fissionable material present in the examination article and generate a plurality of fission products, wherein at least one of the plurality of fission products produces a plurality of fission neutrons. A neutron-to-gamma-ray-converter material may be configured to capture up to all of the plurality of fission neutrons and upon capture to emit internal gamma radiation. A gamma radiation detector is typically configured to detect at least a portion of the internal gamma radiation.

Abstract: Methods and an apparatus for reducing the effect of background ionizing radiation depression in vehicle and container monitoring systems due to shielding effects from components of the vehicle or container or modifications thereof. The methods utilize measurements of background radiation in two spectral regions of interest to calculate a normalization constant, and then utilize the normalization constant to normalize measurements in the same regions of interest when a vehicle or container is tested for the presence of a relevant ionizing radiation source such as 137Cs and 76Ga. Subtracting the two measurements to calculate a net difference provides a substantially valid measure of radiation counts in one spectral region of interest. Preferably the regions of interest abut or overlap, and preferably the spectral widths of the regions of interest are selected so that the attenuation of radiation counts due to background shielding effects in the two regions of interest is substantially equal.

Abstract: Methods and apparatuses for rejecting radioactive interference in a radiation monitoring station. Techniques typically include two radiation detectors positioned to acquire first and second radiation measurements from a moving radiological source in substantially distinct fields of view. A transition zone is established between the fields of view. A function yielding a dependent variable is defined at least in part by the first radiation level measurement and the second radiation level measurement. A detection alert is generated when the dependent variable reaches the first threshold value. In some embodiments a determination is made as to whether the monitoring station is occupied as a condition for generating a detection alert, and in some embodiments a determination is made as to whether the detected radiological source is likely innocuous or offensive prior to generating a detection alert.

Abstract: Methods and an apparatus for reducing the effect of background ionizing radiation depression in vehicle and container monitoring systems due to shielding effects from components of the vehicle or container or modifications thereof. The methods utilize measurements of background radiation in two spectral regions of interest to calculate a normalization constant, and then utilize the normalization constant to normalize measurements in the same regions of interest when a vehicle or container is tested for the presence of a relevant ionizing radiation source such as 137Cs and 76Ga. Subtracting the two measurements to calculate a net difference provides a substantially valid measure of radiation counts in one spectral region of interest. Preferably the regions of interest abut or overlap, and preferably the spectral widths of the regions of interest are selected so that the attenuation of radiation counts due to background shielding effects in the two regions of interest is substantially equal.

Abstract: A computerized system for evaluating a physical phenomenon. In some embodiments a data file defines at least one mathematical expression, and when multiple mathematical expressions are defined they are preferably defined in priority order. Each mathematical expression includes at least one physical variable. In some embodiments the mathematical expressions are Boolean expressions. A data acquisition system is configured to provide a measurement of physical parameters that correspond to the physical variables. In some embodiments the physical variables are radiation levels and the measurements of a physical parameter are radiation measurements. An execution engine is configured for sequentially reading each mathematical expression in the priority order from the data file.