Abstract: An X-ray backscatter imaging system uses frequency modulated X-rays to determine depth of features within a target. An X-ray source generates X-ray radiation modulated by a frequency-modulated bias current. The X-ray radiation impinges upon and is backscattered from multiple depths within the target. A scintillating material receives the backscattered X-rays and generates corresponding photons. A photodetector, having gain modulated by the frequency modulation signal from the local oscillator, receives the photons from the scintillating material and generates an analog output signal containing phase delay information indicative of the distance travelled by the X-rays backscattered from multiple depths within the target. The analog output signal is sampled by an analog-to-digital converter to create a digital output signal. A computer processor performs a discrete Fourier transform on the digital output signal to provide target depth information based on the phase delay information.

Abstract: An X-ray backscatter imaging system uses frequency modulated X-rays to determine depth of features within a target. An X-ray source generates X-ray radiation modulated by a frequency-modulated bias current. The X-ray radiation impinges upon and is backscattered from multiple depths within the target. A scintillating material receives the backscattered X-rays and generates corresponding photons. A photodetector, having gain modulated by the frequency modulation signal from the local oscillator, receives the photons from the scintillating material and generates an analog output signal containing phase delay information indicative of the distance travelled by the X-rays backscattered from multiple depths within the target. The analog output signal is sampled by an analog-to-digital converter to create a digital output signal. A computer processor performs a discrete Fourier transform on the digital output signal to provide target depth information based on the phase delay information.

Abstract: An X-ray backscatter imaging system uses frequency modulated X-rays to determine depth of features within a target. An X-ray source generates X-ray radiation modulated by a frequency-modulated bias current. The X-ray radiation impinges upon and is backscattered from multiple depths within the target. A scintillating material receives the backscattered X-rays and generates corresponding photons. A photodetector, having gain modulated by the frequency modulation signal from the local oscillator, receives the photons from the scintillating material and generates an analog output signal containing phase delay information indicative of the distance travelled by the X-rays backscattered from multiple depths within the target. The analog output signal is sampled by an analog-to-digital converter to create a digital output signal. A computer processor performs a discrete Fourier transform on the digital output signal to provide target depth information based on the phase delay information.

Abstract: An X-ray backscatter imaging system uses frequency modulated X-rays to determine depth of features within a target. An X-ray source generates X-ray radiation modulated by a frequency-modulated bias current. The X-ray radiation impinges upon and is backscattered from multiple depths within the target. A scintillating material receives the backscattered X-rays and generates corresponding photons. A photodetector, having gain modulated by the frequency modulation signal from the local oscillator, receives the photons from the scintillating material and generates an analog output signal containing phase delay information indicative of the distance travelled by the X-rays backscattered from multiple depths within the target. The analog output signal is sampled by an analog-to-digital converter to create a digital output signal. A computer processor performs a discrete Fourier transform on the digital output signal to provide target depth information based on the phase delay information.

Abstract: Disclosed is a radiation monitoring system that has a radiation detector for making radiation measurements within a monitored area. An occupancy sensor may be provided for detecting a presence of an entity in the monitored area, and a motion sensor may be provided for detecting a motion of the entity in the monitored area. In a typical embodiment, a radiation measurement collection system is provided which has a first program logic element for collecting the radiation measurements as collected radiation measurements when the presence of the entity is detected and the motion of the entity is detected. Also provided is a method for monitoring an area for intermittent sources of radiation.

Abstract: Disclosed is a radiation monitoring system that has a radiation detector for making radiation measurements within a monitored area. An occupancy sensor may be provided for detecting a presence of an entity in the monitored area, and a motion sensor may be provided for detecting a motion of the entity in the monitored area. In a typical embodiment, a radiation measurement collection system is provided which has a first program logic element for collecting the radiation measurements as collected radiation measurements when the presence of the entity is detected and the motion of the entity is detected. Also provided is a method for monitoring an area for intermittent sources of radiation.

Abstract: The invention provides a system for removing or minimizing microphonic noise from a radiation detector signal, such as from a neutron detector, without creating excessive false counts in the electronics that count the radiation events. The system solves the microphonic noise problem using a 3-prong approach: (1) maintaining high dynamic range by avoiding large amplification and the possibility of saturation in the analog stages, (2) sampling the amplified analog signal using a high-resolution analog-to-digital converter (ADC), and (3) implementing a digital filtering algorithm that rejects the noise due to microphonics while passing the signal of interest from the neutron interactions.

Abstract: A spectroscopy system is provided having an automatic pole-zero error correction circuit. A gated integrator of the system integrates a shaped pulse and trailing edge of the shaped pulse for sampling by an analog-to-digital converter. A pair of samples are converted along the slope of each integrated shaped pulse passing through the system. The two samples are compared on a pulse by pulse basis. An algorithm generates a control word for affecting a change in a pole-zero network coupled along a shaping amplifier of the system. In response to the control word, an MDAC of the pole-zero network affects a change in the system to correct the pole-zero error. When the pole-zero error is eliminated or reaches an acceptable user level, the correction circuitry automatically shuts off.

Abstract: A method and apparatus for controlling the false alarm rate of a receiver which detects each received signal having a power level greater than a predetermined threshold level which is received within a predetermined detection interval. The receiver is adapted to receive signals in response to source signals having a predetermined transmission period. The signals detected within each transmission period can include an initial signal and a plurality of excess signals received subsequent to the initial signal. The total number of detected signals and the number of excess signals received within the predetermined detection interval are counted and a ratio therebetween is determined. Based upon the ratio of the total number of signals to the number of excess signals, the relationship between the power level of the received signals and the threshold level is adjusted in order to control the false alarm rate of the receiver.