Abstract: An embodiment of a system is described that comprises an ionization chamber electrically coupled with a charge amplifier circuit by a reed switch. The reed switch of the embodiments described herein produces substantially no leakage current and electrically insulates the charge amplifier from the ionization chamber.

Abstract: An embodiment of a system is described that comprises an ionization chamber electrically coupled with a charge amplifier circuit by a reed switch. The reed switch of the embodiments described herein produces substantially no leakage current and electrically insulates the charge amplifier from the ionization chamber.

Abstract: A method of initiating a fluid density measurement includes generating a prime resonance of a test fixture by a startup circuit. The method of initiating a fluid density measurement includes closing a feedback loop in response to generating the prime resonance. The method of initiating a fluid density measurement includes maintaining the prime resonance by closing the feedback loop.

Abstract: A method of initiating a fluid density measurement includes generating a prime resonance of a test fixture by a startup circuit. The method of initiating a fluid density measurement includes closing a feedback loop in response to generating the prime resonance. The method of initiating a fluid density measurement includes maintaining the prime resonance by closing the feedback loop.

Abstract: A method, apparatus, and computer program products for controlling gain in a scintillation detector. Calibration count rates, each representing an integral count rate above a different threshold, are obtained from a photomultiplier tube. Photomultiplier tube gain is adjusted if a result from evaluating a relationship of calibration count rates varies from an expected result based on integral count rate versus threshold for a reference peak in the energy spectrum of the radiation source. An additional, different relationship may also be evaluated and an additional gain adjustment performed when a result indicates that the calibration count rates are not from the reference peak. A same radiation source may be used for collecting test counts and calibration counts.

Abstract: A method for measuring a density profile of a fluid in a process vessel is disclosed. The method includes emitting gamma rays into the fluid and acquiring a backscattered gamma ray counts distribution using at least one position sensitive gamma ray detector disposed proximate the vessel. The method further includes determining the density profile of the fluid contained in the process vessel based on the backscattered gamma ray counts distribution.

Abstract: A method and apparatus in accordance with the present disclosure relate to monitoring gain of a proportional counter. The method includes generating a pulse height spectrum of the proportional counter, defining a first window and a second window within the pulse height spectrum, counting electrical pulses outputted by the proportional counter within the first window of the pulse height spectrum, thereby defining a first window count, counting electrical pulses outputted by the proportional counter within the second window of the pulse height spectrum, thereby defining a second window count, and determining a difference between the first window count and the second window count.

Abstract: A method and apparatus in accordance with the present disclosure relate to monitoring gain of a proportional counter. The method includes generating a pulse height spectrum of the proportional counter, defining a first window and a second window within the pulse height spectrum, counting electrical pulses outputted by the proportional counter within the first window of the pulse height spectrum, thereby defining a first window count, counting electrical pulses outputted by the proportional counter within the second window of the pulse height spectrum, thereby defining a second window count, and determining a difference between the first window count and the second window count.

Abstract: A method, apparatus, and computer program products for controlling gain in a scintillation detector. Calibration count rates, each representing an integral count rate above a different threshold, are obtained from a photomultiplier tube. Photomultiplier tube gain is adjusted if a result from evaluating a relationship of calibration count rates varies from an expected result based on integral count rate versus threshold for a reference peak in the energy spectrum of the radiation source. An additional, different relationship may also be evaluated and an additional gain adjustment performed when a result indicates that the calibration count rates are not from the reference peak. A same radiation source may be used for collecting test counts and calibration counts.

Abstract: A method for measuring a density profile of a fluid in a process vessel is disclosed. The method includes emitting gamma rays into the fluid and acquiring a backscattered gamma ray counts distribution using at least one position sensitive gamma ray detector disposed proximate the vessel. The method further includes determining the density profile of the fluid contained in the process vessel based on the backscattered gamma ray counts distribution.

Abstract: A method for measuring high-energy radiation flux, comprising applying a low voltage to electrodes in an ion chamber filled with a fluid capable of forming ions through the interaction of the fluid with high energy radiation; measuring an ion current signal related to an ion current induced by the low voltage; determining a leakage current; determining a gain; determining a magnitude of the high-energy radiation flux based on the ion current signal, gain, and leakage current; and outputting the result of the magnitude of the high-energy radiation flux.

Abstract: An analyzer having a detector and a neutron source assembly adjacent to the detector is disclosed, wherein the neutron source assembly has a neutron source and a shielding source holder.

Abstract: A method for determining the density of a fluid that includes disposing a gamma-ray source proximate to a vessel containing the fluid is provided. The optimal position of a gamma-ray detector with respect to the gamma-ray source is determined. A gamma-ray detector is position at the optimal position, and the density of the fluid is measured.

Abstract: A method for measuring high-energy radiation includes applying a voltage pulse to electrodes in an ion chamber filled with a gas capable of forming charged ions by the high-energy radiation; measuring an ion current signal related to ion currents induced by the voltage pulse; and determining a magnitude of the high-energy radiation based on the ion current signal.

Abstract: An analyzer having a detector and a neutron source assembly adjacent to the detector is disclosed, wherein the neutron source assembly has a neutron source and a shielding source holder.

Abstract: A method for measuring high-energy radiation flux, comprising applying a low voltage to electrodes in an ion chamber filled with a fluid capable of forming ions through the interaction of the fluid with high energy radiation; measuring an ion current signal related to an ion current induced by the low voltage; determining a leakage current; determining a gain; determining a magnitude of the high-energy radiation flux based on the ion current signal, gain, and leakage current; and outputting the result of the magnitude of the high-energy radiation flux.

Abstract: A method for determining the density of a fluid that includes disposing a gamma-ray source proximate to a vessel containing the fluid is provided. The optimal position of a gamma-ray detector with respect to the gamma-ray source is determined. A gamma-ray detector is position at the optimal position, and the density of the fluid is measured.

Abstract: A method for controlling gain of a scintillation detector includes using a reference radiation source and a photomultiplier tube and controlling the gain of the scintillation detector based on the reference radiation source. The controlling includes detecting change in the gain of the scintillation detector, determining an amount of the change in the gain, outputting a control signal to compensate the amount of the change in the gain, and stabilizing the gain against the reference radiation source based on the control signal. A gain control system for controlling gain of a scintillation detector includes computer-readable instructions stored in the memory for causing the processor to detect change in the gain of the scintillation detector determine an amount of the change in the gain, output a control signal to compensate the amount of the change in the gain, and stabilize the gain against the reference radiation source based on the control signal.

Abstract: A method for controlling gain of a scintillation detector includes using a reference radiation source and a photomultiplier tube and controlling the gain of the scintillation detector based on the reference radiation source. The controlling includes detecting change in the gain of the scintillation detector, determining an amount of the change in the gain, outputting a control signal to compensate the amount of the change in the gain, and stabilizing the gain against the reference radiation source based on the control signal. A gain control system for controlling gain of a scintillation detector includes computer-readable instructions stored in the memory for causing the processor to detect change in the gain of the scintillation detector determine an amount of the change in the gain, output a control signal to compensate the amount of the change in the gain, and stabilize the gain against the reference radiation source based on the control signal.

Abstract: System and methods for measuring the density, level, or interface position of a fluid or fluids in a vessel using gamma-ray backscatter are disclosed. The gamma-ray instruments disclosed may account for vessel wall buildup or deterioration. Methods disclosed herein include detecting gamma rays backscattered by a fluid from a gamma-ray source positioned proximate to a vessel with at least two gamma-ray detectors positioned proximate to the vessel and to each other; and determining a density, level, or interface value of the fluid based upon intensities of backscattered gamma rays received by the two or more gamma-ray detectors; wherein the vessel wall is subject to at least one of buildup and deterioration. The density, level, or interface may be a function of a ratio of the intensity of backscattered gamma rays received by two or more of the detectors.