The current invention utilizes a downhole gamma ray counter having a processor and database to radially allocate gamma ray counts into buckets. Once a circumferential count is completed the buckets are utilized to form a pattern. The created pattern is then compared to various patterns within the database. Once a corresponding pattern is found within the database a value that is assigned to that pattern is transmitted to the surface. On the surface a surface processor compares the value to the values within the surface database finding the pattern assigned to that value. The surface processor and estimates the time of creation of the pattern downhole and uses the estimated time of creation and the pattern from the surface database to create an image of a portion of a wellbore.

A variety of applications can include a gamma ray logging system having a gamma ray detector, where temperature sensitivity of the gamma ray detector is accounted for in the operation of the logging system. Correction of sensitivity of the gamma ray detector can include using a measure of sensitivity drift derived from temperature binned gamma ray spectra from measurements by the gamma ray detector over a calibration period for a number of calibration periods. Additional apparatus, systems, and methods are disclosed.

A variety of applications can include a gamma ray logging system having a gamma ray detector, where temperature sensitivity of the gamma ray detector is accounted for in the operation of the logging system. Correction of sensitivity of the gamma ray detector can include using a measure of sensitivity drift derived from temperature binned gamma ray spectra from measurements by the gamma ray detector over a calibration period for a number of calibration periods. Additional apparatus, systems, and methods are disclosed.

A transmissive ionizing-radiation beam monitoring system includes an enclosure structure with at least one ultra-thin window to an incident ionizing-radiation beam, where the ultra-thin window is highly transmissive to ionizing-radiation. Embodiments include at least one thin or ultra-thin scintillator within the enclosure structure that is substantially directly in an incident ionizing-radiation beam path and transmissive to the incident radiation beam, and at least one ultraviolet (UV) illumination source within the enclosure structure facing the scintillator. Embodiments include at least one machine vision camera within the enclosure structure located out of an incident ionizing-radiation beam path and including a camera body and lens having a projection of its optical axis oriented at an angle of incidence of 4535 degrees to a surface of the scintillator.

A transmissive ionizing-radiation beam monitoring system includes an enclosure structure with at least one ultra-thin window to an incident ionizing-radiation beam, where the ultra-thin window is highly transmissive to ionizing-radiation. Embodiments include at least one thin or ultra-thin scintillator within the enclosure structure that is substantially directly in an incident ionizing-radiation beam path and transmissive to the incident radiation beam, and at least one ultraviolet (UV) illumination source within the enclosure structure facing the scintillator. Embodiments include at least one machine vision camera within the enclosure structure located out of an incident ionizing-radiation beam path and including a camera body and lens having a projection of its optical axis oriented at an angle of incidence of 4535 degrees to a surface of the scintillator.

A spectrometer for downhole applications can be calibrated without using radioactive sources. A spectrum of measured gamma ray counts can be received from a spectrometer in a calibration mode. A spectrum-to-window ratio can be used to determine a relationship between voltage level applied to a photoreceptor of the spectrometer and gain factors. A voltage level associated with a gain factor of one can be identified for use by the spectrometer in a non-calibration mode. The measured gamma ray counts and reference shapes for a plurality of radioactive elements can be used in a least squares fit process to determine an offset to apply to the spectrometer in the non-calibration mode.

A spectrometer for downhole applications can be calibrated without using radioactive sources. A spectrum of measured gamma ray counts can be received from a spectrometer in a calibration mode. A spectrum-to-window ratio can be used to determine a relationship between voltage level applied to a photoreceptor of the spectrometer and gain factors. A voltage level associated with a gain factor of one can be identified for use by the spectrometer in a non-calibration mode. The measured gamma ray counts and reference shapes for a plurality of radioactive elements can be used in a least squares fit process to determine an offset to apply to the spectrometer in the non-calibration mode.

Methods and apparatus for calibrating radioactive sources are described. An array of scintillation detectors forms a receptacle within which a sample or sample container can be retained by a holder. The scintillation detectors are coupled via light transducers such as photomultiplier tubes (PMTs) to independent electronic counters. Coincidence processing of time-tagged events yields a correlated event rate. One or more corrections can be applied as needed, for background counts, deadtime, or random coincidences. Voltage tuning of PMTs yields improved reproducibility. Accuracy of 1% has been demonstrated over a range of 10 kBq -3 MBq.

An apparatus for measuring ionizing radiation includes a detector having a cathode, an anode, a counting gas between the cathode and the anode for generating gas ionization by ionizing radiation, a voltage source for applying a voltage between the cathode and the anode, and a current measuring device for measuring a detector current between the cathode and the anode. The detector current is generated in the counting gas by the ionizing radiation. The apparatus further includes a setting device, wherein the setting device is configured for independently setting the apparatus into different operating modes depending on the measured detector current, and/or wherein the setting device is configured for independently setting the apparatus into different measurement ranges depending on the measured detector current.

An apparatus and method are described which enable real time measurements to measure the margin to criticality in a process for manufacturing fissile materials. An exemplary apparatus includes a neutron source capable of being modulated, an optional moderator to reduce the thermal energy of neutrons from the neutron source, a collimator for controlling the direction of any neutrons emanating in use from the target, a plurality of detector arrays positioned in predetermined locations relative to a process vessel for detecting process variables and for sending signals representative of the process variables in real time to a processor for receiving the signals and converting the detected process variables into margin to criticality measurements.