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.

A variety of applications can include a gamma ray downhole 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 downhole 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.

The present invention relates to determining baseline shift of an electrical signal generated by a photon detector (102) of an X-ray examination device (101). For this purpose, the photon detector comprises a processing unit (103) that is configured to determine a first crossing frequency of a first pulse height threshold by the electrical signal generated by the photon detector. The first pulse height threshold is located at a first edge of a noise peak in the pulse height spectrum of the electrical signal.

The present invention relates to determining baseline shift of an electrical signal generated by a photon detector (102) of an X-ray examination device (101). For this purpose, the photon detector comprises a processing unit (103) that is configured to determine a first crossing frequency of a first pulse height threshold by the electrical signal generated by the photon detector. The first pulse height threshold is located at a first edge of a noise peak in the pulse height spectrum of the electrical signal.

A transmissive ionizing-radiation beam monitoring system includes an enclosure structure including an entrance window and an exit window to an incident ionizing-radiation beam, where the entrance window and the exit window are highly transmissive. The system further includes a thin scintillator within the enclosure structure that is directly in an incident ionizing-radiation beam path and transmissive to the incident radiation beam and an ultraviolet (UV) illumination source within the enclosure structure facing the scintillator for internal system calibration. Embodiments further include a UV photosensor within the enclosure structure positioned to monitor and calibrate the UV illumination source and a machine vision camera within the enclosure structure that includes a lens which views the scintillator through a close proximity mirror including a folded optical axis system located to a side of the scintillator.

A method for X-ray spectral calibration acquires X-ray projections of a calibration phantom formed of known materials. The X-ray spectrum of an X-ray source is calculated according to the acquired X-ray projections. The calculated X-ray spectrum can be stored, transmitted, or displayed.

A method for X-ray spectral calibration acquires X-ray projections of a calibration phantom formed of known materials. The X-ray spectrum of an X-ray source is calculated according to the acquired X-ray projections. The calculated X-ray spectrum can be stored, transmitted, or displayed.

Disclosed is a spectrometry method including: for at least one ionizing-radiation energy E.sub.i, obtaining, for each energy E.sub.i, a curve of the number of photons detected, during a measurement interval, as a function of time, by spectrometer; b) for each curve, computing a ratio of the number of photons detected defined and separate time periods to obtain, for each ionizing-radiation energy E.sub.i, a number a.sub.i, or for each curve, acquiring one or more fitting parameters PAJ.sub.i by making a fit to the corresponding curve with a fitting function; and comparing each number a.sub.i or each fitting parameter or set of fitting parameters PAJ.sub.i with reference constants a.sub.i or, respectively, with reference fitting parameters PAJ.sub.i associated with reference energies E.sub.i to determine, for each number a.sub.i or each fitting parameter or set of fitting parameters PAJ.sub.i, reference energy E.sub.i of the ionizing radiation for which the corresponding curve was measured.

Disclosed is a spectrometry method including: for at least one ionizing-radiation energy E.sub.i, obtaining, for each energy E.sub.i, a curve of the number of photons detected, during a measurement interval, as a function of time, by spectrometer; b) for each curve, computing a ratio of the number of photons detected defined and separate time periods to obtain, for each ionizing-radiation energy E.sub.i, a number a.sub.i, or for each curve, acquiring one or more fitting parameters PAJ.sub.i by making a fit to the corresponding curve with a fitting function; and comparing each number a.sub.i or each fitting parameter or set of fitting parameters PAJ.sub.i with reference constants a.sub.i or, respectively, with reference fitting parameters PAJ.sub.i associated with reference energies E.sub.i to determine, for each number a.sub.i or each fitting parameter or set of fitting parameters PAJ.sub.i, reference energy E.sub.i of the ionizing radiation for which the corresponding curve was measured.