Abstract: In some embodiments, an apparatus and a system, as well as a method and article, may operate to detect gamma radiation as detected gamma radiation, and to determine a relative level of potassium decay energy within a selected band of energy levels, with respect to a combination of at least two of potassium, uranium, or thorium. Further operations may include adjusting at least one of a detector supply voltage or an analyzer gain to place the potassium decay energy at a selected energy level location when the relative level of potassium decay energy exceeds a predetermined threshold, the threshold based on an energy level of a combination of detected gamma radiation within the selected band of energy levels. Additional apparatus, systems, and methods are disclosed.

Abstract: Various embodiments include systems and methods to provide a pulsed chemical neutron source. The pulsed chemical neutron source can be used in well logging applications. Apparatus can be arranged to generate neutrons from a chemical neutron emitter and to pass the neutrons through an aperture of a neutron shield when the chemical neutron emitter aligns with the aperture such that the neutrons are substantially blocked by the neutron shield when the chemical neutron emitter is unaligned with the aperture. In various embodiments, movement of one or more of the chemical neutron emitter or the neutron shield can be controlled such that the aperture and the chemical neutron emitter operatively align with each other during a selected portion of the movement, generating pulses of neutrons output from the neutron shield. Additional apparatus, systems, and methods are disclosed.

Abstract: A method and logging tool for evaluating the cement behind casing. In an embodiment, a collimated source emits gamma rays at selectable elevation angles. A fixed collimated detector received reflected gamma rays. Reflected calibration gamma rays are measured in a wellbore section having a cement layer of known condition. Backscattered evaluation gamma rays are measured in a section of wellbore to be analyzed and are compared with the backscattered calibration gamma rays to provide an indication of the quality of the cement layer at that location.

Abstract: A method and logging tool for evaluating the cement behind casing. In an embodiment, a collimated source emits gamma rays at selectable elevation angles. A fixed collimated detector received reflected gamma rays. Reflected calibration gamma rays are measured in a wellbore section having a cement layer of known condition. Backscattered evaluation gamma rays are measured in a section of wellbore to be analyzed and are compared with the backscattered calibration gamma rays to provide an indication of the quality of the cement layer at that location.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to receive gamma ray measurements from a gamma ray detector; to generate a spectrum based on the gamma ray measurements, the spectrum including channels and count rates for the channels, wherein a channel number of a channel corresponds to energy values associated with the gamma ray measurements; to generate a ratio of total counts in a first window of the spectrum to total counts in a second window of the spectrum, the first window including a first set of channels starting at a low threshold channel and the second window including a second set of channels; and to adjust a gain of the gamma ray detector responsive to a determination that the ratio is different from a desired ratio. Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to receive gamma ray measurements from a gamma ray detector; to generate a spectrum based on the gamma ray measurements, the spectrum including channels and count rates for the channels, wherein a channel number of a channel corresponds to energy values associated with the gamma ray measurements; to generate a ratio of total counts in a first window of the spectrum to total counts in a second window of the spectrum, the first window including a first set of channels starting at a low threshold channel and the second window including a second set of channels; and to adjust a gain of the gamma ray detector responsive to a determination that the ratio is different from a desired ratio. Additional apparatus, systems, and methods are disclosed.

Abstract: Various embodiments include systems and methods to provide a pulsed chemical neutron source. The pulsed chemical neutron source can be used in well logging applications. Apparatus can be arranged to generate neutrons from a chemical neutron emitter and to pass the neutrons through an aperture of a neutron shield when the chemical neutron emitter aligns with the aperture such that the neutrons are substantially blocked by the neutron shield when the chemical neutron emitter is unaligned with the aperture. In various embodiments, movement of one or more of the chemical neutron emitter or the neutron shield can be controlled such that the aperture and the chemical neutron emitter operatively align with each other during a selected portion of the movement, generating pulses of neutrons output from the neutron shield. Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, an apparatus and a system, as well as a method and article, may operate to detect gamma radiation as detected gamma radiation, and to determine a relative level of potassium decay energy within a selected band of energy levels, with respect to a combination of at least two of potassium, uranium, or thorium. Further operations may include adjusting at least one of a detector supply voltage or an analyzer gain to place the potassium decay energy at a selected energy level location when the relative level of potassium decay energy exceeds a predetermined threshold, the threshold based on an energy level of a combination of detected gamma radiation within the selected band of energy levels.

Abstract: Various embodiments can include apparatus and methods to operate and provide a position-sensitive detector. In various embodiments, a detector may include an illuminating device, a photodetector array, and a number of elemental circuit units, where an arrangement of the number of elemental circuit units with the photodetector array can provide a mechanism to identify a position of a light generating event in the illuminating device. Additional apparatus, systems, and methods are disclosed.

Abstract: A graphene transfer method using water vapor-assisted determination of CVD-grown graphene film on the Cu foil. By using the polymer film as a supporting layer, we found that graphene can be directly detached from the Cu foil as a consequence of water intercalated at the graphene-Cu interface(s), by a ‘dry transfer’ method. The delaminated graphene films are continuous over large area. This nondestructive method also worked for the transfer of graphene grown on a Cu single crystal without sacrificing the expensive crystal, thus affording the possibility of producing high-quality graphene and reusing the substrate. The Cu foil and single crystal can both be repeatedly used for many times, which may reduce the cost of graphene synthesis and is environmentally more benign. Our method affords the advantages of high efficiency, likely industrial scalability, minimal use of chemicals, and the reusability of the Cu foil in multiple growth and delamination cycles.

Abstract: A neutron detector includes a hollow shaped lithium-6-containing scintillator configured to produce a light signal in response to a neutron incident on the scintillator, a gamma-absorbing core that at least partially fills the inside of the hollow scintillator, and a device configured to produce an electrical signal in response to the light emitted from the scintillator.

Abstract: Various embodiments can include apparatus and methods to operate and provide a position-sensitive detector. In various embodiments, a detector may include an illuminating device, a photodetector array, and a number of elemental circuit units, where an arrangement of the number of elemental circuit units with the photodetector array can provide a mechanism to identify a position of a light generating event in the illuminating device. Additional apparatus, systems, and methods are disclosed.

Abstract: A neutron detector includes a hollow shaped lithium-6-containing scintillator configured to produce a light signal in response to a neutron incident on the scintillator, a gamma-absorbing core that at least partially fills the inside of the hollow scintillator, and a device configured to produce an electrical signal in response to the light emitted from the scintillator.