Abstract: An apparatus for cosmogenic neutron sensing to detect moisture includes a thermal neutron proportional counter. A housing is formed at least partially from a moderating material, which is positioned around the thermal neutron proportional counter. A proportional counter electronics unit is within the housing and has a preamplifier and a shaping amplifier. The preamplifier and shaping amplifier are directly connected to the thermal neutron proportional counter. At least one photovoltaic panel provides electrical power to the thermal neutron proportional counter. A data logger is positioned vertically above the thermal neutron proportional counter and proportional counter electronics unit. A signal from the thermal neutron proportional counter is transmitted through the proportional counter electronics unit and is received by the data logger. The signal indicates a moisture content within a measurement surface of the thermal neutron proportional counter.

Abstract: An apparatus for cosmogenic neutron sensing to detect moisture includes a thermal neutron proportional counter. A housing is formed at least partially from a moderating material, which is positioned around the thermal neutron proportional counter. A proportional counter electronics unit is within the housing and has a preamplifier and a shaping amplifier. The preamplifier and shaping amplifier are directly connected to the thermal neutron proportional counter. At least one photovoltaic panel provides electrical power to the thermal neutron proportional counter. A data logger is positioned vertically above the thermal neutron proportional counter and proportional counter electronics unit. A signal from the thermal neutron proportional counter is transmitted through the proportional counter electronics unit and is received by the data logger. The signal indicates a moisture content within a measurement surface of the thermal neutron proportional counter.

Abstract: An external cavity structure including: a light source for generating a light beam; a dispersive system which in combination with the light source defines a cavity, the dispersive system for directing a selected wavelength of the light beam back into the light source, the dispersive system including a grating for selecting said wavelength of the light beam; and a beam-conditioner positioned within the cavity along a light path between the light source and the dispersive system, the beam conditioner including a beam deflecting element for changing the direction of propagation of the light beam as that light beam that travels between the light source and the dispersive system.

Abstract: A coated, embrittlement resistant optical fiber thermometer fiber is disclosed, which can be a sapphire or silica fiber with a metallic coating which prevents the fiber from becoming brittle at high temperature, and enhances transmission of radiation through the fiber. The coating can be applied over a thin "conductive" film attached to the fiber exterior using vacuum metallization, sputtering, or organo-metallic deposition. The coating may comprise pure platinum electroplated over a thin conductive film. The fiber may include a first end terminating in a blackbody radiator in a furnace and a second end terminating at a receptor apparatus. A coated fiber of the present invention provides a hermetic seal around the fiber to prevent its exposure to hydroxyl ions in the atmosphere. Fibers of the invention will remain flexible even after exposure to temperatures well over 1000 degrees Centigrade. The coating also prevents unwanted external radiation from entering the fiber.

Abstract: A precious metal blackbody radiator fired on a silica or sapphire fiber is disclosed for use in an optical fiber thermometer. The fiber can be coated or uncoated. If a coated fiber is used, the fiber can be a silica or sapphire fiber, protected with an outer metallic coating, such as platinum, which may be electroplated over a thin electrically conductive film coated on the fiber. The blackbody radiator may be mounted on a first end of the fiber, and the fiber may have a second end terminating at a receptor apparatus. The blackbody may comprise semisolid platinum paste placed on a coated or uncoated fiber, dried, and fired over a flame or in a high-temperature furnace. The firing step causes strong adhesion of the blackbody to the fiber.