Abstract: A neutron detection apparatus is provided which includes a selected number of surfaces of lithium-6 coated wire mesh and which further includes a gas mixture in contact with each sheet of lithium-6 coated wire mesh for selectively reacting to charged particles emitted or radiated by the lithium-6 coated mesh. A container is provided to seal the lithium-6 coated mesh and the gas mixture in a volume from which water vapor and atmospheric gases are excluded, the container having one or more walls which are transmissive to neutrons. Monitoring equipment in contact with the gas mixture detects the generation of charged particles in the gas mixture and, in response to such charged particles, provides an indication of the flux of neutrons passing through the volume of the detector.

Abstract: A neutron detector is disclosed which uses the moderating material as the structural support for the neutron detector element. A thin metal liner is affixed to the inside of the plastic moderating material encasement for containing a neutron detecting gas. A high voltage supply is connected to an electrical conductor which extends between the ends of the encasement and serves to furnish output pulses to a pulse counter upon the occurrence of ionization of the counting gas in response to neutron flux through the volume of the detector.

Abstract: A device for monitoring low levels of light emission in a selected underwr environment is provided with a photodetector having a light sensitive surface oriented into the environment, the photodetector generating electrical signals which are representative of light impinging upon the light sensitive surface. A window is positioned between the light sensitive surface and the underwater environment to protect the photodetector from the underwater environment, and a first material is positioned between the window and the underwater environment to prevent biological growth upon the window. A second material is placed in cooperative relationship with the first material to shift the wavelengths of certain light photons occurring in the underwater environment from a first wavelength range to a second wavelength range, in order to increase the attenuation lengths of the photons before they pass through the window.