Lithium-6 foil neutron detector - Patent 4365159 A neutron detection apparatus is provided which includes a selected number f flat surfaces of lithium-6 foil, and which further includes a gas mixture in contact with each of the flat surfaces for selectively reacting to charged particles emitted by or radiated from the lithium foil. A container is provided to seal the lithium foil 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 reactions taking place in the gas mixture, and, in response to such reactions, provides notice of the flux of neutrons passing through the volume of the detector. The invention disclosed and claimed herein pertains to the field of neutron detection devices of the type which employ lithium-6, in a solid form, to respond to neutrons by radiating charged particles into an ionizable counting gas. More specifically, the invention pertains to detection devices of the above type wherein the lithium radiator is configured to provide one or more flat surfaces of lithium-6 foil in contact with ionizable gas, each surface being in spaced parallel relationship with an array of high voltage count wires which indirectly measure neutron activity by sensing pulses of gas ionization. Even more particularly, the invention pertains to detection devices of the above type wherein a plurality of flat lithium-6 foil surfaces may be stacked in parallel layers with one another, and with arrays of counting wires, in order to provide a neutron detector which is of very high sensitivity and which is yet capable of being contained in a package which is extremely portable, compact, and durable.