This is a gas gain ion chamber ionization detector similar to those that flew in Aerobee rockets in the late 1950's to early 1960's. The lithium fluoride window in this detector was designed to be transparent to radiation in the range from 1050 to 1300 Angstroms. The charges generated by the impact of the photons on the interior gas then traveled to the oppositely charged electrode. Additional collisions of the ions and electrons with filling gas on their way to the electrodes generated more charges and in effect amplified the signal.
This artifact is part of a collection of high energy detectors from the Naval Research Laboratory (see A19880001000-19880017000). It was transferred to NASM in 1987 and is currently stored at the Garber facility.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.