Cylindrical aluminum filter ionization chamber for use on Solrad satellites III through XI in the 1960s and 1970s. The metal grid in this detector was designed to filter out all radiation but X-rays. The charges generated by the impact of the photons on the interior gas the 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 Catalogue #s 19880001000-19880017000). It was transferred to NASM in 1987.
This object is on display in Boeing Aviation Hangar at the Steven F. Udvar-Hazy Center in Chantilly, VA.