Prototype ORNL Indirect Reading Pocket Chambers (ca. 1950s)
I have no information about these indirect reading pocket dosimeters except that they came from Oak Ridge National Laboratory (ORNL) and were stored with the ORNL prototype beta dosimeters also in the collection.
The one at the top of the picture has a barrel made of heavy brass and it uses the aluminum caps taken from a Victoreen pocket chamber (the end is stamped on three separate lines: B, 4162, 3A). It is approximately 1/2" in diameter and 5 1/4" long. Perhaps it was designed to be as insensitive to betas as possible. On the other hand, it might have been developed for evaluating neutron exposures. Who knows?
The aluminum barreled chamber at the bottom of the photograph has no scavenged parts, at least externally. It is approximately 1/2" in diameter and 5 1/2" long.