RCL Model 103 (?) GM Tube (late 1950s)
This Radiation Counter Laboratories GM tube is something of a mystery. It doesn't have a model number indicated on it, and it doesn't match any of the RCL tubes for which I have descriptions.
Given its appearance, it would seem to belong in the RCL 103 series. An RCL catalog states "The RCL Series 103 Detectors are sensitive to beta and low energy gamma radioactivity. Constructed from thin-wall glass or metal tubing, they are suitable for a wide variety of general purpose radioactive detection requirements… Series 103 detectors are virtually insensitive to count rate variation due to temperature change, are non-photosensitive, and exhibit no hysteresis."
Size: 4 3/4" long and 1/2" in diameter
Cathode: Most likely a tin oxide coating on inside of glass wall
Wall thickness: Thin, probably 30 mg/cm²
Base: 3 prong
Donated by the University of Kansas courtesy of Michael Lemon.
Radiation Counter Laboratories catalog, Radiation Detectors, no date.