RCL Mark 1 Model 11X GM Tubes  (ca. early 1950s)

The Radiation Counter Laboratories Mark 1 Model 11 is a glass walled GM tube probably manufactured in the early 1950s.  While the Model 11 is described in the Atomic Energy Commission Radiation Instrument Catalog,  I have not yet found any literature describing the Model 11X.  There is one obvious difference between the two: the Model 11 employed a silver coating on the inside of the glass as the cathode, while the Model 11X used a wire screen. The purpose of the screen would be to increase the tubes efficiency for gamma rays. As such, I suspect the "X" in the Model designation refers to extended.  There is a similar relationship between the RCL Mark 1 Models 3 and 3X in the collection.

Such a tube would primarily be employed in survey instruments.


Size:  6" long,  3/4" diameter

Wall: glass, 300 mg/cm2

Cathode: Stainless steel screen 

Operating voltage:  875 - 1075 volts (for the Model 11)

Gas: neon, amyl acetate quench (for the Model 11)



AEC Radiation Instrument Catalog, page date July 1, 1950


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Last updated: 07/25/07
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