Victoreen Model VG 10A End Window GM Tubes  (ca. late 1940s)

The Model VG 10A end window GM detector was manufactured by the Victoreen Instrument Company of  Cleveland Ohio.   Like most end window GMs, it was designed for measuring the beta activity in samples that were often held in planchets positioned below the detector window. While these tubes also responded to gamma rays, their gamma efficiency was comparatively poor.

Of the two pictured here, only the one on the left has a label identifying it as the Model 10A. The other, which has no label or identification marks, is identical except for two things:  it doesn't have a brass cap, and the window has a reflective coating (aluminum/steel?).  This coating was probably used to prevent light from penetrating the thin mica window -  the standard VG 10 tubes were photosensitive.

John Victoreen indicated that he began making end window GMs for the Manhattan District activities during WWII (BRH Vignettes of Early Radiation Workers).
 

Size:  4 1/4" long,  2 1/4" diameter

Window: mica, 1 1/8" diameter, 2.9 mg/cm2

Operating voltage:  1200 volts

Gas: argon with 8% organic vapor at 120 mm Hg

Reference

AEC Radiation Instrument Catalog, page date July 1, 1949, page BG-1A4C

Nucleonics April 1948, page 85

Donated by Ron Kathren

GM Detectors             Museum Directory

Last updated: 07/25/07
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