Clarkstan Alpha Counter (ca. 1950-47)

The 1950's Clarkstan Model 501 "Alpha Counter" was a spinthariscope for the "immediate, positive detection of radioactive ores." After dark-adapting their eyes for 5 to 10 minutes, the user would hold the end of the spinthariscope containing the scintillation screen against the sample (e.g., uranium ore), and count the number of scintillations. Depending on the density, and several other factors, a count rate of 50 scintillations per minute might indicate a sample containing 20% uranium. The red lens was used to prevent or suppress the glow that occurred when the screen was exposed to light (other than red).

Manufactured by Clarkstan Corp. of Los Angeles. When Clarkstan later became the Pacific Transducer Corp., they continued to market the Model 501.

References

• Product Notice, Nucleonics Vol. 7 (2) August 1950, page 95.
• U.S. Patent 2,652,499.