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An Improved Analyzer for Determining Helium-4 in Parts-per-billion Range.
MISSING :7 pages
The Bureau of Mines has modified its parts-per-billion helium-4 analyzer to improve the analytical capabilities of the instrument. The modifications resulted in the following improvements: (1) the analytical precision of the instrument for 10 consecutive analyses was improved to +/-1 ppb at the 5,000-ppb helium-4 level, (2) the helium-4 sensitivity was increased almost tenfold, and (3) the minimum detectable limit for helium-4 was improved to 0.5 Ppb. The modifications made to improve the instrument included replacing the ion-source control circuit with a direct-current solid-state design, controlling the temperature of the ion source, stabilizing and reducing the pumping rate of the vacuum system, and optimizing peak integration.
IH; Report of Investigations
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division