Abstract
A mass spectrometer for the analysis of ultra trace samples of gases, particularly noble gsaes, is described. The mass spectrometer is 90°-sector type and its ion trajectory radius is 200mm. Its main parts are made of stainless steel. The vacum system is extremely clean and easily maintainable. The evacuating system includes a molecular pump or a 3″oil diffusion pump (Apiezon oil C). By 48 hours evacuation and thorough bakeout, the ultimate pressure of the analyser in the order of 10-9mmHg is attainable. The instrument may be operated in the static mode and the detailed procedure is described. The incremental characteristics of back ground peaks and the diffused peak of argon at MA=80 were investigated. Fission product isotopic rare gases and isotopic ratios of uranium were determined.
