High precision noble gas isotope measurement by NGX multi-collector noble gas mass spectrometer

Tamura, Hajimu; Kokubu, Yoko   ; Umeda, Koji

JAEA installed an IsotopX NGX noble gas mass spectrometer with an water sample oriented preparation system in Tono Geoscience Center to measure helium accumulation age and neon isotope ratio of ground water for estimation of ground water stability on long term geological stability survay on geological disposal of nuclear waste. High precision isotope analysis by multi-collector mass spectrometer is neccessary tool for neon isotope analysis of young ground water due to small isotopic variation of neon for nucleogenic reaction or mixing of volcanic fluids in ground water. NGX-004 was configured for simultanous measurement of neon isotopes with 2 faradays for Ne and Ne, and 1 SEM for Ne spaced out 1 m/z each other. 10.084 0.002 of Ne/Ne and 0.02598 0.00004 of Ne/Ne were obtained by ohm faraday and ohm faraday, and ion count and ohm faraday, which is able to resolve 0.2% difference.