TY - JOUR
T1 - Accurate Determination of the Absolute 3He/4He Ratio of a Synthesized Helium Standard Gas (Helium Standard of Japan, HESJ)
T2 - Toward Revision of the Atmospheric 3He/4He Ratio
AU - Mishima, Kenji
AU - Sumino, Hirochika
AU - Yamada, Takahito
AU - Ieki, Sei
AU - Nagakura, Naoki
AU - Otono, Hidetoshi
AU - Oide, Hideyuki
N1 - Funding Information:
This work was supported by JSPS KAKENHI, grants JP16H02194 (to K.M.) and JP24654058 (to H.S.). The work at the Materials and Life Science Experimental Facility of the J-PARC was supported by S-type project of KEK (proposal 2014S03). All data and fit results in Figure 5 can be found in the supporting information.
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/10
Y1 - 2018/10
N2 - The helium standard of Japan, referred to as HESJ, is an interlaboratory standard for the 3He/4He ratio. While the ratio of 3He and 4He of the HESJ was previously determined by a relative comparison to atmospheric helium, the absolute value of the 3He/4He ratio of the HESJ has not been directly determined yet. Therefore, it relies on the early measurements of that of atmospheric helium. The accuracy of the absolute 3He/4He ratios of the atmosphere and other working standards including HESJ is crucial in some applications of helium isotopes, such as tritium-3He dating, surface-exposure age determination based on cosmogenic 3He, and the accurate measurement of the neutron lifetime. In this work, new control samples of helium gases with 3He/4He ratios of 14, 28, and 42 ppm were fabricated with accuracy of 0.25–0.38% using a gas-handling system for a neutron lifetime experiment at Japan Proton Accelerator Research Complex. The relative 3He/4He ratios of these samples and the HESJ were measured using a magnetic-sector type, single-focusing, noble gas mass spectrometer with a double collector system. As a result, the absolute 3He/4He ratio of the HESJ was determined as 27.36 ± 0.11 ppm. The atmospheric 3He/4He ratio was determined as 1.340 ± 0.006 ppm, based on this work.
AB - The helium standard of Japan, referred to as HESJ, is an interlaboratory standard for the 3He/4He ratio. While the ratio of 3He and 4He of the HESJ was previously determined by a relative comparison to atmospheric helium, the absolute value of the 3He/4He ratio of the HESJ has not been directly determined yet. Therefore, it relies on the early measurements of that of atmospheric helium. The accuracy of the absolute 3He/4He ratios of the atmosphere and other working standards including HESJ is crucial in some applications of helium isotopes, such as tritium-3He dating, surface-exposure age determination based on cosmogenic 3He, and the accurate measurement of the neutron lifetime. In this work, new control samples of helium gases with 3He/4He ratios of 14, 28, and 42 ppm were fabricated with accuracy of 0.25–0.38% using a gas-handling system for a neutron lifetime experiment at Japan Proton Accelerator Research Complex. The relative 3He/4He ratios of these samples and the HESJ were measured using a magnetic-sector type, single-focusing, noble gas mass spectrometer with a double collector system. As a result, the absolute 3He/4He ratio of the HESJ was determined as 27.36 ± 0.11 ppm. The atmospheric 3He/4He ratio was determined as 1.340 ± 0.006 ppm, based on this work.
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U2 - 10.1029/2018GC007554
DO - 10.1029/2018GC007554
M3 - Article
AN - SCOPUS:85055548013
SN - 1525-2027
VL - 19
SP - 3995
EP - 4005
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
IS - 10
ER -