³⁹Ar/Ar measurements using ultra-low background proportional counters

Jeter Hall; Craig E Aalseth; Ricco M Bonicalzi; Jill M Brandenberger; Anthony R Day; Paul H Humble; Emily K Mace; Mark E Panisko; Allen Seifert

doi:10.1016/j.apradiso.2015.10.006

³⁹Ar/Ar measurements using ultra-low background proportional counters

Appl Radiat Isot. 2016 Jan:107:187-190. doi: 10.1016/j.apradiso.2015.10.006. Epub 2015 Oct 8.

Authors

Jeter Hall¹, Craig E Aalseth², Ricco M Bonicalzi², Jill M Brandenberger², Anthony R Day², Paul H Humble², Emily K Mace², Mark E Panisko², Allen Seifert²

Affiliations

¹ Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States. Electronic address: jeter@pnnl.gov.
² Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States.

PMID: 26516993
DOI: 10.1016/j.apradiso.2015.10.006

Abstract

Age-dating groundwater and seawater using the (39)Ar/Ar ratio is an important tool to understand water mass-flow rates and mean residence time. Low-background proportional counters developed at Pacific Northwest National Laboratory use mixtures of argon and methane as counting gas. We demonstrate sensitivity to (39)Ar by comparing geological (ancient) argon recovered from a carbon dioxide gas well and commercial argon. The demonstrated sensitivity to the (39)Ar/Ar ratio is sufficient to date water masses as old as 1000 years.

Keywords: (39)Ar; Low level couning; Water age-dating.