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

Journal Article · Fri Jan 08 04:00:00 EST 2016 · Applied Radiation and Isotopes

DOI:https://doi.org/10.1016/j.apradiso.2015.10.006· OSTI ID:1241079

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

Age dating groundwater and seawater using 39Ar/Ar ratios is an important tool to understand water mass flow rates and mean residence time. For modern or contemporary argon, the 39Ar activity is 1.8 mBq per liter of argon. Radiation measurements at these activity levels require ultra low-background detectors. Low-background proportional counters have been developed at Pacific Northwest National Laboratory. These detectors use traditional mixtures of argon and methane as counting gas, and the residual 39Ar from commercial argon has become a predominant source of background activity in these detectors. We demonstrated sensitivity to 39Ar by using geological or ancient argon from gas wells in place of commercial argon. The low level counting performance of these proportional counters is then demonstrated for sensitivities to 39Ar/Ar ratios sufficient to date water masses as old as 1000 years.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1241079
• Report Number(s): PNNL-SA-98510
• Journal Information: Applied Radiation and Isotopes, Journal Name: Applied Radiation and Isotopes Vol. 107; ISSN 0969-8043
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

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