@article{6e107b3718ce467c8cdde11918b25e2a,
title = "A study of the trace 39Ar content in argon from deep underground sources",
abstract = "The discovery of argon from deep underground sources with significantly less 39Ar than atmospheric argon was an important step in the development of direct dark matter detection experiments using argon as the active target. We report on the design and operation of a low-background single-phase liquid argon detector that was built to study the 39Ar content of this underground argon. Underground argon from the Kinder Morgan CO2 plant in Cortez, Colorado was determined to have less than 0.65% of the 39Ar activity in atmospheric argon, or 6.6 mBq/kg specific 39Ar activity.",
keywords = "Ar, Dark matter instrumentation, Low-background counting, Low-radioactivity technique, Underground argon",
author = "J. Xu and F. Calaprice and C. Galbiati and A. Goretti and G. Guray and T. Hohman and D. Holtz and An Ianni and M. Laubenstein and B. Loer and C. Love and Martoff, {C. J.} and D. Montanari and S. Mukhopadhyay and A. Nelson and Rountree, {S. D.} and Vogelaar, {R. B.} and A. Wright",
note = "Funding Information: We acknowledge the hospitality of the Kimballton Underground Research Facility, and thank the management and staff at Lhoist North America – Kimballton for their valuable support and assistance. We thank Martin Cassidy and Martin Schoell for their invaluable help in identifying suitable sampling locations in New Mexico and Colorado. We thank the management and staff of Kinder Morgan for their support and assistance in hosting us at the Doe Canyon facility in Cortez, Colorado. We gratefully acknowledge the loan of the plastic scintillator muon veto and electronics from Fermi National Accelerator Laboratory and thank Stephen Pordes for his helpful contributions. We thank the Princeton Plasma Physics Laboratory for the use of some additional lead shielding. This work was supported by NSF Grants PHY0704220 and PHY0957083 . AW acknowledges support from the Princeton Dicke Fellow program . We acknowledge valuable discussions with, and support from, our colleagues in the DarkSide collaboration . Publisher Copyright: {\textcopyright} 2015 Elsevier B.V. All rights reserved.",
year = "2015",
month = jun,
doi = "10.1016/j.astropartphys.2015.01.002",
language = "English (US)",
volume = "66",
pages = "53--60",
journal = "Astroparticle Physics",
issn = "0927-6505",
publisher = "Elsevier",
}