Depletion of 39Ar for Liquid Argon detectors of Dark Matter Search Original Research Article

In large scale argon-based experiments, the background due to the radioactive decay of naturally occurring 39Ar in argon extracted from the atmosphere can overwhelm the rare events from dark matter interactions. Depletion of 39Ar and the search for a source of argon other than the atmosphere is of paramount importance to the success of these experimental endeavors. We describe our efforts in the extraction of argon from water in ancient deep underground sources and in 39Ar depletion using methods such as laser isotope separation.