Jul 24 – 28, 2017
Other Institutes
Canada/Eastern timezone

Low Radioactivity Argon for Rare Event Searches

Jul 26, 2017, 3:45 PM
Executive Learning Center

Executive Learning Center

Contributed talk Labs and Low Background Labs and Low Background


Dr Henning Back (Pacific Northwest National Laboratory)


The DarkSide-50 two-phase liquid argon (LAr) detector has been searching for weakly interacting massive particle (WIMP) dark matter for the past three years, and during the last two years has been successfully operating the detector with argon that was extracted from underground CO$_2$ wells in Cortez, Colorado in the US. This source of argon has been long shielded from cosmic rays entering Earth’s atmosphere, and thus should have a lower concentration of the cosmogenically produced isotope of $^{39}$Ar that beta decays with an endpoint energy that causes the beta spectrum to entirely cover the LAr WIMP search region. A 70-day exposure of the underground argon (UAr) inside DS-50 demonstrated that the UAr extracted from Colorado contains $^{39}$Ar a factor >1000 less than atmospheric argon. This large reduction in $^{39}$Ar opens the door for the construction of much larger LAr detectors that can be used for the direct detection of WIMP dark matter, as well as other rare-event searches. This talk will focus on the details of two new projects called Urania and Aria, which aim to extract 100 kg/day of UAr from the same source of gas as that used to extract the UAr for DS-50 and then
further purify it, in an effort to procure 50 tonnes of detector grade UAr for use in a 20-tonne fiducial volume detector called DarkSide-20k and set to begin operations at the beginning of the next decade.

Presentation materials