2016: Results from the first use of low radioactivity argon in a dark matter search

Phys. Rev. D 93, 081101(R)

P. Agnes et al. (DarkSide Collaboration) M. Wójcik, G. Zuzel & K. Pelczar




Liquid argon is a bright scintillator with potent particle identification properties, making it an attractive target for direct-detection dark matter searches. The DarkSide-50 dark matter search here reports the first WIMP search results obtained using a target of low-radioactivity argon. DarkSide-50 is a dark matter detector, using a two-phase liquid argon time projection chamber, located at the Laboratori Nazionali del Gran Sasso. The underground argon is shown to contain Ar39 at a level reduced by a factor (1.4±0.2)×103 relative to atmospheric argon. We report a background-free null result from (2616±43)  kg d of data, accumulated over 70.9 live days. When combined with our previous search using an atmospheric argon, the 90% C.L. upper limit on the WIMP-nucleon spin-independent cross section, based on zero events found in the WIMP search regions, is 2.0×10−44  cm2 (8.6×10−44  cm2, 8.0×10−43  cm2) for a WIMP mass of 100  GeV/c2 (1  TeV/c2, 10  TeV/c2).