DarkSide-50 532-day dark matter search with low-radioactivity argon

The DarkSide-50 direct-detection dark matter experiment is a dual-phase argon time projection chamber operating at Laboratori Nazionali del Gran Sasso. This paper reports on the blind analysis of a $(16\text{ }660\ifmmode\pm\else\textpm\fi{}270)\text{ }\mathrm{kg}\text{ }\mathrm{d}$ exposure using a target of low-radioactivity argon extracted from underground sources. We find no events in the dark matter selection box and set a 90% C.L. upper limit on the dark matter--nucleon spin-independent cross section of $1.14\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}44}\text{ }\text{ }{\mathrm{cm}}^{2}$ ($3.78\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}44}\text{ }\text{ }{\mathrm{cm}}^{2}$, $3.43\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}43}\text{ }\text{ }{\mathrm{cm}}^{2}$) for a WIMP mass of $100\text{ }\text{ }\mathrm{GeV}/{c}^{2}$ ($1\text{ }\text{ }\mathrm{TeV}/{c}^{2}$, $10\text{ }\text{ }\mathrm{TeV}/{c}^{2}$).