Backgrounds in the DEAP-3600 Dark Matter Experiment
  The DEAP-3600 experiment, located at SNOLAB, is searching for dark matter
with a single phase liquid argon (LAr) target. For a background-free exposure
of 3000 kg$\cdot$yr, the projected sensitivity to the spin-independent
WIMP-nucleon cross section at 100 GeV/c$^2$ WIMP mass is 10$^{-46}$ cm$^{2}$.
  The experimental signature of dark matter interactions is keV-scale argon
recoils producing 128 nm LAr scintillation photons which are wavelength shifted
and observed by 255 PMTs. To reach the large background-free exposure, a
combination of careful material selection, passive shielding, active vetoes,
fiducialization and pulse shape discrimination (PSD) is used. The main concept
of the background rejection in DEAP-3600 is the powerful PSD, employing the
large difference between fast and slow components of LAr scintillation light.
The designed background level of DEAP-3600 is less than 0.6 events in a 3000
kg$\cdot$yr exposure. The experiment was filled in November 2016 and is
currently taking dark matter search data.
