Long term operation with the DarkSide-50 detector
  DarkSide is a staged experimental project based on radiopure argon aiming at
direct dark matter detection. The DarkSide-50 (DS-50) detector is currently
operating underground at the Gran Sasso National Laboratory. DS-50 detector is
a dual-phase, 50 kg, liquid argon time-projection-chamber readout by 38
cryogenic PMTs (Hamamatsu R11065), surrounded by an active liquid scintillator
veto and contained in a water Cherenkov detector acting as a muon veto. DS-50
has been been operating continuously since 2013, first with atmospheric argon
and subsequently filled in 2015 with argon from an underground source, allowing
a reduction of the Ar-39 isotope by more than a factor 1000. Features of the
DS-50 detector are described, long term operations and stability are reported
and its performances in scintillation light detection discussed. Results on
dark matter searches obtained with DarkSide-50 detector are briefly reported.
