The DarkSide program aims at detecting weakly interacting particle dark matter using dual-phase Liquid Argon Time Projection Chambers (LAr TPC) of increasing sensitivity, down to the so-called “atmospheric neutrino floor”. One of the distinctive features of the program is the use of underground argon with significantly lower 39Ar than atmospheric argon.
The first detector of the program, DarkSide-50 (DS-50) is running at LNGS since 2013. It is the first detector of its kind with a large (30 tonnes), liquid scintillator neutron veto and water Cherenkov (1,000 tonnes) muon veto concentrically enveloping the dark matter target. An initial 1,422 kg*day exposure run with atmospheric argon yielded a null result of the dark matter search and zero background from radioactive sources. Operations with underground argon started in March 2015, and results from a background-free 2,616 kg*day exposure have been recently published. The achieved background levels combined with the demonstrated background rejection capability point to a possible background-free exposure of 1 tonne-yr for DS-50. In addition, data show a 1,400-fold reduction of 39Ar relative to atmospheric argon, demonstrating the feasibility of much larger
We will review the DS-50 results and illustrate its physics reach. We will present the future of the DarkSide program, the 20-tonne DS-20k experiment. DS-20k is designed for a background-free exposure of 100 tonne-years, with a projected sensitivity to WIMP-nucleon cross section of better than 10-47 cm2 for WIMPs of mass 1 TeV/c2, a mass scale of special interest because above the reach of the LHC.
Details of the detector and timeline of DS-20k will be presented.