The former ArDM infrastructure can be of great use for developments in the radiopure argon program of the future experiment Dark Side (DS-20k). DArT at ArDM is a proof-of-concept for a facility to determine the radio-purity of argon with high precision. The goal is to measure the intrinsic remnant contamination, particularly 39Ar and 85Kr, of argon samples purified at the distillation column (Aria), and/or recuperated from the CO2 gas well (Urania) of the Kinder-Morgan plant, Colorado (USA). In a first phase we plan to operate a small single-phase LAr chamber of about 1 liter volume inside ArDM at LSC. For this purpose the ArDM detector will run in the single phase operational mode as an active veto for internal and external backgrounds. For the reason of retaining the dual phase setup for later measurements and faster experimental turnover, we decided to build a new single-phase setup with two sets of each 6 low background PMTs in the top and in the bottom, of the same type as presently used in ArDM. This allows for a dedicated and optimised setup for DArT, which can be easily swapped with the presently installed dual phase setup. The dual phase setup can be re-used later for measurements with highest sensitivities where a large detector volume is needed (fiducialization), once depleted argon is available in large quantities.
Structure for DArT at ArDM