Speaker
Description
To satisfy the sensitivity requirements for the next generation of liquid xenon dark matter detectors, the radon-induced background must be reduced at least by one order of magnitude with respect to the level reached by the current detector generation (XENONnT 222-Rn activity ~ 1 muBq/kg). The existing technology might not be sufficient to reach this goal; therefore, other strategies must be studied. In particular, 222-Rn, the daughter of 226-Ra, which is present in every material, enters the active region by emanation from the detector surfaces. Therefore, at the Max-Planck-Institut für Kernphysik (MPIK), different surface coating techniques have been intensely studied as radon barriers. Electrodeposition of pure copper has been demonstrated to be a promising mitigation technique: We have achieved a thousandfold Rn reduction on a 2×2 cm2 stainless steel sample previously irradiated with 226-Ra at the ISOLDE facility at CERN. Following the successful small-scale tests, the setup underwent an upgrade, which allowed the coating of larger vessel-like samples. The state of the coating project will be presented, and upcoming operations will be discussed.
