Reduction of ^{222}hbox {Rn}-induced backgrounds in a hermetic dual-phase xenon time projection chamber

Abstract

The continuous emanation of ^{222}hbox {Rn} from detector surfaces causes the dominant background in current liquid xenon time projection chambers (TPCs) searching for dark matter. A significant reduction is required for the next generation of detectors which are aiming to reach the neutrino floor, such as DARWIN. ^{222}hbox {Rn}-induced backgrounds can be reduced using a hermetic TPC, in which the sensitive target volume is mechanically separated from the rest of the detector containing the majority of Rn-emanating surfaces. We present a hermetic TPC that mainly follows the well-established design of leading xenon TPCs and has been operated successfully over a period of several weeks. By scaling up the results achieved to the DARWIN-scale, we show that the hermetic TPC concept can reduce the ^{222}hbox {Rn} concentration to the required level, even with imperfect separation of the volumes.