Speaker
Description
Next generation liquid noble gas detectors for the search of weakly interacting massive particles (WIMPs), such as XLZD, aim to increase their sensitivity down to the neutrino fog. This ambitious goal can only be achieved by further reducing the detector backgrounds dominated by LXe intrinsic isotopes of $^{85}$Kr and $^{222}$Rn to a factor ten below the unshieldable solar and atmospheric neutrino background.
It could be shown for XENONnT that cryogenic distillation is a suitable method for reducing these backgrounds, paired with stringent material selections and specialized detector designs. XLZD will require an approximately 20-times higher radon purification flow, which necessitates the development of new technologies to provide the required cooling and heating power associated with the cryogenic distillation process while meeting the requirements of the various underground laboratories.
In the ERC Advanced Grand project LowRad the technical foundations for the next generation cryogenic krypton and radon removal systems are developed. This includes among other things a krypton concentrator and a radon removal system including a cryogenic heat pump. The concentrator aims to reduce the krypton enriched xenon off-gas losses during cryogenic distillation by another factor 1000 (to 6 g/day) making a continuous online distillation during regular detector operation feasible. The cryogenic heat pump of the radon removal system is necessary to address the heating and cooling power demands of 60 kW each (equivalent to 125 kW electrical power) of future radon removal systems (XLZD-sized, 1600 kg/h), which is required to reduce the $^{222}$Rn background to less than 0.1 µBq/kg, or less than 1 atom in 100 mol xenon. This talk will present the working principles and design choices of each system, show the status of both demonstrators currently developed in Münster, and outlines the prospects for the next steps towards the final systems for XLZD.
The project is financed through the ERC AdG "LowRad" project number 101055063.