Flow and thermal modelling of the argon volume in the DarkSide-20k TPC

Abstract

The DarkSide-20k dark matter experiment, currently under construction at LNGS, features a dual-phase time projection chamber (TPC) with a ~50 t argon target from an underground well. At this scale, it is crucial to optimise the argon flow pattern for efficient target purification and for fast distribution of internal gaseous calibration sources with lifetimes of the order of hours. To this end, we have performed computational fluid dynamics simulations and heat transfer calculations. The residence time distribution shows that the detector is well-mixed on time-scales of the turnover time (~40 d). Notably, simulations show that despite a two-order-of-magnitude difference between the turnover time and the half-life of ${}^{83\text{m}}$Kr of 1.83 h, source atoms have the highest probability to reach the centre of the TPC 13 min after their injection, allowing for a homogeneous distribution before undergoing radioactive decay. We further analyse the thermal aspects of dual-phase operation and define the requirements for the formation of a stable gas pocket on top of the liquid. We find a best-estimate value for the heat transfer rate at the liquid-gas interface of 62 W with an upper limit of 144 W and a minimum gas pocket inlet temperature of 89 K to avoid condensation on the acrylic anode. This study also informs the placement of liquid inlets and outlets in the TPC. The presented techniques are widely applicable to other large-scale, noble-liquid detectors.

arXiv comment37 pages, 19 figures, 7 tables. Updated to match the published journal version

References in corpus (18)

• DarkSide-20k: A 20 Tonne Two-Phase LAr TPC for Direct Dark Matter Detection at LNGS
• Search for Neutrinoless Double-Beta Decay with the Complete EXO-200 Dataset
• Results from the first use of low radioactivity argon in a dark matter search
• Dark Matter Search Results from 4.2 Tonne-Years of Exposure of the LUX-ZEPLIN (LZ) Experiment
• A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics
• Online ${}^{222}$Rn removal by cryogenic distillation in the XENON100 experiment
• Study of radon reduction in gases for rare event search experiments
• Results from a Calibration of XENON100 Using a Source of Dissolved Radon-220
• Calibration of liquid argon and neon detectors with ${}^{83}K{r}^m$
• Design, construction and commissioning of a high-flow radon removal system for XENONnT
• Review of Liquid Argon Detector Technologies in the Neutrino Sector
• Natural Convection Heat Transfer from an Isothermal Plate
• Liquid-phase purification for multi-tonne xenon detectors
• Application and modeling of an online distillation method to reduce krypton and argon in XENON1T
• The DarkSide-20k experiment
• Benchmarking the design of the cryogenics system for the underground argon in DarkSide-20k
• A liquid-phase loop-mode argon purification system
• The simulation of the DarkSide-20k calibration