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This paper details the first application of a software tagging algorithm to reduce radon-induced backgrounds in liquid noble element time projection chambers, such as XENON1T and XENONnT. The convection velocity field in XENON1T was mapped out usingandevents, and the rms convection speed was measured to be. Given this velocity field,background events can be tagged when they are followed byanddecays, or preceded bydecays. This was achieved by evolving a point cloud in the direction of a measured convection velocity field, and searching foranddecays ordecays within a volume defined by the point cloud. In XENON1T, this tagging system achieved abackground reduction ofwith an exposure loss of, despite the timescales of convection being smaller than the relevant decay times. We show that the performance can be improved in XENONnT, and that the performance of such a software-tagging approach can be expected to be further improved in a diffusion-limited scenario. Finally, a similar method might be useful to tag the cosmogenicbackground, which is relevant to the search for neutrinoless double-beta decay.
Published by the American Physical Society 2024 Free, publicly-accessible full text available July 1, 2025 -
In this work, we expand on the XENON1T nuclear recoil searches to study the individual signals of dark matter interactions from operators up to dimension eight in a chiral effective field theory (ChEFT) and a model of inelastic dark matter (iDM). We analyze data from two science runs of the XENON1T detector totalingexposure. For these analyses, we extended the region of interest fromtoto enhance our sensitivity for signals that peak at nonzero energies. We show that the data are consistent with the background-only hypothesis, with a small background overfluctuation observed peaking between 20 and, resulting in a maximum local discovery significance offor theChEFT channel for a dark matter particle ofandfor an iDM particle ofwith a mass splitting of. For each model, we report 90% confidence level upper limits. We also report upper limits on three benchmark models of dark matter interaction using ChEFT where we investigate the effect of isospin-breaking interactions. We observe rate-driven cancellations in regions of the isospin-breaking couplings, leading to up to 6 orders of magnitude weaker upper limits with respect to the isospin-conserving case.
Published by the American Physical Society 2024 Free, publicly-accessible full text available June 1, 2025 -
Abstract The multi-staged XENON program at INFN Laboratori Nazionali del Gran Sasso aims to detect dark matter with two-phase liquid xenon time projection chambers of increasing size and sensitivity. The XENONnT experiment is the latest detector in the program, planned to be an upgrade of its predecessor XENON1T. It features an active target of 5.9 tonnes of cryogenic liquid xenon (8.5 tonnes total mass in cryostat). The experiment is expected to extend the sensitivity to WIMP dark matter by more than an order of magnitude compared to XENON1T, thanks to the larger active mass and the significantly reduced background, improved by novel systems such as a radon removal plant and a neutron veto. This article describes the XENONnT experiment and its sub-systems in detail and reports on the detector performance during the first science run.
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Abstract The precision in reconstructing events detected in a dual-phase time projection chamber depends on an homogeneous and well understood electric field within the liquid target. In the XENONnT TPC the field homogeneity is achieved through a double-array field cage, consisting of two nested arrays of field shaping rings connected by an easily accessible resistor chain. Rather than being connected to the gate electrode, the topmost field shaping ring is independently biased, adding a degree of freedom to tune the electric field during operation. Two-dimensional finite element simulations were used to optimize the field cage, as well as its operation. Simulation results were compared to
calibration data. This comparison indicates an accumulation of charge on the panels of the TPC which is constant over time, as no evolution of the reconstructed position distribution of events is observed. The simulated electric field was then used to correct the charge signal for the field dependence of the charge yield. This correction resolves the inconsistent measurement of the drift electron lifetime when using different calibrations sources and different field cage tuning voltages.$${}^{83\textrm{m}}\hbox {Kr }$$ Free, publicly-accessible full text available February 8, 2025 -
Abstract Xenon dual-phase time projections chambers (TPCs) have proven to be a successful technology in studying physical phenomena that require low-background conditions. With
of liquid xenon (LXe) in the TPC baseline design, DARWIN will have a high sensitivity for the detection of particle dark matter, neutrinoless double beta decay ($$40\,\textrm{t}$$ ), and axion-like particles (ALPs). Although cosmic muons are a source of background that cannot be entirely eliminated, they may be greatly diminished by placing the detector deep underground. In this study, we used Monte Carlo simulations to model the cosmogenic background expected for the DARWIN observatory at four underground laboratories: Laboratori Nazionali del Gran Sasso (LNGS), Sanford Underground Research Facility (SURF), Laboratoire Souterrain de Modane (LSM) and SNOLAB. We present here the results of simulations performed to determine the production rate of$$0\upnu \upbeta \upbeta $$ Xe, the most crucial isotope in the search for$${}^{137}$$ of$$0\upnu \upbeta \upbeta $$ Xe. Additionally, we explore the contribution that other muon-induced spallation products, such as other unstable xenon isotopes and tritium, may have on the cosmogenic background.$${}^{136}$$ -
Abstract We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive
meson muoproduction at COMPASS using 160 GeV/$$\rho ^0$$ c polarised and$$ \mu ^{+}$$ beams impinging on a liquid hydrogen target. The measurement covers the kinematic range 5.0 GeV/$$ \mu ^{-}$$ $$c^2$$ 17.0 GeV/$$< W<$$ , 1.0 (GeV/$$c^2$$ c )$$^2$$ 10.0 (GeV/$$< Q^2<$$ c ) and 0.01 (GeV/$$^2$$ c )$$^2$$ 0.5 (GeV/$$< p_{\textrm{T}}^2<$$ c ) . Here,$$^2$$ W denotes the mass of the final hadronic system, the virtuality of the exchanged photon, and$$Q^2$$ the transverse momentum of the$$p_{\textrm{T}}$$ meson with respect to the virtual-photon direction. The measured non-zero SDMEs for the transitions of transversely polarised virtual photons to longitudinally polarised vector mesons ($$\rho ^0$$ ) indicate a violation of$$\gamma ^*_T \rightarrow V^{ }_L$$ s -channel helicity conservation. Additionally, we observe a dominant contribution of natural-parity-exchange transitions and a very small contribution of unnatural-parity-exchange transitions, which is compatible with zero within experimental uncertainties. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow one to evaluate in a model-dependent way the role of parton helicity-flip GPDs in exclusive production.$$\rho ^0$$ -
Abstract Understanding propagation of scintillation light is critical for maximizing the discovery potential of next-generation liquid xenon detectors that use dual-phase time projection chamber technology. This work describes a detailed optical simulation of the DARWIN detector implemented using Chroma, a GPU-based photon tracking framework. To evaluate the framework and to explore ways of maximizing efficiency and minimizing the time of light collection, we simulate several variations of the conventional detector design. Results of these selected studies are presented. More generally, we conclude that the approach used in this work allows one to investigate alternative designs faster and in more detail than using conventional Geant4 optical simulations, making it an attractive tool to guide the development of the ultimate liquid xenon observatory.more » « less