Showing papers by "Kate C. Miller published in 2019"
Columbia University1, Stockholm University2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, University of Turin7, New York University Abu Dhabi8, University of Zurich9, Rensselaer Polytechnic Institute10, University of Amsterdam11, Max Planck Society12, Weizmann Institute of Science13, University of Freiburg14, University of Nantes15, Purdue University16, University of California, San Diego17, University of Chicago18, Nagoya University19, Pierre-and-Marie-Curie University20, Université Paris-Saclay21, Rice University22, University of California, Los Angeles23
TL;DR: Constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment are reported, and no DM or CEvNS detection may be claimed because the authors cannot model all of their backgrounds.
Abstract: We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keVee, we observe 30 MeV/c2, and absorption of dark photons and axionlike particles for mχ within 0.186–1 keV/c2.
412 citations
Columbia University1, Stockholm University2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, New York University Abu Dhabi7, University of Zurich8, Rensselaer Polytechnic Institute9, University of Amsterdam10, Max Planck Society11, Weizmann Institute of Science12, University of Freiburg13, University of Nantes14, University of California, San Diego15, University of Chicago16, Nagoya University17, Purdue University18, Pierre-and-Marie-Curie University19, Université Paris-Saclay20, Rice University21, University of California, Los Angeles22
TL;DR: The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases and sets exclusion limits on the WIMP-nucleon interactions.
Abstract: We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3×10-42 cm2 at 30 GeV/c2 and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.
241 citations
Columbia University1, Stockholm University2, University of Bologna3, University of Mainz4, University of Münster5, University of Coimbra6, University of Turin7, New York University Abu Dhabi8, University of Zurich9, Rensselaer Polytechnic Institute10, University of Amsterdam11, Max Planck Society12, Weizmann Institute of Science13, University of Freiburg14, University of Nantes15, Purdue University16, University of California, San Diego17, University of Chicago18, Nagoya University19, Pierre-and-Marie-Curie University20, Université Paris-Saclay21, Rice University22, University of California, Los Angeles23
TL;DR: A probe of low-mass dark matter with masses down to about 85 MeV/c^{2} is reported on by looking for electronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1T experiment, and exploiting an approach that uses ionization signals only allows for a lower detection threshold.
Abstract: Direct dark matter detection experiments based on a liquid xenon target are leading the search for dark matter particles with masses above ∼5 GeV/c2, but have limited sensitivity to lighter masses because of the small momentum transfer in dark matter-nucleus elastic scattering. However, there is an irreducible contribution from inelastic processes accompanying the elastic scattering, which leads to the excitation and ionization of the recoiling atom (the Migdal effect) or the emission of a bremsstrahlung photon. In this Letter, we report on a probe of low-mass dark matter with masses down to about 85 MeV/c2 by looking for electronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1T experiment. Besides the approach of detecting both scintillation and ionization signals, we exploit an approach that uses ionization signals only, which allows for a lower detection threshold. This analysis significantly enhances the sensitivity of XENON1T to light dark matter previously beyond its reach.
184 citations
TL;DR: The direct observation of 2νECEC in 124Xe with the XENON1T dark-matter detector is reported, demonstrating that the low background and large target mass of xenon-baseddark-matter detectors make them well suited for measuring rare processes and highlights the broad physics reach of larger next-generation experiments.
Abstract: Two-neutrino double electron capture (2νECEC) is a second-order weak-interaction process with a predicted half-life that surpasses the age of the Universe by many orders of magnitude1. Until now, indications of 2νECEC decays have only been seen for two isotopes2,3,4,5, 78Kr and 130Ba, and instruments with very low background levels are needed to detect them directly with high statistical significance6,7. The 2νECEC half-life is an important observable for nuclear structure models8,9,10,11,12,13,14 and its measurement represents a meaningful step in the search for neutrinoless double electron capture—the detection of which would establish the Majorana nature of the neutrino and would give access to the absolute neutrino mass15,16,17. Here we report the direct observation of 2νECEC in 124Xe with the XENON1T dark-matter detector. The significance of the signal is 4.4 standard deviations and the corresponding half-life of 1.8 × 1022 years (statistical uncertainty, 0.5 × 1022 years; systematic uncertainty, 0.1 × 1022 years) is the longest measured directly so far. This study demonstrates that the low background and large target mass of xenon-based dark-matter detectors make them well suited for measuring rare processes and highlights the broad physics reach of larger next-generation experiments18,19,20.
81 citations
TL;DR: The first direct observation of two-neutrino double electron capture (2NEECEC) was reported in this paper, with the XENON1T Dark Matter detector.
Abstract: Two-neutrino double electron capture ($2
u$ECEC) is a second-order Weak process with predicted half-lives that surpass the age of the Universe by many orders of magnitude. Until now, indications for $2
u$ECEC decays have only been seen for two isotopes, $^{78}$Kr and $^{130}$Ba, and instruments with very low background levels are needed to detect them directly with high statistical significance. The $2
u$ECEC half-life provides an important input for nuclear structure models and its measurement represents a first step in the search for the neutrinoless double electron capture processes ($0
u$ECEC). A detection of the latter would have implications for the nature of the neutrino and give access to the absolute neutrino mass. Here we report on the first direct observation of $2
u$ECEC in $^{124}$Xe with the XENON1T Dark Matter detector. The significance of the signal is $4.4\sigma$ and the corresponding half-life $T_{1/2}^{2
u\text{ECEC}} = (1.8\pm 0.5_\text{stat}\pm 0.1_\text{sys})\times 10^{22}\;\text{y}$ is the longest ever measured directly. This study demonstrates that the low background and large target mass of xenon-based Dark Matter detectors make them well suited to measuring other rare processes as well, and it highlights the broad physics reach for even larger next-generation experiments.
73 citations
TL;DR: The XENON1T detector as discussed by the authors is a dual-phase time projection chamber, which measures simultaneously the scintillation and ionization signals produced by interactions in target volume, to reconstruct energy and position, as well as the type of the interaction.
Abstract: The XENON1T experiment searches for dark matter particles through their scattering off xenon atoms in a 2 metric ton liquid xenon target. The detector is a dual-phase time projection chamber, which measures simultaneously the scintillation and ionization signals produced by interactions in target volume, to reconstruct energy and position, as well as the type of the interaction. The background rate in the central volume of XENON1T detector is the lowest achieved so far with a liquid xenon-based direct detection experiment. In this work we describe the response model of the detector, the background and signal models, and the statistical inference procedures used in the dark matter searches with a 1 metric ton×year exposure of XENON1T data, that leads to the best limit to date on WIMP-nucleon spin-independent elastic scatter cross section for WIMP masses above 6 GeV/c2.
71 citations
Columbia University1, University of Amsterdam2, Stockholm University3, University of Bologna4, University of Mainz5, University of Münster6, University of Coimbra7, New York University Abu Dhabi8, University of Zurich9, Rensselaer Polytechnic Institute10, Max Planck Society11, Weizmann Institute of Science12, University of Freiburg13, University of California, San Diego14, University of Chicago15, University of Naples Federico II16, Nagoya University17, Purdue University18, Rice University19, University of California, Los Angeles20
TL;DR: The XENON1T experiment at the Laboratori Nazionali del Gran Sasso is the most sensitive direct detection experiment for dark matter in the form of weakly interacting particles (WIMPs) with masses above 6 ǫ c2 scattering off nuclei as mentioned in this paper.
Abstract: The XENON1T experiment at the Laboratori Nazionali del Gran Sasso is the most sensitive direct detection experiment for dark matter in the form of weakly interacting particles (WIMPs) with masses above 6 GeV/c2 scattering off nuclei. The detector employs a dual-phase time projection chamber with 2.0 metric tons of liquid xenon in the target. A one metric ton×year exposure of science data was collected between October 2016 and February 2018. This article reports on the performance of the detector during this period and describes details of the data analysis that led to the most stringent exclusion limits on various WIMP-nucleon interaction models to date. In particular, signal reconstruction, event selection, and calibration of the detector response to nuclear and electronic recoils in XENON1T are discussed.
49 citations
TL;DR: In this article, the scalar coupling of weakly interacting massive particles (WIMPs) to pions was shown to be coherently enhanced by the total number of nucleons and therefore may dominate in scenarios where spin independent WIMP-nucleon interactions are suppressed.
Abstract: We present first results on the scalar coupling of weakly interacting massive particles (WIMPs) to pions from 1 t yr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most nonrelativistic operators, these pion-exchange currents can be coherently enhanced by the total number of nucleons and therefore may dominate in scenarios where spin-independent WIMP-nucleon interactions are suppressed. Moreover, for natural values of the couplings, they dominate over the spin-dependent channel due to their coherence in the nucleus. Using the signal model of this new WIMP-pion channel, no significant excess is found, leading to an upper limit cross section of 6.4×10-46 cm2 (90% confidence level) at 30 GeV/c2 WIMP mass.
32 citations
TL;DR: In this paper, the authors present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current interactions with final state (i.e., final state π^0$s).
Abstract: We present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current $
u_{\mu}$ interactions with final state $\pi^0$s. We employ a fully-automated reconstruction chain capable of identifying EM showers of $\mathcal{O}$(100) MeV energy, relying on a combination of traditional reconstruction techniques together with novel machine-learning approaches. These studies demonstrate good energy resolution, and good agreement between data and simulation, relying on the reconstructed invariant $\pi^0$ mass and other photon distributions for validation. The reconstruction techniques developed are applied to a selection of $
u_{\mu} + {\rm Ar} \rightarrow \mu + \pi^0 + X$ candidate events to demonstrate the potential for calorimetric separation of photons from electrons and reconstruction of $\pi^0$ kinematics.
22 citations
TL;DR: In this article, the authors describe the methodology developed for deriving spatial distortions, the drift velocity and the electric field from UV-laser measurements, from liquid argon time projection chambers (LArTPCs).
Abstract: Liquid argon time projection chambers (LArTPCs) are now a standard detector technology for making accelerator neutrino measurements, due to their high material density, precise tracking, and calorimetric capabilities. An electric field (E-field) is required in such detectors to drift ionized electrons to the anode to be collected. The E-field of a TPC is often approximated to be uniform between the anode and the cathode planes. However, significant distortions can appear from effects such as mechanical deformations, electrode failures, or the accumulation of space charge generated by cosmic rays. The latter is particularly relevant for detectors placed near the Earth's surface and with large drift distances and long drift time. To determine the E-field in situ, an ultraviolet (UV) laser system is installed in the MicroBooNE experiment at Fermi National Accelerator Laboratory. The purpose of this system is to provide precise measurements of the E-field, and to make it possible to correct for 3D spatial distortions due to E-field non-uniformities. Here we describe the methodology developed for deriving spatial distortions, the drift velocity and the E-field from UV-laser measurements.
22 citations
TL;DR: In this article, the position and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss is calibrated using crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position.
Abstract: We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron attachment to impurities, diffusion, and recombination. The overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. Using this method, we obtain an absolute energy scale uncertainty of 2\% in data. We use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. This data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. As an example, the proton selection efficiency is increased by 2\% after detector calibration.
Columbia University1, Stockholm University2, University of Amsterdam3, University of Bologna4, University of Mainz5, University of Münster6, University of Coimbra7, New York University Abu Dhabi8, University of Zurich9, Rensselaer Polytechnic Institute10, Max Planck Society11, Weizmann Institute of Science12, University of Freiburg13, University of Nantes14, University of California, San Diego15, University of Chicago16, Nagoya University17, Purdue University18, Pierre-and-Marie-Curie University19, Université Paris-Saclay20, Rice University21, University of California, Los Angeles22
TL;DR: The XENON1T liquid xenon time projection chamber is the most sensitive detector built to date for the measurement of direct interactions of weakly interacting massive particles with normal matter and the data acquisition system (DAQ) is constructed from commercial, open source, and custom components to digitize signals from the detector and store them for later analysis.
Abstract: The XENON1T liquid xenon time projection chamber is the most sensitive detector built to date for the measurement of direct interactions of weakly interacting massive particles with normal matter. The data acquisition system (DAQ) is constructed from commercial, open source, and custom components to digitize signals from the detector and store them for later analysis. The system achieves an extremely low signal threshold by triggering each channel independently, achieving a single photoelectron acceptance of (93 ± 3)%, and deferring the global trigger to a later, software stage. The event identification is based on MongoDB database queries and has over 98% efficiency at recognizing interactions at the analysis threshold in the center of the target. A readout bandwidth over 300 MB/s is reached in calibration modes and is further expandable via parallelization. This DAQ system was successfully used during three years of operation of XENON1T.
TL;DR: The XENON1T liquid xenon time projection chamber is the most sensitive detector built to date for the measurement of direct interactions of weakly interacting massive particles with normal matter as discussed by the authors.
Abstract: The XENON1T liquid xenon time projection chamber is the most sensitive detector built to date for the measurement of direct interactions of weakly interacting massive particles with normal matter. The data acquisition system (DAQ) is constructed from commercial, open source, and custom components to digitize signals from the detector and store them for later analysis. The system achieves an extremely low signal threshold below a tenth of a photoelectron using a parallelized readout with the global trigger deferred to a later, software stage. The event identification is based on MongoDB database queries and has over 97% efficiency at recognizing interactions at the analysis energy threshold. A readout bandwidth over 300 MB/s is reached in calibration modes and is further expandable via parallelization. This DAQ system was successfully used during three years of operation of XENON1T.