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  1. Abstract

    Quasi-periodic eruptions (QPEs) are luminous bursts of soft X-rays from the nuclei of galaxies, repeating on timescales of hours to weeks1–5. The mechanism behind these rare systems is uncertain, but most theories involve accretion disks around supermassive black holes (SMBHs) undergoing instabilities6–8or interacting with a stellar object in a close orbit9–11. It has been suggested that this disk could be created when the SMBH disrupts a passing star8,11, implying that many QPEs should be preceded by observable tidal disruption events (TDEs). Two known QPE sources show long-term decays in quiescent luminosity consistent with TDEs4,12and two observed TDEs have exhibited X-ray flares consistent with individual eruptions13,14. TDEs and QPEs also occur preferentially in similar galaxies15. However, no confirmed repeating QPEs have been associated with a spectroscopically confirmed TDE or an optical TDE observed at peak brightness. Here we report the detection of nine X-ray QPEs with a mean recurrence time of approximately 48 h from AT2019qiz, a nearby and extensively studied optically selected TDE16. We detect and model the X-ray, ultraviolet (UV) and optical emission from the accretion disk and show that an orbiting body colliding with this disk provides a plausible explanation for the QPEs.

     
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    Free, publicly-accessible full text available October 24, 2025
  2. null (Ed.)
    Prior to 2004, geological sampling in the Arctic Ocean was mainly restricted to near-surface Quaternary sediments. Thus, the long-term pre-Quaternary geological history is still poorly known. With the successful completion of the Arctic Coring Expedition (ACEX) (Integrated Ocean Drilling Program Expedition 302) in 2004, a new era in Arctic research began. Employing a novel multivessel approach, the first mission-specific platform (MSP) expedition of the Integrated Ocean Drilling Program proved that drilling in permanently ice-covered regions is possible. During ACEX, 428 m of Quaternary, Neogene, Paleogene, and Campanian sediment on Lomonosov Ridge were penetrated, providing new and unique insights into Cenozoic Arctic paleoceanographic and climate history. Although it was highly successful, ACEX also had three important limitations. The ACEX sequence contains either a large hiatus spanning the time interval from late Eocene to middle Miocene (based on the original biostratigraphic age model) or an interval of strongly reduced sedimentation rates (based on a more recent Os-Re-isotope-based age model). This is a critical time interval, spanning the time when prominent changes in global climate took place during the transition from the early Cenozoic Greenhouse Earth to the late Cenozoic Icehouse Earth. Furthermore, generally poor recovery during ACEX prevented detailed and continuous reconstruction of Cenozoic climate history. Finally, a higher-resolution reconstruction of Arctic rapid climate change during Neogene and Pleistocene times could not be achieved during ACEX. Therefore, Expedition 377 (Arctic Ocean Paleoceanography [ArcOP]) will return to the Lomonosov Ridge for a second MSP-type drilling campaign with the International Ocean Discovery Program to fill these major gaps in our knowledge on Arctic Ocean paleoenvironmental history through Cenozoic times and its relationship to global climate history. The overall goal of this drilling campaign is to recover a complete stratigraphic sedimentary record of the southern Lomonosov Ridge to meet our highest priority paleoceanographic objective, the continuous long-term Cenozoic climate history of the central Arctic Ocean. Furthermore, sedimentation rates two to four times higher than those of ACEX permit higher-resolution studies of Arctic climate change. The expedition goal can be achieved through careful site selection, the use of appropriate drilling technology and ice management, and by applying multiproxy approaches to paleoceanographic, paleoclimatic, and age-model reconstructions. The expedition will complete one primary deep drill hole (proposed Site LR-11B) to 900 meters below seafloor (mbsf), supplemented by a short drill site (LR-10B) to 50 mbsf, to recover an undisturbed uppermost (Quaternary) sedimentary section. This plan should ensure complete recovery so scientists can construct a composite section that spans the full age range through the Cenozoic. 
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  3. The international collaboration designing and constructing the Deep Underground Neutrino Experiment (DUNE) at the Long-Baseline Neutrino Facility (LBNF) has developed a two-phase strategy toward the implementation of this leading-edge, large-scale science project. The 2023 report of the US Particle Physics Project Prioritization Panel (P5) reaffirmed this vision and strongly endorsed DUNE Phase I and Phase II, as did the European Strategy for Particle Physics. While the construction of the DUNE Phase I is well underway, this White Paper focuses on DUNE Phase II planning. DUNE Phase-II consists of a third and fourth far detector (FD) module, an upgraded near detector complex, and an enhanced 2.1 MW beam. The fourth FD module is conceived as a "Module of Opportunity", aimed at expanding the physics opportunities, in addition to supporting the core DUNE science program, with more advanced technologies. This document highlights the increased science opportunities offered by the DUNE Phase II near and far detectors, including long-baseline neutrino oscillation physics, neutrino astrophysics, and physics beyond the standard model. It describes the DUNE Phase II near and far detector technologies and detector design concepts that are currently under consideration. A summary of key R&D goals and prototyping phases needed to realize the Phase II detector technical designs is also provided. DUNE's Phase II detectors, along with the increased beam power, will complete the full scope of DUNE, enabling a multi-decadal program of groundbreaking science with neutrinos. 
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    Free, publicly-accessible full text available December 1, 2025
  4. ProtoDUNE Single-Phase (ProtoDUNE-SP) is a 770-ton liquid argon time projection chamber that operated in a hadron test beam at the CERN Neutrino Platform in 2018. We present a measurement of the total inelastic cross section of charged kaons on argon as a function of kaon energy using 6 and7GeV/cbeam momentum settings. The flux-weighted average of the extracted inelastic cross section at each beam momentum setting was measured to be380±26mbarnsfor the6GeV/csetting and379±35mbarnsfor the7GeV/csetting.

    Published by the American Physical Society2024 
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    Free, publicly-accessible full text available November 1, 2025
  5. The Module-0 Demonstrator is a single-phase 600 kg liquid argon time projection chamber operated as a prototype for the DUNE liquid argon near detector. Based on the ArgonCube design concept, Module-0 features a novel 80k-channel pixelated charge readout and advanced high-coverage photon detection system. In this paper, we present an analysis of an eight-day data set consisting of 25 million cosmic ray events collected in the spring of 2021. We use this sample to demonstrate the imaging performance of the charge and light readout systems as well as the signal correlations between the two. We also report argon purity and detector uniformity measurements and provide comparisons to detector simulations. 
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    Free, publicly-accessible full text available September 1, 2025
  6. Abstract

    Doping of liquid argon TPCs (LArTPCs) with a small concentration of xenon is a technique for light-shifting and facilitates the detection of the liquid argon scintillation light. In this paper, we present the results of the first doping test ever performed in a kiloton-scale LArTPC. From February to May 2020, we carried out this special run in the single-phase DUNE Far Detector prototype (ProtoDUNE-SP) at CERN, featuring 720 t of total liquid argon mass with 410 t of fiducial mass. A 5.4 ppm nitrogen contamination was present during the xenon doping campaign. The goal of the run was to measure the light and charge response of the detector to the addition of xenon, up to a concentration of 18.8 ppm. The main purpose was to test the possibility for reduction of non-uniformities in light collection, caused by deployment of photon detectors only within the anode planes. Light collection was analysed as a function of the xenon concentration, by using the pre-existing photon detection system (PDS) of ProtoDUNE-SP and an additional smaller set-up installed specifically for this run. In this paper we first summarize our current understanding of the argon-xenon energy transfer process and the impact of the presence of nitrogen in argon with and without xenon dopant. We then describe the key elements of ProtoDUNE-SP and the injection method deployed. Two dedicated photon detectors were able to collect the light produced by xenon and the total light. The ratio of these components was measured to be about 0.65 as 18.8 ppm of xenon were injected. We performed studies of the collection efficiency as a function of the distance between tracks and light detectors, demonstrating enhanced uniformity of response for the anode-mounted PDS. We also show that xenon doping can substantially recover light losses due to contamination of the liquid argon by nitrogen.

     
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  7. Abstract

    In this work, we present the results of searches for signatures of dark matter decay or annihilation into Standard Model particles, and secret neutrino interactions with dark matter.Neutrinos could be produced in the decay or annihilation of galactic or extragalactic dark matter.Additionally, if an interaction between dark matter and neutrinos exists then dark matter will interact with extragalactic neutrinos.In particular galactic dark matter will induce an anisotropy in the neutrino sky if this interaction is present.We use seven and a half years of the High-Energy Starting Event (HESE) sample data, which measures neutrinos in the energy range of approximately 60 TeV to 10 PeV, to study these phenomena.This all-sky event selection is dominated by extragalactic neutrinos.For dark matter of ∼ 1 PeV in mass, we constrain the velocity-averaged annihilation cross section to be smaller than 10-23cm3/s for the exclusiveμ+μ-channel and 10-22cm3/s for the bb̅ channel.For the same mass, we constrain the lifetime of dark matter to be larger than 1028s for all channels studied, except for decaying exclusively to bb̅ where it is bounded to be larger than 1027s.Finally, we also search for evidence of astrophysical neutrinos scattering on galactic dark matter in two scenarios.For fermionic dark matter with a vector mediator, we constrain the dimensionless coupling associated with this interaction to be less than 0.1 for dark matter mass of 0.1 GeV and a mediator mass of 10-4GeV.In the case of scalar dark matter with a fermionic mediator, we constrain the coupling to be less than 0.1 for dark matter and mediator masses below 1 MeV.

     
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