arXiv subjects

R. Acciarri

Publications and source records attributed to R. Acciarri.

At least 19 recordsLinked to original sources

arXiv2026

Measurements of transverse kinematic imbalance in muon neutrino charged-current interactions on argon with a single proton and no pions in the final state with SBND

This letter presents the first neutrino-argon cross-section measurement from the Short-Baseline Near Detector (SBND) at the Fermi National Accelerator Laboratory. We report the nominal flux-averaged single-differential cross sections of muon neutrino charged-current interactions on argon with a single proton and no pions in the final state as functions of the transverse kinematic imbalance variables. Using a subset of Run~1 data corresponding to $8.8\times10^{19}$ protons-on-target, we select 12,804 signal candidates with a purity of 91%. The extracted cross sections discriminate strongly among event-generator predictions, owing to the high statistics and the design of the analysis. Among the compared models, none successfully describes all three variables, with the largest discrepancies in the transverse missing momentum variable. These results set new benchmarks for neutrino-argon interaction modeling, which is crucial for high-precision measurements at current and future accelerator neutrino experiments.

hep-ex↗

arXiv2026

Search for Neutrino-Produced Long-Lived Particles Using the SBND Cosmic Ray Tagger Beam Telescope

The Short-Baseline Near Detector (SBND) is a liquid argon time projection chamber in Fermilab's Short-Baseline Neutrino Program, positioned 110 meters from the neutrino target along the Booster Neutrino Beam (BNB). In addition to its neutrino physics goals, SBND enables searches for new physics, including long-lived particles (LLPs) produced via neutrino-nucleus upscattering that decay into visible final states. Although neutrino data taking with the full SBND experiment began in December 2024, a subset of the Cosmic Ray Tagger (CRT) system operated from 2017--2018 as a standalone detector, referred to as the CRT Beam Telescope, collecting data corresponding to $2.95\times 10^{20}$ protons on target from the BNB. Originally intended for commissioning and performance studies, the substantial dataset collected also enables searches for displaced LLP decays. This paper presents the first search for physics beyond the Standard Model using data from the SBND CRT Beam Telescope, targeting LLP decays into electron-positron pairs. We observe no significant excess above the expected background and set 90% confidence-level upper limits on an effective production cross section at the level of $10^{-38}$ cm$^2$ for laboratory decay lengths of 0.3-100 m. These results complement existing searches by probing displaced decay signatures at meter-scale decay lengths.

hep-ex↗

arXiv2026

Short-Baseline Near Detector (SBND): Design and Initial Performance

The Short-Baseline Near Detector (SBND) is a 112 tonne active mass liquid argon time projection chamber (LArTPC) situated in the Booster Neutrino Beam at Fermilab, forming part of the Short-Baseline Neutrino (SBN) Program. SBND began operation in 2024 and has since accumulated the world's largest sample of neutrino-argon interactions. This paper describes the as-built detector and presents performance results from the first year of beam operation. All detector systems performed at or above design requirements. The liquid argon purity achieved an electron lifetime exceeding 30ms, ten times the design requirement, for more than 95% of Run 1. The TPC wire plane readout achieved noise levels at the theoretical minimum for the given wire geometry (an average of 388e$^-$ for the 4m long collection plane wires) with 99.3% of readout channels live. Together, the liquid argon purity and TPC performance are enabling extremely clean event reconstruction in the SBND TPC. The photon detection system, consisting of passive reflectors and multiple active components (PMTs and X-ARAPUCAs), has achieved a light yield exceeding 10 photoelectrons per MeV throughout the detector volume and a timing resolution of a few nanoseconds, sufficient to resolve the 19ns bunch structure of the Booster Neutrino Beam. A nearly 4$π$ cosmic ray tagger system surrounds the TPC to mitigate cosmic backgrounds in neutrino and BSM physics analyses. The data acquisition system has demonstrated stable performance up to an event rate of 8Hz, and a data collection efficiency of 98.6% was achieved throughout SBND's first neutrino run in 2025. These results demonstrate that SBND represents the state of the art in multi-tonne-scale LArTPC detector performance.

hep-ex↗

arXiv2026

Charge readout electronics for the DUNE horizontal drift far detector: design and performance in ProtoDUNE-HD

DUNE (Deep Underground Neutrino Experiment) is a long-baseline neutrino oscillation experiment currently under construction, whose far detectors will be the largest liquid argon time projection chambers ever built. This detector design calls for custom-built cryogenic front-end electronics to meet its performance requirements. This paper describes the charge readout electronics that will be used in the DUNE horizontal drift (HD) far detector and presents performance results using data from the ProtoDUNE-HD detector, a 770 ton liquid argon time projection chamber operated at the CERN Neutrino Platform in 2024 that served as the final prototype of the DUNE HD design.

physics.ins-det↗

arXiv2026

A Bayesian approach to the long-baseline neutrino oscillation sensitivity of DUNE

The sensitivity of the Deep Underground Neutrino Experiment (DUNE) to neutrino oscillation is evaluated using a Bayesian Markov Chain Monte Carlo (MCMC) approach. This analysis uses the same underlying sensitivity inputs as previous DUNE studies [Eur. Phys. J. C 80, 978 (2020)], and therefore does not present updated DUNE sensitivities, but instead explores the additional inferences accessible using a Bayesian approach. We present four-dimensional posterior probability distributions of the oscillation parameters, highlighting the breadth of correlation in the parameter space of interest, especially between $\sin^2 θ_{23}$ and $\sin^2 θ_{13}$. We exploit the flexibility of the Bayesian framework to incorporate parameter constraints post hoc and assess the impact of applying a reactor short-baseline $θ_{13}$ constraint. A significant increase in the sensitivity to the $θ_{23}$ octant is found when including the constraint. Posterior distributions of derived quantities can be easily constructed from MCMC results. This work presents the first study of DUNE's sensitivity to the Jarlskog invariant, $J$, a quantity that provides a parametrisation-independent measure of charge-parity violation in the leptonic sector.

hep-ex↗

arXiv2026

Operation and performance of ProtoDUNE Dual Phase liquid argon time projection chamber

ProtoDUNE-DP was the largest ever built Liquid Argon Time Projection Chamber (LArTPC) operating in Dual-Phase (DP) mode, with a liquid target and charge read-out placed in the gas. It had an active volume of $6\times6\times6$\,m$^3$ corresponding to an active mass of 300\,t (total LAr mass of 720\,t), constructed at the CERN Neutrino Platform and took data from 2019 to 2020 with cosmic muons. In ProtoDUNE-DP the electric drift field is oriented in the vertical direction, causing the electrons to drift vertically towards the anode at the top. The ionization charge is then extracted into the gaseous argon above the liquid surface, amplified by Townsend avalanches, and collected by the charge readout planes. The detector experienced significant technical problems affecting the long-term operation of the Charge Readout Planes, formed by the Large Electron Multipliers, but other critical segments demonstrated required performance including the delivery of -300 kV to the TPC cathode, verification of replaceable charge read-out electronics, and operation of the photon detection system. ProtoDUNE-DP experience resulted in improved designs of the Vertical Drift LArTPC.

physics.ins-det↗

arXiv2026

Production and installation of wavelength-shifting reflective light enhancers for the Short-Baseline Near Detector

We report on the design, production, and installation of a wavelength-shifting reflective system on the cathode of the Short-Baseline Near Detector (SBND), a liquid argon time projection chamber located along the Fermilab Booster Neutrino Beam. To increase and homogenize scintillation-light collection, 64 double-sided plates were fabricated from FR4, laminated with specular reflector film and coated with 300 $μ$g/cm$^2$ of tetraphenyl butadiene (TPB) wavelength shifter using controlled physical vapor deposition. The coating uniformity was validated through dedicated measurements of deposited mass and profilometry studies. Because exposure to ambient blue/UV light could degrade the TPB, protective filtering and controlled storage conditions were implemented during handling and installation. The coated plates were assembled between conductive meshes for high-voltage compatibility and installed in situ during detector integration. This system constitutes the largest TPB-coated area deployed in a neutrino detector. It operates in conjunction with SBND's photon detection system, which consists of photomultiplier tubes and X-ARAPUCAs. Early light-collection measurements show high uniformity and light response across the detector, supporting improved triggering, calorimetry, and position reconstruction in SBND.

physics.ins-det↗

arXiv2026

Operation of a Modular 3D-Pixelated Liquid Argon Time-Projection Chamber in a Neutrino Beam

The 2x2 Demonstrator, a prototype for the Deep Underground Neutrino Experiment (DUNE) liquid argon (LAr) Near Detector, was exposed to the Neutrinos from the Main Injector (NuMI) neutrino beam at Fermi National Accelerator Laboratory (Fermilab). This detector prototypes a new modular design for a liquid argon time-projection chamber (LArTPC), comprised of a two-by-two array of four modules, each further segmented into two optically-isolated LArTPCs. The 2x2 Demonstrator features a number of pioneering technologies, including a low-profile resistive field shell to establish drift fields, native 3D ionization pixelated imaging, and a high-coverage dielectric light readout system. The 2.4 tonne active mass detector is flanked upstream and downstream by supplemental solid-scintillator tracking planes, repurposed from the MINERvA experiment, which track ionizing particles exiting the argon volume. The antineutrino beam data collected by the detector over a 4.5 day period in 2024 include over 30,000 neutrino interactions in the LAr active volume-the first neutrino interactions reported by a DUNE detector prototype. During its physics-quality run, the 2x2 Demonstrator operated at a nominal drift field of 500 V/cm and maintained good LAr purity, with a stable electron lifetime of approximately 1.25 ms. This paper describes the detector and supporting systems, summarizes the installation and commissioning, and presents the initial validation of collected NuMI beam and off-beam self-triggers. In addition, it highlights observed interactions in the detector volume, including candidate muon anti-neutrino events.

physics.ins-det↗

arXiv2026

First Measurement of $π^+$-Ar and $p$-Ar Total Inelastic Cross Sections in the Sub-GeV Energy Regime with ProtoDUNE-SP Data

The ProtoDUNE-SP detector, a kiloton-scale prototype for the Deep Underground Neutrino Experiment (DUNE) far detector, is the largest liquid argon time projection chamber built to date. Operated at CERN from 2018 to 2020, it collected both cosmic-ray data and a beam consisting of positively-charged particles with discrete momentum settings across a range of 0.3 GeV/$c$ to 7 GeV/$c$. In this letter, we report the total inelastic cross section measurements for $π^+$--Ar and $p$--Ar interactions using selected $π^+$ and proton samples from the 1 GeV/$c$ beam data, spanning kinetic energies of 500--900~MeV and below 450~MeV, respectively. These energy ranges are directly relevant to hadrons produced in DUNE. The measured cross sections are consistent with predictions and provide a dataset that was previously unavailable for argon targets. These measurements are essential for constraining neutrino-argon interaction models and achieving the precision physics goals of the upcoming DUNE experiment.

nucl-ex↗

arXiv2026

Sampling Off-Axis Neutrino Fluxes with the Short-Baseline Near Detector

The Short-Baseline Near Detector (SBND), the near detector in the Short-Baseline Neutrino Program at Fermi National Accelerator Laboratory, is located just 110 m from the Booster Neutrino Beam target. Thanks to this close proximity, relative to its 4 m $\times$ 4 m front face, neutrinos enter SBND over a range of angles from $0^{\circ}$ to approximately $1.6^{\circ}$, enabling the detector to sample variations in the neutrino flux as a function of angle-a technique known as PRISM, referred to here as SBND-PRISM. In this paper, we show how muon- and electron-neutrino fluxes vary as a function of the neutrino beam axis angle and how this can be exploited to expand the physics potential of SBND. We make use of a model that predicts an angle-dependent electron-neutrino excess signal to illustrate this effect, such as $ν_μ\to ν_e$ oscillations. We present how SBND-PRISM provides a method to add robustness against uncertainties in cross-section modeling and, more generally, uncertainties that do not depend on the spatial position of neutrino interaction inside the detector. The fluxes, along with their associated covariance matrices, are made publicly available with this publication.

hep-ex↗

arXiv2026

Reconstruction of atmospheric neutrinos in DUNE's horizontal-drift far-detector module

This paper reports on the capabilities in reconstructing and identifying atmospheric neutrino interactions in one of the Deep Underground Neutrino Experiment's (DUNE) far detector modules, a liquid argon time projection chamber (LArTPC) with horizontal drift (FD-HD) of ionization electrons. The reconstruction is based upon the workflow developed for DUNE's long-baseline oscillation analysis, with some necessary machine-learning models' retraining and the addition of features relevant only to atmospheric neutrinos such as the neutrino direction reconstruction. Where relevant, the impact of the detection of the charged particles of the hadronic system is emphasized, and comparisons are carried out between the case when lepton-only information is considered in the reconstruction (as is the case for many neutrino oscillation experiments), versus when all particles identified in the LArTPC were included. Three neutrino direction reconstruction methods have been developed and studied for the atmospheric analyses: using lepton-only information, using all reconstructed particles, and using only correlations from reconstructed hits. The results indicate that incorporating more than just lepton information significantly improves the resolution of both neutrino direction and energy reconstruction. The angle reconstruction algorithms developed in this work result in no strong dependence on particle direction for reconstruction efficiencies or neutrino flavor identification. This comprehensive review of the reconstruction of atmospheric neutrinos in DUNE's FD-HD LArTPC is the first step towards developing a first neutrino oscillation sensitivity analysis, which will ready DUNE for its first measurements.

hep-ex↗

arXiv2025

Supernova Pointing Capabilities of DUNE

The determination of the direction of a stellar core collapse via its neutrino emission is crucial for the identification of the progenitor for a multimessenger follow-up. A highly effective method of reconstructing supernova directions within the Deep Underground Neutrino Experiment (DUNE) is introduced. The supernova neutrino pointing resolution is studied by simulating and reconstructing electron-neutrino charged-current absorption on 40Ar and elastic scattering of neutrinos on electrons. Procedures to reconstruct individual interactions, including a newly developed technique called ``brems flipping'', as well as the burst direction from an ensemble of interactions are described. Performance of the burst direction reconstruction is evaluated for supernovae happening at a distance of 10 kpc for a specific supernova burst flux model. The pointing resolution is found to be 3.4 degrees at 68% coverage for a perfect interaction-channel classification and a fiducial mass of 40 kton, and 6.6 degrees for a 10 kton fiducial mass respectively. Assuming a 4% rate of charged-current interactions being misidentified as elastic scattering, DUNE's burst pointing resolution is found to be 4.3 degrees (8.7 degrees) at 68% coverage.

hep-ex↗

arXiv2025

Measurement of Exclusive $π^+$--argon Interactions Using ProtoDUNE-SP

We present the measurement of $π^{+}$--argon inelastic cross sections using the ProtoDUNE Single-Phase liquid argon time projection chamber in the incident $π^+$ kinetic energy range of 500 -- 800 MeV in multiple exclusive channels (absorption, charge exchange, and the remaining inelastic interactions). The results of this analysis are important inputs to simulations of liquid argon neutrino experiments such as the Deep Underground Neutrino Experiment and the Short Baseline Neutrino program at Fermi National Accelerator Laboratory. They will be employed to improve the modeling of final state interactions within neutrino event generators used by these experiments, as well as the modeling of $π^{+}$--argon secondary interactions within the liquid argon. This is the first measurement of $π^+$--argon absorption at this kinetic energy range as well as the first ever measurement of $π^{+}$--argon charge exchange.

hep-ex↗

arXiv2025

Identification of low-energy kaons in the ProtoDUNE-SP detector

The Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment with a rich physics program that includes searches for the hypothetical phenomenon of proton decay. Utilizing liquid-argon time-projection chamber technology, DUNE is expected to achieve world-leading sensitivity in the proton decay channels that involve charged kaons in their final states. The first DUNE demonstrator, ProtoDUNE Single-Phase, was a 0.77 kt detector that operated from 2018 to 2020 at the CERN Neutrino Platform, exposed to a mixed hadron and electron test-beam with momenta ranging from 0.3 to 7 GeV/c. We present a selection of low-energy kaons among the secondary particles produced in hadronic reactions, using data from the 6 and 7 GeV/c beam runs. The selection efficiency is 1\% and the sample purity 92\%. The initial energies of the selected kaon candidates encompass the expected energy range of kaons originating from proton decay events in DUNE (below $\sim$200 MeV). In addition, we demonstrate the capability of this detector technology to discriminate between kaons and other particles such as protons and muons, and provide a comprehensive description of their energy loss in liquid argon, which shows good agreement with the simulation. These results pave the way for future proton decay searches at DUNE.

hep-ex↗

arXiv2025

Towards mono-energetic virtual $ν$ beam cross-section measurements: A feasibility study of $ν$-Ar interaction analysis with DUNE-PRISM

Neutrino-nucleus cross-section measurements are critical for future neutrino oscillation analyses. However, our models to describe them require further refinement, and a deeper understanding of the underlying physics is essential for future neutrino oscillation experiments to realize their ambitious physics goals. Current neutrino cross-section measurements provide clear deficiencies in neutrino interaction modeling, but almost all are reported averaged over broad neutrino fluxes, rendering their interpretation challenging. Using the DUNE-PRISM concept (Deep Underground Neutrino Experiment Precision Reaction Independent Spectrum Measurement) -- a movable near detector that samples multiple off-axis positions -- neutrino interaction measurements can be used to construct narrow virtual fluxes (less than 100 MeV wide). These fluxes can be used to extract charged-current neutrino-nucleus cross sections as functions of outgoing lepton kinematics within specific neutrino energy ranges. Based on a dedicated simulation with realistic event statistics and flux-related systematic uncertainties, but assuming an almost-perfect detector, we run a feasibility study demonstrating how DUNE-PRISM data can be used to measure muon neutrino charged-current integrated and differential cross sections over narrow fluxes. We find that this approach enables a model independent reconstruction of powerful observables, including energy transfer, typically accessible only in electron scattering measurements, but that large exposures may be required for differential cross-section measurements with few-\% statistical uncertainties.

hep-ex↗

arXiv2025

Spatial and Temporal Evaluations of the Liquid Argon Purity in ProtoDUNE-SP

Liquid argon time projection chambers (LArTPCs) rely on highly pure argon to ensure that ionization electrons produced by charged particles reach readout arrays. ProtoDUNE Single-Phase (ProtoDUNE-SP) was an approximately 700-ton liquid argon detector intended to prototype the Deep Underground Neutrino Experiment (DUNE) Far Detector Horizontal Drift module. It contains two drift volumes bisected by the cathode plane assembly, which is biased to create an almost uniform electric field in both volumes. The DUNE Far Detector modules must have robust cryogenic systems capable of filtering argon and supplying the TPC with clean liquid. This paper will explore comparisons of the argon purity measured by the purity monitors with those measured using muons in the TPC from October 2018 to November 2018. A new method is introduced to measure the liquid argon purity in the TPC using muons crossing both drift volumes of ProtoDUNE-SP. For extended periods on the timescale of weeks, the drift electron lifetime was measured to be above 30 ms using both systems. A particular focus will be placed on the measured purity of argon as a function of position in the detector.

physics.ins-det↗

arXiv2025

Neutrino Interaction Vertex Reconstruction in DUNE with Pandora Deep Learning

The Pandora Software Development Kit and algorithm libraries perform reconstruction of neutrino interactions in liquid argon time projection chamber detectors. Pandora is the primary event reconstruction software used at the Deep Underground Neutrino Experiment, which will operate four large-scale liquid argon time projection chambers at the far detector site in South Dakota, producing high-resolution images of charged particles emerging from neutrino interactions. While these high-resolution images provide excellent opportunities for physics, the complex topologies require sophisticated pattern recognition capabilities to interpret signals from the detectors as physically meaningful objects that form the inputs to physics analyses. A critical component is the identification of the neutrino interaction vertex. Subsequent reconstruction algorithms use this location to identify the individual primary particles and ensure they each result in a separate reconstructed particle. A new vertex-finding procedure described in this article integrates a U-ResNet neural network performing hit-level classification into the multi-algorithm approach used by Pandora to identify the neutrino interaction vertex. The machine learning solution is seamlessly integrated into a chain of pattern-recognition algorithms. The technique substantially outperforms the previous BDT-based solution, with a more than 20\% increase in the efficiency of sub-1\,cm vertex reconstruction across all neutrino flavours.

hep-ex↗

arXiv2025

First Observation of Antiproton Annihilation At Rest on Argon in the LArIAT Experiment

We report the first observation and measurement of antiproton annihilation at rest on argon using the LArIAT experiment. Antiprotons from a charged particle test beam that come to rest inside LArIAT's liquid argon time projection chamber (LArTPC) are identified through beamline instrumentation and LArTPC track reconstruction algorithms. The multiplicity of charged particle tracks originating from the annihilation vertex is manually assessed through hand-scanning, resulting in a distribution with a mean of 3.2 $\pm$ 0.4 tracks and a standard deviation of 1.3 tracks. This is consistent with an automated track reconstruction, which produces a mean of 2.8 $\pm$ 0.4 tracks and a standard deviation of 1.2 tracks. Good agreement is found between data and Monte Carlo simulations for both methods. Additionally, we report the shower multiplicity and particle identification of outgoing tracks, both of which align closely with theoretical predictions. These findings will contribute to modeling of intranuclear annihilation interactions on argon, including scenarios such as neutron-antineutron oscillations.

hep-ex↗