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

TL;DR

This work demonstrates the first end-to-end reconstruction of atmospheric neutrinos in a DUNE FD-HD LArTPC module, adapting the long-baseline analysis workflow with retrained ML models and atmospheric-specific features. By incorporating the hadronic final state alongside the lepton, the study shows significant improvements in neutrino energy and direction reconstruction and provides a robust framework for neutrino flavor identification through CVN and PID tools. A hybrid direction-reconstruction approach combining lepton, hadron, and calorimetric information yields angular resolutions of about 25° at 1 GeV and 7–9° at 10 GeV, with energy-resolution improvements in the 10–20% range for CC events. These results establish a solid foundation for DUNE's first atmospheric-neutrino oscillation sensitivity analyses and highlight the detector's capability to study a broad energy range and a wide variety of topologies, including partially contained events.

Abstract

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.

Figures (23)

• Figure 1: At-scale depiction of the 'DUNE HD 1x2x6' geometry (red) within the full HD module geometry (black). The plane of APAs (purple) is flanked by the two CRP planes (light red). Also shown, the wires layout of the planes $u$, $v$, and $w$, together with the right-handed coordinate system used in which the zenith angle ($\theta_y$) is marked.
• Figure 2: Neutrino energy distributions for CC and NC events separated in various categories. 'Simulated' label corresponds to all simulated events, while 'Selected' label refers only to events passing the fiducial volume (FV) cut as well as the reconstructed final state particle selection. The number of events (Left) and the event fraction (Right) with respect to the amount of simulated events per bin, for fully contained (FC) and partially contained (PC) events.
• Figure 3: Resolution distributions of the reconstructed primary interaction vertex, for (from Left to Right) the $x$, $y$, and $z$ directions, for CC interactions, with all flavors combined. The mean ($\mu$) and standard deviation ($\sigma$) for each distribution are also listed.
• Figure 4: Proportion of vertices reconstructed within 1cm in a given direction from the true vertex, as a function of the zenith angle $\theta^{\rm{true}}_{y}$, for (from Left to Right) the $x$, $y$, and $z$ directions. Results are shown for three neutrino-energy intervals, for CC FC events only.
• Figure 5: Efficiency versus true particle momentum (Left), and complementary cumulative distributions for completeness (Middle) and purity (Right). The complementary cumulative distributions represent the fraction of events with completeness/purity above a certain x-value.