Supernova Pointing Capabilities of DUNE

TL;DR

This paper presents a framework to determine the direction to a core-collapse supernova from the neutrino burst detected by DUNE. It uses two main interaction channels—neutrino-electron elastic scattering and electron-neutrino charged-current absorption on argon-40—and introduces a brems flipping technique to resolve head-tail ambiguities in track reconstruction. A maximum-likelihood approach combines channel-specific directional information to yield burst pointing, with key results showing 68% pointing resolutions of 3.4° for 40 kton and 6.6° for 10 kton under perfect event classification, degrading to 4.3° and 8.7° when a 4% misclassification rate is present. The study demonstrates DUNE’s potential as a significant contributor to multimessenger astronomy, while outlining avenues for latency reduction, cross-detector synergy, and improved channel tagging to further enhance pointing performance.

Abstract

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.

Figures (17)

• Figure 1: Geant4 illustration of the energy deposition for examples of two event types: (a) $\nu_e$CC: A 25 MeV electron neutrino is absorbed by an argon nucleus resulting in the excitation of the nucleus and the emission of an electron. (b) eES: An incoming electron neutrino of 12 MeV scatters elastically in the LAr. Bremsstrahlung gammas are preferentially emitted in the forward direction of the primary electron. The $\nu_e$CC primary electron tracks are on average longer than eES tracks due to the lower energies of the eES recoils; in contrast, $\nu_e$CC electrons tend to retain most of the energy of the incoming neutrino. Gamma tracks are not shown in the display, but red blips (representing electrons) from gamma interactions with the argon (primarily Compton scatters) can be seen.
• Figure 2: Comparison of the cross-section-weighted energy and angular distributions of electrons for the $\nu_e + \prescript{40}{}{} \text{Ar}$$\nu_e$CC events in red and the eES events in blue. The angular plots are shown as a function of the cosine of the angle between the neutrino direction and the final-state electron direction. For both types of interactions, the supernova energy spectrum is assumed for the incoming neutrinos. (a): distribution of the energy of incoming neutrinos (continuous line) and outgoing electrons (dashed line). (b): distribution of the cosine of the scattering angle. (c) and (d): two-dimensional distributions showing the relative number of events as a function of both the neutrino energy and the cosine of the scattering angle, for the two types of interactions.
• Figure 3: The contribution of Fermi and Gamow-Teller transitions to the angular distribution for $\nu_e$CC events, generated from MARLEY for the GVKM flux model. For this model's neutrino spectrum, the angular correlation cancels out to a good approximation.
• Figure 4: Example standard DUNE event display of an eES event. The colors show a heat map of the charge deposited on each wire segment per time tick. From top to bottom, the three plots show the view of the three wire planes, U, V, and X respectively, for one APA of the LArTPC. The trajectories with numerical labels are reconstructed tracks, where "0" corresponds to the primary electron track, while "1" and "2" refer to the bremsstrahlung-induced blips.
• Figure 5: A graphical illustration of the sky fraction calculation for an example probability function in $\theta$. The sky fraction is the summed widths of the shaded regions, $x_1 + x_2$ divided by the domain width of $P(x)$, which is 2. The integration bounds $x_1$ and $x_2$ are set at the point where $P(x)$ crosses value $y$. The cut-off value $y$ is lowered until the integral of the shaded region equals 68% of the total integral of $P(x)$.