Double cascade reconstruction in KM3NeT/ARCA

TL;DR

This paper presents a reconstruction algorithm for double cascade signatures in KM3NeT/ARCA, enhancing neutrino astronomy by accurately identifying tau neutrino interactions with sub-degree angular resolution.

Contribution

The paper introduces a specialized reconstruction method for double cascades in KM3NeT/ARCA, improving detection and angular resolution of tau neutrinos.

Findings

Angular deviation reaches sub-degree for tau lengths >25 meters

Reconstruction algorithm effectively identifies double cascades

Enhanced neutrino flavor identification capabilities

Abstract

The detection of astrophysical $\nu_\tau$ is an important verification of the observed flux of high-energy neutrinos. A flavour ratio of approximately $\nu_{e} : \nu_\mu : \nu_\tau \approx 1 : 1 : 1$ is predicted for astrophysical neutrinos measured at Earth due to neutrino oscillations. On top of this, the $\nu_\tau$ offers a unique channel for neutrino astronomy due to absence of an atmospheric $\nu_\tau$ background contribution. When a $\nu_\tau$ interacts it produces a particle cascade and often a $\tau$ lepton which in turn decays mainly into another cascade. This results in a double cascade signature. An excellent angular resolution can be achieved when both cascade vertices are reconstructed. The KM3NeT/ARCA detector, which is under construction in the Mediterranean sea, will be able to detect this signature due to its timing and spatial resolution for cascades. We will discuss the dedicated reconstruction algorithm and performance for reconstructing double cascades using KM3NeT. The angular deviation reaches sub-degree level for tau lengths larger than 25 meters.