A simulation study of tau neutrino events at the ICAL detector in INO

TL;DR

This simulation study demonstrates that tau neutrino events at the ICAL detector can confirm atmospheric tau neutrino presence with high confidence and improve neutrino oscillation parameter measurements.

Contribution

First detailed simulation of tau neutrino-induced events at ICAL, showing their potential to detect tau neutrinos and refine oscillation parameters.

Findings

Tau neutrino presence can be confirmed at nearly 4σ confidence with 10 years of data.

Tau events are sensitive to $ heta_{23}$ and $ riangle m^2_{3i}$ oscillation parameters.

Combining tau events with muon analysis enhances parameter measurement precision.

Abstract

We present the first detailed simulation study of tau neutrino-induced charged current (CC) events from atmospheric neutrino interactions in the Iron Calorimeter (ICAL) detector at the proposed India-based Neutrino Observatory (INO) laboratory. Since the intrinsic atmospheric neutrino flux at few to 10s of GeV energy comprises only electron and muon neutrinos (and anti-neutrinos) with negligible tau neutrino component, any signature of atmospheric tau neutrinos is a signal for neutrino oscillations. We study the tau leptons produced through these CC interactions via their hadronic decay. These events appear as an excess over the neutral current (NC) background where hadrons are the only observable component. We find that the presence of tau neutrinos in the atmospheric neutrino flux can be demonstrated to nearly $4\sigma$ confidence with 10 years data; in addition, these events are sensitive to the neutrino oscillation parameters, $\sin^2\theta_{23}$ and $\vert \Delta m_{31}^2 \vert$ (or $\vert \Delta m_{32}^2 \vert$), in the 2--3 sector. Finally, we show that combining these events with the standard muon analysis which is the core goal of ICAL further improves the precision with which these parameters, especially the octant of $\theta_{23}$, can be measured.