First simulation study of trackless events in the INO-ICAL detector to probe the sensitivity to atmospheric neutrinos oscillation parameters.

The proposed India-based Neutrino Observatory will host a 50 kton magnetized iron calorimeter (ICAL) with resistive plate chambers as its active detector element. Its primary focus is to study charged-current interactions of atmospheric muon neutrinos via the reconstruction of muons in the detector. We present the first study of the energy and direction reconstruction of the final state lepton and hadrons produced in charged current interactions of atmospheric electron neutrinos at ICAL and the sensitivity of these events to neutrino oscillation parameters $\theta_{23}$ and $\Delta m_{32}^2$. However, the signatures of these events are similar to those from neutral-current interactions and charged-current muon neutrino events in which the muon track is not reconstructed. On including the entire set of events that do not produce a muon track, we find that reasonably good sensitivity to $\theta_{23}$ is obtained, with a relative $1\sigma$ precision of 15% on the mixing parameter $\sin^2\theta_{23}$, which decreases to 21%, when systematic uncertainties are considered.