Energy and Direction Estimation of Neutrinos in muonless events at ICAL

Abstract

In this paper, we study events without identifiable muon tracks in the Iron Calorimeter detector at the India-based Neutrino Observatory. Such events are dominated by high energy (E$_\nu>$1 GeV) $\nu_e$ charged current interactions, which have been studied only in a few experiments so far. The charged particles, produced in these neutrino interactions, give rise to a set of hits in the detector. We attempt to reconstruct the energy and the direction of the neutrino in such events. We study the energy distribution for a given pattern of hits of these events and find that the Landau distribution provides a good fit. % The parameters of the fit can be correlated to the energy of the neutrino. We define two kinematic variables based on the hit distribution and use them to determine the cosine of the polar angle of the neutrino direction ($\cos \theta$). There is a moderate correlation between these variables and the $\cos \theta$. These provide us enough information to prepare calibration charts for looking up the energy and direction of the incident neutrino.