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Atmospheric neutrino experiments can determine the neutrino mass hierarchy for any value of $delta_{CP}$. The Iron Calorimeter (ICAL) detector at the India-based Neutrino Observatory can distinguish between the charged current interactions of $ u_mu$ and $bar{ u}_mu$ by determining the charge of the produced muon. Hence it is particularly well suited to determine the hierarchy. The hierarchy signature is more prominent in neutrinos with energy of a few GeV and with pathlength of a few thousand kilometers, $textit{i.e.}$ neutrinos whose direction is not close to horizontal. We use adaptive neural networks to identify such events with good efficiency and good purity. The hierarchy sensitivity, calculated from these selected events, reaches a $3 sigma$ level, with a $Delta chi^2$ of 9.
The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles.
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 $1sigma$ precision of 15% on the mixing parameter $sin^2theta_{23}$, which decreases to 21%, when systematic uncertainties are considered.
We investigate the sensitivity of the Karlsruhe Tritium Neutrino Experiment (KATRIN) to keV-scale sterile neutrinos, which are promising dark matter candidates. Since the active-sterile mixing would lead to a second component in the tritium $beta$-spectrum with a weak relative intensity of order $sin^2theta lesssim 1times10^{-6}$, additional experimental strategies are required to extract this small signature and to eliminate systematics. A possible strategy is to run the experiment in an alternative time-of-flight (TOF) mode, yielding differential TOF spectra in contrast to the integrating standard mode. In order to estimate the sensitivity from a reduced sample size, a new analysis method, called self-consistent approximate Monte Carlo (SCAMC), has been developed. The simulations show that an ideal TOF mode would be able to achieve a statistical sensitivity of $sin^2theta sim 5times10^{-9}$ at one $sigma$, improving the standard mode by approximately a factor two. This relative benefit grows significantly if additional exemplary systematics are considered. A possible implementation of the TOF mode with existing hardware, called gated filtering, is investigated, which, however, comes at the price of a reduced average signal rate.
The proposed ICAL detector at INO is a large sized underground magnetized iron detector. ICAL is designed to reconstruct muon momentum using magnetic spectrometers. Energy measurement using magnets fail for muons in TeV range, since the angular deflection of the muon in the magnetic field is negligible and the muon tracks become nearly straight. A new technique for measuring the energy of muons in the TeV range is used by the CCFR neutrino detector, known as the Pair-Meter technique. This technique estimates muon energy from measurements of the energy deposited by the muon in many layers of an iron-calorimeter through e$^+$ and e$^-$ pair production. In this work we have performed Geant4 based preliminary analysis for iron plates and have demonstrated the observational feasibility of very high energy muons (1TeV-1000TeV) in a large mass underground detector operating as a pair-meter. This wide range of energy spectrum will be helpful for studying the cosmic rays in the Knee region and an understanding of the atmospheric neutrino flux for the present and future ultra high-energy atmospheric neutrino experiments.
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$_ u>$1 GeV) $ u_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.