No Arabic abstract
The India-based Neutrino Observatory (INO) will host a 50 kt magnetized iron calorimeter (ICAL@INO) for the study of atmospheric neutrinos. Using the detector resolutions and efficiencies obtained by the INO collaboration from a full-detector GEANT4-based simulation, we determine the reach of this experiment for the measurement of the atmospheric neutrino mixing parameters ($sin^2 theta_{23}$ and $|Delta m_{32}^2 |$). We also explore the sensitivity of this experiment to the deviation of $theta_{23}$ from maximal mixing, and its octant.
The main goal of the IceCube Deep Core Array is to search for neutrinos of astrophysical origins. Atmospheric neutrinos are commonly considered as a background for these searches. We show that the very high statistics atmospheric neutrino data can be used to obtain precise measurements of the main oscillation parameters.
The standard three-neutrino (3nu) oscillation framework is being increasingly refined by results coming from different sets of experiments, using neutrinos from solar, atmospheric, accelerator and reactor sources. At present, each of the known oscillation parameters [the two squared mass gaps (delta m^2, Delta m^2) and the three mixing angles (theta_12}, theta_13, theta_23)] is dominantly determined by a single class of experiments. Conversely, the unknown parameters [the mass hierarchy, the theta_23 octant and the CP-violating phase delta] can be currently constrained only through a combined analysis of various (eventually all) classes of experiments. In the light of recent new results coming from reactor and accelerator experiments, and of their interplay with solar and atmospheric data, we update the estimated N-sigma ranges of the known 3nu parameters, and revisit the status of the unknown ones. Concerning the hierarchy, no significant difference emerges between normal and inverted mass ordering. A slight overall preference is found for theta_23 in the first octant and for nonzero CP violation with sin delta < 0; however, for both parameters, such preference exceeds 1 sigma only for normal hierarchy. We also discuss the correlations and stability of the oscillation parameters within different combinations of data sets.
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 do a re-analysis to asses the impact of the results of the Borexino experiment and the recent 2.8 KTy KamLAND data on the solar neutrino oscillation parameters. The current Borexino results are found to have no impact on the allowed solar neutrino parameter space. The new KamLAND data causes a significant reduction of the allowed range of $Delta m^2_{21}$, determining it with an unprecedented precision of 8.3% at 3$sigma$. The precision of $Delta m^2_{21}$ is controlled practically by the KamLAND data alone. Inclusion of new KamLAND results also improves the upper bound on $sin^2theta_{12}$, but the precision of this parameter continues to be controlled by the solar data. The third mixing angle is constrained to be $sin^2theta_{13} < 0.063$ at $3sigma$ from a combined fit to the solar, KamLAND, atmospheric and CHOOZ results. We also address the issue of how much further reduction of allowed range of $Delta m^2_{21}$ and $sin^2theta_{12}$ is possible with increased statistics from KamLAND. We find that there is a sharp reduction of the $3sigma$ ``spread with enhanced statistics till about 10 KTy after which the spread tends to flatten out reaching to less than 4% with 15 KTy data. For $sin^2theta_{12}$ however, the spread is more than 25% even after 20 KTy exposure and assuming $theta_{12} < pi/4$, as dictated by the solar data. We show that with a KamLAND like reactor ``SPMIN experiment at a distance of $sim$ 60 km, the spread of $sin^2theta_{12}$ could be reduced to about 5% at $3sigma$ level while $Delta m_{21}^2$ could be determined to within 4%, with just 3 KTy exposure.
Recent Super-Kamiokande data on the atmospheric neutrino anomaly are used to test various mechanisms for neutrino oscillations. It is found that the current atmospheric neutrino data alone cannot rule out any particular mechanism. Future long-baseline experiments should play an important role in identifying the underlying neutrino oscillation mechanism.