Three-neutrino oscillations of atmospheric neutrinos,θ13, neutrino mass hierarchy and iron magnetized detectors

Abstract

We derive predictions for the Nadir angle (θ n ) dependence of the ratio N µ − /N µ + of the rates of the µ− and µ + multi-GeV events, and for the µ − −µ + event rate asymmetry, INO, etc.) in the case of 3-neutrino oscillations of the atmospheric ν µ and ν µ , driven by one neutrino mass squared difference,is shown to be particularly sensitive to the Earth matter effects in the atmospheric neutrino oscillations, and thus to the values of sin 2 θ 13 and sin 2 θ 23 , θ 13 and θ 23 being the neutrino mixing angle limited by the CHOOZ and Palo Verde experiments and that responsible for the dominant atmospheric ν µ → ν τ (ν µ →ν τ ) oscillations. It is also very sensitive to the type of neutrino mass spectrum which can be with normal (∆m 2 31 > 0) or with inverted (∆m 2 31 < 0) hierarchy. We find that for sin 2 θ 23 > ∼ 0.50, sin 2 2θ 13 > ∼ 0.06 and |∆m 2 31 | = (2− 3)× 10 −3 eV 2 , the Earth matter effects produce a relative difference between the integrated asymmetriesĀ µ − µ + andĀ 2ν µ − µ + in the mantle (cos θ n = 0.30− 0.84) and core (cos θ n = 0.84−1.0) bins, which is bigger in absolute value than approximately ∼ 15%, can reach the values of (30 − 35)%, and thus can be sufficiently large to be observable. The sign of the indicated asymmetry difference is anticorrelated with the sign of ∆m 231 . An observation of the Earth matter effects in the Nadir angle distribution of the asymmetry A µ − µ + (ratio N µ − /N µ + ) would clearly indicate that sin 2 2θ 13 > ∼ 0.06 and sin 2 θ 23 > ∼ 0.50, and would lead to the determination of the sign of ∆m 2 31 .

Charge-separated atmospheric neutrino-induced muons in the MINOS far detector

“…However, distortions from matter effects are estimated to be small for most of the θ 13 range compatible with the CHOOZ limit [22]. The average induced ν µ /ν µ event rate asymmetry is estimated to be less than 10% [23]. Therefore, at our current level of statistical accuracy we can ignore matter effects and describe ν µ (ν µ ) → ν τ (ν τ ) oscillations using the two flavor approximation in Eq.…”

India-based neutrino observatory (INO): Physics reach and status report

“…The key point to note is that there is very little sensitivity to δ CP over the relevant E, θ zenith range. Matter effects are therefore sensitive to the mass ordering of the 2-3 states [15,16,17], provided θ 13 is sufficiently large; as has now been established by the reactor neutrino experiments [4]. Fig.…”

Measuring the mass hierarchy with muon and hadron events in atmospheric neutrino experiments

“…(12) and all other quantities are as defined in the previous section. Since the hadrons are tagged with their corresponding muon from the respective charged current interaction, we can distinguish between the hadrons associated with the µ − from the ones associated with the µ + .…”

“…Eq. (12). We then introduce the zenith angle resolution function of the hadron as well and further bins the data into hadron angles.…”

“…We smear the zenith angle binned data by the Gaussian smearing function R Θ H in addition to the smearing functions for the muon zenith angle resolution and hadron energy resolution shown in Eq. (12). The simulation results for the angular resolution of the hadron shower in ICAL are yet to be made public by the INO collaboration.…”