The 2-3 mixing and mass split: atmospheric neutrinos and magnetized spectrometers
Abhijit Samanta, A. Yu. Smirnov
备注:
15 pages, 1 new figure added, typos corrected, discussion extended. Improvement of the ICAL sensitivities with adding the information on hadrons is studied
We study dependence of the atmospheric $ν_μ$ and $\barν_μ$ fluxes on the deviations of the 2-3 mixing from maximal, $|45^\circ - θ_{23}|$, on the $θ_{23}$-octant and on the neutrino mass splitting $Δm_{32}^2$. Analytic expressions for the $θ_{23}-$deviation effect and the octant asymmetry are derived. We present conservative estimations of sensitivities of the iron (magnetized) calorimeter detectors (ICAL) to these parameters. ICAL can establish the $θ_{23}$-deviation at higher than 3$σ$ confidence level if $| 45^\circ - θ_{23}| > 6^{\circ}$ with the exposure of 1 Mton$\cdot$yr. Sensitivity to the octant is low for zero or very small 1-3 mixing, but it can be substantially enhanced for $θ_{13} > 3^\circ$. ICAL can measure the difference of $Δm_{32}^2$ in $ν$ and $\barν$ channels (the CPT test) with accuracy $0.8\times 10^{-4}$ eV$^2$ (3$σ$) with 1 Mton$\cdot$yr exposure, and the present MINOS result can be excluded at $>5σ$ confidence level. We discuss possible ways to further improve sensitivity of the magnetized spectrometers.
Discrimination of mass hierarchy with atmospheric neutrinos at a magnetized muon detector
在磁化铁量能计探测器上,考虑μ子能量和事件的天顶角,研究了大气中微子的质量等级。对于$χ^2$分析,我们已经迁移的事件的数量从中微子能量和天顶角仓到μ子能量和天顶角仓使用的二维能量-角度相关的分辨率功能。在$\log_{10} E - L^{0.4}$平面的二维网格中进行数据的分箱,以在$χ^2$分析中更好地反映振荡模式。然后考虑到大气中微子通量和截面的所有可能的系统不确定性,将$χ^2$边缘化。研究了振荡参数范围对边缘化的影响。边缘化的$θ_{13}$的范围的下限被认为是非常重要的,在确定的敏感性等级为一个给定的$θ_{13}$。最后,我们证明了在$>$ 90% C. L.条件下可以区分大气中微子的质量等级.如果是$θ_{13} \ge 5^\circ$的下限。
Atmospheric neutrinos travel very long distances through earth matter. It is expected that the matter effects lead to significant changes in the neutrino survival and oscillation probabilities. Initial analysis of atmospheric neutrino data by the Super- Kamiokande collaboration is done using the vacuum oscillation hypothesis, which provided a good fit to the data. In this work, we did a study to differentiate the effects of vacuum oscillations and matter modified oscillations in the atmospheric neutrino data. We find that magnetized iron detector, ICAL at INO, can make a 3 sigma discrimination…
The proposed Iron Calorimeter (ICAL) detector at Indian Neutrino Observatory(INO) will be a large (50 kt) magnetized detector located 1270 m underground at Bodi West Hills in Tamilnadu. ICAL is capable of identifying the charge of the particles. In this paper its potential for the measurement of the muon charge ratio is explored by means of a detailed simulation-based study, first using the CORSIKA code and then comparing it with an analytical model (the "pika" model). The estimated muon charge ratio is in agreement with the existing experimental observations, its measure can be extended by IN…
Use of low energy atmospheric neutrinos is considered for precision measurement of neutrino mixing parameters. At around energy $E \simeq$ a few $\times$100 MeV and baseline $L$ of a few $\times$1000 km, CP phase effect is $\sim$10 times larger than that of the conventional LBL accelerator neutrino experiments. We report here a few progresses: (1) To analyze physics in the region, a new perturbative framework at around the solar-scale enhancement is developed. (2) To know the characteristic features of CP $δ$ dependence of the atmospheric neutrinos at low energies, we plot the ratio of the $ν_…