Active-sterile neutrino oscillations at INO-ICAL over a wide mass-squared range

Abstract

We perform a detailed analysis for the prospects of detecting active-sterile oscillations involving a light sterile neutrino, over a large Δm412 range of 10−5 eV2 to 102 eV2, using 10 years of atmospheric neutrino data expected from the proposed 50 kt magnetized ICAL detector at the INO. This detector can observe the atmospheric νμ and ν¯ μ separately over a wide range of energies and baselines, making it sensitive to the magnitude and sign of Δm412 over a large range. If there is no light sterile neutrino, ICAL can place competitive upper limit on |Uμ4|2 ≲ 0.02 at 90% C.L. for Δm412 in the range (0.5−5)×10−3 eV2. For the same |Δm412| range, ICAL would be able to determine its sign, exploiting the Earth’s matter effect in μ− and μ+ events separately if there is indeed a light sterile neutrino in Nature. This would help identify the neutrino mass ordering in the four-neutrino mixing scenario.