Sensitivity of ICAL to TeV Gamma Rays at INO

Abstract

We report the sensitivity of Iron CALorimeter (ICAL) detector to the detection of TeV gamma rays from various astrophysical sources at India-based Neutrino Observatory (INO). The ICAL detector is proposed to be of 51 kton with an average magnetic field of \(\sim \)1.3 T. The electromagnetic showers generated by high-energy gamma rays at the atmosphere will produce down-going muons through either muon pair production or pion decay. The gamma rays can be traced by detecting these muons using ICAL. Most of the space- and underground-based experiments have detected them directly and indirectly, but the advantage of using ICAL for their detection is to measure the \(\mu ^{+}\) to \(\mu ^{-}\) ratio, which is 1 in case of pair production, at very high energy (\(\ge \)50 GeV). Here, we have shown its detection ability for the appropriate astrophysical 2FHL sources listed in “The Second Catalog of Hard Fermi-LAT Sources,” where the signal-to-noise ratio is suppressed by factor of 5\(\sigma \) for ICAL running period of five years for spectral index of \(\le \)0.45.