Simulation Studies of MACE Gamma Ray Telescope : Estimation of Integral Sensitivity, Angular Resolution and Energy Resolution

Abstract

The MACE (Major Atmospheric Cherenkov Experiment) is an Imaging Atmospheric Cherenkov Telescope (IACT) located in Hanle, India. It has highest altitude of 4270 m among all the IACTs in the world. The high altitude of MACE along with its large reflector having diameter of 21 m is expected to yield wide energy coverage of $\sim$ 20 GeV to $\sim$ 20 TeV. We have carried out detailed Monte Carlo simulations of the MACE response to gamma and cosmic ray showers in this energy range for various zenith angles between 0$^{\circ}$ to 60$^{\circ}$. We estimated the variation of integral flux sensitivity, angular resolution and energy resolution as a function of energy, at various zenith angles. We find that the energy threshold of the MACE remains steady between $\sim$ 30 GeV to $\sim$ 50 GeV over the zenith angle range of 0$^{\circ}$ to 40$^{\circ}$ with integral flux sensitivity of $\sim$ 2 \% Crab. The Angular resolution of the MACE improves from 0.21$^{\circ}$ near the energy threshold to 0.07$^{\circ}$ at energy of > 1 TeV for zenith angle range of 0$^{\circ}$ to 40$^{\circ}$. The expected energy resolution of the MACE in the zenith angle range of 0$^{\circ}$ to 40$^{\circ}$ varies from $\sim$ 40 \% near energy threshold to $\sim$ 20 \% for energies above 1 TeV. The MACE will detect Crab like point source within few minutes at all zenith angles, with best detection time of $\sim$ 80 seconds occurring at zenith angle of 25$^{\circ}$.