A large underground water Cherenkov muon detector array with the Tibet air shower array for Gamma-ray astronomy in the 100 TeV region: detector design and simulation

We are planning to build a large water-Cherenkov-type muon detector array around the Tibet air shower array for Gamma-ray astronomy in the 100 TeV Region. In this paper, we describe the design of the Tibet MD array and details of the Monte Carlo simulation to demonstrate the sensitivity of the Tibet AS+MD array.