Simulation of muon-induced neutral particle background for a shallow depth Iron Calorimeter detector

The Iron Calorimeter (ICAL) detector at the India based Neutrino Observatory (INO) is planned to be set up in an underground cavern with a rock overburden of more than 1 km. This overburden reduces the cosmic muon flux by a factor of 10⁶ with respect to that at the sea level. In this paper, we examine the possibility of a 100 m shallow depth ICAL (SICAL) detector. The cosmic muons would have to be detected in a veto detector with an efficiency of 99.99% in order to have the same level of muon background leaking undetected through the veto detector as at the 1 km depth underground site. However, an additional background arises from interactions of cosmic muons with the rock. Since the neutral particles produced in such interactions can pass through the veto detector without any interaction, they can possibly mimic neutrino events in the ICAL. In this paper, the results of a GEANT4 based simulation study to estimate the background signals due to muon induced interactions with the rock for the SICAL is presented.