Characterization of the muography background using the Muon Telescope (MuTe)

Abstract

In this work, we estimate the background components in muography using the MuTe: a hybrid muon telescope composed of two subdetectors -a scintillator hodoscope and a Water Cherenkov Detector (WCD). The hodoscope records the trajectories of particles crossing the telescope, while the WCD measures their energy loss. The MuTe hodoscope reconstructs 3841 different directions with an angular resolution of 32 mrad for an inter-panel distance of 2.5 m. The spatial resolution can reach $\sim$25.6 m assuming an 800 m distance to the target. The WCD measures the deposited energy from 50 MeV to 1.5 GeV with a resolution of 0.72 MeV. MuTe discriminates muography background sources such as: upward coming muons, scattered muons, the soft component of Extensive Air Showers (EAS), and particles arriving simultaneously. They are filtered by using measurements of deposited energy (WCD) and Time-of-Flight. The WCD differentiates single muons, electrons/positrons, and multiparticle events. On the other hand, the ToF measurements allow us to estimate the muon momentum establishing an energy threshold to decrease the background contribution of scattered muons. Upward coming muons are rejected by means of the particle arrival direction determined by the ToF sign. We concluded that near 36% of the recorded events belong to the electromagnetic component (electrons and positrons), roughly 30.4% is caused by multiple particle events that arrive with time differences < 100 ns and the last 34% are caused by muons. The muonic soft component (< 1 GeV/c) represents 46% of the single-muon events. The upward going particles add up the 22% of the total flux crossing the MuTe.