The knowledge of the atmospheric muon flux in cosmic rays at ground level is of considerable interest in various particle physics and applied physics experiments, in particular to calibrate Monte Carlo models used in atmospheric shower simulations and for precision studies of neutrino oscillations. In the literature there is no systematic study of the muon component at ground level at different measurement points on the Earth’s surface (latitude, longitude and altitude).
The ACROMASS (Atmospheric Cosmic Ray Observatory using a Magnetic Altazimuth Silicon Spectrometer) experiment of the National Institute for Nuclear Physics (INFN Italy) aims to study the main components of secondary cosmic rays at ground level with particular attention to low-energy components. ACROMASS includes some subdetectors such as a magnetic spectrometer, a time-of-flight (TOF) and an electromagnetic calorimeter that have the task of performing Particle-IDentification (PID). The TOF subdetector will be presented, which aims at discriminating between muons and protons at low momentum p<1GeV/𝑐. The detector, consisting of fast segmented plastic scintillators and silicon photomultipliers as light sensors, is coupled to a high temporal resolution readout electronics, the SAMPIC module designed by a collaboration including CEA/IRFU/SEDI Saclay (France) and CNRS/LAL/SERDI Orsay (France). The detector and the first tests carried out on its operation in terms of temporal performance will be presented.