Measurement of the atmospheric muon counting rate at ground level as a function of the zenith angle using Geiger-Müller tubes and a Rossi coincidence circuit

Cosmic rays are high-energy particles originating from space that interact with the Earth's atmosphere, producing cascades of secondary particles, including muons. In this paper we present an experiment carried out within the Outreach Cosmic Ray Activities (OCRA) project promoted by the italian National Institute for Nuclear Physics (INFN), in which we measured the muon rate at ground level as a function of the zenith angle using a detection system based on Geiger-Müller tubes coupled to a Rossi coincidence circuit. The results show that the rate decreases with increasing zenith angle, in agreement with the known zenith-angle dependence of atmospheric muons.