The Study of the Birth of Dimuon on the NA64 Experiment

After no phenomena beyond the Standard Model were detected at the LHC collider at CERN for a number of years, CERN began to pay more attention to the diversification of research. One of the experiments in this direction is NA64 on particle beams from the SPS accelerator. The main research area of this experiment is the search for a Dark photon through a signature with significant lost (undetected) energy. In this experiment, it is important to study background events and their properties in detail, especially those that are similar to a signal. The muon pairs (dimuons) formed inside the electromagnetic shower share an important number of characteristics with signal events, and it can be detected in the modules of hadron calorimeters, and reproduced using simulation. It is possible to use dimuons to check the accuracy of Monte Carlo simulation of the NA64 installation based on the Geant4 package, as well as to calibrate the detector.