High efficiency muon registration system based on scintillator strips

Experiments such as mu2e (FNAL, USA) and COMET (KEK, Japan) seek the direct muon-to-electron conversion to study Charged Lepton Flavor Violation processes. A highly efficient (up to 99.99% efficiency) cosmic muon detection system is needed to achieve a single-event sensitivity below 10−17. In this article, the possibility of attaining such efficiency in the short and long term is discussed for modules based on 7-mm- or 10-mm-thick and 40-mm-wide plastic scintillation strips with a single 1.2 mm WLS fiber glued into the groove along the strip and using MPPC/SiPM for light detection. A Simplified Light Yield Distribution (SLYD) method to estimate the efficiency of the module is proposed, and the simulation results obtained with GEANT 4 for a system based on a 4-by-4 array of 7x40x3000 mm strips are compared with the experimental data. It is found that for the systems requiring efficiency of 99.99% and higher, it is important to improve the light yield as much as possible and to achieve the smallest possible gap between neighbor scintillation volumes is important.