Design optimization of plastic scintillators with wavelength-shifting fibers and silicon photomultiplier readouts in the top veto tracker of the JUNO-TAO experiment

Plastic scintillators (PSs) embedded with wavelength-shifting fibers are widely used in high-energy particle physics, such as in muon taggers, as well as in medical physics and other applications. In this study, a simulation package was built to evaluate the effects of the diameter and layout of optical fibers on the light yield with different configurations. The optimal optical configuration was designed based on simulations and validated using two PS prototypes under certain experimental conditions. A top veto tracker (TVT) for the JUNO-TAO experiment, comprising four layers of 160 strips of PS, was designed and evaluated. The threshold was evaluated when the muon tagging efficiency of a PS strip was >99%. The efficiency of three layer out of four layer of TVT is >99%, even with a tagging efficiency of a single strip as low as 97%, using a threshold of 10 photoelectrons and assuming a 40% silicon PM photon detection efficiency.