Beam test of a 1/3-size DTOF prototype for the STCF experiment

A DTOF (DIRC-like Time-of-Flight) detector, based on detection of internally reflected Cherenkov light (DIRC), has been proposed for particle identification (PID) in the endcap region of the Super Tau-Charm Facility (STCF). To validate its performance, a 1/3-size prototype featuring a fan-shaped planar fused silica radiator was constructed and tested using hadrons with momenta up to 5 GeV/c. The results demonstrate that the prototype achieves a particle detection efficiency exceeding 99.9%. A separation power of 4.40σ and a single track timing precision of ∼26 ps were observed for π/p at 4 GeV/c normal incidence. The timing and particle identification performance at other incident angles are slightly inferior to those at normal incidence, leaving room for further optimization. These performance metrics align well with Geant4 simulations, confirming that the DTOF prototype meets the requirements of the STCF experiment.