Scan over rotation angle of the prtDIRC. 500 pi+@1.7GeV/c each angle. No lens. Beam test geometry (07.2014). Rotation point is 330 mm away from prism. Bottom prism-plate steps is 30.6 mm. Hit pattern Time spectrum Geant geometry screenshots. (click for zoom) MCP layout: Step1 (30.6 mm): Step2 (0 mm):