A scintillating tile hodoscope with WLS fibre readout

We describe the construction and performance of a hodoscope consisting of 127 hexagonal scintillating tiles covering hermetically a surface of about 1 m diameter. Each tile is read out on one face by five wavelength-shifting (WLS) fibres that are embedded and glued into the surface of the scintillator. The fibres serve the double purpose of primary light collection and subsequent light transmission to high gain photomultipliers located outside the active hodoscope area. Each individual tile detects the passage of a minimum ionizing particle with an efficiency >99%. Taking into account the small gaps due to the light-tight wrapping of each tile, the global efficiency of the hodoscope is ≥98%. As a test beam application of this detector, we present measurements of the albedo from a compensating lead/scintillating fibre calorimeter which was installed behind the scintillating tile hodoscope.