An APD linear array for scintillating fiber tracker read-out

We report the feasibility study to apply Avalanche Photo Diodes (APD) to the read-out of a scintillating fiber tracker. The merits of using an APD to this purpose are its high tolerance to the magnetic field, high quantum efficiency and the possibility to operate it at room temperature. e produced several batches of avalanche photo-diode linear arrays which have different layer and pixel configurations and have measured their basic characteristics (e.g. bias voltage dependence of the gain, of the leak current and the uniformity). We also performed a realistic test using a multi-layer Scintillating Fiber Tracker (SFT). Clear MIP signals from a ∼80 cm long 7-layered SFT were detected at 5°C using the newest APD array.