We present the development and performance of compact Scintillating Fiber (SciFi) detectors read out with Si-PMs for tracking and timing to be used at very high particle rates. The compact size, fast response, and insensitivity to magnetic fields make these detectors suitable for a variety of applications. Different scintillating fiber materials have been evaluated to achieve the best performance.
In particular, we will present and discuss the performance of the SciFi tracker / time of flight detector under construction for the Mu3e experiment at PSI searching for the neutrinoless decay mu+ -> e+e-e+ at very high rates. To suppress all forms of combinatorial background, a very thin (thickness < 0.2% of radiation length) SciFi detector with few 100 ps time resolution, efficiency in excess of 96%,and spatial resolution of ~100 um has been developed. Moreover the SciFi detector will help to determine the charge of the recurling tracks in the central region of the apparatus by time of flight measurements.