Characterization technique of sub-millimeter scintillating fibers

The characterization of sub-millimeter scintillatingoptical fibers involves the measurement of the attenuation length,which is one of the main properties together with the yield andthe trapping efficiency, given the use of these fibers in the designof particle detectors. Every technique considered allows for theoptical coupling of the scintillating fibers to suitable photosensors, at one or both ends. What essentially changes is thecause of scintillation light within the fibers, which comes from aUV laser or radioactive source. We have developed an alternativetechnique that is based on the use of cosmic rays as a uniformscintillation source. In this paper we present the results of thismethod compared to others obtained using standard ones.