Scintillating optical fiber trajectory detectors

Abstract

Measurements of attenuation in several types of plastic scintillating optical fibers give attenuation lengths varying from 0.8 to 1.5 m. By comparing attenuation as a function of wavelength in fibers of different thicknesses we infer the contributions to the attenuation from reflection losses and bulk scintillation losses. We find good agreement between these values and calculated estimates of attenuation in scintillator. We have also calculated the effective scintillation efficiency of small fibers relative to that of bulk scintillator (for scintillator with dimethyl POPOP as the waveshifting dye) for the two cases of optically coupled and decoupled fibers. Scintillating fiber ribbons made of 200 μm square cross section fibers were exposed to relativistic iron nuclei at the LBL Bevalac, and positional resolution of 70 μm was obtained. Relativistic neon and carbon were also detected in these ribbons. In a similar exposure of 100 μm fibers to 50 MeV/n nitrogen nuclei at the NSCL cyclotron, Michigan State University, a positional resolution of about 50 μm was obtained.