Fabrication and measurements of plastic scintillating fibers

Sixty kilometers of plastic scintillating fibers, 1 mm in diameter, have be en manufactured using a preform/tube technology. The fibers consist of a po lystyrene core surrounded by a polymethylmethacrylate cladding. The fabrica tion method is described and evaluated both qualitatively and quantitativel y. A great effort has been made in order to measure the optical properties of the polymer at the different steps of the production. The global process efficiency is not more than 40% due to the yield of the polymerization pro cess. Using a ternary blue scintillator, the mean light yield for a minimum ionizing particle, passing through a 1 mm diameter fiber at a distance of 1 m, is 5.4 +/- 0.6 photoelectrons. The mean attenuation length fitted betw een 0.5 and 2.0 m is 1.9 +/- 0.2 m. Some specific experiments that give ind ependent measurements of core and interface losses are also reported. The p rincipal cause of light loss is due to the lack of transparency of the poly styrene which leads to a spectral shift in fiber emission. This absorption already appears in the preform rods indicating that the purification and th e polymerization process are of great importance. The attenuation length re lated to core losses is measured at the level of 3 m. The interface losses are about 10(-5)-10(-4) per reflection leading to an equivalent attenuation length of 7 m. (C) 1999 Elsevier Science B.V. All rights reserved.