Aluminization of Scintillating Fibers for the Luminosity Detector of ATLAS

We report on tests on 25 cm long squared, 5mmx5mm SCF-3HF optical scintillating fibers, which have been aluminized by the magnetron sputtering technique in Lisbon during 2005. Two groups of fibers were used: 9 isolated fibers (Set I) and 20 stacked inside an acrylic piece (Set II). Fibers in Set I were used to measure the attenuation length of the fibers and were processed in Lisbon but not aluminized. Fibers in Set II were polished in a milling machine with a diamond blade and aluminium coated at one end. The other end was polished at CERN. From this set 10 were cut and polished at 90º with the axis of the fiber and the other 10 the end to be aluminized has been cut at 45º. The reflectivity of the aluminium mirror has been measured in a dedicated test bench. Preliminary results give a value of reflectivity of 51% for the fibers with a 90º cut.