The design and construction of a scintillating fiber tracking detector

Abstract

The central detector of the upgraded UA2 experiment at CERN includes a cylindrical tracking and electromagnetic preshower detector which employs 1 mm diameter scintillating fibers as the sensitive medium. The device is two meters long and extends from 38 to 44 cm in its radial dimension. Sixty thousand fibers are arranged in 24 cylindrical layers, the outer six preceded by 1.5 radiation lengths of lead, permitting the localized detection of electromagnetic showers. This design was made possible by the development of plastic scintillating fibers with attenuation lengths of over 1.5 m and with a light yield sufficient to assure a detection efficiency greater than 90% for minimum ionizing particles traversing the fiber at any point along its 2 m length. In this article we describe the fabrication and performance of the fibers, the assembly procedure used in the construction of the detector, and the degree of uniformity achieved.