<title>Results of a beam test using scintillating fibers and solid state photodetectors</title>

Abstract

ABSTRACT A 96-channel, 3-superlayer scintillating fiber tracking system has been tested in a 5 0eV/c ir beam. The scintillating fibers were 830 jim in diameter, spaced 850 jm apart within a layer, and4.3 m in length. These were coupled to 6 m long clear waveguides and finally to Visible LightPhoton Counters (VLPCs). A spatial resolution of ' 150 jim for a double-layered ribbon was achieved with this tracking system.. 1. INTRODUCTION A scintillating fiber is an optical fiber with a doped core and one or more claddings. Its coreemits light upon the passage of a ch&ged particle. A fraction of the light (3 to 4%) is captured inthe fiber and propagates to a clear waveguide, and finally to a photodetector. A system of manyfibers in known locations can be used to track charged particles. The photodetector of choice isthe Visible Light Photon Counter1 (VLPC), a solid state photodetector which has high quantum efficiency (55% to 85%), moderate gain (#*s 2 x 10'), and fast time response. However, VLPCs mustbe operated at low temperature (6—10 K).A scintillating fiber tracking system has many attractive features: (1) It has good spatial reso-lution as a result of the small scintifiating fiber diameter. (2) The small diameter ('s