Manufacturing Methodology for Single- and Multilayer Square Scintillating Fiber-Based Ribbons for Direct Coupling to Linear Photosensor Arrays

Abstract

High-Energy and Nuclear Physics research facilities around the world demand cutting-edge instruments dedicated to exploring the signatures of particles knocked out by collisions at ultra-relativistic energies. Each instrument is a class of its own, but shares underlying technologies proven to solve specific challenges. Polymer-based scintillating fibers (cross sections typically below 1 mm2) are sensitive to a large range of particle types and broad energy ranges and provide a fast response, fine spatial segmentation, and a low material budget, making them suitable for particle tracking, beam monitoring, and timing applications. Indeed, scintillating fibers can cover a large variety of shapes and sizes when assembled as ribbons, also allowing for multilayer designs. While most multilayer fiber detectors employ round-section fibers in staggered layers configuration, the square cross section permits regular arrangements with gapless fully packed ribbons and a quasi-uniform distribution of sensitive material. This work presents the manufacturing process developed at the Detector Laboratory of GSI Helmholtzzentrum für Schwerionenforschung (Germany) for manufacturing single- and multilayer ribbons made of scintillating square fibers. The complete production sequence is described, including fiber winding and positioning, bonding of layers, stacking and alignment of multilayer ribbons, integration of mechanical interfaces, machining and surface finishing of the optical couplings, and quality control procedures. Dedicated tooling was developed for each production stage to provide mechanical reproducibility and scalability. The process can be fully adapted to different fiber sizes, ribbon widths and lengths, and layer configurations, enabling the production of both small prototypes and large-format modules. This technology, already validated in operative instruments, is being deployed in a new generation of experiments for the international Facility for Antiproton and Ion Research (FAIR) research center.