A High Resolution Scintillating Fiber Gamma-Ray Telescope

Abstract

Scintillating fibers coupled to position sensitive photomultipliers have good angular precision and good energy resolution in detecting gamma-rays. Recently high photon yielding and long attenuation length step index scintillating plastic fibers have been developed. Scintillating fibers of 1 mm diameter made of polystyrene doped with butyl-PBD (λ = 420 nm) and clad with PMMA (poly mptAylmetacrylate), have resulted attenuation lengths over 2 meters. Scintillating fibers stacked up into scintillating fiber planes U, V and W that are rotated by 60° angle relative to each other and coupled to position sensitive photomultipliers can be used as high resolution imaging gamma-ray detectors. With this arrangement the Compton electron or pair production point can be determined by the scintillation photons reaching the photomultipliers. A 3-dimensional conversion point accuracy is expected to be 6 _rms~1 mm. A large variety of Compton and/or pair production gamma-ray telescopes using scintillator blocks coupled to vacuum photomultipUer tubes has been built earlier for space based experiments. In these cases the scintillator block dimensions were large thus limiting the angular accuracies and resolutions. Here we are presenting the design of a large area gamma-ray detector with high angular and energy resolution for space based experiments, using scintillating fibers and recently developed position sensitive photomultiplier tubes. This detector is under development at the UCLA/UTD laboratories.