Erlangen 2026 – scientific programme

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T: Fachverband Teilchenphysik

T 53: Scintillator Detectors II

T 53.2: Talk

Wednesday, March 18, 2026, 16:30–16:45, KH 01.014

Increasing Photon Capture Rate of Wavelength-Shifting Fibers for Opaque Scintillator Experiments — •Bastian Keßler and Sebastian Böser for the NuDoubt collaboration — Johannes Gutenberg-Universität Mainz

Wavelength-shifting optical fibers are widely used to collect and guide scintillation light from large detector volumes to photosensors, making them ideal for water Cherenkov and scintillator-based detectors. A key limitation, however, is their low photon capture efficiency, which degrades energy resolution of fiber-based detectors.

Building on prior work, we show that capture efficiency can be enhanced by optimizing the fibers absorption profile and adding a low-refractive-index outer cladding to boost total internal reflection. Although this reduces the fibers effective active area - rendering it less suitable for transparent detectors - it is advantageous in opaque scintillators, where photons remain localized and may hit the fiber multiple times before they get absorbed in the scintillator.

In this work, we study the impact on photon capture rate, cluster size, and timing performance in the hybrid opaque scintillator experiment NuDoubt++. Also, results of the first prototypes of optimized wavelength-shifting fibers (OWLs) are shown.

Keywords: wavelength-shifting fibers; NuDoubt; Opaque scintillator