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arXiv · 2602.23563

Characterization of UV optical components for photon detector calibration in liquid argon TPCs

B. Behera·M. Bilal Azam·Z. Djurcic·A. Heindel·I. Helgeson·T. Hyden·D. Leon Silverio·S. Magill·D. A. Martinez Caicedo·M. Oberling·K. Pickner·A. Rafique·J. Rodríguez Rondon·D. Torres Muñoz·C. Winkers·L. Xia
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Abstract

Large liquid argon time projection chambers (LArTPCs) require stable and well-characterized delivery of ultraviolet (UV) light for in situ calibration of photosensors at cryogenic temperatures. This article reports bench-top and cryogenic measurements of the optical components used in a UV light calibration system, including multi-mode fused-silica fibers, SMA-to-SMA connectors, optical fiber feedthroughs, and light-diffuser assemblies. Light loss in several fiber types and SMA connectors was measured across wavelengths from \qtyrange{275}{970}{nm}. In addition, light-loss measurements of the tested fibers after several liquid-nitrogen thermal cycles showed no statistically significant degradation relative to baseline measurements, and high-rate pulsed exposure (30-90 million pulses from a \qty{275}{nm} LED) likewise showed no measurable aging in jacketed fibers. A compact, palm-sized, 3D-printed PEEK diffuser housing with stacked UV-grade fused-silica diffusers yields Lambertian emission and the most uniform angular distribution. Optical components exhibiting improved UV transmission were deployed successfully in multiple DUNE small- and large-scale prototypes, demonstrating reliable operation of UV light calibration systems. These findings inform component selection and calibration procedures for achieving reliable, uniform UV light delivery in large-scale cryogenic detectors such as DUNE.

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B. Behera, M. Bilal Azam, Z. Djurcic, A. Heindel, I. Helgeson, T. Hyden, D. Leon Silverio, S. Magill, D. A. Martinez Caicedo, M. Oberling, K. Pickner, A. Rafique, J. Rodríguez Rondon, D. Torres Muñoz, C. Winkers, L. Xia. 2026-02-27. Characterization of UV optical components for photon detector calibration in liquid argon TPCs. https://arxiv.org/abs/2602.23563

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