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T: Fachverband Teilchenphysik

T 45: Neutrino Physics III

T 45.4: Talk

Wednesday, March 18, 2026, 17:00–17:15, AudiMax

Qualification Measurements Toward a New KATRIN Rear Wall — •Kerstin Trost¹, Dominic Batzler¹, Marco Röllig¹, Marius Schaufelberger¹, Marie Schäfer¹, Michael Sturm¹, and Mart van den Bosch² for the KATRIN collaboration — ¹Karlsruhe Institute of Technology, Germany — ²Eindhoven University of Technology, Netherlands

Starting this year, the KATRIN experiment is undergoing a major upgrade to enable the search for sterile neutrinos in the keV mass range. This upgrade introduces a significant systematic uncertainty arising from electron backscattering at the upstream end of the tritium source, the Rear Wall (RW). To mitigate this effect, two new RW candidates, beryllium and microstructured silicon, are currently under investigation as they are expected to reduce the backscattering probability significantly.

This presentation discusses the ongoing qualification program for these Rear Wall candidates, including systematic studies of tritium accumulation as well as an ozone-based decontamination procedure. The stability of both materials under ozone exposure is assessed to ensure long-term compatibility with routine decontamination cycles. Furthermore, charge-up effects and potential surface modifications induced by ozone treatments are analyzed using Auger Electron Spectroscopy (AES). These characterization measurements form a crucial step toward implementing an optimized Rear Wall for the upcoming KATRIN keV sterile neutrino measurement phase.

Keywords: keV sterile neutrinos; Tritium; contamination; decontamination; AES