Heidelberg 2022 – wissenschaftliches Programm
T 29.3: Eingeladener Vortrag
Dienstag, 22. März 2022, 14:50–15:15, T-H16
From GERDA to LEGEND - Hunting no neutrinos — •Christoph Wiesinger — Max-Planck-Institut für Physik, München — Physik-Department, Technische Universität München, Garching
Hidden by their tiny mass, neutrinos may carry a profound secret with far-reaching consequences for both particle physics and cosmology. Given zero electric charge and no color, they may be Majorana particles - fermions that are their own anti-particles. Double beta decay offers a unique probe for this hypothesis. Finding no neutrinos, but solely two electrons sharing the full available decay energy, would prove lepton number non-conservation and reveal the Majorana character of neutrinos. The superb spectroscopic performance of high-purity germanium detectors provides exceptional discovery potential for this mono-energetic peak. The Germanium Detector Array (GERDA) experiment has operated 40 kg of enriched germanium in an instrumented low-background liquid argon environment. In a total exposure of more than 100 kg yr, taken under record-low background conditions, no signal was found. The corresponding half-life limit for neutrinoless double beta decay of 76Ge is >1.8·1026 yr at 90% C.L., and coincides with the median sensitivity for the null hypothesis. The Large Enriched Germanium Experiment for Neutrinoless double beta Decay (LEGEND) is about to expand this search towards 1028 yr and beyond. Following LEGEND-200, the initial 200-kg phase currently under construction, LEGEND-1000 will probe the full parameter space spanned by the inverted ordering scenario.