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T: Fachverband Teilchenphysik
T 75: Neutrino Physics without Accelerators 6
T 75.6: Vortrag
Mittwoch, 23. März 2022, 17:35–17:50, T-H34
In-situ characterization of germanium detectors from 39Ar decays for low-energy data modeling in GERDA and LEGEND — •Luigi Pertoldi for the GERDA collaboration — TU München, Germany
A reliable estimate of the active volume of high-purity germanium (HPGe) detectors, defined as the internal volume in which charge collection efficiency (CCE) reaches its maximum, is a fundamental piece of a detector’s response model. Typical HPGe detectors feature a null or incomplete CCE in correspondence with the lithium-doped, high-voltage bias contact. In this contribution, a new method for determining the active volume of HPGe detectors immersed in liquid argon (LAr), will be presented. The method exploits the shape of the low-energy distribution of 39Ar β− decays, naturally occurring in atmospheric LAr and recorded by the detectors, which strongly depends on the CCE profile. The technique is applied to physics data by the GERDA experiment and used to characterize the deployed detectors in-situ. As a consequence, a first model of the low-energy data spectrum recorded by the experiment will also be shown. The developed technique will be useful for the LEGEND experiment, which aims to perform searches of new-physics phenomena at low energies. Moreover, by using these novel 39Ar-based active volume estimates, we aim to obtain a precise and unbiased estimate of the two-neutrino double-beta decay rate of 76Ge. This research is supported by the BMBF through the Verbundforschung 05A20WO2 and by the DFG through the Excellence Cluster ORIGINS and the SFB1258.