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T: Fachverband Teilchenphysik

T 84: Search for Dark Matter IV

T 84.7: Vortrag

Donnerstag, 3. April 2025, 17:45–18:00, VG 4.102

Study of spurious clustered electron emission signals in XENONnT — •Alexis Michel and Alexey Elykov — Karlsruhe Institute of Technology, Institute for Astroparticle Physics

In direct search of dark matter, dual-phase xenon time projection chambers (TPCs) like XENONnT are widely used. This kind of detector has a target of liquid xenon (LXe) with a layer of gaseous xenon (GXe) above. Alongside the prompt scintillation signal, interactions in the TPC produce ionization electrons. These are drifted upward as a cloud of electrons by an applied electric field and extracted into the GXe to produce a secondary scintillation signal.

The extraction into the gas is not always complete and electrons can stay behind. What then happens to those electrons is not exactly known yet. Previous experiments often observed a number of spurious signal types, which could be associated with delayed extraction of trapped electrons. One such signal type takes the form of significantly delayed localized bursts of electrons (e-burst).

Understanding the origin of this background is of key importance for low-energy searches that look for particle interaction products down to the single- and few-electron level. Moreover, characterization of the e-burst background could shed light on the microphysics processes at the liquid-gas xenon interface, informing the operation and design of the current and future generation of xenon TPCs.

In this talk I will present the recent results and progress on studies of such signals and their correlation with detector conditions.

Keywords: XENONnT; dual-phase Xe TPC