SMuK 2023 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 118: Dark Matter II
T 118.2: Vortrag
Donnerstag, 23. März 2023, 16:05–16:20, POT/0006
A high resolution scanning set-up for defect detection on electrodes — •Alexander Deisting1, Jan Lommler1, Shumit Mitra1, Uwe Oberlack1,2, Fabian Piermaier2, Quirin Weitzel2, and Daniel Wenz1 — 1Institut für Physik & Exzellenzcluster PRISMA+, Universität Mainz — 2PRISMA Detector Laboratory, Universität Mainz
Achieving as low backgrounds as possible is key when operating time projection chambers (TPCs) for dark matter searches. One source of background signals is the (field) emission of electrons from the electrodes inside the detector. For dual phase TPCs, similar to XENONnT, these electrodes are meshes or grids with wire diameters of 200−300 µm, operated at a high voltage (HV) ≫1 kV.
The scanning set-up at the PRISMA Detector Laboratory features a high resolution camera mounted to a gantry robot system. The camera’s resolution of 1.4×1.4 µm2 provides detailed images of electrode wires. A 3D confocal microscope with a resolution better than 1 µm is used for studies on the µm scale. We will present results of mesh-scans.
The high resolution images uncover an abundance of microscopic “defects” but they do not show whether a found spot will enhance electron emission and thus the background signals in the TPC or not. To asses the defects’ nature we extended the set-up with an overview camera and a HV supply. An electrode wire in a gas may emit electrons, resulting in a corona discharge, which the overview camera records. We present the set-up and report on our progress of matching regions of corona discharges with defects uncovered in the high resolution scan.