Design and production of the high voltage electrode grids and electron extraction region for the LZ dual-phase xenon time projection chamber

Abstract

The dual-phase xenon time projection chamber (TPC) is a powerful tool for direct-detection experiments searching for WIMP dark matter, other dark matter models, and neutrinoless double-beta decay. Successful operation of such a TPC is critically dependent on the ability to hold high electric fields in the bulk liquid, across the liquid surface, and in the gas. Careful design and construction of the electrodes used to establish these fields is therefore required. We present the design and production of the LUX-ZEPLIN (LZ) experiment's high-voltage electrodes, a set of four woven mesh wire grids. Grid design drivers are discussed, with emphasis placed on design of the electron extraction region. We follow this with a description of the grid production process and a discussion of steps taken to validate the LZ grids prior to integration into the TPC.

Detecting low-energy interactions and the effects of energy accumulation in materials

“…While effects of wire material and wire conditioning on electron emission in dual-phase detectors were extensively studied (studies for LUX are the most recent example [66] ), there were no attempts to separate effects and processes in metal and metal oxide from effects and processes in solid physisorbed layers on the wire surface. Some observationslike periods of strong electron emission when voltage is first applied to the detector or re-applied after a sufficiently long break -are pointing to the existence of such effects.…”