A. Gnat | Searcharxiv

arXiv2026

Production of GEM-like structures for cryogenic applications, using laser-cutting techniques

A novel concept for electroluminescence (EL) structures was recently proposed. In it, a wavelength-shifting material is deposited inside the holes of GEM-like structures which, after suitable optical treatment of its electrodes, improves the light collection and detection efficiency in noble gas TPCs. This new development directly addresses problems related with the scalability of future dual-phase TPCs for rare-event searches, matching (and potentially exceeding) the performance of conventional EL techniques. We report the newest developments on the production of such structures using laser-based techniques, namely the manufacture of a first batch of the so-called FAT-GEMs. This process allows low-cost and reproducible manufacturing of a high volume of such structures. In addition to the detailed description of the production, we present a performance assessment in pure argon, at a gas density close to the one expected in LAr conditions. An energy resolution of 23.5$\pm$1~\% (FWHM) at 5.9~keV was obtained, indicating a consistent improvement over previous batch. The optical treatment of the electrode surfaces has been greatly simplified and modestly improved, while charging-up effects arising from the use of laminates eliminated.

physics.ins-det↗

arXiv2024

Production of GEM-like structures using laser-cutting techniques

To enhance the ionization yield of liquid argon time projection chambers (LArTPC) used in dark matter and neutrino experiments it was proposed the use of dopants in LAr, with ionization energies below the scintillation threshold of Ar. While dual-phase LArTPCs have excellent sensitivity to single ionization electrons, their compatibility with photosensitive dopants is hindered by gas-phase electroluminescence photons ionizing the dopants, leading to a positive feedback loop. This can be addressed by optically decoupling the gaseous and liquid phases with a barrier that transmits electrons. A possible solution relies on the use of a pair of structures based on Gaseous Electron Multipliers(GEMs) with misaligned holes. Rather than amplifying electron signals in gas pockets within their holes, their holes will be filled with LAr and a low biasing voltage, so that incident drifting electrons are drawn into the holes but not amplified. Instead, amplification will occur in the gas phase above the structures. Its core element is a GEM-like structure machined from polyethylene naphthalate(PEN). Since PEN scintillates in the visible spectrum, the risk of increased radioactivity due to the larger mass compared to traditional wire grids is negated by the potential to veto its own radioactivity. As such, these structures may also be a useful alternative to wire grids. In this work, we report the newest developments on the production of GEM-like structures using laser-based techniques, namely the manufacture of the first batch PEN and PMMA-based GEM-like structures. This process allows low-cost, reproducible fabrication of a high volume of such structures. In addition to being a low radioactive technique, we expect that it will allow the scaling up of the production of these structures at a reduced cost. First tests indicate good electrical stability, while the performance assessment is still ongoing.

physics.ins-det↗