Screener3D: a Gaseous Time Projection Chamber for Ultra-low Radioactive Material Screening

For experiments searching for rare signals, background events from the detector itself are one of the major limiting factors for search sensitivity. Screening for ultra-low radioactive detector material is becoming ever more essential. We propose to develop a gaseous Time Projection Chamber (TPC) with Micromegas readout for radio-screening purposes. The TPC records three-dimensional trajectories of charged particles emitted from a flat sample placed inside the active volume. The detector is able to distinguish the origin of an event and identify the particle types with information from trajectories, which improves the screening sensitivity significantly. For $alpha$ particles from the sample surface, we find that our proposed detector can reach a sensitivity of better than 100~$mu$Bq$cdot$m$^{-2}$ within two days.