Screener3D: a gaseous time projection chamber for ultra-low radioactive material screening

Abstract

In experiments searching for rare signals, background events from the detector itself are some of the major factors limiting search sensitivity. Screening for ultra-low radioactive detector materials is becoming ever more essential. We propose to develop a gaseous time projection chamber (TPC) with a Micromegas readout for radio screening. The TPC records three-dimensional trajectories of charged particles emitted from a flat sample placed in the active volume of the detector. The detector can distinguish the origin of an event and identify the particle types with information from trajectories, which significantly increases the screening sensitivity. For a particles from the sample surface, we observe that our proposed detector can reach a sensitivity higher than 100 l Bq m -2 within two days.

AlphaCAMM, a Micromegas-based camera for high-sensitivity screening of alpha surface contamination

“…During the development of this work, a similar concept has been proposed in [25] and [26]. In [25] a dedicated conceptual design and MonteCarlo simulations including the detector response are presented, while in [26] some experimental data are shown.…”

A Gaseous Time Projection Chamber with Micromegas Readout for Low Radioactive Material Screening

“…The counting efficiency is calculated based on simulation and cross-validated with a commercial silicon detector. A dedicated simulation program based on GEANT4 has been developed to study the detector response [13,25]. In addition to the 241 Am calibration source, we also measured a copper sample intentionally contaminated with alpha radioactivities.…”

“…Therefore, those events tend to have short tracks. Similar to what we have reported in [13], we have used a fiducial cut with a fiducial distance from the inner surface of the field cage larger than 27 mm, an angle cut to select upward-going tracks, and a nHits≥10 cut to suppress background.…”

“…Selection cut efficiencies based on tracks are also studied with Monte Carlo simulations based on the Geant4 toolkit [27]. The detector response to tracks is simulated with the REST framework [25] and details of our setup have been discussed in [13]. For the 241 Am source placed at one spot, the selection efficiency with three cuts applied is 85.0 ± 1.5%.…”

“…Therefore, precise determination of surface contamination is gaining more attention recently. Gaseous detectors have been proposed [11][12][13][14] for such purposes, complementing the bulk contamination detection technologies.…”