A gaseous time projection chamber with Micromegas readout for low-radioactive material screening

Abstract

PurposeLow-radioactive material screening is becoming essential for rare event search experiments, such as neutrinoless double beta decay and dark matter searches in underground laboratories. A gaseous time projection chamber (TPC) can be used for such purposes with large active areas and high efficiency.MethodsA gaseous TPC with a Micromegas readout plane of approximately \(20 \times 20\) \(\hbox {cm}^2\) is successfully constructed for surface alpha contamination measurements.ResultsWe have characterized the energy resolution, gain stability, and tracking capability with calibration sources.ConclusionWith the unique track-related background suppression cuts of the gaseous TPC, we have established that the alpha background rate of the TPC is (\(0.13\pm 0.03\))\(\times 10^{-6}\) Bq/\(\hbox {cm}^2\), comparable to the leading commercial solutions.