Test of \textit{Topmetal-${II}^{-}$} In Liquid Nitrogen For Cryogenic Temperature TPCs

Abstract

\textit{Topmetal-${II}^{-}$} is a highly pixelated direct charge sensor that contains a 72$\times$72 pixel array of 83$\hat{I}¼$m pitch size. The key feature of \textit{Topmetal-${II}^{-}$} is that it can directly collect charges via metal nodes of each pixel to form two-dimensional images of charge cloud distributions. \textit{Topmetal-${II}^{-}$} was proved to measure charged particles without amplification at room temperature. To measure its performance at cryogenic temperature, a \textit{Topmetal-${II}^{-}$} sensor is embedded into a liquid nitrogen dewar. The results presented in this paper show that \textit{Topmetal-${II}^{-}$} can also operate well at this low temperature with a noise (ENC) of 12 e${}^{-}$ lower than that at room temperature (13 e${}^{-}$). From the noise perspective, \textit{Topmetal-${II}^{-}$} is a promising candidate for the next generation readout of liquid argon and xenon Time Projection Chamber (TPC) used in experiments searching for neutrinoless double beta decay and dark matter.

5 pages