First operation and drift field performance of a large area double phase LAr Electron Multiplier Time Projection Chamber with an immersed Greinacher high-voltage multiplier

TL;DR

This paper reports the successful operation of a large-area double-phase liquid-argon time projection chamber with an immersed Greinacher high-voltage multiplier, demonstrating stable performance and high-quality 3D imaging suitable for future large-scale detectors.

Contribution

It presents the first operation of a large-area double-phase LAr LEM-TPC with an immersed Greinacher HV multiplier, achieving stable high-voltage and high-quality imaging in cryogenic conditions.

Findings

Largest chamber with 76x40 cm² active area successfully operated.

Stable double-phase operation with high-quality 3D imaging.

Effective high-voltage generation using immersed Greinacher multiplier.

Abstract

We have operated a liquid-argon large-electron-multiplier time-projection chamber (LAr LEM-TPC) with a large active area of 76 $\times$ 40 cm$^2$ and a drift length of 60 cm. This setup represents the largest chamber ever achieved with this novel detector concept. The chamber is equipped with an immersed built-in cryogenic Greinacher multi-stage high-voltage (HV) multiplier, which, when subjected to an external AC HV of $\sim$1 kV$_{\mathrm{pp}}$, statically charges up to a voltage a factor of $\sim$30 higher inside the LAr vessel, creating a uniform drift field of $\sim$0.5 kV/cm over the full drift length. This large LAr LEM-TPC was brought into successful operation in the double-phase (liquid-vapor) operation mode and tested during a period of $\sim$1 month, recording impressive three-dimensional images of very high-quality from cosmic particles traversing or interacting in the sensitive volume. The double phase readout and HV systems achieved stable operation in cryogenic conditions demonstrating their good characteristics, which particularly suit applications for next-generation giant-scale LAr-TPCs.