First operation of a double phase LAr Large Electron Multiplier Time Projection Chamber with a two-dimensional projective readout anode

TL;DR

This paper reports the first successful operation of a double phase Liquid Argon LEM-TPC with a 2D readout, demonstrating high-quality imaging, stable gain, and promising performance for neutrino and dark matter detection.

Contribution

It presents the first operational results of a novel double phase LAr LEM-TPC with a 2D readout, showing stable gain and high-quality imaging capabilities.

Findings

Achieved stable gain of 27 with high signal-to-noise ratio

Collected and reconstructed cosmic muon events for performance characterization

Demonstrated high-quality images and effective energy loss measurements

Abstract

We have previously reported on the construction and successful operation of the novel double phase Liquid Argon Large Electron Multiplier Time Projection Chamber (LAr LEM-TPC). This detector concept provides a 3D-tracking and calorimetric device capable of adjustable charge amplification, a promising readout technology for next-generation neutrino detectors and direct Dark Matter searches. In this paper, we report on the first operation of a LAr LEM-TPC prototype - with an active area of 10$\times$10 cm$^2$ and 21 cm drift length - equipped with a single 1 mm thick LEM amplifying stage and a two dimensional projective readout anode. Cosmic muon events were collected, fully reconstructed and used to characterize the performance of the chamber. The obtained signals provide images of very high quality and the energy loss distributions of minimum ionizing tracks give a direct estimate of the amplification. We find that a stable gain of 27 can be achieved with this detector configuration corresponding to a signal-over-noise ratio larger than 200 for minimum ionizing tracks. The decoupling of the amplification stage and the use of the 2D readout anode offer several advantages which are described in the text.