# First Operation of a Resistive Shell Liquid Argon Time Projection Chamber -- A new Approach to Electric-Field Shaping

## TL;DR

This paper introduces a novel resistive shell technology for liquid argon TPCs that simplifies design, reduces background, and demonstrates successful long-term operation at high electric fields.

## Contribution

The paper presents a new resistive foil-based approach for electric field shaping in TPCs, replacing traditional field cages with fewer components and enhanced reliability.

## Key findings

- Successful long-term operation at 1.5 kV/cm electric field
- Reduced passive material near active volume
- Feasibility of electric field shaping with resistive shells

## Abstract

We present a new technology for the shaping of the electric field in Time Projection Chambers (TPCs) using a carbon-loaded polyimide foil. This technology allows for the minimisation of passive material near the active volume of the TPC and thus is capable to reduce background events originating from radioactive decays or scattering on the material itself. Furthermore, the high and continuous electric resistivity of the foil limits the power dissipation per unit area and minimizes the risks of damages in the case of an electric field breakdown. Replacing the conventional field cage with a resistive plastic film structure called 'shell' decreases the number of components within the TPC and therefore reduces the potential points of failure when operating the detector. A prototype liquid argon (LAr) TPC with such a resistive shell and with a cathode made of the same material was successfully tested for long term operation with electric field values up to about 1.5 kV/cm. The experiment shows that it is feasible to successfully produce and shape the electric field in liquefied noble-gas detectors with this new technology.