# Feasibility study of TPC at electron positron colliders at $Z$ pole operation

## TL;DR

This study assesses the feasibility of using Time Projection Chamber (TPC) technology at electron-positron colliders operating at the Z pole, focusing on charge density, occupancy, and ion backflow control for future collider designs.

## Contribution

It provides a detailed simulation-based feasibility analysis of TPC application at CEPC and FCC-ee Z pole operations, identifying key parameters and ion backflow control requirements.

## Key findings

- TPC feasible at CEPC Z pole with ion backflow control
- Applicable TPC parameters for FCC-ee Z pole identified
- High luminosity increases occupancy but remains manageable

## Abstract

TPC is a promising technology for the future electron positron colliders. However, its application might be limited at high event rate and high hit occupancies. In this paper, we study the feasibility of using TPC at the circular electron positron collider (CEPC) at $Z$ pole using full simulated $Z \rightarrow q\bar{q}$ samples. By evaluating the local charge density and voxel occupancy at different TPC parameters. Our study shows that the TPC could be applied to the CEPC $Z$ pole operation if back flow ion is controlled to per mille level. We also suggest the applicable TPC parameters for FCC-ee $Z$ pole operations, whose instant luminosity is $2\times 10^{36} \mathrm{cm^2\,s^{-1}}$, 2 orders of magnitude higher than that of CEPC.