ALICE TPC upgrade for High-Rate operations

TL;DR

The paper presents an upgrade to the ALICE TPC using GEM technology to enable high-rate data collection at the LHC, eliminating dead time and improving performance in high luminosity conditions.

Contribution

It introduces a new GEM-based TPC design with enhanced ion back flow suppression and continuous readout capabilities for high-rate heavy-ion experiments.

Findings

Achieved ion back flow below 1%

Supported continuous data streaming up to 1 TByte/s

Maintained energy resolution better than 12% for X-rays

Abstract

A new type of Time Projection Chamber (TPC) has been proposed for the upgrade of the ALICE (A Large Ion Collider Experiment at CERN) so as to cater to the high luminosity environment expected at the Large Hadron Collider (LHC) facility in future. This device will rely on the intrinsic ion back flow (IBF) suppression of Micro-Pattern Gas Detectors (MPGD) based technology in particular the Gas Electron Multiplier (GEM). GEM is to minimise the space charge effect in the main drift volume and thus will not require the standard gating grid and the resulting intrinsic dead time. It will thus be possible to read all minimum bias Pb--Pb events that the Large Hadron Collider (LHC) will deliver at the anticipated peak interaction rate of 50 kHz for the high luminosity heavy-ion era in Run 3. New read-out electronics will send the continuous data stream to a new online farm at rates up to 1~TByte/s. The new read-out chambers will consist of stacks of 4 GEM foils combining different hole pitches. In addition to a low ion back flow ($<$ 1\%) other important requirements are good energy resolution (better than 12\% (sigma) for $^{55}$Fe X-rays) and operational stability.