Addendum to the Technical Design Report for the Upgrade of the ALICE Time Projection Chamber

This is the addendum to the TDR of the upgrade of the ALICE Time Projection Chamber (CERN-LHCC-2013-020 ; ALICE-TDR-016). The key objective of the upgrade is the replacement of the present MWPC-based readout chambers by detectors that allow continuous operation without active ion gating. In the TDR, we propose a solution that employs stacks of four Gas Electron Multipliers (GEMs) and demonstrate that it fulfills the design specifications, in particular in terms of intrinsic position resolution, energy resolution, and ion backflow. In this document we demonstrate with additional results from both detector R&D and simulations that the technological solution chosen in the TDR has sufficient safety margin for a successful campaign with the upgraded detector in RUN 3 and beyond.