Simulation and Measurement Campaigns for Characterization and Performance Improvement of the CERN Heavy Ion Linac3

In the framework of the LHC Injector Upgrade programme (LIU), several activities have been carried out to improve the GTS-LHC ion source and Linac3 performance (Linac3 providing the charged heavy ion beams for CERN exper-iments). A restudy of the beam dynamics and transport through the linac was initiated, through a campaign of systematic machine measurements and parallel beam simulations, generalising techniques developed for beam characterization during Linac4 commissioning. The work here presented will review the most relevant findings and lessons learnt in the process.