Preparation of a primary argon beam for the CERN fixed target physics

The fixed target experiment NA61 in the North Area of the Super Proton Synchrotron is studying phase transitions in strongly interacting matter. Up to now they used the primary beams available from the CERN accelerator complex (protons and lead ions) or fragmented beams created from the primary lead ion beam. To explore a wider range of energies and densities a request was made to provide primary argon and xenon beams. This paper describes the results of the setting up and 10 week test run of the Ar¹¹⁺ beam from the 14.5 GHz ECR ion source and the linear accelerator (Linac3) at CERN.