Cern Linac4 beam dynamics studies and commissioning up to 12 MeV

Linac4 is a normal conducting, 160 MeV H− ions accelerator that is being con- structed within the scope of the LHC Injectors Upgrade project. Linac4 will be con- nected to the Proton Synchrotron Booster during the next long LHC shutdown and it will replace the current 50 MeV proton linac, Linac2. Linac4 is being commissioned progressively with the installation of the accel- erating structures into the Linac4 tunnel. Movable diagnostic benches, with various instruments, are used at each step to allow the detailed characterization of operational parameters that will play a key role in the overall future performance. The first three stages of the commissioning, up to 12 MeV beam energy, were completed by the end of 2014 with a temporary version of the ion source. Using the permanent diagnostic instruments and a movable diagnostic bench, the Low Energy Beam Transport (LEBT) at 45 keV, the Radio Frequency Quadrupole (RFQ) and Medium Energy Beam Trans- port (MEBT) at 3 MeV, as well as the first tank of the Drift Tube Linac (DTL) at 12 MeV were fully characterized.