• W. Höfle, M. Hernandez Flano, J. Lollierou, D. Valuch
  CERN, Geneva
• S. Chel, M. Desmons, G. Devanz, O. Piquet
  CEA, Gif-sur-Yvette
• R. Paparella, P. Pierini
  INFN/LASA, Segrate (MI)

In the framework of the preparatory phase for the luminosity upgrade of the LHC (SLHC-PP ) it is foreseen to characterize two superconducting RF cavities and demonstrate compliance of the required SPL field stability in amplitude and phase using a prototype LLRF system. We report on the preparation for testing of two super-conducting low-beta cavities at 50 Hz pulse repetition rate including the setting-up of the low level RF control system to evaluate the performance of the piezo-tuning system and cavity field stability in amplitude and phase. Results from tests with 50 Hz pulse repetition rate are presented. Simulations of the RF system are used to predict the necessary specifications for power and bandwidth to control the cavity field and derive specifications for the RF system and its control.

This project has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under the Grant Agreement no 212114

• C. Rossi, P. Bourquin, J.-B. Lallement, A.M. Lombardi, S.J. Mathot, D. Pugnat, M.A. Timmins, G. Vandoni, M. Vretenar
  CERN, Geneva
• M. Desmons, A. France, Y. Le Noa, J. Novo, O. Piquet
  CEA, Gif-sur-Yvette

The construction of Linac4, the new 160 MeV CERN H^- injector, has started with the goal of improving the LHC injection chain from 2015 with a new higher energy linac. The low energy front end of Linac4 is based on a 352 MHz, 3-m long Radiofrequency Quadrupole (RFQ) accelerator. The RFQ accelerates the 70 mA, 45 keV H^- beam from the RF source to the energy of 3 MeV. The fabrication of the RFQ has started at CERN in 2009 and is presently in progress, aiming at the completion of the full structure by early 2011. The RFQ consists of three modules, one meter each; the fabrication alternates machining phases and stress relief cycles, for copper stabilization. Two brazing steps are required: one to assemble the four parts composing a module and a second one to install the stainless steel flanges. In order to monitor that the tight mechanical and alignment budget is not exceeded, metrology measurements at the CERN workshop and RF bead-pull measurements are performed during the fabrication process. In this paper we report results obtained during the machining and the assembly of the first two modules of the Linac4 RFQ and data produced by RF measurements performed during their fabrication.