• F. Gerigk, P. Bourquin, A. Dallocchio, G. Favre, J.-M. Geisser, L. Gentini, J.-M. Giguet, S.J. Mathot, M. Polini, D. Pugnat, B. Riffaud, S. Sgobba, T. Tardy, P. Ugena Tirado, M. Vretenar, R. Wegner
  CERN, Geneva

The PIMS cavities for Linac4 are made of 7 coupled cells operating in pi-mode at 352 MHz frequency. The mechanical concept is derived from the 5-cell cavities used in the LEP machine, whereas cell length and coupling are adapted for proton acceleration in the range from 50 to 160 MeV. Linac4 will be the first machine to employ this type of cavities for low-beta protons. During the first years of operation the PIMS will be used at low duty cycle as part of the consolidated LHC proton injector complex. It is designed, however, to operate eventually in a high duty cycle (10%) proton injector, which could be used as proton front-end for neutrino or RIB applications. To prepare for the series construction of the 12 PIMS units the first cavity (10² MeV beam energy) has been designed and constructed at CERN, to be used as a hot prototype for RF tests and as a pre-series mechanical unit. In this paper we report on some of the design features, the construction experience, and first measurements.

• 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.