• 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.

• S. Ramberger, P. Bourquin, Y. Cuvet, A. Dallocchio, G. De Michele, F. Gerigk, J.-M. Giguet, J.-B. Lallement, A.M. Lombardi, E. Sargsyan, M. Vretenar
  CERN, Geneva

The design of the Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN has been made ready for production: H–ion beams of up to 40 mA average pulse current are to be accelerated from 3 to 50 MeV by three RF tanks operating at 352.2 MHz and at duty cycles of up to 10%. In order to provide a margin for longitudinal matching from the chopper line, the longitudinal acceptance has been increased. The synchronous phase starts at -35° in tank1 and ramps linearly to -24° over the tank while it went from -30° to -20° in the previous design. The accelerating gradient has been lowered to 3.1 MV/m in Tank1 and increased to 3.3 MV/m in Tank2 and Tank3 for a better distribution of RF power between tanks that is compatible with a mechanical design. To make the transverse acceptance less sensitive to alignment and gradient errors, the focusing scheme has been changed to FFDD over all 3 tanks. Design features that were demonstrated in earlier reports have been improved for series production. Results of high power RF tests of the DTL prototype equipped with PMQs are reported that test the voltage holding in the first gaps in presence of magnetic fields.

• F. Gerigk, S. Atieh, S. Calatroni, O. Capatina, E. Ciapala, M. Eshraqi, L.M.A. Ferreira, R. Garoby, M. Hernandez Flano, W. Höfle, E. Lebbos, A.M. Lombardi, E. Montesinos, Th. Otto, V. Parma, P.A. Posocco, T. Renaglia, M. Schuh, V. Vlachoudis, W. Weingarten, S. Weisz
  CERN, Geneva
• R. Calaga
  BNL, Upton, Long Island, New York

During the past 2 years the Superconducting Proton Linac (SPL) study has grown into an international collaboration with the goal of optimising the architecture of a pulsed superconducting (SC) high-power proton linac. This effort includes the study and prototyping of major technical components, such as SC high-gradient cavities, power couplers, the RF distribution system, HOM couplers, cryo-modules, focusing elements, etc. Even though the effort is driven by CERN specific needs, the established design principles are valid for a range of superconducting linac projects. In this paper we report on the latests decisions concerning the machine architecture and on the ongoing R&D effort for technical components.