• W. Hartung, S. Bricker, C. Compton, K. Elliott, M. Hodek, J.P. Holzbauer, M.J. Johnson, O.K. Kester, F. Marti, S.J. Miller, D. Norton, J. Popielarski, L. Popielarski, J. Wlodarczak, R.C. York
  NSCL, East Lansing, Michigan
• A. Facco
  INFN/LNL, Legnaro (PD)
• E.N. Zaplatin
  FZJ, Jülich

Niobium quarter-wave resonators (QWRs) and half-wave resonators (HWRs) are being developed at Michigan State University for two projects: a 3 MeV per nucleon superconducting linac for re-acceleration of exotic ions (ReA3, under construction, requiring 15 resonators), and a 200 MeV per nucleon driver linac for the Facility for Rare Isotope Beams (FRIB, under design, requiring 344 resonators). The QWRs (80.5 MHz, optimum beta = 0.041 and 0.085) are required for both ReA3 and FRIB. Both include stiffening elements and frictional dampers. Nine beta = 0.041 QWRs have been fabricated; seven of them have been Dewar tested successfully with a helium vessel for use in ReA3. Production and testing of ten beta = 0.085 QWRs is in progress. The HWRs (322 MHz, optimum beta = 0.29 and 0.53, required for FRIB) are designed for mechanical stiffness and low peak surface magnetic field. A prototype beta = 0.53 HWR has been fabricated, and a prototype beta = 0.29 HWR is planned. This paper will cover the RF and mechanical requirements, the resonator and vessel design, and Dewar testing of production resonators.

• C. Compton, J. Bierwagen, S. Bricker, J. DeLauter, K. Elliott, W. Hartung, M. Hodek, J.P. Holzbauer, M.J. Johnson, O.K. Kester, F. Marti, D. R. Miller, S.J. Miller, D. Norton, J. Popielarski, L. Popielarski, N. Verhanovitz, K. Witgen, J. Wlodarczak, R.C. York
  NSCL, East Lansing, Michigan

Superconducting quarter-wave resonators, half-wave resonators, and cryomodules are being prototyped and fabricated at Michigan State University (MSU) for two ion linac projects. The 3 MeV per nucleon reaccelerator project (ReA3) is under construction as an upgrade to MSU's nuclear physics research program. ReA3 requires 15 production resonators, housed in three cryostats, with commissioning to begin in 2010. In parallel, MSU is engaged in a future laboratory upgrade, the Facility for Rare Isotope Beams (FRIB). FRIB requires a 200 MeV per nucleon driver linac, which includes 344 resonators (four different betas) housed in 52 cryomodules. FRIB development work is underway, with the prototyping of a FRIB cryomodule planned for early 2011. In addition, the acquisition strategy for FRIB resonators and cryomodules is being finalized, and the technology transfer program is being initiated. The status of the resonator and cryomodule production effort will be presented in this paper, including an overview of the acquisition strategy for FRIB.

• Z. Li, L. Ge, K. Ko
  SLAC, Menlo Park, California
• W. Hartung, J.P. Holzbauer, J. Popielarski
  NSCL, East Lansing, Michigan

In the driver linac of the Facility for Rare Isotope Beams (FRIB), multipacting is an issue of concern for the superconducting resonators, which must accelerate the ion beams from 0.3 MeV per nucleon to 200 MeV per nucleon. While most of the multipacting bands can be conditioned and eliminated with RF, hard multipacting barriers may prevent the resonators from reaching the design voltage. Using the ACE3P code suite, multipacting bands can be computed and analysed with the Track3P module to identify potential problems in the resonator design. This paper will present simulation results for multipacting in half-wave and quarter-wave resonators for the FRIB driver linac and compare the simulations with RF measurements on the resonators.