WEC —  Cavities/LINAC Operations   (20-Jun-12   14:00—16:00)
Chair: A.M. Porcellato, INFN/LNL, Legnaro (PD), Italy

Paper	Title	Page
WEC01	Production 72 MHz β=0.077 Superconducting Quarter-wave Cavities for ATLAS	174
	M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, B. Mustapha, P.N. Ostroumov, T. Reid ANL, Argonne, USA
	A total of eight 72 MHz β=0.077 superconducting quarter-wave cavities have recently been completed at Argonne National Laboratory. Seven of these will installed into the ATLAS superconducting heavy-ion linac as part of a beam intensity upgrade, with one remaining for the purposes of continuing to push the performance limits in these structures. Cavities were fabricated using techniques adapted the worldwide effort push niobium cavities close to the material limits. Key developments include the use of electropolishing on the complete helium-jacketed cavity. Wire EDM has been used instead of traditional niobium machining in order to minimize performance limiting defects near the weld seams. Hydrogen degassing at 600C after electropolishing has also been performed. Initial test results show practical acceleration at 4 Kelvin with cavity voltages, Vacc>3 MV/cavity and at 2 Kelvin with Bpeak>120 mT and Vacc>5 MV/cavity.
	Slides WEC01 [2.843 MB]
WEC02	Status of the HIE-ISOLDE Project at CERN	175
	Y. Kadi, A.P. Bernardes, Y. Blumenfeld, E. Bravin, S. Calatroni, R. Catherall, M.A. Fraser, B. Goddard, D. Parchet, E. Siesling, G. Vandoni, W. Venturini Delsolaro, D. Voulot, L.R. Williams CERN, Geneva, Switzerland
	The HIE-ISOLDE project represents a major upgrade of the ISOLDE facility with a mandate to significantly improve the quality and increase the intensity and energy of radioactive nuclear beams produced at CERN. The project will expand the experimental nuclear physics programme at ISOLDE by focusing on an upgrade of the existing REX linac with a 40 MV superconducting linac comprising thirty-two niobium-on-copper sputter-coated quarter-wave resonators housed in six cryomodules. The new linac will raise the energy of post-accelerated beams from 3 MeV/u to over 10 MeV/u. The upgrade will be staged to first deliver beam energies of 5.5 MeV/u using two high-β cryomodules placed downstream of REX, before the energy variable section of the existing linac is replaced with two low-β cryomodules and two additional high-β cryomodules are installed to attain over 10 MeV/u with full energy variability from as low as 0.45 MeV/u. An overview of the project including a status summary of the different R&D activities and the schedule will be given here.
	Slides WEC02 [19.513 MB]
WEC03	The SC CW LINAC Demonstrator – 1st Test of an SC CH-cavity with Heavy Ions	182
	S. Mickat, L.A. Dahl GSI, Darmstadt, Germany M. Amberg, K. Aulenbacher, W.A. Barth, V. Gettmann, S. Mickat HIM, Mainz, Germany D. Bänsch, F.D. Dziuba, D. Mäder, H. Podlech, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany
	The superconducting (sc) continuous wave (cw) LINAC Demonstrator is a collaboration project between GSI, the Helmholtz Institute Mainz (HIM), and the Institute for Applied Physics (IAP) at the Goethe University Frankfurt. The aim is a full performance test of a 217 MHz sc Crossbar H-mode (CH) cavity, which provides gradients of 5.1 MV/m at a total length of 0.69 m. In addition the Demonstrator comprises two 9.3 Tesla sc solenoids. The configuration of a CH-cavity embedded by two sc solenoids is taken from a conceptual layout of a new sc cw LINACwith nine CH-cavities and seven solenoids. Such an accelerator is highly desired by a broad community of users requesting heavy ion beam energies in the Coulomb barrier range. A successful test of such an sc multigap structure are an important milestone towards the proposed cw-LINAC.
	Slides WEC03 [1.842 MB]
WEC04	Operation of Superconducting Linac and Commissioning of the Last Linac at IUAC Delhi	185
	S. Ghosh, R. Ahuja, J. Antony, S. Babu, J. Chacko, A. Choudhury, G.K. Chowdhury, T.S. Datta, R.N. Dutt, R. Joshi, D. Kanjilal, S. Kar, J. Karmakar, M. Kumar, R. Kumar, D.S. Mathuria, K.K. Mistri, A. Pandey, P. Patra, P.N. Prakash, A. Rai, A. Roy, J. Sacharias, B.K. Sahu, A. Sarkar, S.S. Sonti IUAC, New Delhi, India
	The major part of the superconducting linac at IUAC has been operational for the past few years and the last accelerating module is in the final stage of completion. The full linac system consists of five cryostats, housing a total of twenty seven niobium quarter wave resonators. At present, the Superbuncher, the first two linac accelerating modules and the Rebuncher are operational and ion beams in the mass range 12C to 107Ag from Pelletron accelerator have been further accelerated and delivered to conduct experiments. A method of random phase focusing to select the accelerating phase of the resonators between 70° and 110° has been successfully tried to reduce the final time width of the beam bunch. Presently, to improve the accelerating fields of the linac resonators in phase locked condition, efforts are dedicated towards improvement of the cooling efficiency of the drive coupler, enhancement of the microphonics damping efficiency with mixtures of SS-balls and testing of an alternate tuning mechanism based by Piezo Crystal. The beam acceleration through the complete linac is to be performed by end of the summer of 2012.
	Slides WEC04 [2.810 MB]
WEC05	Design Studies for a New Heavy Ion Injector Linac for FAIR	191
	B. Schlitt, W.A. Barth, G. Clemente, W. Vinzenz GSI, Darmstadt, Germany
	As the GSI UNILAC started operation in 1975, it will be more than 40 years old when the commissioning of the future Facility for Antiproton and Ion Research (FAIR) at GSI will start. To assure reliable operation for FAIR and to provide beams for a variety of experiments, three separate linacs are proposed: 1.) A new superconducting cw heavy-ion linac behind the upgraded high charge state injector HLI shall provide ion beams with high duty cycle and adjustable energy in the MeV/u region for the super-heavy element program as well as for further UNILAC experiments. 2.) A dedicated 70 MeV proton linac will serve as injector for the FAIR pbar physics program. 3.) To deliver high-intensity heavy-ion beams for FAIR, the existing post-stripper linac should be replaced by a new high energy linac with short beam pulses, low pulse repetition rate, and fixed end energy. Conceptual design studies for the latter machine using 108 MHz IH-type drift tube structures will be presented, including a proposal to increase the ion charge states for synchrotron injection as well as a linac beam energy upgrade using 325 MHz CH structures.
	Slides WEC05 [6.013 MB]