• S. Hesselbach, G.A. Moortgat-Pick
  Durham University, Durham
• I.R. Bailey, L.J. Jenner
  Cockcroft Institute, Warrington, Cheshire
• J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• S. Riemann, A. Schälicke, A. Ushakov
  DESY Zeuthen, Zeuthen
• J. Rochford
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• L. Zang
  The University of Liverpool, Liverpool

Energy deposition in the conversion targets of positron sources for future linear colliders will lead to thermal shock waves which could limit the targets' lifetimes. For the International Linear Collider baseline source, we have studied the energy deposition in a target taking the higher harmonics of the undulator radiation fully into account and applying hydrodynamical models for the resulting heat flow to determine the thermal stress in the target and to assess its survivability.

• P. Goudket, S.C. Appleton, R. Bate, C.D. Beard, B.D. Fell, J.-L. Fernandez-Hernando, P.A. McIntosh, S.M. Pattalwar
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• P.K. Ambattu, G. Burt, A.C. Dexter, B.D.S. Hall, M.I. Tahir
  Cockcroft Institute, Lancaster University, Lancaster

The ILC crab cavities require very tight phase control in order to operate within the ILC parameters. In order to verify that the phase control system met the design tolerances, two single-cell niobium 3.9GHz superconducting dipole-mode cavities were tested in a liquid helium cryostat. The preparation of the cavities, design of the testing apparatus and performance of the phase control system are described in this paper.

• G. Ellwood
  STFC/RAL, Chilton, Didcot, Oxon
• J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• M. Slater, N.K. Watson
  Birmingham University, Birmingham

Spoilers in the ILC Beam Delivery System are required to survive without failure a minimum of 1-2 direct impacts of 250 GeV-500 GeV bunch of electrons or positrons, in addition to maintaining low geometric and resistive wall wake fields. The likelihood of spoiler survival was determined using finite element models of thermal and mechanical properties of the spoilers, with realistic patterns of energy deposition as input. The second phase of an experiment to calibrate the finite element models using electron beam data will be performed in the ATF2 extraction line, by subjecting a small sample of Ti-6Al-4V to bunches of electrons. The displacement of the surface will be measured with a Velocity Interferometer System of Any Reflector (VISAR). This paper shows the project plan as well as results of the simulations and expected readout from the VISAR.

• J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• J. Resta-López
  JAI, Oxford

The postlinac energy collimation system of the Compact Linear Collider (CLIC) protects the machine by intercepting mis-steered beams due to possible failure modes in the linac. The collimation is based in a spoiler-absorber scheme. The mission of the spoiler is to protect the main downstream absorber by dispersing the beam, via multiple Coulomb scattering, in case of a direct hit. We present the design of energy spoilers for CLIC, considering the following requirements: spoiler survival to the deep impact of an entire bunch train, and minimisation of spoiler wakefield effects during normal operation. Different configurations of the spoiler are studied in order to achieve an optimum performance.

• J.-L. Fernandez-Hernando
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme “Structuring the European Research Area”, contract number RIDS-011899

After different wakefield test beams and radiation damage studies a prototype design for the International Linear Collider (ILC) spoilers of the betatron collimation system in the Beam Delivery System (BDS) is under development. Studies of activation and residual equivalent dose rate are needed in order to achieve an optimum design as well as to assess the radiation shielding requirements.

• J.-L. Fernandez-Hernando, D. Angal-Kalinin
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
• R. Losito, V. Vlachoudis
  CERN, Geneva

Linac4 is a 160 MeV H^- linac which will replace the existing Linac2, a 50 MeV proton linac, at CERN as a first step of the upgraded LHC proton injector chain. No collimation system is foreseen in the baseline design but it will become mandatory for opreation at highest duty cycle in order to reduce activation of the machine. Such a system will also help to reduce activation at low duty cycle. A review of different collimation options, initial studies on collimator designs capable of intercepting beam power of 10, 25 and 50 Watts at energies between 50 and 160 MeV, the activation of such designs and the downstream elements are shown in this paper.