• 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.

• L. Zang
  The University of Liverpool, Liverpool
• I.R. Bailey, A. Wolski
  Cockcroft Institute, Warrington, Cheshire

A model has been created in Geant4 to simulate the key elements of an undulator-based positron source for CLIC: the goal is to consider such a source as an alternative to the present baseline concept. The parameters of the undulator and capture device have been optimized for a range of operating scenarios. In each case we have calculated the rate of positron production, positron polarization and capture efficiency. We discuss the strengths and weaknesses of the undulator scheme in CLIC.

• L. Zang
  The University of Liverpool, Liverpool
• I.R. Bailey, A. Wolski
  Cockcroft Institute, Warrington, Cheshire

An undulator-based source has been chosen as a part of the baseline configuration for the International Linear Collider (ILC) to generate an intense beam of polarised positrons. A photon collimator placed between the undulator and the target can be used to adjust the size, intensity and polarisation of the photon beam impacting the target, and can also protect the target station and limit the activation of downstream components. In this paper, we calculate quantities such as the energy deposition, temperature change, activation and dose rate for different designs of the photon collimator, and consider the advantages and disadvantages for each case.