Heat Load and Stress Studies for an Design of the Photon Collimator for   the ILC Positron Source
  The ILC baseline design for the positron source is based on radiation from a helical undulator to produce positrons in a thin target. Since the photon beam created in the helical undulator is circularly polarized, the generated positron beam is longitudinally polarized. Using a photon collimator upstream the positron target the positron polarization can be enhanced. However, the photon beam intensity yields a huge thermal load in the collimator material. In this paper the thermal load and heat dissipation in the photon collimator is discussed and design solutions are suggested. 
F. Staufenbiel (1), O. S. Adeyemi (2), V. Kovalenko (2), G.   Moortgat-Pick (2,3), L. Malysheva (2), S. Riemann (1), A. Usha...
physics.acc-ph