Update on the ILC Positron Source Study at ANL

We present an update on the ANL ILC positron source study. We examined the impact of different drive beam energies on the positron yield and polarization for the ILC RDR baseline undulator. The e⁺ yield is found to drop rapidly as the drive beam energy is reduced. We studied different undulator parameters for their effect on the positron yield and polarization when working at lower drive beam energies. Using a lower K (B field level) can increase the photon energy, but it is still very difficult to bring the yield up for low drive beam energies. For 250 GeV drive beam options, we studied the RDR undulator performance as a function of K. Instead of powering off some sections of the undulator, one can also consider lowering the B field to bring the positron yield back to the desired 1.5 e⁺/e⁻. We also studied the liquid lead target option for ILC positron source and the energy deposition in the reference design Ti target wheel.
Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan