Novel Designs for Undulator Based Positron Sources

At least three proposed future colliders (ILC, CLiC and LHeC) require a positron source with a yield greater than 10 e+s−1. An undulator-based positron source has the potential to provide the required yield. This design generates gamma rays by using a high energy electron beam traveling through a superconducting helical undulator. The gamma rays then pair produce in a titanium alloy target to produce positrons. This is the ILC baseline positron source. Two drawbacks to the undulator-based positron source are that it couples the positron source to the electron beam operation and that it exhibits a low conversion efficiency of photons to positrons. A self-seeding undulator-based positron source has been proposed[1]. This starts with a low intensity positron beam which travels through the undulator to produce more positrons which are recirculated through the source to increase the intensity until the design yield is achieved. Multiple targets can be added to increase the conversion efficiency of the positron source. In this study I present simulation results for such a design and consider the feasibility of this design at the ILC, CLiC or LHeC.