WP4: Polarised Positron Source

Cut away of SC test piece	Multi-wire Winding Model

3D design of permanent magnet undulator	Two halves of PM undulator

Efficient production of polarised positrons can be achieved using a helical undulator based system, where circularly polarised photons (10 MeV) generated from a high-energy electron beam in the undulator produce longitudinally polarised electron-positron pairs in a thin target. While a conceptual design of a non-polarised (planar undulator) based source exists, critical R&D for both polarised and non-polarised sources still remains. Specifically: design of the spin rotation and spin flipper systems; design of the photon collimator; optimisation of system parameters to achieve maximum polarisation and positron yields; understanding of the systematic polarisation errors; engineering design and full simulation of the system; location and performance specifications of the required diagnostics (low-energy polarimeter).