Proposal of a high-field superconducting wiggler for a slow positron source at SPring-8

A low-energy positron beam is a unique probe of materials. In high-energy electron and positron storage rings it is possible to generate intense synchrotron radiation with a photon energy of 1-3 MeV by installing a high-field (8-10 T) superconducting wiggler. High-energy photons are converted to low-energy positrons by using a suitable target-moderator system. For an 8 GeV electron storage ring at a beam current of 100 mA, final yields are estimated to be about 10⁸-10¹⁰ slow-e⁺ s^-1 or larger depending on the moderation efficiency, with the size of the positron source 10¹-10² cm². In the present work a wiggler magnetic system of 10 T is proposed. The main parameters of the superconducting wiggler are presented.