• W. Liu, W. Gai
  ANL, Argonne
• L. Rinolfi
  CERN, Geneva
• J. Sheppard
  SLAC, Menlo Park, California

We pro­pose a vi­able positron source scheme that uses cir­cu­lar­ly po­lar­ized gamma rays gen­er­at­ed from the main 250 GeV elec­tron beam. The beam pass­es through a he­li­cal su­per­con­duct­ing un­du­la­tor with a mag­net­ic field of ~ 1 Tesla and a pe­ri­od of a few cen­time­ters. The gam­ma-rays pro­duced in the un­du­la­tor in the en­er­gy range be­tween ~ 3 MeV ~ 100 MeV will be di­rect­ed to a ti­ta­ni­um tar­get and pro­duces po­lar­ized positrons. The positrons are then cap­tured, ac­cel­er­at­ed and trans­port­ed to a damp­ing ring. De­tailed pa­ram­e­ter stud­ies of this scheme in­clud­ing positron yield, un­du­la­tor pa­ram­e­ter de­pen­dence and tar­get com­po­si­tion and ge­om­e­try will be pre­sent­ed. Ef­fects on the 250 GeV drive beam, in­clud­ing emit­tance, en­er­gy spread and en­er­gy loss from the beam pass­ing through the un­du­la­tor will also be dis­cussed.