TAR Reject gamma converted at high radius rDecayVertex (rDecayVertex<220) ht 25000FoBeampipe 0.29% radiation length 200。‖wap:014% o radiation length Air: 0. 1% radiation lend 15000 8 IFC: 0.36%radiation length B且 10000 STAR Preliminary 5000 TPC gas signed DCA for e+-(0.6<p <0.7 GeVic epto60070 92460°8010012014016010200240 igned dca for e+vs pt STAR Preliminary 5455 Rejection electron from gamma converted at IFC and TPc gas p (GeV/c) e Jin-------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------- F. Jin 10 Rejection electron from gamma converted at IFC and TPC gas Beampipe 0.29% radiation length wrap: 0.14% radiation length Air: 0.1% radiation length IFC: 0.36% radiation length Reject gamma converted at high radius Beam pipe TPC Inner Field Cage TPC gas