Solid Background

• • energy flux on EC
    • geant3 has EM process total energy cut at 1MeV
    • Both SIDIS and PVDIS have confirmed energy flux on EC by the genat3 simulation in the proposals.
    • geant4 geometry and materiel checked, no simple mistake found.
    • with energy cut on 1MeV, SIDIS geant4 result is close SIDIS geant3, but PVDIS geant4 is still one order larger than PVDIS geant3.
    • More careful study like particle type, hit processing under way.

solid_BaBar_SIDIS_background_vertex of hits on forward EC

solid_BaBar_PVDIS_nobaffle_background_vertex of hits on forward EC

• • rate on GEM
    • rate on GEM need more study, particular from photon-induced rate, SBS has more mature simulation tested with data, their photon-induced rate is about twice of electron rate, need to learn from them.