  A simulation workflow is under development to interface particle data
transfer and matching of geometry between the electromagnetic (EM) cavity
simulation code ACE3P and radiation code Geant4. The target is to simulate dark
current (DC) radiation effects for the KEK 56-cell S-band accelerating
structure using ACE3P and Geant4, and benchmark against KEK experiment data. As
a first step, ACE3P DC simulations using a 7-cell structure have been performed
by first calculating the operating mode in the structure and then tracking
field-emitted electrons under the influence of the EM fields of the mode. The
ACE3P simulation results agree well with the EM software CST for an
accelerating gradient of 21.8 MV/m. The reader/writer I/O in ACE3P and the
transfer of particle data from Track3P to Geant4 for DC radiation effects
studies have been implemented. The simulation workflow between the two codes
will be demonstrated with the goal of performing large-scale simulations for
the KEK 56-cell structure. In addition to modeling DC effects in linacs, the
integrated simulation workflow will be applicable to studying positron source
and capture structure for future lepton colliders.
