  This work is the second part of a simulation study investigating the
processing of densely packed and moving granular assemblies by positron
emission particle tracking (PEPT). Since medical PET scanners commonly used for
PEPT are very expensive, a PET-like detector system based on cost-effective
organic plastic scintillator bars is being developed and tested for its
capabilities. In this context, the spatial resolution of a resting positron
source, a source moving on a freely designed model path, and a particle motion
given by a DEM (Discrete Element Method) simulation is studied using Monte
Carlo simulations and the software toolkit Geant4. This not only extended the
simulation and reconstruction to a moving source but also significantly
improved the spatial resolution compared to previous work by adding
oversampling and iteration to the reconstruction algorithm. Furthermore, in the
case of a source following a trajectory developed from DEM simulations, a very
good resolution of about 1 mm in all three directions and an average
three-dimensional deviation between simulated and reconstructed events of 2.3
mm could be determined. Thus, the resolution for a realistic particle motion
within the generic grate system (which is the test rig for further experimental
studies) is well below the smallest particle size. The simulation of the
dependence of the reconstruction accuracy on tracer particle location revealed
a nearly constant efficiency within the entire detector system, which
demonstrates that boundary effects can be neglected.
