  The acceleration of protons and electrons to high (sometimes GeV/nucleon)
energies by solar phenomena is a key component of space weather. These solar
energetic particle (SEP) events can damage spacecraft and communications, as
well as present radiation hazards to humans. In-depth particle acceleration
simulations have been performed for idealized magnetic fields for diffusive
acceleration and particle propagation, and at the same time the quality of MHD
simulations of coronal mass ejections (CMEs) has improved significantly.
However, to date these two pieces of the same puzzle have remained largely
decoupled. Such structures may contain not just a shock but also sizable sheath
and pileup compression regions behind it, and may vary considerably with
longitude and latitude based on the underlying coronal conditions. In this
work, we have coupled results from a detailed global three-dimensional MHD
time-dependent CME simulation to a global proton acceleration and transport
model, in order to study time-dependent effects of SEP acceleration between 1.8
and 8 solar radii in the 2005 May 13 CME. We find that the source population is
accelerated to at least 100 MeV, with distributions enhanced up to six orders
of magnitude. Acceleration efficiency varies strongly along field lines probing
different regions of the dynamically evolving CME, whose dynamics is influenced
by the large-scale coronal magnetic field structure. We observe strong
acceleration in sheath regions immediately behind the shock.
