  Interplanetary Coronal Mass Ejection (ICME) shocks are known to accelerate
particles and contribute significantly to Solar Energetic Particle (SEP)
events. We have performed Magnetohydrodynamic-Particle in Cell (MHD-PIC)
simulations of ICME shocks to understand the acceleration mechanism. These
shocks vary in Alfv\'enic Mach numbers as well as in magnetic field
orientations (parallel \& quasi-perpendicular). We find that Diffusive Shock
Acceleration (DSA) plays a significant role in accelerating particles in a
parallel ICME shock. In contrast, Shock Drift Acceleration (SDA) plays a
pivotal role in a quasi-perpendicular shock. High-Mach shocks are seen to
accelerate particles more efficiently. Our simulations suggest that background
turbulence and local particle velocity distribution around the shock can
indirectly hint at the acceleration mechanism. Our results also point towards a
few possible \textit{in situ} observations that could validate our
understanding of the topic.
