Authors: Ashraf Moradi (University of Arizona), Joe Giacalone (University of Arizona)

In this study we investigate the impact of the diffusion on the transport of solar energetic particles (SEPs) into the interplanetary space. A numerical simulation is developed using the test particle model that solves the Lorentz equation for each individual SEP. 2 million solar energetic protons in the energy range of 60 keV to 10 MeV are impulsively released at 10 solar radii and followed for 22 hours and their arrival time, pitch angle, energy and latitude and longitude at 0.5 AU is recorded. The interplanetary magnetic field is assumed to be the average Parker Spiral with a flat HCS in the Ecliptic plane. Pitch-angle scattering is included by implementing an ad hoc scattering that is energy and radial distance dependent. By varying the energy and radial distance weight on parallel mean free path, we determine how the diffusion can modify the onset time and other properties of intensity profile of the SEPs at 0.5 AU. The results of this study are relevant to both EPI-Lo and EPI-Hi observations onboard Parker Solar Probe.