Authors: A. Santa Fe Dueñas (UTSA/SwRI), R. W. Ebert (SwRI/UTSA), G. Li (UAH), Z. Ding (CmPA KULeuven), M. A. Dayeh (SwRI/UTSA), M. I. Desai (SwRI/UTSA) and L. K. Jian (NASA GSFC)

We investigate the East-West asymmetry in energetic storm particle (ESP) heavy ion intensities during solar cycles (SC) 23 and 24. We use observations from NASA’s ACE and STEREO missions of helium (He), oxygen (O) and iron (Fe) intensities from ~0.13 to 3 MeV/nucleon at coronal mass ejection (CME) driven interplanetary shocks. We examine the longitudinal distribution of ESP intensities and the correlation of ESP intensities with the near Sun CME speed for eastern and western events. Initial results suggest that eastern ESP events in SC 23 are slightly more efficient at producing heavy ions below 3 MeV/nucleon compared to SC 24; however, for western events, the difference increases up to about one order of magnitude.