ACE/NOZOMI multispacecraft observations of solar energetic particles

We report multispacecraft measurements of solar energetic particle (SEP) events using Nozomi and ACE. During July 1998 to April 2002 while Nozomi was cruising toward Mars, both Nozomi and ACE observed many SEP events associated with coronal mass ejections (CMEs) and interplanetary shocks originating from different longitudes. These observations can reveal the longitudinal extent of CME-driven shocks and the accelerated particle populations. We use proton and electron data extending from ~40keV to ~1MeV measured with the EIS instruments on NOZOMI and the ULEIS and EPAM instruments on ACE. ACE and Nozomi have observed consistent number of proton events using daily average fluxes. In spite of their large longitudinal separation, 20 % of those events were simultaneously observed by ACE and NOZOMI. We also found more than 60 % of those events have been occurred after fast (>700km/s) halo CME which is significantly higher probability than chance coincidence. Three examples of individual event have been studied with hourly averaged data. On March 29, 2000, Nozomi observed CME which launched backside of Sun. On July 14, 2000 event and April 21, 2002 event, both of spacecrafts observed same SEP event with different longitudes which represent different intensity time profiles.