Acceleration characteristic of a large SEP event

We report on the observations of the solar energetic particle fluxes measured by FY-2, GOES, and solar cosmic rays by stations of spaceship earth associated with the Bastille Day solar energetic particle event. Injection profiles of solar energetic protons as functions of coronal mass ejection heights are estimated. We find that the peak of the 26 MeV to 300 MeV injection profile of the SEPs occurs when the CME height reaches greater 15 Rs and that the onset occurs no earlier than the maxima of the flare impulsive phase. It means that the SEPs injection in the 26 MeV to 300 MeV did not result from flare impulsive phase, but from CME-driven IPshock. But for relativistic proton, his time-intensity profile is different from lower and moderate energetic protons, the injection time is associated with flare impulsive phase, and the ratio of ³He/⁴He is about 0.1 in the energy of 3.5-26 MeV/nucl and much larger than the coronal value(about 0.0005). Usually ³He enhancement is a valuable diagnostic of the impulsive flare acceleration. Therefore the highest energetic particles are accelerated from flare impulsive phase (i.c. reconnection region), then accelerated in coronal shock again. We also display the EUV(SOHO/EIT) difference images at 195 A^from before and after the event, it shows three ``dimming'' regions appear on the two sides of the ribbons, comparing with the MDI data, it is clearly seen the dimming regions have monopolarites, so the dimming region are the most likely to be transient coronal holes(TCHS), they may be give the way for escaping of energetic particle come from flare.