  In large gradual solar energetic particle (SEP) events, especially the
ground-level enhancement (GLE) events, where and how energetic particles are
accelerated is still a problem. By using imaging data from TRACE, Yohkoh/HXT,
SOHO/MDI and SOHO/EIT, along with the data from the GOES, Apatity NM, and
SOHO/LASCO CME catalog, the evolution of the X5.7 two-ribbon flare and the
associated SEP event on 14 July 2000 are studied. It is found that the magnetic
reconnection in this event consists of two parts, and the induced electric
field Erec is temporally correlated with the evolution of hard X-ray and
gamma-ray emission. In particular, the first hard X-ray and gamma-ray emission
peak occurred at 10:22 UT, corresponding to the magnetic reconnection in the
western part of the flare ribbons and the maximum Erec of 9.5 V/cm; the second
emission peak at 10:27 UT, corresponding to the eastern part and the maximum
Erec of 13.0 V/cm. We also analyze the SEP injection profiles as functions of
time and CME-height, and find two-component injection which may result from
different acceleration mechanisms. A reasonable conclusion is that reconnection
electric field makes a crucial contribution to the acceleration of relativistic
particles and to the impulsive component of the large gradual SEP event, while
CME-driven shocks play a dominant role in the gradual component.
