  We investigated the relationship between the spectral structures of type II
solar radio bursts in the hectometric and kilometric wavelength ranges and
solar energetic particles (SEPs). To examine the statistical relationship
between type II bursts and SEPs, we selected 26 coronal mass ejection (CME)
events with similar characteristics (e.g., initial speed, angular width, and
location) observed by the Large Angle and Spectrometric Coronagraph (LASCO),
regardless of the characteristics of the corresponding type II bursts and the
SEP flux. Then, we compared associated type II bursts observed by the Radio and
Plasma Wave Experiment (WAVES) onboard the Wind spacecraft and the SEP flux
observed by the Geostationary Operational Environmental Satellite (GOES)
orbiting around the Earth. We found that the bandwidth of the hectometric type
II bursts and the peak flux of the SEPs has a positive correlation (with a
correlation coefficient of 0.64). This result supports the idea that the
nonthermal electrons of type II bursts and the nonthermal ions of SEPs are
generated by the same shock and suggests that more SEPs may be generated for a
wider or stronger CME shock with a longer duration. Our result also suggests
that considering the spectral structures of type II bursts can improve the
forecasting accuracy for the peak flux of gradual SEPs.
