  We have studied whether the jet in a collapse-driven supernova can be a key
process for the rapid-process (r-process) nucleosynthesis. We have examined the
features of a steady, subsonic, and rigidly rotating jet in which the
centrifugal force is balanced by the magnetic force. As for the models in which
the magnetic field is weak and angular velocity is small, we found that the
r-process does not occur because the final temperature is kept to be too high
and the dynamical timescale becomes too long when the neutrino luminosities are
set to be high. Even if the luminosities of the neutrinos are set to be low,
which results in the low final temperature, we found that the models do not
give a required condition to produce the r-process matter. Furthermore, the
amount of the mass outflow seems to be too little to explain the solar-system
abundance ratio in such low-luminosity models. As for the models in which the
magnetic field is strong and angular velocity is large, we found that the
entropy per baryon becomes too small and the dynamical timescale becomes too
long. This tendency is, of course, a bad one for the production of the
r-process nuclei. As a conclusion, we have to say that it is difficult to cause
a successful r-process nucleosynthesis in the jet models in this study.
