  We examine magnetorotationally driven supernovae as sources of $r$-process
elements in the early Galaxy. On the basis of thermodynamic histories of tracer
particles from a three-dimensional magnetohydrodynamical core-collapse
supernova model with approximated neutrino transport, we perform
nucleosynthesis calculations with and without considering the effects of
neutrino absorption reactions on the electron fraction ($Y_{e}$) during
post-processing. We find that the peak distribution of $Y_{e}$ in the ejecta is
shifted from $\sim0.15$ to $\sim0.17$ and broadened toward higher $Y_{e}$ due
to neutrino absorption. Nevertheless, in both cases the second and third peaks
of the solar $r$-process element distribution can be well reproduced. The rare
progenitor configuration that was used here, characterized by a high rotation
rate and a large magnetic field necessary for the formation of bipolar jets,
could naturally provide a site for the strong $r$-process in agreement with
observations of the early galactic chemical evolution.

Solar and Stellar Astrophysics