  We reach the robust conclusion that, by combining the observed cosmic rays of
r-process elements with the fact that the velocity of the neutron-star-merger
ejecta is much higher than that of the supernova ejecta, either (1) the reverse
shock in the neutron-star-merger ejecta is a very inefficient accelerator that
converts less than 0.003% of the ejecta kinetic energy to the cosmic-ray energy
or (2) the neutron star merger is not the origin of the Galactic r-process
elements. We also find that the acceleration efficiency should be less than
0.1% for the reverse shock of the supernova ejecta with the observed cosmic
rays lighter than the iron.
