Thanks for the reminder on spallation, and you're right, Gd and Dy have pretty decent cross sections.
But the thing is this; I distinctly remember being surprised that nuclei with a mass 80 amu or so below what I was used to seeing could fission and further surprised that the reaction was...
Got a question about fissionable (as opposed to fissile) elements.
I vaguely remember the minimum A number for (theoretically) fissionable elements is somewhere in the vicinity of 153 to 156.
But I don't recall the exact figure, neither google nor ask.com have been of help and I'd like...