Ok, I did a bit of research. It seems that Pb-208 has a very small absorption cross section for neutrons so you'll probably see very little Pb-209. http://en.

Ok, I did a bit of research. It seems that Pb-208 has a very small absorption cross section for neutrons so you'll probably see very little Pb-209. http://en.wikipedia.org/wiki/Neutron_cross_section http://en.wikipedia.org/wiki/Neutron_cross_section http://www.ncnr.nist.gov/resources/n-lengths/elements/pb.html http://www.ncnr.nist.gov/resources/n-lengths/elements/pb.htm...