Information on mass chains and nuclides available on this website:

WWW TUNL

⁸n has not been observed in the interaction of 0.7 and 400 GeV protons with uranium: the cross section is < 2.3 x 10^-5 μb (TU77) at 0.7 GeV and < 0.2 μb at 400 GeV (TU77B). See also (DE77M) and (SA78G).