Information on mass chains and nuclides available on this website:

WWW TUNL

⁸n has not been observed in the interaction of 700 MeV or of 400 GeV protons with uranium: the cross section is < 2.3 x 10^-5 μb (TU77; 700 MeV), < 0.2 μb (TU77B; 400 GeV). See also (79AJ01).