Helium Production by 9.85-MeV Neutrons in Elemental Iron, Nickel, and Copper and in ⁵⁶Fe and ^58,60,61ni

Helium production cross sections for the elements iron, nickel, and copper and for the isotopes ⁵⁶Fe, ^S8Ni, ⁶⁰Ni, and ⁶¹Nifor 9.85-MeV neutrons have been measured by irradiation with an intense, quasi-monoenergetic neutron source followed by helium analysis with isotope dilution gas mass spectrometry. The results are in fair agreement with (n,α) cross sections measured by alpha-particle detection and integration over the alpha-particle energies and angular distributions.