Neutron Emission Cross Sections at 25.7 MeV: ⁵¹V, ⁵⁶Fe, ⁶⁵Cu, ⁹³Nb, and ²⁰⁹Bi

Inelastic scattering of 25.7-MeV neutrons to unresolved final states with excitation energies up to ∼13 MeV were measured for monoisotopic samples of ⁵¹V, ⁵⁶Fe, ⁶⁵Cu, ⁹³Nb, and ²⁰⁹Bi. Neutrons were produced via T(d,n)⁴ He reaction in a gas cell that provides a background-free source spectrum above E_n = 12 MeV. Time-of-flight spectra were taken at several angles between 25 and 145 deg using the beam-swinger spectrometer. The technique of dynamic biasing proved valuable in providing maximum detector efficiency and low background throughout the broad range of neutron energies. Data were converted to energy spectra, corrected for detector efficiency, averaged over 1-MeV bins, and corrected for sample attenuation and multiple scattering.