DETERMINATION OF THE NEUTRON-FLUX AND ENERGY-SPECTRUM IN THE LOW-TEMPERATURE FAST-NEUTRON FACILITY IN CP-5, CALCULATIONS OF PRIMARY-RECOIL AND DAMAGE-ENERGY DISTRIBUTION, AND COMPARISONS WITH EXPERIMENT

We have determined the absolute differential neutron-energy spectrum for the low-temperature fast-neutron irradiation facility in the CP-5 reactor by means of a 20-foil activation technique. This technique employs the most recent version of the SAND-II computer code, which iteratively unfolds the neutron spectrum by fitting the foil activities. A Monte Carlo routine was also employed to calculate standard-deviation errors in each neutron-energy group. Using this differential neutron spectrum we have calculated, for numerous elements, total recoil cross sections, detailed primary-recoil group distributions, total damage-energy cross sections, damage-energy distributions, and an error analysis based on the uncertainties in the neutron spectrum. The significance of this information with respect to the interpretation of various neutron radiation-damage experiments, including sputtering, disordering of ordered alloys, and changes in critical current of A-15 compound superconductors is discussed. A detailed comparison is made among initial resistivity-damage rates for five widely different (well characterized) neutron sources, fission fragments, and heavy ions. © 1979.