The production of /sup 38/Ar and /sup 39/Ar by 14-MeV neutrons on /sup 39/K

The authors have determined the cross sections for the production of /sup 38/Ar and /sup 39/Ar from the (n,n'rho) and (n,rho) reactions by neutrons of -- 14 MeV incident on /sup 39/K. Three potassium-bearing specimens were irradiated with fluences of --10/sup 17/ neutrons, and the argon isotopes were measured by mass spectrometry. Previously reported measurements are in substantial disagreement with our results. Values from the three new measurements are consistent with each other and our computational modeling. Nevertheless, there remains an unexplained increase in the cross sections for both reactions as the neutron energy increases from --14.5 to 14.8 MeV