Determination of Excitation Function of Triton Emission Reaction on Aluminum from Threshold up to 30 MeV via Activation in Diverse Neutron Fields and Unfolding Code Calculations

Aluminum samples, together with sets of 12 flux monitor foils having different reaction thresholds, were irradiated in 6 different deuteron/beryllium neutron fields (E_d = 17.5 to 30 MeV). The shapes of the neutron spectra were determined by spectrum unfolding, using the known excitation functions of the monitor nuclides and their measured activities. In a second calculational step, the excitation function for the f(n, t)+(n, tn)] process on ²⁷Al was obtained from the neutron flux distributions and the measured tritium activities. At both calculational stages the iterative code SAND-II and the generalized least-squares unfolding code were applied, the latter yielding additionally the error covariance matrix. The excitation function thus obtained has a maximum cross-section value of ∼8 mb at 25.5 MeV and compares well with the values obtained using monoenergetic neutrons in the region of 14 to 19 MeV.