MEASUREMENTS OF THE AL-27(n,α) AND MG-24(n,p) CROSS SECTION BETWEEN 8 MEV AND 15 MEV
D-3300 Braunschweig, Fed. Rep. of Germany
Maria Wagner, Gerhard Winkler
Institut für Radiumforschung und Kernphysik
A-1090 Vienna, Austria
By means of deuterons impinging on a deuterium gas cell, 'monoenergetic' neutrons between 8.3 MeV and 14.7 MeV were generated with the D(d,n)He-3 reaction. Samples of aluminum and magnesium were irradiated at a distance of 9 cm from the neutron target. The samples were placed back-to-back to a U-238 fission chamber acting as a neutron fluence monitor. Empty gas cell irradiations allowed the contribution of parasitic neutrons produced in the structural material of the gas cell to be subtracted. Neutron time-of-flight spectra were recorded simultaneously with the activation procedure to determine the continuous neutron energy distribution of the D(d,np) break-up component and to correct its contribution to the activation process. The radioactivity of the samples was measured with a germanium detector calibrated against a large sodium iodide well-type detector. Below 13.6 MeV the excitation functions of both reactions were measured in steps of about 0.25 MeV. The relative uncertainties of the final data were smaller than 3 % below 11 MeV and smaller than 4 % below 12.5 MeV.
KEYWORDS: Neutron cross section, Al-27(n,α) and Mg-24(n,p) relative to U-238(n,f), En=8.3 to 14.7 MeV