Calculation and Normalization of Selected 26Mg (alpha, n) Cross Sections

An evaporated $^{26}$Mg target on tantalum backing was exposed to $\alpha$-particle beam using the 2-MeV Van de Graaff accelerator at Goethe University Frankfurt, and the $^{26}$Mg ($\alpha$, n) cross section calculated for five beam energies between 1830 and 2000 keV. The use of a $^{3}$He spectrometer at zero degrees relative to the target allowed separation of neutrons in the region of interest from thermal neutrons. Cross sections were normalized with respect to $^{11}$B($\alpha$, n) cross sections for the corresponding energies, which were also measured using the 2-MeV Van de Graaff. While both targets showed evidence of deterioration throughout the process, this was more obviously evident for the $^{26}$Mg target. As this measurement follows prior target development and characterization, investigating appropriate target backings and thicknesses for this measurement, the significant deterioration observed provides additional information about $^{26}$Mg target stability under beam. When considered in combination with complications when using thinner targets, these observations suggest a need for thick targets and further characterization of target deterioration in order to increase the accuracy of further cross section measurements.