Cross sections of fast neutron induced reactions on selenium isotopes

Cross sections for^{74, 76, 77, 78}Se(n, p)^{74, 76, 77, 78}As,⁷⁶,Se(n,2n)⁷⁵Se and⁸⁰Se(n, α)⁷⁷,Ge reactions have been measured in the energy range from 13.0 to 16.6 MeV by the activation technique using Ge(Li) detectorγ-ray spectroscopy. Samples of selenium of natural isotopic composition were used as targets. The measurements provide information on the evolution of the (n, p) excitation functions with the increasing target neutron number (isotopic effect). The reaction model combining the compound nucleus and the preequilibrium emission processes is used to interpret these three types of reactions. The isotopic trend for the (n, p) reactions due to the neutron-proton competition in the compound nucleus is satisfactorily reproduced. However, a further experimental and theoretical work is needed for a better understanding of the origins of discrepancies which are suggested to be related to the precompound aspects of the assumed reaction model.