Studies Of The Observables For Neutron-induced ²³⁵U(²³⁹Pu) Fission Reaction And Proton-induced ⁶Li Reaction

Nuclear energy is an important clean energy source that has received widespread at-tention in the world.Nuclear energy mainly comes from fission reactions of heavy nuclei induced by neutrons and fusion reactions of light nuclei.²³⁵U and²³⁹Pu are important nuclides.Deuterium-tritium reaction dominates in fusion reactions.Although deuterium is abundant in nature,tritium needs to be produced through artificial nuclear reactions.Proton-induced⁶Li is one of the important reactions for generating tritium.First,Pre-neutron fragment mass yields in the vicinity of the thermal neutron energy are highly important for applications because of the larger fission cross sections of the²³⁵U（n,f）and²³⁹Pu（n,f）reactions.In this paper,pre-neutron fragment mass yields at incident energies from thermal up to 20 Me V are systematically studied using an empirical fission potential（EFP）model,the potential parameters of which are obtained from the measured data.The energy dependences of the peaks and valleys of the pre-neutron fragment mass yields are described by exponential and linear functions for the²³⁵U（n,f）and²³⁹Pu（n,f）reactions,respectively.The energy dependences of the evaporation neutrons,which play a crucial role in the reasonable description of pre-neutron fragment mass yields,are also obtained from the fission cross sections.The pre-neutron fragment mass yields in this study are not only consistent with the results of previous studies in regions of several Me Vs but also agree well with existing measured data at incident energies from thermal up to 20 Me V.The results show that the feasibility of this EFP model is verified in this extended energy region.At the request of the Institute of Nuclear physics and chemistry of China Academy of Engineering Physics,a blind calculation was performed to obtain the initial fragment mass distribution of the²³⁵U（n,f）fission reaction at a neutron incident energy of 14.8 Me V.The calculated results can well reproduce the latest measurement data.Second,Based on the statistical theory of light nucleus reactions（STLN）,taking into account the Coulomb barrier effect of the incident particles,as well as energy,angular mo-mentum,and parity conservation in the outgoing particle process,a theoretical model for proton-induced⁶Li nuclear reactions has been further developed.Moreover,the analysis of the first residual nuclei to the discrete levels of the secondary residual nucleus emission processes for p+⁶Li reaction is performed in detail.The double differential cross sections of all reaction products of p+⁶Li in the incident energy region below 20 Me V are given for the first time.The calculated double differential cross sections of total outgoing proton,deuteron,³He andαat E_p=14 Me V agree well with the available experimental data for different outgoing angles and the experimental data include the influence of contamination in the target,which is denoted in the figure.The measured data indicates that the two-body breakup and the three-body breakup process needs to be involved,and the pre-equilibrium reaction mechanism dominates the reaction processes.The ENDF-6 formatted data,which includes all of the reaction cross sections,double differential cross sections of nucleon and light composite charged particles for p+⁶Li reaction,are also obtained by PUNF code.