Study On ~9Be(d,?)~7Li Reaction In Extremely Low Energy Region And Optimal Design Of Laser Neutron Source

The work of this paper is mainly divided into two parts.The first part is about the astrophysical energy region ~9Be(d,?)~7Li direct measurement of S(E)factor of ~7Li reaction.Beryllium is one of the important elements in primary nuclear synthesis.The study of its consumption and generation mechanism is of great significance to astrophysics.In addition,the nuclear reaction cross section between beryllium and fusion fuel in low energy region has high reference value for the upgrading and development of fusion reactor.In this paper,the energy spectrum of ion produced by d-~9be reaction in the energy range of 66-94 ke V was measured by using the low-energy high current acceleration platform of the electron optical research center of Tohoku University in Japan,and ~9Be(d,?₀)~7Li and ~9Be(d,?₁)~7Li^*.The energy step of deuterium ion beam in the experiment is 2 ke V.In the data analysis part,the S(E_i)factor of the above two reactions at each energy point in the interval is calculated by using the thin target yield formula,and the S(E)factor expression in the energy region is obtained by using the thick target yield formula.Finally,the R-matrix fitting of the experimental data is carried out by using AZURE2 code combined with the high-energy region data to obtain the S(0)of the two reaction channels respectively.The second part is to optimize the design of laser neutron source by simulation.Laser driven fast neutron source has the characteristics of short pulse,small size and high flux,and has a wide application prospect in the field of physics.In this paper,GEANT4 is used to simulate the p/d bombardment of reactant targets(CD₂,Li D,Li T and Li F)with known energy spectrum.The p/d energy spectrum comes from the experiments carried out by relevant personnel of eight Institutes of Chinese Academy of physics on SG-IIU device.In this paper,the neutron spectrum,angular distribution and forward neutron yield of each beam target combination are obtained by simulation.By comparison,for the total neutron yield of the two ions,the neutron yield obtained by lit target is the highest.In order to determine the additional neutron source in lid target relative to Li F target,we use CD₂ target instead of Li D,and analyze the additional neutron source from many angles.Finally,through the simulation of p-Li D schemes with different thicknesses,the optimal Li D target thickness is 7.57 mm.To sum up,the conclusions of this work are as follows:1.The S-factor expressions of ~9Be(d,?₀)~7Li and ~9Be(d,?₁)~7Li^*reactions in the energy range of 66-94 ke V are reported for the first time.2.The S_bare(0)of ~9Be(d,?₀)~7Li and ~9Be(d,?₁)~7Li^*reactions are 2.799 Me V·b and17.35 Me V·b respectively3.By simulating the nuclear reaction process of different beam-target combinations,the Li D target with a thickness of 7.57 mm is finally obtained,which may be the optimal target parameter of Li D scheme.