Direct Measurement Of S(E) Factor For The P-~9Be Reactions At Astrophysical Energy Region

Primary nucleus synthesis and stellar evolution are one of the most important subject in the field of nuclear astrophysics.However,it is incapable to deduce the abundance of light nuclear elements in stars accurately based on the existing models,such as Lithium,Beryllium,Boron,etc.The cross section of fusion reaction of light nuclei is of great significance to understand the mechanism of element consumption,formation,and the evolution process of the stars,as well as verify the validity of existed theoretical models.Therefore,the cross section of fusion reaction of light nuclei in the energy region of astrophysics must be measured accurately.However,the astrophysical energy region?Gamov?is far below the Coulomb barrier of the reaction nucleus,and the nuclear reaction can only occur via the quantum tunneling effect with a very small reaction cross section??b,pb?.Therefore,it is of great challenge to directly measure the cross section in this energy region.At present,the usual method is to convert the reaction cross section into the S?E?factor which varies slowly with decreasing energy,and then extrapolate the S?E?factor to Gamov energy region to obtain the ultra-low cross section.Regarding to the p-⁹Be reaction,the direct-measured data are very few and large uncertainty,and even the data reported in the literature have large discrepancies at low energies.Hereby,based on our previous work of d-d,p/d-⁶Li/⁷Li reactions,as well as combined with the current research status of the p-⁹Be reactions,we proposed the direct measurement of p-⁹Be cross section data from 18 to 100 keV in this work.The energy spectra of charged particles of the ⁹Be?p,??⁶Li and ⁹Be?p,d?⁸Be reactions from 18 to 100 keV??E=2 keV?were measured by a low-energy,high-current,ion-beam accelerator at Research Center for Electron Photon Science of Tohoku University,Japan.Thick-target yields were also obtained including 43 energy points in each of the above two reaction channels.In addition,Monte Carlo method was used to simulate the energy spectrum of the p-⁹Be reaction,which was verified by the experimental energy spectrum.Finally,both of the experimental results and the reported data were analyzed by direct-resonance coupling theory and R-matrix theory.The corresponded bare S?E?factor and screening potential U_s of the ⁹Be?p,??⁶Li and⁹Be?p,d?⁸Be reactions were obtained.Furthermore,the p-⁹Be reaction rates were calculated using the experimental data of astrophysical interest.In conclusion,the following results are presented:1).The bare S?E?factor expressions of ⁹Be?p,a?⁶Li and ⁹Be?p,d?⁸Be reactions have been clearly reported for the first time;2).Under the condition of this experiment,the screening potential U_s was 566±85 eV for the p-⁹Be reactions;3).The reaction rates of the above two reaction channels in the temperature range of 0.01-1 T₉ were calculated,which improved the precision of the database.