The 13^C（a, n）160 reaction is believed to be the main neutron source reaction for the s-process in asymptotic giant branch （AGB） stars. The astrophysical S-factors of this reaction have been determined based on an...The 13^C（a, n）160 reaction is believed to be the main neutron source reaction for the s-process in asymptotic giant branch （AGB） stars. The astrophysical S-factors of this reaction have been determined based on an evaluation of the a spectroscopic factor of the 1/2＋ subthreshold state in 17^O （Ex = 6.356 MeV） by using the 13^C（11^B, 7^Li）17^O a transfer reaction. Our result confirms that the 1/2＋ subthreshold resonance is dominant for the 13^C（a, n）16^O reaction at low energies of astrophysical interest.展开更多
In this paper, the network equation for the slow neutron capture process （s-process） of heavy element nucleosynthesis is investigated. Dividing the s-process network reaction chains into two standard forms and using...In this paper, the network equation for the slow neutron capture process （s-process） of heavy element nucleosynthesis is investigated. Dividing the s-process network reaction chains into two standard forms and using the technique of matrix decomposition, a group of analytical solutions for the network equation are obtained. With the analytical solutions, a calculation for heavy element abundance of the solar system is carried out and the results are in good agreement with the astrophysical measurements.展开更多
The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak d...The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak decay rates for all the nuclei on the reaction chain. The present work analyzes systematically the neutron capture rates (cross sections) for the s-process nuclei, including ～3000 rates on ～200 nuclei. The network calculations for the constant temperature s-process have been performed using the different data sets selected as the nuclear inputs to investigate the uncertainties in the predicted s-abundances. We show that the available cross sections of neutron capture on many s-process nuclei still carry large uncertainties, which lead to low accuracy in the determination of s-process isotope abundances. We analyze the neutron capture cross section data for the same unique isobar nucleus accorded by year from previous work. Such an analysis indicates that the s-process has been studied for more than fifty years and there exist two research stages around 1976 and 2002, respectively. The needs and opportunities for future experiments and theoretical tools are highlighted to remove the existing shortcomings in the neutron capture rates.展开更多
基金supported by National Basic Research Program of China (No.2007CB815003)National Natural Science Foundation of China(Nos.10705053,11021504,10720101076,10735100 and 10975193)
文摘The 13^C（a, n）160 reaction is believed to be the main neutron source reaction for the s-process in asymptotic giant branch （AGB） stars. The astrophysical S-factors of this reaction have been determined based on an evaluation of the a spectroscopic factor of the 1/2＋ subthreshold state in 17^O （Ex = 6.356 MeV） by using the 13^C（11^B, 7^Li）17^O a transfer reaction. Our result confirms that the 1/2＋ subthreshold resonance is dominant for the 13^C（a, n）16^O reaction at low energies of astrophysical interest.
基金supported by the National Natural Science Foundation of China (Grant No 10447141)the Youth Foundation of Beijing University of Chemical Technology,China (Grant No QN0622)
文摘In this paper, the network equation for the slow neutron capture process （s-process） of heavy element nucleosynthesis is investigated. Dividing the s-process network reaction chains into two standard forms and using the technique of matrix decomposition, a group of analytical solutions for the network equation are obtained. With the analytical solutions, a calculation for heavy element abundance of the solar system is carried out and the results are in good agreement with the astrophysical measurements.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11021504, 11175258, 11275068 and 11175001)the Major State Basic Research Development Program of China (Grant No.2013CB834406)
文摘The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak decay rates for all the nuclei on the reaction chain. The present work analyzes systematically the neutron capture rates (cross sections) for the s-process nuclei, including ～3000 rates on ～200 nuclei. The network calculations for the constant temperature s-process have been performed using the different data sets selected as the nuclear inputs to investigate the uncertainties in the predicted s-abundances. We show that the available cross sections of neutron capture on many s-process nuclei still carry large uncertainties, which lead to low accuracy in the determination of s-process isotope abundances. We analyze the neutron capture cross section data for the same unique isobar nucleus accorded by year from previous work. Such an analysis indicates that the s-process has been studied for more than fifty years and there exist two research stages around 1976 and 2002, respectively. The needs and opportunities for future experiments and theoretical tools are highlighted to remove the existing shortcomings in the neutron capture rates.
