The neutron capture reaction on a neutron-rich near closed-shell nucleus 82Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae. By carr...The neutron capture reaction on a neutron-rich near closed-shell nucleus 82Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae. By carrying out a DWBA analysis for the experimental angular distribution of 82Ge(d, p)83Ge reaction we obtain the single particle spectroscopic factors, S2,5/2 and S0,1/2 for the ground and first excited states of 83Ge=82Gen, respectively. And then these spectroscopic factors are used to calculate the direct capture cross sections for the 82Ge(n, γ)83Ge reaction at energies of astrophysical interest. The optical potential for neutron scattering on unstable nucleus 82Ge is not known experimentally. We employed a real folding potential which was calculated by using the proper 82Ge density distribution and an effective nucleon-nucleon force DDM3Y. The neutron capture reactions on neutron-rich closed-shell nuclei are expected to be dominated by the direct capture to bound states. We will show that the direct capture rates on these nuclei are sensitive to the structure of the low-lying states.展开更多
在大爆炸原初核合成(Big Bang Nucleosynthesis,BBN)反应网络中,11B(p,γ)12C反应是合成12C核素的最主要反应之一,对该反应进行精确测量有重要意义。由于库仑势垒的作用,天体物理感兴趣的低能区11B(p,γ)12C反应截面极低,直接测量比较困...在大爆炸原初核合成(Big Bang Nucleosynthesis,BBN)反应网络中,11B(p,γ)12C反应是合成12C核素的最主要反应之一,对该反应进行精确测量有重要意义。由于库仑势垒的作用,天体物理感兴趣的低能区11B(p,γ)12C反应截面极低,直接测量比较困难,一般可以采用谱因子方法进行间接测量。实验使用HI-13串列加速器Q3D磁谱仪和二维位置灵敏半导体探测器(Two-dimensional Position Sensitive Silicon Detector,2D-PSSD),测量了12C(11B,12C)11B弹性转移反应的角分布,并利用扭曲波波恩近似(Distorted wave Born approximation,DWBA)理论对实验角分布进行分析,得到了12C的质子谱因子,进而根据辐射俘获理论得到了11B(p,γ)12C直接辐射俘获反应的天体物理S(E)因子及反应率。展开更多
The observation of 26 Al is an useful tool for γ-ray astronomy and in studies of galactic chemical evolution. The most likely mechanism for 26A1 nucleosynthesis is in the hydrogen burning Mg Al cycle, and the 26A1 pr...The observation of 26 Al is an useful tool for γ-ray astronomy and in studies of galactic chemical evolution. The most likely mechanism for 26A1 nucleosynthesis is in the hydrogen burning Mg Al cycle, and the 26A1 production reaction 25Mg(p,γ)26Al at the important temperature range below T = 0.2 GK is still not well known. The spectroscopic factor of 58 ke V resonance level in 26A1 is determined with shell model calculation and then used to deduce the resonance strength of the 25Mg(p,γ)26Al reaction. The result provides a reference for the future 25Mg(p,γ)26Al direct measurement at Jinping underground laboratory.展开更多
基金Supported by NSFC of China (10475115, 10775182, 10435010)MSBRDP of China (2007CB815000)
文摘The neutron capture reaction on a neutron-rich near closed-shell nucleus 82Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae. By carrying out a DWBA analysis for the experimental angular distribution of 82Ge(d, p)83Ge reaction we obtain the single particle spectroscopic factors, S2,5/2 and S0,1/2 for the ground and first excited states of 83Ge=82Gen, respectively. And then these spectroscopic factors are used to calculate the direct capture cross sections for the 82Ge(n, γ)83Ge reaction at energies of astrophysical interest. The optical potential for neutron scattering on unstable nucleus 82Ge is not known experimentally. We employed a real folding potential which was calculated by using the proper 82Ge density distribution and an effective nucleon-nucleon force DDM3Y. The neutron capture reactions on neutron-rich closed-shell nuclei are expected to be dominated by the direct capture to bound states. We will show that the direct capture rates on these nuclei are sensitive to the structure of the low-lying states.
文摘在大爆炸原初核合成(Big Bang Nucleosynthesis,BBN)反应网络中,11B(p,γ)12C反应是合成12C核素的最主要反应之一,对该反应进行精确测量有重要意义。由于库仑势垒的作用,天体物理感兴趣的低能区11B(p,γ)12C反应截面极低,直接测量比较困难,一般可以采用谱因子方法进行间接测量。实验使用HI-13串列加速器Q3D磁谱仪和二维位置灵敏半导体探测器(Two-dimensional Position Sensitive Silicon Detector,2D-PSSD),测量了12C(11B,12C)11B弹性转移反应的角分布,并利用扭曲波波恩近似(Distorted wave Born approximation,DWBA)理论对实验角分布进行分析,得到了12C的质子谱因子,进而根据辐射俘获理论得到了11B(p,γ)12C直接辐射俘获反应的天体物理S(E)因子及反应率。
基金supported by the National Natural Science Foundation of China(Grant Nos.11490563,11375269 and 11321064)the National Key Basic Research Development Program(Grant No.2013CB834406)
文摘The observation of 26 Al is an useful tool for γ-ray astronomy and in studies of galactic chemical evolution. The most likely mechanism for 26A1 nucleosynthesis is in the hydrogen burning Mg Al cycle, and the 26A1 production reaction 25Mg(p,γ)26Al at the important temperature range below T = 0.2 GK is still not well known. The spectroscopic factor of 58 ke V resonance level in 26A1 is determined with shell model calculation and then used to deduce the resonance strength of the 25Mg(p,γ)26Al reaction. The result provides a reference for the future 25Mg(p,γ)26Al direct measurement at Jinping underground laboratory.
