硼-11质子辐射俘获反应的实验研究

Proton radiative capture reaction on ^(11)B

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。

Background： In big bang nucleosynthesis （BBN） network, ^11B（p,γ）^12C reaction is believed to be one of the most important reactions for the production of 12C nucleus, and precise measurement of this reaction rates is helpful to understand the abundance of ^12C. At energies of astrophysical interest, direct measurement of ^11B（p,γ）^12C reaction is very difficult because of the coulomb barrier, but it can be derived by the proton spectroscopic factor of ^12C. Elastic transfer reaction is a good tool to extract single nucleon spectroscopic factor because the reaction has same entrance and exit channels and involves only one spectroscopic factor. So the angular distribution of the ^12C（^21B,^12C）^11B elastic transfer reaction was chosen to extract the proton spectroscopic factor of ^12C. Purpose： This paper＇s purpose is to calculate the proton spectroscopic factor of ^12C and deduce the astrophysical S（E）-factors and reaction rates of ^11B（p,γ）^12C direct radiative capture reaction. Methods： The angular distribution of ^12C（^11B,^12C）^11B elastic transfer reaction was measured by using the Q3D magnetic spectrograph of HI-13 tandem accelerator and two-dimensional position sensitive silicon detector （2D-PSSD）. The proton spectroscopic factor of ^12C was then derived by using the distorted wave Born approximation （DWBA） analysis. Results： The proton spectroscopic factor of ^12C was determined and then the astrophysical S（E）-factors and reaction rates of llB（p,7）12C direct radiative capture reaction were deduced successfully. Conclusion： ^12C（^11B,^12C）^11B elastic transfer reaction is a good tool to extract the proton spectroscopic factor of lEc, and then the astrophysical S-factors and reaction rates of ^11B（p,γ）^12C direct radiative capture reaction could be deduced by using the proton spectroscopic factor of 12C. The BBN network calculation which includes ^11B（p,γ）^12C is underway.