关键天体反应18Ne(α，p)21Na的实验研究

Experimental Study of Key^(18)Ne(α, p)^(21)Na Astrophysical Reaction

在X射线暴高温高密度的环境中,18Ne(α,p)21Na很可能是由热CNO循环突破到rp过程的一个重要反应。到目前为止,人们测得的反应率还存在很大的不确定性。实验中用CRIB(CNS Radioactive Ion Beam separator)提供的21Na放射性束轰击8.8 mg/cm2的聚乙烯厚靶,利用放置在θlab=-14°,0°,14°处的3套硅条探测器望远镜阵列对反冲轻粒子进行鉴别和测量,测得在一段能区(Ex=5.5～9.2MeV)内21Na(p,p)21Na的激发函数。通过对21Na(p,p)共振弹性散射截面进行R矩阵拟合,得到了22Mg共振能级的自旋宇称以及质子宽度等信息,从而为计算18Ne(α,p)21Na反应率提供了实验参数。

The 18Ne（α,p）21Na reaction is thought to be one of the key breakout reaction from the hot CNO cycle to the rp-process in X-ray bursts. Over stellar temperatures achieved in XRBs, this rate has not been sufficiently determined. The experiment was performed using CRIB （CNS Radioactive Ion Beam separator） at the Center for Nuclear Study （CNS） of the University of Tokyo. An 89 MeV 21Na radioactive ion beam was produced and bombarded an 8.8 mg/cm2 thick polyethylene target. The recoiled light particles were detected with three Micron silicon AE-E telescopes centered at angles of 0lab = 0°, ＋ 14° and -14° with respect to the beam direction, respectively. The 21Na＋p elastic-scattering excitation functions were reconstructed with a thick-target method over energies Ex = 5.5 ,- 9.2 MeV. The resonance parameters have been determined through an R-matrix analysis, which will be used to evaluate the 18Ne（α, p）21Na reaction rate.