核ANC和激发态中子晕

Nuclear Asymptotic Normalization Coefficientsand Neutron Halo of the Excited States

利用转移反应1 1 B(d ,p) 1 2 B和1 2 C(d ,p) 1 3C抽取1 2 B 1 1 B +n和1 3C 1 2 C +n重叠函数的核渐近归一化常数 ,计算了1 2 B和1 3C核中价中子密度分布的均方根半径及其在核外的几率 .实验结果表明 ,1 2 B的第二 (Jπ=2 - ) ,第三 (Jπ=1 - )激发态和1 3C的第一 (Jπ=1 2 +)激发态为中子晕态 ,而1 3C的第三 (Jπ=5 2 +)激发态是中子皮态 .考察了库仑势和角动量对晕形成的阻碍效应 .

We have extracted the nuclear asymptotic normalization coefficients for the virtual transitions 12B 11B+n and 13C 12C+n via two transfer reactions 11B(d, p) 12B and 12C(d, p) 13C. With these coefficients, root-mean-square radii for the valence neutron in 12B and 13C have been calculated. Our results show that the second (J π=2 -), third (J π=1 -) excited states in 12B, and the first (J π=1/2 +) excited state in 13C are neutron halo states, whereas the third (J π=5/2 +) excited state in 13C is a neutron skin state. The retard effects of the Coulomb potential and the orbital angular momentum on halo formation have been quantitatively examined. A unified scaling law for the mean-square radius versus the effective nucleon separation energy is established for the systems with a neutron or proton in a weekly bound state.