Investigation of excited states in 22Mg via resonant elastic scattering of 21Na+p and its astrophysical implications

The excited states in 22Mg have been investigated by the resonant elastic scattering of 21Na + p.A 4.0 MeV/nucleon 21Na beam was separated by the Center for Nuclear Study (CNS) radioactive ion beam separator (CRIB) and then used to bombard a thick (CH2)n target. The energy spectra of recoiled protons were measured at scattering angles of θc.m. ≈ 172◦, 146◦, and 134◦, respectively. A wide energy-range of excitation function in 22Mg (up to Ex ∼ 8.9 MeV) was obtained simultaneously with a thick-target method, and a state at 7.06 MeV was newly observed. The resonant parameters were deduced from an R-matrix analysis of the center-of-mass (c.m.) differential cross-section data with a SAMMY-M6-BETA code. The astrophysical resonant reaction rate for the 18Ne(α,p)21Na reactionwas recalculated based on the present parameters.Generally speaking,the present rates are much smaller than the previous ones.

利用双n／p���探测对称能的密度依赖性

利用同位旋和动量相关的相对论强子输运模型IBUU04,以中心碰撞124Sn+124Sn(132Sn+124Sn), 112Sn+112Sn双反应系统在E／A=50MeV(400MeV)为例,在两种不同的对称能作用下,研究了发射粒子谱中双n／p���随时间和动能的演化．计算双n／p���的好处是它缩弱了库仑效应与探测低能中子的低效率的影响．计算结果表明,无论是在高密还是低密情况下,双n／p���的动能分布都敏感地依赖于对称能,因此双n／p���是探测对称能的一个理想探针．

~(40)Ar~(10+)激发半导体功能材料P-Si表面的激发光谱

报道了用ECR离子源的高电荷态离子~(40)Ar~(10+)入射到p���Si表面的实验研究,通过实验测量到的Si原子和Si~(2+)离子的200nm-1000nm光谱,研究了谱线产生的机理。实验结果表明:低速高电荷态离子与固体表面相互作用中,可有效地激发原子和离子的特征谱线,分析了这一现象和相互作用过程的发光机理。

~(27,28)P+~(28)Si总反应截面增强及可能相关的机制

测量了27,28P���相应同中子异位素在28Si靶上的中能反应截面.测得N=12和13同中子异位素的反应截面在Z=15处突然增大.对Z≤14同中子异位素和28P���实验数据结果可以用改进的光学极限近似的Glauber理论很好地描述.28P���反应截面能够用扩大核芯以改进的Glauber理论来解释.但是,用改进光学极限和少体近似的Glauber理论却低估了27P���实验数据.理论分析表明,扩大的核芯加质子晕可能是响应27P+28Si反应截面增强的机制.