推广的Glauber理论及其在晕核散射中的应用

Extended Glauber Theory and Its Application in Halo Nucleus Scattering

介绍了推广到晕核散射的Glauber理论 ,并用其研究晕核14Be的散射问题 .弹核的密度分布分别采用谐振子密度分布和相对论平均场理论计算得到具有两个晕中子结构的密度分布 ,对晕核模型的多重积分采用蒙特卡洛数值积分方法 .计算了不同能量下14Be,12 Be与靶核12 C散射的反应截面 ,并与实验结果进行比较 ,14Be的两个中子采用具有晕中子密度分布的理论计算与实验符合较好 ,而采用不具有晕中子密度分布的结果与实验值相差较大 .

We introduced an extended Glauber theory for a halo nucleus scattering, where the halo nucleons and the nuclear core were treated separately. Expressions of reaction and interaction cross sections of the halo nucleus scattering were derived. We took the halo structure of the projectile nucleus into account and adopted an improved optical limit approximation. In the framework of the extended Glauber theory, we studied the reaction cross section for the halo nucleus 14 Be scattering on a target 12 C. For comparison, the reaction cross sections of 12 Be+ 12 C were calculated as well. The density distribution of target 12 C is taken from experiments, and those of the projectiles 12 Be and 14 Be were obtained by two methods. One is that the harmonic oscillator wave functions for 12 Be and 14 Be are used. The length of harmonic oscillator is adjusted to reproduce the reaction cross section of 12 Be+ 12 C at the high energy E = 790MeV/u . The density distribution of 14 Be was also calculated self consistently in the relativistic mean field (RMF) theory, with a long tail wave functions for the two neutrons in 14 Be. It was found that the calculated reaction cross sections for 12 Be+ 12 C at E = 790MeV/u and E =56.5MeV/u were in good agreement with the experimental data no matter harmonic oscillator or RMF wave functions were used. In contrast, the experiments of the reaction cross sections for 14 Be+ 12 C could only be reproduced when the wave functions of two 2 s 1/2 neutrons spreaded over with a long tail. It comes to a conclusion that two outside neutrons in 14 Be form a halo structure.