Distortion effects on the neutron knockout from exotic nuclei in the collision with a proton target
Distortion effects on the neutron knockout from exotic nuclei in the collision with a proton target
复制标题
与质子靶碰撞时奇异核中子敲除的畸变效应
DOI：
10.1103/physrevc.93.054612
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发表时间：
2016
影响因子：
3.1
通讯作者：
A. Deltuva
中科院分区：
文献类型：
--
作者：
E. Cravo;R. Crespo;A. Deltuva
背景：反应理论在实验数据的解释中起着重要作用，需要准确地识别和包括所有相关的动力学效应，以提取可靠的结构信息。从高能奇异核抛射体与质子靶碰撞中对核子（中子/质子）的敲除，可以了解核子的价层和内壳层的结构.目的：我们的目的是阐明核子敲除过程中畸变对计算观测值的影响，特别是计算观测值对敲除粒子的结合能和角动量以及核质量的依赖性.方法：采用Faddeev/Alt-Grassberger-Sandhas（Faddeev/AGS）三体方法，对420 MeV/u入射粒子与质子靶碰撞中，稳定核和奇异核的核子被敲除进行了精确计算。结果：Faddeev/AGS公式准确地预测了：（i）畸变参数对分离能的系统性的近似对数依赖关系，（ii）全截面与PWIA截面的比值对非对称性参数的近似线性依赖关系，（iii）非对称性参数对全截面与PWIA截面的近似线性依赖关系。（iii）从PWIA计算的横向核心动量分布和完整的Faddeev/AGS精确的方法，这表明畸变效应不修改完全排他性的可观通过一个共同的renormalization factor.Conclusions：要提取更深的壳结构信息，需要准确地包括畸变效应。一个系统的分析，使估计总截面的核子敲出一个给定的壳层的核在/远离稳定线的核景观。通过与实验结果的比较，可以对所采用的相互作用和结构模型有更好的理解。
Background:Reaction theory plays a major role in the interpretation of experimental data and one needs to identify and include accurately all the relevant dynamical effects in order to extract reliable structure information. The knockout of a nucleon (neutron/proton) from a high energy exotic nucleus projectile colliding with a proton target allows to get insight on the structure of its valence and inner shells.Purpose:We aim to clarify the role of the distortion on the calculated observables for nucleon knockout, in particular, the dependence of the calculated observables on the binding energyand angular momentumof the knockout particle, and on the mass of the projectile core,. We consider mainly the knockout of a neutron that may be either in the valence or in the inner shell of the projectile nucleus.Method:Exact three-body Faddeev/Alt-Grassberger-Sandhas (Faddeev/AGS) calculations are performed for the nucleon knockout from stable and exotic nuclei in the collision of 420 MeV/u projectile beams with a proton target. Results are compared with plane-wave impulse approximation (PWIA) calculations.Results:The Faddeev/AGS formalism accurately predicts: (i) a systematic nearly logarithmic dependence of the distortion parameter on the separation energy; (ii) roughly linear dependence of the ratio of the full to the PWIA cross section on the asymmetry parameter; (iii) a distinct behavior between the calculated transverse core momentum distribution from the PWIA and full Faddeev/AGS exact approach which indicates that distortion effects do not modify fully exclusive observables through a common renormalization factor.Conclusions:To extract structure information on deeper shells one needs to include distortion effects accurately. A systematic analysis enables to estimate the total cross section for knockout of a nucleon from a given shell of nuclei at/away the stability line of the nuclear landscape. The comparison with experimental results may provide understanding on the used interaction and structure model.