宇宙线传播及宇宙线能谱异常起源的研究

发布时间：2018-05-18 13:30

本文选题：宇宙线 + 幂律谱　；参考：《河北师范大学》2012年硕士论文

【摘要】：宇宙线被物理学家喻为神秘的天外来客，它是来自地球之外的高能微观粒子。自1912年发现宇宙线至今已有一百年时间，在这期间人们对宇宙线进行了连续不断的实验探测和理论研究。但是到目前为止，关于宇宙线粒子的几个根本性问题我们仍然无法得到清晰完美的答案，例如宇宙线的起源、加速和传播等问题。宇宙线问题成为现代物理学中最重要也是最基本的问题之一。本论文主要讨论造成宇宙线能谱异常的原因，并利用GALPROP对两种解释模型中的次级粒子预期值进行比较。我们首先简述宇宙线物理的有关知识，然后对数值求解银河系宇宙线传播的程序包GALPROP进行详细介绍，继而在此基础之上对近几年宇宙线能谱异常的问题进行讨论。关于宇宙线能谱的观测，，在气球实验CREAM之前的观测结果中，宇宙线的标准能谱是单一幂律谱。然而最新的CREAM实验观测表明，从质子到铁的元素能谱在～200GeV/核子能段出现了异常的变硬，明显不同于一般的单一幂律谱。接着卫星实验PAMELA公布的最新数据显示，质子和氦核的能谱在刚度为～200GV的地方也出现了拐折，而且和ATIC、CREAM的结果是自洽的，且不同于单一幂律谱。有关这一反常现象的理论讨论很多，本文重点讨论其中的两种：一种理论认为，这种能谱异常变硬是由宇宙线粒子注入到星际空间时非线性加速机制造成的；另一种理论则认为，能谱的拐折是临近的单一源能谱和背景能谱叠加造成的。另外，我们要重点比较这一异常现象对于反质子、正电子、伽玛射线的预言在这两种模型中的不同。我们利用GALPROP的宇宙线扩散+对流模型对CREMA和PAMELA能谱进行了很好的解释，接着我们对质子和氦核产生的反质子，以及伽玛射线进行了计算，发现能谱的异常确实造成了反质子和伽玛射线的预言在两种模型中不同。另外我们还计算了正电子能谱，经过比较，两者也存在相应的差异。
[Abstract]:Cosmic ray is regarded by physicists as a mysterious alien. It is a high-energy microparticle from outside the earth. It has been a hundred years since the discovery of cosmic rays in 1912. During this period, continuous experimental exploration and theoretical study of cosmic rays have been carried out. But so far, we can not get a clear and perfect answer to several fundamental questions about cosmic ray particles, such as the origin, acceleration and propagation of cosmic rays. Cosmic ray problem has become one of the most important and basic problems in modern physics. This paper mainly discusses the causes of cosmic ray energy spectrum anomalies and compares the expected values of secondary particles in the two interpretation models by GALPROP. We first introduce briefly the knowledge of cosmic ray physics, then introduce in detail the program package GALPROP for numerical solution of cosmic ray propagation in the Milky way, and then discuss the problem of cosmic ray energy spectrum anomaly in recent years. With regard to the observation of cosmic ray energy spectrum, the standard energy spectrum of cosmic ray is a single power law spectrum in the observation results before the balloon experiment CREAM. However, the latest CREAM observations show that the energy spectra from proton to iron show abnormal hardening at the energy level of 200GeV / nucleon, which is obviously different from the general single power law spectrum. Then the latest data released by satellite experiment PAMELA show that the energy spectrum of proton and helium nucleus also turns at the stiffness of 200GV, and it is self-consistent with the result of ATIC-CREAM and is different from the single power law spectrum. There are many theoretical discussions about this anomalous phenomenon, two of which are mainly discussed in this paper: one theory is that the abnormal hardening of the energy spectrum is caused by the nonlinear acceleration mechanism when cosmic ray particles are injected into interstellar space; The other theory holds that the energy spectrum turn is caused by the superposition of the adjacent single source energy spectrum and the background energy spectrum. In addition, we will focus on the comparison of the predictions of this anomaly for antiprotons, positron and gamma rays in these two models. We use GALPROP's cosmic ray diffusion convection model to explain the CREMA and PAMELA spectra, and then we calculate the antiprotons produced by protons and helium nuclei, as well as gamma rays. It is found that the anomalous energy spectrum does cause the antiproton and gamma ray predictions to differ between the two models. In addition, we also calculated the positron energy spectrum, and after comparison, there is a corresponding difference between the two.
【学位授予单位】：河北师范大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：P172.4

【参考文献】