重离子核反应中等质量余核温度的研究

发布时间：2018-05-09 11:36

本文选题：重离子核反应 + 温度　；参考：《河南师范大学》2017年硕士论文

【摘要】：在重离子反应中,余核的温度研究一直是一个比较重要的研究方向。两体碰撞模型可以用来描述重离子碰撞反应系统的演化过程。两体碰撞模型认为重离子反应系统经历了压缩、膨胀等一系列过程,反应系统的体积先变小再变大,系统的温度T伴随着系统的压缩、碰撞过程也经历了从高到低的变化。本文的主要内容分为两个部分:第一部分主要提出了一种针对中等质量余核的改进的温度探针。此温度探针主要利用包含三个等量异位素的等量异位素产额比(IYR)的差来提取余核的温度。在此温度探针中,三个等量异位素的结合能的差△B代替了它们的自由能的差△F。利用改进的等量异位素产额比差的方法分析了 140AMeV ~(40,48)Ca + 9Be (181Ta)和~(58,64)Ni + 9Be(181Ta)炮弹碎裂反应的实验数据、1A GeV ~(124,136)Xe + Pb炮弹碎裂反应实验数据以及1A GeV ~(112,124)Sn+~(112,124)Sn反应中的实验数据,提取了这些反应所产生的中等质量余核的温度T_(IB)。结果表明:~(40,48)Ca和~(58,64)Ni反应得到的大部分余核的温度T_(IB)的值处在0.6 MeV到3.5 MeV区域中;1~(24)Xe和~(112,124)Sn反应得到的大部分余核的温度T_(IB)的值处在0.5 MeV到2.5 MeV区域中;然而136Xe反应得到的大部分余核的温度T_(IB)的值处在0.5 MeV到4.0 MeV区域中。总之,在本文所研究的反应中的中等余核的温度都比较低。第二部分主要研究了中等质量余核的温度与质量数之间的依赖关系。研究发现,用改进的等量异位素产额比差的方法分析的最终的余核的温度值和初始余核的温度值一样都符合方程T=C(1-k·A)的分布趋势(其中C和k是参数)。余核的温度与质量数A的这种依赖关系可以解释为余核的自由能差AF或者结合能差AB与质量数A的关系。在0.5 MeVT4.0MeV的温度区域内,原子核的自由能差AF和结合能差AB都依赖质量数A,并且符合拟合线方程y=1/[C(1-k·A)]。对于确定的原子核,用改进的等量异位素产额比差的方法提取的在0.5 MeV T 4.0 MeV的温度区域内的余核的温度值的分布也符合拟合线方程y = 1 / [C(1 -k·A)]的趋势。
[Abstract]:In heavy ion reaction, the temperature of conucleus has been an important research direction. The two-body collision model can be used to describe the evolution of heavy ion collision reaction system. The two-body collision model holds that the heavy ion reaction system has undergone a series of processes, such as compression and expansion. The volume of the reaction system first becomes smaller and then becomes larger. The temperature of the system T is accompanied by the compression of the system, and the collision process has undergone a change from high to low. The main contents of this paper are divided into two parts: in the first part, an improved temperature probe for medium mass conuclei is proposed. This temperature probe mainly uses the difference of isometric heterotopic yield ratio (IYR) of three isobaric elements to extract the residual temperature. In this temperature probe, the difference in binding energy of the three isobaric elements B replaces the difference of their free energy. In this paper, the experimental data of the fragmentation reactions of the projectiles of 140AMeV (4048U) Ca 9Be (181Ta) and Ni9Be181Ta() have been analyzed by using the improved method of isobaric yield ratio. The experimental data of the fragmentation reaction of the projectile of 1A GeV / 124136C Xe Pb and 1A GeV 112124Sn / 112124Sn have been analyzed. The temperature of medium mass conucleus produced by these reactions was extracted. The results show that the temperature of most of the residual nuclei produced by the reaction of 40 ~ 40 ~ (48) C ~ (2 +) C ~ (2 +) with Ni is in the range of 0. 6 MeV to 3. 5 MeV. The temperature of most of the residual nuclei obtained from the reaction between 0. 6 MeV and 3. 5 MeV is in the range of 0. 5 MeV to 2. 5 MeV. The temperature of the majority of the residual nuclei obtained by the reaction of 1: 1 212124 ~ Sn is in the range of 0. 5 MeV to 2. 5 MeV. However, the temperature of most of the conuclei obtained by 136Xe reaction is in the range of 0. 5 MeV to 4. 0 MeV. In conclusion, the temperature of the intermediate conuclei in the reactions studied in this paper is relatively low. In the second part, the dependence between temperature and mass number of conuclei with medium mass is studied. It is found that the temperature values of the final conuclei analyzed by the improved isobaric yield ratio method are the same as the temperature values of the initial conuclei (where C and k are the parameters of the equation T=C(1-k A). The dependence of cokernel temperature on mass number A can be explained by the relationship between free energy difference AF or binding energy difference AB and mass number A. In the temperature range of 0. 5 MeVT4.0MeV, the free energy difference (AF) and the binding energy difference (AB) of the nucleus depend on the mass number A. For the determined nuclei, the temperature distribution of the conuclei in the temperature region of 0.5 MeV T 4.0 MeV extracted by the improved isometric heterotopic yield ratio method is also in line with the trend of the fitting line equation y = 1 / [C0. 1 -k A].
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O571.6

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