微观半经典Vlasov框架下的巨偶极共振的系统学与同位旋效应

用微观半经典Vlasov方法研究了同位旋矢量巨偶极共振(GDR)的系统学.计算的GDR强度分布的峰位能量和宽度与实验结果是一致的,并与经验公式相符.计算还表明峰位能量有微小的同位旋效应,而峰的宽度几乎没有同位旋效应.     

“颈”发射过程中的中等质量碎片的研究

系统地研究“颈”发射过程中的中等质量碎片,能使我们更好地理解中能核反应的动力学和热力学性质.采用具有不同的同位旋靶核研究了靶同位旋与中等质量碎片的关系,以及区分反应过程中类弹、类靶产生的中等质量碎片和“颈”发射过程中产生的中等质量碎片.HJ4/9] By systematic study of the IMF produced the “neck”emission process, one can understand much better about the dynamics and thermodymanics of the intermediate energy nuclear reaction. The isospin dependence of IMF emission was studied for the reaction system with different isospin target nucleus and the different IMF production mechanisms that originate from projectile like、 target like and the “neck” were distinguished.     

康普顿背散射技术对贮存环电子束诊断及其应用-II贮存环电子束的极化度测量

简单介绍以激光 电子康普顿背散射原理为基础建立的康普顿背散射极化仪, 采用它能实时、 非破坏性地监测电子束的极化. 该项工作可作为上海激光电子γ源（SLEGS）低能γ束应用研究的内容之一. The Compton backscattering polarimeter is described briefly on the basis of the principle of Compton backscattering in this paper. The polarization of the electron beam can be measured and monitored on time and nondestructively. The project will be one of applications of low energy γ ray beam of SLEGS.     

利用SLEGS开展夸克和胶子层次上的核物理研究

通过对国际上中能核物理的发展,特别是前沿领域中的现状的回顾,阐述了利用在上海原子核所计划建造的第三代同步辐射加速器(SSRF)上建立新一代的激光 电子康普顿背散射γ射线源(SLEGS)从事夸克和胶子层次上的中能核物理研究的科学目标及研究内容. The proposed SLEGS (Shanghai Laser Electron backscattering Gamma Source) will be a circular and linear polarization, new generation, high quality γ ray source with Eγ=0.2-0.87 GeV. The major scientific focus of nuclear physics research at SLEGS will be investigations of the microscopic quark gluon aspects of nucleons , nucleon resonance states and nuclei to test and develop non perturbative QCD. Using polarized photon induced reactions on unpolarized and polarized nucleon target such as γN→γ N, ...     

Scaling of anisotropic flows and nuclear equation of state in intermediate energy heavy ion collisions

Elliptic flow ($v_2$) and hexadecupole flow ($v_4$) of light clusters have been studied in detail for 25 MeV/nucleon $^{86}$Kr + $^{124}$Sn at large impact parameters by using a quantum molecular dynamics model with different potential parameters. Four sets of parameters including soft or hard equation of state (EOS) with or without symmetry energy term are used. Both number-of-nucleon ($A$) scaling of the elliptic flow versus transverse momentum ($p_{\rm t}$) and the scaling of $v_4/A^{2}$ versus $(p_{\rm t}/A)^2$ have been demonstrated for the light clusters in all above calculation conditions. It is also found that the ratio of $v_4/{v_2}^2$ maintains a constant of 1/2 which is independent of $p_{\rm t}$ for all the light fragments. Comparisons among different combinations of the EOS and the symmetry potential term show that the above scaling behaviours are sound and independent of the details of potential, while the strengths of flows are sensitive to the EOS and the symmetry potential term.     

Isoscaling of projectile-like fragments

In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion--ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters α and β have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on α than β. For cold fragments, a monotonic increase of α and β with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.     

TMSR白光中子源本底屏蔽设计

为了满足钍基熔盐堆对核数据的需求,中国科学院上海应用物理研究所自行设计并建造了紧凑型的15 MeV电子加速器驱动的白光中子源。电子直线加速器、中子产生靶以及探测器系统处于同一个实验大厅,中子/伽马射线本底较高,原有屏蔽并不能满足在低能区进行热中子物理实验测量的低中子本底需求。为了降低热中子本底,提高在热区的测量能力,需要对中子源进行局部屏蔽。根据调试运行经验以及模拟计算结果,分析了中子伽马射线本底的来源,利用MCNP5模拟计算了混凝土、铅、含硼聚乙烯对中子/伽马射线的屏蔽效果,优化设计了局部屏蔽方案。模拟计算结果显示,该屏蔽方案可将热中子本底降低三个量级,伽马本底降低两个量级。屏蔽后的实验测量结果表明,探测器处的有效热中子与本底热中子的比值达到约100:1,屏蔽效果显著,为后续在热中子能区顺利开展中子物理测量实验奠定了基础。     

Temperature dependent fission fragment distribution in the Langevin equation

The temperature dependent width of the fission fragment distributions was simulated in the Langevin equation by taking two-parameter exponential form of the fission fragment mass variance at scission point for each fission event. The result can reproduce experimental data well, and it permits to make reliable estimate for unmeasured product yields near symmetry fission.     

F同位素的反应总截面测量和17F可能的质子皮结构

应用透射法对中能区F同位素与C靶的反应总截面进行了测量.发现¹⁷F的反应总截面比其邻近同位素的反应总截面稍有增强.用Glauber模型和BUU模型对F同位素进行了差异因子d的分析.¹⁷F的差异因子d比其附近同位素稍有增强.分析结果表明¹⁷F可能存在质子皮结构.     

中等质量核激发态奇异核结构的研究

在球形非线性相对论平均场(RMF)的理论框架下, 研究了β稳定线附近中等质量(z=20—50)奇A核在激发态下存在的晕或皮结构, 提取了价核子与核芯均方根半径的比值(R_vc), 并结合单中子或质子的分离能(Sn(p)), 讨论了具有晕或皮结构的激发态所呈现出来的带状分布, 说明了壳层结构与离心势垒对激发态晕或皮结构形成的重要影响.