非对称核物质不可压缩系数的微观计算(英文)

在带微观三体力的Brueckner-Hartree-Fock方法下研究了非对称核物质的不可压缩系数,得到了不可压缩系数的同位旋以及密度依赖, 并做了进一步的讨论。在一定密度下,不可压缩系数作为同位旋非对称度的函数随同位旋单调递增。 预测了非对称核物质在平衡态的同位旋依赖性质并与其他理论方法做了比较。 We have investigated the incompressibility of asymmetric nuclear matter within the Brueckner Hartree Fock approach extended to include a microscopic three body force. The isospin dependence and density dependence of the nuclear incompressibility have been obtained and discussed. It is shown that the incompressibility at a fixed density increases monotonically as a function of isospin asymmetry. The isospin asymmetry dependence of the equilibrium properties of asymmetric nuclear matter is also predicted and compared with the results of other theoretical approaches.     

应用蒙特卡罗方法对比研究ADS颗粒靶和块状靶（英文）

应用蒙特卡罗软件FLUKA对比研究了颗粒靶和块状实体靶在中子、质子泄露,中子、质子流强,能量沉积,残余核活度及Gamma射线剂量率的差异。最终结果显示在靶的轴对称方向,相较块状靶,颗粒靶中的中子流强和能量沉积更加均匀,且侧壁泄露中子更多而反冲中子较少。除此之外,在散裂产物放射性方面,尽管有部分核素两种靶具有相似的活度,但是颗粒靶总的放射性活度要比块状靶低。因此以上特性使得颗粒靶相较块状实体靶更适合用于ADS的靶。Using the Fluka Monte Carlo code,the comparison study between granular target and monolith target in neutron and proton leakages,neutron and proton fluxes,energy deposition density and residual radioactivity as well as gamma dose rates were presented.Results shows that the neutron flux and energy deposition in tungsten spheres target are more homogeneous along the axial direction than monolith target.What's more,the granular target has a more lateral neutron yield and a relatively small amount of neutrons in the backward direction.In addition,the total radioactivity is found to be comparatively lower in granular target,although for some nuclei,the value of their activities are similar for both targets.So the above features make the granular target more suitable as a ADS target.     

非对称核物质中核子动量分布的微观理论计算(英文)

在Extended Brueckner Hartree Fock（EBHF）近似下, 采用Argonne V18势作为核子 核子相互作用, 计算了基态非对称核物质中核子动量的分布。 对核子的动量分布对同位旋不对称度的依赖关系进行了描述和讨论。 结果表明, 在不对称度为零时, 质子与中子有着基本相同的动量分布。 随着不对称度的增加, 在各自的费米面以下, 质子动量分布减小而中子动量分布增大。 对费米面处的准粒子强度也进行了计算和讨论。 本结果较好地满足了两个理论检验标准Migdal Luttinger theorem 和粒子数守恒律。 We calculate the momentum distribution of nucleons in asymmetric nuclear matter within the framework of the extended Brueckner Hartree Fock approximation at zero temperature, use Argonne V18 potential as two nucleons potential. The isospin asymmetry dependence of the nucleon momentum distribution predicted and discussed. It is shown that as the asymmetry increases, the proton momentum distribution become smaller while the neutron one gets higher below their respective Fermi surfaces with respect to their common values in symmetric nuclear matter. The quasi particle strength at the Fermi momentum also calculated and discussed, we got an improved fulfillment of the Migdal Luttinger theorem and nucleon number conservation.     

645 MeV Xe35+离子辐照SiO2在线光发射的研究

离子辐照可以改变二氧化硅(SiO₂)的晶体结构和光学性质.采用645 MeV Xe³⁵⁺离子辐照SiO₂单晶,在辐照过程中,利用光栅光谱仪测量在200—800 nm范围内的光发射.在发射光谱中,观测到中心位于461和631 nm的发射带.这些发射带是弗伦克尔激子辐射退激产生的,其强度与辐照离子能量和辐照离子剂量密切相关.实验结果表明:发射光强随离子在固体中的电子能损呈指数增加.由于离子辐照对晶体造成损伤,发射光谱强度随辐照剂量的增加而降低.文中讨论了这些与晶体结构有关的发射带,结合能量损失机制讨论了激子形成和退激过程.快重离子辐照过程中发射光谱的原位测量对研究辐照改性具有重要意义,有助于揭示离子辐照引起晶体损伤的物理机制.     

Study of neutron activation yields in spallation reaction of 400 MeV/u carbon on a thick lead target

The spallation-neutron yield was studied experimentally by bombarding a thick lead target with 400 MeV/u carbon beam. The data were obtained with the activation analysis method using foils of Au, Mn, Al, Fe and In. The yields of produced isotopes were deduced by analyzing the measured γ spectra of the irradiated foils. According to the isotopes yields, the spatial and energy distributions of the neutron field were discussed. The experimental results were compared with Monte Carlo simulations performed by the GEANT4+FLUKA code.