A possible proton pygmy resonance in 17Ne

The low-lying electric dipole strengths in proton-rich nuclei ¹⁷F and ¹⁷Ne, which can be produced at HIRFL-CSR in Lanzhou, are investigated. In the framework of the covariant density functional theory the self-consistent relativistic Hartree Bogoliubov model and the relativistic quasiparticle random phase approximation with the NL3 parameter set and Gogny pairing interaction are adopted in the calculations. A pronounced dipole peak appears below 10 MeV in ¹⁷Ne, but does not occur in ¹⁷F. The properties of this low-lying E1 excitation in ¹⁷Ne are studied, which may correspond to a proton pygmy resonance with different characteristics from those of giant dipole resonance.     

The fractal measurement of experimental images of supersonic turbulent mixing layer

Flow visualization of supersonic mixing layer has been studied based on the high spatiotemporal resolution Nano-based Planar Laser Scattering(NPLS) method in SML-1 wind tunnel. The corresponding images distinctly reproduced the flow structure of laminar,transitional and turbulent region,with which the fractal measurement can be implemented. Two methods of measuring fractal dimension were introduced and compared. The fractal dimension of the transitional region and the fully developing turbulence region of supersonic mixing layer were measured based on the box-counting method. In the transitional region,the fractal dimension will increase with turbulent intensity. In the fully developing turbulent region,the fractal dimension will not vary apparently for different flow structures,which em-bodies the self-similarity of supersonic turbulence.     

Relativistic RPA and Giant Resonances in β Stable and Unstable Nuclei

The nuclear isoscalar and isovector giant resonances in stable and unstable nuclei are studied in the framework of the relativistic random phase approximation. The classical meson propagators with nonlinear self-interactions are constructed in momentum space from the second variation of the action. The relativistic models with the parameter sets, TMI and NLSH, which provide good account of static ground state properties, can also well describe the collective states of nuclei, such as giant resonances. The isovector giant dipole resonances in the unstable Ar isotope chain are investigated.     

A possible proton pygmy resonance in ~(17)Ne

The low-lying electric dipole strengths in proton-rich nuclei 17F and 17Ne, which can be produced at HIRFL-CSR in Lanzhou, are investigated. In the framework of the covariant density functional theory the self-consistent relativistic Hartree Bogoliubov model and the relativistic quasiparticle random phase approximation with the NL3 parameter set and Gogny pairing interaction are adopted in the calculations. A pronounced dipole peak appears below 10 MeV in17Ne, but does not occur in 17F. The prop erties of t...     

What kind of optical model potentials should be used for deuteron stripping reactions?

This paper presents the results of a study that compares CTOM, a microscopic optical model potential(OMP), which is an optical model co-created by the China Nuclear Data Center & Tuebingen University, to CH89, which is a typical phenomenological OMP.The respective OMPs were tested by applying them to the modelling of nucleon elastic scattering and(d,p) transfer reactions involving14C,36S, and58Ni targets at both low and relatively high energies. The results demonstrated that although both potentials successfully accounted for the angular distributions of both the elastic scattering and transfer cross sections, the absolute values of the transfer cross sections calculated using CTOM were approximately 25% larger than those calculated using CH89. This increased transfer cross sections allowed CTOM to produce single particle strength reduction factors for the three reactions that were consistent with those extracted from(e,e′p) reactions as well as with more recent(p,2p) and(p,pn) reactions. Notch tests suggested that nucleon elastic scattering and transfer reactions are sensitive to different regions of the OMP;accordingly,phenomenological OMPs, which are constrained only by elastic scattering cross sections, may not be sufficient for nucleon transfer reactions. Therefore, we suggest that microscopic OMPs, which reflect more theoretical considerations, should be preferred over phenomenological ones in calculations of direct nuclear reactions.     

自组装方法与三维光子晶体制作

光子晶体,特别是三维光子晶体,可能成为信息处理和通信等领域的新型功能材料.光子晶体的制作方法可分为"自上而下"的物理方法和"自下而上"的化学自组装方法.化学自组装方法是制作三维光子晶体最为经济有效的方法.本文在阐述自组装方法的种类、一般过程、优点和不足等内容的基础上,分别分析和总结了带有各种功能缺陷的三维光子晶体的制作,这些缺陷主要包括线缺陷、面缺陷和点缺陷.从研究中可以看出,化学自组装方法通常需要结合其他方法才能实现缺陷的嵌入.近些年,三维光子晶体制作在材料选取、结构设计和方法改进等方面都有一些最新进展,本文对此进行了较为详尽的评述,并对我们课题组的研究进行了总结.最后对光子晶体的研究和制作方向进行了展望.     

在相对论平均场框架下Pr同位素链的基态性质

在相对论平均场框架下研究了Pr同位素链的基态性质.对关联的处理采用了BCS方法,并使用了与同位旋有关的对力常数,对不成对的核子采用了‘阻塞法’,并考虑了核的轴对称形变.计算结果表明,包含非线性介子自相互作用的相对论平均场理论可以在很大的同位旋范围内很好地描述Pr同位素链的结合能、形变、中(质)子密度分布、同位素位移等.理论计算的结果与有限力程小液滴模型的结果符合得很好.特别检验了描述对关联的BCS近似在Pr链的适用范围和适用的程度.     

An experimental study of aero-optical aberration and dithering of supersonic mixing layer via BOS

The optical performance of supersonic mixing layer is heavily deteriorated by the aero-optical aberration and dithering of coherent structures, but current measuring methods limit the spatiotemporal resolution in relevant studies. A high resolution whole-field aero-optical aberration and dithering measuring method based on the Background Orient Schlieren (BOS) technique was studied. The systematic structure, sensitivity and resolution of BOS are analyzed in this paper. The aero-optical aberration and dither...     

A flow control study of a supersonic mixing layer via NPLS

The flow control of a supersonic mixing layer was studied in a supersonic mixing layer wind tunnel with convective Mach number (Mc) at 0.5. The passive control of the mixing layer was achieved by perturbation tapes on the trailing edge of the splitter plate. The control effects of 2D and 3D perturbation tapes with different sizes were compared. The mixing layer was visualized via NPLS, and the transient fine structures were identifiable in NPLS images, which were used to analyze the effects of flow control. The results show that the 2D tapes can enhance the 2D characteristic of the mixing layer, delaying mixing layer transition; and the 3D tapes can enhance the 3D characteristic of the mixing layer, advancing mixing layer transition. 3D structures of the mixing layer were visualized, and the H-type Λ vortexes were found with 3D tapes control.     

Large Third-Order Optical Nonlinearity and Fast Response of a Squarylium Dye

The third-order optical nonlinearities and responses of a squarylium dye, 2,4-di-3-guaiazulenyl-1,3-dihydroxycyclobutenediylium dihydroxide, in tetrahydrofuran （THF） solution and in polystyrene （PS） coating films are measured by the femtosecond degenerate four-wave mixing technique under resonant conditions. The molecular hyperpolarizability γ of the squarylium dye in the THF solution is determined to be 3.0 × 10^-29 esu at 764 nm, and its electronic component γe is determined to be 1.1 × 10^-29 esu. The third-order nonlinear susceptibility X^（3） of one of the present PS coating films containing the squarylium dye is as high as 3.1 × 10^-8 esu at 80Ohm, and its electronic component Xe^（3） is 1.3 × 10^-8 esu.