搜索结果: 61-75 共查到“知识库 核结构”相关记录248条 . 查询时间(3.719 秒)
ISCOs in Extremal Reissner Nordstrom Spacetimes
Extremal Reissner Nordstrom Spacetimes Innermost Stable Circular Orbits
2010/3/17
Circular geodesic orbits, both timelike and null, in extremal Reissner-Nordstrom spacetimes, are examined with regard to their stability, and compared with similar orbits in the non-extremal situation...
The LAGUNA design study- towards giant liquid based underground detectors for ne utrino physics and astrophysics and proton decay searches
LAGUNA design proton decay astrophysics
2010/3/15
The feasibility of a next generation neutrino observatory in Europe is being considered within the LAGUNA design study. To accommodate giant neutrino detectors and shield them from cosmic rays, a new ...
MV级EPID成像中靶材料与厚度的优化选择
Monte-Carlo方法 MV级 靶 Geant4 EPID
2011/8/17
MV级电子射野成像系统（EPID）产生的图像相对于kV级对比度差，其中靶的材料和尺寸是一重要因素。采用Monte-Carlo软件包Geant4程序对6 MV医用直线加速器进行模拟，对MV级EPID成像中靶材料与厚度进行优化选择。计算结果表明，低原子序数的薄靶有利于改善成像质量，在无均整器的情况下，3 mm厚的Cu靶或10 mm厚的Al靶更适用于6 MV的电子射野成像系统。
核介质中强子性质的手征σ模型研究
手征σ模型 强子有效质量 重整化方法
2009/11/27
采用手征σ模型描述核多体系统，考虑真空极化的影响，首先由核物质的饱和性质确定模型参数，进一步研究了强子性质在核介质中的变化。手征σ模型的研究结果给出，核子和ω介子的有效质量随核物质密度的增大而减小，但σ介子的有效质量随密度的增大而增大。这些结果与不满足手征对称性的Walecka模型结果进行了比较。计算中采用的重整化方法会对结果有一定的影响。
逆运动学弹性共振散射方法在非束缚核结构研究中的应用
放射性核束 非束缚核 核结构
2009/11/27
简要介绍了近几年发展起来的厚靶逆运动学弹性共振散射方法在非稳定核结构测量中的应用。它是研究非束缚态核结构的实验方法之一。通过测量反冲轻核的激发函数，提取共振态的能量、自旋宇称和衰变宽度等。主要用于研究非稳定核素的结构、核天体物理中相关核的阈能共振态的能级参数测量等。
简要回顾原子核形状相变研究的现状，并将相干态理论与角动量投影方法相结合，在不区分质子玻色子和中子玻色子的相互作用玻色子模型（IBM-1）框架下，对角动量驱动的轴对称情况下的具有U（5）、SU（3）对称性以及两种对称性之间过渡区的原子核的形状相变进行了具体研究。
原子核反核子谱的自旋对称性
相对论平均场理论 自旋 对称性
2009/11/27
简要介绍原子核反核子谱的自旋对称性。通过分析包含标量势和矢量势的核子及反核子
Dirac方程的性质，给出核子谱的赝自旋对称性和反核子谱的自旋对称性的起因。对于反核子双重
态，除了它们的能量非常接近以外，它们的波函数也几乎严格地满足自旋对称性所要求的关系。
Instantons revisited: dynamical tunnelling and resonant tunnelling
Tunnelling dynamical tunnelling resonant tunnelling instantons semiclassical methods Wick rotation complex time
2010/4/8
Starting from trace formulae for the tunnelling splittings (or decay rates) analytically continued in the complex time domain, we obtain explicit semiclassical expansions in terms of complex trajector...
Exploring the light-quark interaction
Bethe-Salpeter equations bound-states confinement dynamical chiral symmetry breaking Dyson-Schwinger equations Faddeev equation nucleon electromagnetic form factors
2009/11/17
Two basic motivations for an upgraded JLab facility are the needs: to determine the essential nature of light-quark confinement and dynamical chiral symmetry breaking (DCSB); and to understand nucleo...
The N* physics program at Jefferson Lab
nucleon resonances transition form factors NΔ transition Roper magnetic dipole
2009/11/17
Recent measurements of nucleon resonance transition form factors with CLAS at Jefferson Lab are discussed. The new data confirm the assertion of the symmetric constituent quark model of the Roper as t...
Strategies for baryon resonance analysis
pion-nucleon scattering meson exchange mode analytic structure of the scattering amplitude
2009/11/17
The analytic properties of scattering amplitudes provide a meeting point for
experimental and theoretical investigations of baryon resonances. Pole positions and residues allow for a parameterization...
Collective versus Single--Particle Motion in Quantum Many--Body Systems from the Perspective of an Integrable Model
Single--Particle Motion Quantum Many--Body Systems Integrable Model
2010/4/8
We study the emergence of collective dynamics in the integrable Hamiltonian system of two finite ensembles of coupled harmonic oscillators. After identification of a collective degree of freedom, the ...
We recently performed a series of improvement on evaluation of eigenvalues without complicated iterations. In this work we firstdiscuss evaluation of the lowest eigenvalue for given systems, by which ...
Level Crossing of N*(1535)hole and η Modes and Partial Restoration of Chiral Symmetry in ηmesic Nuclei
A etamesic nuclei N*(1535) in medium partial restoration of chiral symmetry
2009/10/29
We investigate the properties of the ηnucleus interaction by postulating the N*(1535) dominance for ηN system. Since the mass gap of N* and N is very close to the η meson mass, there is the possi...
Ground State Structure of Hs Superheavy Isotopes
superheavy nucleus nuclear structure pairing
2009/10/29
The ground state properties of Hs nuclei studied in the framework of the relativistic mean field theory revealed that more stable isotopes are located on the proton abundant side of the chain. The...