Comparison of Triton Bound-State Properties Using Different Separable Representations of Realistic Nucleon-Nucleon Potentials

 The quality of two different separable expansion methods (W-matrix and Ernst-Shakin-Thaler) is investigated. We compare the triton binding energies and components of the triton wave functions obtained in this way with the results of a direct two-dimensional treatment. The Paris, Bonn A and Bonn B potentials are employed as underlying two-body interactions, their total angular momenta being incorporated up to . It is found that the most accurate results based on the Ernst-Shakin-Thaler method agree within 1.5% or better with the two-dimensional calculations, whereas the results for the W-matrix representation are less accurate. Received February 9, 1999; accepted for publication February 13, 1999     

Travelling Wave Solutions for Konopelchenko-Dubrovsky Equation Using an Extended sinh-Gordon Equation Expansion Method

The sinh-Gordon equation expansion method is further extended by generalizing the sinh-Gordon equation and constructing new ansatz solution of the considered equation. As its application, the (2+1)-dimensional Konopelchenko-Dubrovsky equation is investigated and abundant exact travelling wave solutions are explicitly obtained including solitary wave solutions, trigonometric function solutions and Jacobi elliptic doubly periodic function solutions, some of which are new exact solutions that we have never seen before within our knowledge. The method can be applied to other nonlinear evolution equations in mathematical physics.     

Travelling Wave Solutions for Konopelchenko-Dubrovsky Equation Using an Extended sinh-Gordon Equation Expansion Method

The sinh-Gordon equation expansion method is further extended by generMizing the sinh-Gordon equation and constructing new ansatz solution of the considered equation. As its application, the （2＋1）-dimensional Konopelchenko-Dubrovsky equation is investigated and abundant exact travelling wave solutions are explicitly obtained including solitary wave solutions, trigonometric function solutions and Jacobi elliptic doubly periodic function solutions, some of which are new exact solutions that we have never seen before within our knowledge. The method can be applied to other nonlinear evolution equations in mathematical physics.     

A Three-Dimensional Treatment of the Three-Nucleon Bound State

Recently a formalism for a direct treatment of the Faddeev equation for the three-nucleon bound state in three dimensions has been proposed. It relies on an operator representation of the Faddeev component in the momentum space and leads to a finite set of coupled equations for scalar functions which depend only on three variables. In this paper we provide further elements of this formalism and show the first numerical results for chiral NNLO nuclear forces.     

Studies on the Bound-State Spectrum of Hyperbolic Potential

Bound states of hyperbolic potential is investigated by means of a generalized pseudospectral method. Significantly improved eigenvalues, eigenfunctions are obtained efficiently for arbitrary n, ? quantum states by solving the relevant non-relativistic Schrödinger equation allowing a non-uniform, optimal spatial discretization. Eigenvalues accurate up to tenth decimal place are reported for a large range of potential parameters; thus covering a wide range of interaction. Excellent agreement with available literature results is observed in all occasions. Special attention is paid for higher states. Some new states are given. Energy variations with respect to parameters in the potential are studied in considerable detail for the first time.     

一种宽能谱多球中子谱仪能量响应的MC模拟

利用蒙特卡罗程序FLUKA模拟计算了聚乙烯慢化球和辅助材料慢化球对低能中子到高能中子的响应函数曲线。结果表明,对纯聚乙烯球来说,随着聚乙烯层厚度的增加,响应曲线峰逐步右移,峰值在高能区有所下降,对20 Me V以上的中子,无论纯聚乙烯球的尺寸有多大,其响应均下降到很低的程度;对辅助材料慢化球来说,中子能量小于1 Me V时,辅助材料慢化球与聚乙烯慢化球的响应曲线相似,但当中子能量大于20 Me V时,中子与辅助材料层发生(n,xn)反应,慢化球的响应呈显著上升趋势。分析计算结果,最终能够确定宽能谱多球中子谱仪的尺寸组合。     

用MCNPx程序计算宽能谱中子雷姆仪的响应曲线

利用MCNPx程序计算了宽能谱中子雷姆仪的响应曲线。计算表明,增加铅层对低能中子的响应没有明显的影响,但在高能区(几百MeV以上)宽能谱中子雷姆仪的响应与铅层的厚度有关。铅层厚度为0．6cm时响应比普通雷姆仪提高约3倍,当铅层厚度增加到1．2cm时响应高约5倍。虽然计算结果与ICRP建议书中的H^*(10)曲线相比还有一定的差别,但改变慢化体的结构对提高高能中子的探测效率是有明显效果的。The responses of two extended neutron rein counters as function of neutron energy was ca1cuated Monte Carlo code,MCNPx,was applied in the calculations．Isotropic neutron incidence was employed．The results show that the neutron response is independent on thickness of lead 1aver at low energies,and it is clearly increased with thickness of lead layer at high energies．Although tt1e shape of the response curve does not completely agree with the H (10) curve in ICRP 74 report ,the resuhs obtained give good bases for the practical use of the new instrument in high—energy neutron fields     

On the Mean-Field Limit of Bosons with Coulomb Two-Body Interaction

In the mean-field limit the dynamics of a quantum Bose gas is described by a Hartree equation. We present a simple method for proving the convergence of the microscopic quantum dynamics to the Hartree dynamics when the number of particles becomes large and the strength of the two-body potential tends to 0 like the inverse of the particle number. Our method is applicable for a class of singular interaction potentials including the Coulomb potential. We prove and state our main result for the Heisenberg- picture dynamics of “observables”, thus avoiding the use of coherent states. Our formulation shows that the mean-field limit is a “semi-classical” limit.     

Extrapolation of the Bound-State Energy within the SS-HORSE Method

Physics of Atomic Nuclei - A new method for extrapolating bound-state energies obtained in a harmonic-oscillator basis is proposed. This method also makes it possible to calculate asymptotic...     

New Exact Solutions for Konopelchenko-Dubrovsky Equation Using an Extended Riccati Equation Rational Expansion Method

Taking the Konopelchenko-Dubrovsky system as a simple example, some families of rational formal hyperbolic function solutions, rational formal triangular periodic solutions, and rational solutions are constructed by using the extended Riccati equation rational expansion method presented by us. The method can also be applied to solve more nonlinear partial differential equation or equations.     

Incorporation of Three-Nucleon Force in the Effective-Interaction Hyperspherical-Harmonic Approach

It is shown how a bare three-nucleon force is incorporated into the formalism of the effective interaction approach for hyperspherical harmonics. As a practical example we calculate the ground-state properties of ³H and ³He using the Argonne V18 nucleon-nucleon potential and the Urbana IX three-nucleon force. A very good convergence of binding energies and matter radii is obtained. We also find a very good agreement of our results compared to other high-precision calculations.     

The Barbieri-Remiddi Solution of the Bound-State Problem in QED

We derive the so-called Barbieri-Remiddi solution of the Bethe-Salpeter equation in QED in its general form and discuss its application to the bound-state energy spectrum.     

Phase of Two-Body Bose-Einstein Condensates with Collision

By using of the invariant theory, we have studied the phase of two-body Bose-Einstein condensates with collision, the dynamical and geometric phases are presented respectively. The Aharonov-Anandan phase is also obtained in the case of considering the cyclical evolution.     

Translationally Invariant Single Particle Picture of the Three-Nucleon System

An ansatz of a single particle picture, known for example from the shell model, has been used to construct a model wave function which is as close as possible to an exact three-body wave function. The exact wave function is obtained by solving the Faddeev equation with the Malfliet–Tjon potential. In order to judge the quality of the model wave function, we compare correlation functions of the model wave function and the exact solution. The correlation functions differ significantly at small distances but are close to each other for larger values of their arguments.     

Accurate Evaluation of the Cubic Lattice Green Functions Using Binomial Expansion Theorems

A new, simple, and efficient technique for the accurate evaluation of the lattice Green functions is presented. Using binomial expansion theorems, these functions are expressed through the binomial coefficients and basic integrals. The extensive test calculations show that the proposed algorithm in this work is the most efficient method in practical computations. Finally, in order to show the practical use of analytical expressions found some computation examples and comparisons with literature are made.