Calculations of Three-Nucleon Reactions

Faddeev calculations using the chiral three-nucleon force in next-to-next-to-next-to-leading-order show that this force is too weak to provide an explanation for the low-energy A _y puzzle. The large discrepancy between data and theory for the neutron–neutron quasi-free-scattering cross section in low energy neutron–deuteron breakup requires a modification of the ${^{1}S_0}$ neutron–neutron force. We discuss the consequences that a bound ${^{1}S_0}$ state of two neutrons has on neutron–deuteron scattering observables. At higher energies we compare the solutions of the non-relativistic three-nucleon Faddeev equations with three-nucleon force included to the solutions of its Poincaré invariant version.     

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.     

Novel Three-Nucleon-Force Terms in the Three-Nucleon System

 We include two specific three-nucleon-force terms of pion-range–short-range form in our momentum-space calculations for the three-nucleon continuum. These two terms are expected by chiral perturbation theory to be non-negligible. We study the effects of these terms in elastic neutron-deuteron scattering and pay special attention to the neutron vector-analyzing power A _y . Received September 16, 1999; accepted for publication October 20, 1999     

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.     

X光激光实验研究进展

自１９８７年开展Ｘ光激光实验以来,在许多物理机制研究上取得重要进展,尤其利用电子碰撞激发机制实现了一系列类氖锗离子的Ｘ光激光增益．在驱动能量～６００Ｊ、脉宽～１．２ｎｓ条件下,首先获得１９．６～２８．６ｎｍ间的５条跃迁增益线,ＧＬ值约８,利用平面Ｘ光反射镜又实现双程放大．时间分辨的强度提高１０倍．在此基础上．又完成低能量驱动和预－主脉冲驱动的Ｘ光激光增益实验,为在较低驱动能量下实现高增益和准单线的Ｘ光激光输出探索有效的技术途径． This paper introduces the progress on X-ray laser investigations in CAEP,including the experiments of X-ray lasers gain of Ne-like Ge pumped by electron-collision excitation, double-pass amplification of X-ray laser, low enery double-pulse driving and X-raylasers pumped by other schemes. The attentions are paid to the experimental principles, designs and results. Some suggestions of future investigations are also discussed.     

Improved Method for Partial-Wave Decomposition of Two-Pion Exchange Three-Nucleon Force

In this article an efficient method to calculate the matrix elements of three-nucleon force is presented. The new method is improved version of partial-wave decomposition of Hüber et al. (Few-Body Syst 22:107, 1997), which simplifies expression to be evaluated as well as permits to reduce computational effort. Proposed method naturally applies to Faddeev-type calculations.     

侧边抛磨光纤中传输光功率变化的实验研究

针对轮式光纤侧边抛磨法制备的侧边抛磨光纤,研究了在侧边抛磨区覆盖不同折射率的材料时,侧边抛磨光纤传输光功率随覆盖材料折射率变化的特性.研究表明,侧边抛磨光纤中传输光功率会随抛磨区覆盖材料折射率的变化而改变.当覆盖材料的折射率小于1.437 8时,光功率损耗近似为零；而当覆盖材料的折射率逐渐增大接近1.452 1时,光功率损耗迅速增大至最大值.当覆盖材料的折射率由1.453 2逐渐增大时,光功率损耗由最大值逐渐减小,最终维持在某个确定的值.侧边抛磨光纤并不是抛磨深度越深,损耗就越大.侧边抛磨光纤中传输的光功率存在波长相关损耗(WDL）.实验结果与理论结论符合较好.     

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.     

Energy Dependence of the πN Amplitude and the Three-Nucleon Interaction

By calculating the contribution of the ππ three-body force to the three-nucleon binding energy in terms of the πN amplitude using perturbation theory, we are able to determine the importance of the energy dependence and the contribution of the different partial waves of the πN amplitude to the three-nucleon force. A separable representation of the non-pole πN amplitude allows us to write the three-nucleon force in terms of the amplitude for NN → NN*, propagation of the NNN* system, and the amplitude for NN* → NN , with N* being the πN quasi-particle amplitude in a given state. The division of the πN amplitude into a pole and non-pole part gives a procedure for the determination of the πNN form factor within the model. The total contribution of the three-body force to the binding energy of the triton for the separable approximation to the Paris nucleon-nucleon potential (PEST) is found to be very small mainly as a result of the energy dependence of the πN amplitude, the cancellation between the S- and P-wave πN amplitudes, and the soft πNN form factor. Received April 12, 1994; revised November 11, 1994; accepted for publication December 1, 1994     

Experimental Investigations of the Binary Interaction of Polydisperse Sprays

Experimental investigations of the interaction of two polydisperse semi-hollow cone sprays are presented. The process, although of considerable significance for the chemical industry and applications like flue gas cleaning, has not been well-covered in the existing literature. This may be due to difficulties in getting general results from experiments involving particular geometries, like conical sprays, with fixed spray angle and geometrical arrangement of the nozzles. The present work develops a representation of the effects of the spray interaction on the spray drops in the resulting two-phase flow. The measurement technique used is phase-Doppler anemometry (PDA), which provides information about the size and two velocity components of the drops at each measurement position in the sprays. A factorial design of the experiments allows the influence of the intersection angle and the liquid flowrate of the sprays on an integral mean drop size in a spray cross section to be quantified. For varying values of these parameters, the downstream evolution of the interacting sprays is quantified in terms of the smoothness of profiles of the number-mean drop size. The collisional interaction of the spray drops is identified as the reason for the observed increase of the mean drop size caused by the spray interaction.     

A New Look into the Partial-Wave Decomposition of Three-Nucleon Forces

We demonstrate that the partial-wave decomposition of three-nucleon forces used up to now in momentum space has to be necessarily unstable for high partial waves. This does not affect the applications performed up to now, which were restricted to low partial waves. We present a new way to perform the partial-wave decomposition free of that defect. This is exemplified for the most common two-pion-exchange Tucson-Melbourne three-nucleon force. For the lower partial waves the results of the old method are reproduced. Received November 13, 1996; accepted for publication January 17, 1997     

Dependence of the Three-Nucleon Binding Energy on Some Different Effects

The bound state of three-nucleon system is studied as a three-body problem which is solved following the different approaches of the Faddeev formalism as well as the unitary pole approximation. The three-body problem is reduced to a set of coupled integral equations by using separable approximations. Numerical calculations are carried out for the resulting integral equations and the separable expansion. In the present work, we calculate the ground-state binding energy of the bound three-nucleon system ³H. The main interest of the present work is to investigate the sensitivity of the three-nucleon binding energy to different effects. For this reason, we study the dependence of this energy on different forms of local and separable nucleon-nucleon potentials, the effective range of the nucleon-nucleon interaction, and on the percent of the D state in the deuteron wave function. Also we test the sensitivity of the three-nucleon binding energy to the considered number of terms from the separable expansion.     

超高能诱发核反应的国际合作实验研究进展

综述超高能诱发核反应的国际合作实验进展及相关的重离子物理研究现状.内容包括:1.有关夸克物质(夸克胶子等离子体QGP)的理论预言.2.超高能重离子碰撞的实验:(1)BNL/AGS能区的固定靶实验回顾;(2)CERN/SPS能区的固定靶实验回顾;(3)BNL/RHIC能区的对撞实验现状;(4)CERN/LHC能区的对撞实验现状.     

中子引起氘核破裂反应的实验研究

对25 MeV中子引起氘核破裂反应的中子-中子准自由散射和17.36 MeV中子引起氘核破裂反应的中子-中子末态相互作用进行了细致的研究。首先,以小于5%的不确定度,精确测量了25MeV中子-中子准自由散射出射的中子三重微分截面。实验数据用基于现实核子-核子势(CD-Bonn,Argonne!18,Nijm I和II)的理论计算配合Monte-Carlo模拟进行了分析。实验结果比基于CD-Bonn势的理论预言高(16.0±4.6)%,进一步证实了目前的理论在中子-中子准自由散射方面还无法准确描述实验数据。其次,通过运动学非完全测量,精确测量了17.36 MeV中子引起氘核破裂反应在0°角附近出射的质子能谱,用基于现实核子-核子势(CD-Bonn、Bonn-B和Nijm I)的理论计算以及Monte-Carlo模拟分析了所测得的质子能谱,确定了中子-中子散射长度ann=(-16.8±0.6)fm。     

Experimental Investigations of a Model of the Human Visual System

Optics and Spectroscopy - The basic principles of a multichannel model of the visual system of a human that functions as an operator performing surveillance on images formed by optoelectronic...     

Resonating-Group Study of Three-Nucleon Bound State and p+d Scattering

The multi-configuration resonating-group method is employed to study the properties of the three-nucleon system. The model space is spanned by p+d, p+d', n+ 2p, and a large number of their associated pseudo-inelastic configurations. The nucleon-nucleon potential used is the Minnesota potential which contains nuclear central, Coulomb, and spin-orbit components. The results show that the calculated p+d complex phase shifts agree well with the values obtained by an empirical analysis of experimental data. Differential scattering and total reaction cross sections in the p+d system are calculated at centre-of-mass energies up to 32 MeV. Without adjusting any parameter, it is found that the agreement between calculation and experiment is quite satisfactory. The effects of successively enlarging the model space have also been examined. Here the finding is that, in order to obtain reliable results, all three types of cluster configurations must be included in the calculation. Received March 11, 1994; revised June 17, 1994; accepted for publication August 6, 1994     

Faddeev Calculations of Breakup Reactions with Realistic Experimental Constraints

We present a method to integrate predictions from a theoretical model of a reaction with three bodies in the final state over the region of phase space covered by a given experiment. The method takes into account the true experimental acceptance, as well as variations of detector efficiency, and eliminates the need for a Monte-Carlo simulation of the detector setup. The method is applicable to kinematically complete experiments. Examples for the use of this method include several polarization observables in dp breakup at 270MeV. The calculations are carried out in the Faddeev framework with the CD Bonn nucleon-nucleon interaction, with or without the inclusion of an additional three-nucleon force.