Study of 3He + Nucleus Scattering with a Simplified Resonating-Group Method

 A simplified resonating-group method, called model K, is used to analyze ³He + nucleus scattering data for target nuclei with nucleon number ranging from 40 to 208 and for ³He energies ranging from 70 to 130 MeV. The results show that a rather satisfactory agreement between calculated and experimental differential-scattering cross sections can be obtained if one allows the value of the exchange-mixture parameter in the nucleon-nucleon potential to deviate somewhat from that in the corresponding N + nucleus case. With the model-K nonlocal interaction, an equivalent local internuclear potential is also constructed with a WKB procedure. Here it is found that, with a proper consideration of nucleon-exchange effects, one can explain nearly all of the energy dependence of the real part of the phenomenologically determined optical potential in ³He + nucleus scattering. Received May 31, 1999; revised November 9, 1999; accepted for publication December 20, 1999     

Calculation of quasi-stationary state parameters within the algebraic version of the resonating-group method

The dynamical equations of the algebraic version of the resonatinggroup method are used to determine the positionsE _res,l and the widths _l of quasi-stationary states or, what is equivalent, to find the polesE _l =E _resl –i _l /2 of theS-matrix in the fourth quadrant of thek-plane. Concrete calculations are performed for the -decay of⁸Be. A comparison with the results of other authors and with experiment is made.     

Allowance for the Coulomb interaction in the framework of an algebraic version of the resonating group method

The Coulomb proton interaction is taken into account in the problem of light atomic nucleus scattering using an algebraic version of the resonating group method. Specific formulas are obtained for calculating the elastic scattering phases. The elastic pα scattering phases, the positions of resonances and their widths are calculated for some NN potentials. Theoretical values of the quantities under consideration adequately describe experimental data.     

Spurious states of the dirac equation in a finite basis set

The occurrence of spurious states for the Dirac equation in a finite basis set is considered. For a Coulomb central-field potential, the spectra of the radial Dirac operator in a finite basis set (without using the kinetic balance) are shown to coincide for two different values of the relativistic quantum number κ that differ in sign. For an attractive Coulomb potential, this means that, for any basis set, spurious states p _1/2, d _3/2, … (κ > 0) arise, whose energies exactly coincide with energies of the states 1s _1/2, 2p _3/2, … (κ < 0), respectively. In addition, the negative spectra of the Dirac operator in a finite basis set for κ > 0 and κ < 0 also coincide.     

Switching of transmission resonances in a two-channels coupler: A Boundary Wall Method scattering study

In this work, we study the transmission characteristics of a two-channels coupler model system using the Boundary Wall Method (BWM) to determine the solution of the corresponding scattering problem of an incident plane wave. We show that the BWM provides detailed information regarding the transmission resonances. In particular, we focus on the case of single channel input aiming to explore the energy switching performance of the coupler. We show that the coupler geometry can be tailored to allow for the first transmission resonances to be predominantly transmitted on specific output channels, an important characteristic for the realization of logical operations.     

Quasiscarred resonances in a spiral-shaped microcavity

We study resonance patterns of a spiral-shaped dielectric microcavity with chaotic ray dynamics. Many resonance patterns of this microcavity, with refractive indices n=2 and 3, exhibit strong localization of simple geometric shape, and we call them quasiscarred resonances in the sense that there is, unlike conventional scarring, no underlying periodic orbits. It is shown that the formation of a quasiscarred pattern can be understood in terms of ray dynamical probability distributions and wave properties like uncertainty and interference.     

Production of resonances in a thermal model

We discuss the π ⁺ π ^? invariant-mass correlations and the resonance production in a thermal model with single freeze-out. The predictions are confronted with the data from the STAR Collaboration.     

Spurious center-of-mass effect in the local density approximation

An additional spurious center-of-mass effect is caused by using the local density approximation for the density dependent effective interactions. The approximate correction term is suggested and its contribution for the light even-even nuclei is calculated. This contribution is found to be of about +9 MeV and its slight tendency to increase the size and to decrease the deformation of the nucleus is noted.     

Multiple omnidirectional resonances in a metamaterial sandwich

Multiple omnidirectional resonances are found in a sandwich structure consisting of a left-handed metamaterial cavity and two single-negative-permittivity reflection walls. These resonances appear because the phase shift of left-handed metamaterial can cancel the reflection phase shift of single-negative-permittivity metamaterials at every incidence angle. By using such particular structure, a kind of structure possessing multiple omnidirectional resonances in both polarizations has been designed. In addition, issues associated with energy loss are discussed.     

Power resonances in a Raman gas laser

The observation of a new type of resonance due to double-quantum transitions in the standing-wave field of a Raman gas laser is reported. A resonance dip with a width equal to that of the optically forbidden transition was experimentally detected in the output-vs-timing curve of a Raman Ne laser (λ=1.15 m) upon pumping by radiation of a He−Ne laser at 1.52 m. The theory presented shows that the resonance arises in the third order of perturbation theory when in resonant SRS the line is inhomogeneously broadened. The resonance can be considered as resulting from the overlap of dips in the velocity distribution of the nonlinear polarization induced by the standing laser wave.     

Single-particle resonances in a deformed relativistic potential

The positive-parity single-neutron levels in an axially-deformed relativistic quadrupole Woods-Saxon potential are analyzed. Neutron states are obtained as the solutions of the corresponding single-particle Dirac equation, using the coupled-channels method in the coordinate space. The evolution of the levels close to the continuum threshold and, in particular, the occurrence of singleneutron resonant states as the functions of the axial deformation parameter 0 β 0.5, are examined using the eigenphase representation. Calculations are performed for different values of the radius of the potential (R/r 0 ) 3 , corresponding to a variation of the mass number A.     

基于平面超材料的Fano谐振可调谐研究

基于两段相同金属分裂环谐振器构成的单层结构, 从理论及实验方面研究了平面超材料的可调谐Fano谐振. 实验测量了平面超材料对TE和TM入射波的电磁响应, 利用电磁波的入射角度控制Fano谐振的强度, 实现了谐振的开关特性, 谐振频率红移可达到21%. 基于有限元法给出了平面超材料的场分布, 强的正常色散表明平面超材料的电磁响应可类比经典电磁诱导透明现象, 仿真与实验结果相符合. 对称结构超材料Fano谐振的开/关特性为超材料性能的可调谐控制提供了有效途径.     

Observation of sub-Fourier resonances in a quantum-chaotic system

We experimentally show that the response of a quantum-chaotic system can display resonance lines sharper than the inverse of the excitation duration. This allows us to discriminate two neighboring frequencies with a resolution nearly 40 times better than the limit set by the Fourier inequality. Furthermore, numerical studies indicate that there is no limit, but the loss of signal, to this resolution, opening ways for the development of sub-Fourier quantum-chaotic signal processing.     

Perpendicular observation of resonances in a maxwellian magnetoplasma

In a direction of observation perpendicular to the magnetic field of a maxwellian magnetoplasma, both experimental and numerical results show that the relative excitation of the characteristic resonances depend on the electron density and temperature when the frequency extends from once to three times the electron gyrofrequency.