Alpha decay in electron surrounding

The influence of atomic electron shells on the constant of alpha decay of heavy and mediummass nuclei was considered in detail. A method for simultaneously taking into account the change in the potential-barrier shape and the effect of reflection of a diverging Coulomb wave in the classically allowed region was developed. The ratios of decay probabilities per unit time for a bare nucleus and the respective neutral atom were found for some alpha-decaying isotopes.     

Theory of the nucleation of protein macromolecular ions

Protein molecules are amphoteric and exist in aqueous solution as macromolecular ions that carry a charge which depends upon temperature and pH. Despite the repulsive Coulomb forces acting between them, protein macromolecular ions can form crystals in pH buffered solutions of strong electrolytes. It is proposed that the first step in the mechanism of crystallization is the formation of crystal nuclei made from partially discharged macromolecular ions that have exchanged H⁺ with the buffer. We suggest that the strength of the bare Coulomb repulsive force is weakened by the Debye-Hückel plasma screening provided by the inert electrolyte. This screening causes the rate of nucleus formation to increase with increasing ionic strength. Extending classic nucleation theory to account for these various charge effects, the results are applied to the case of lysozyme and a calculation is made of the dependence of the steady state nucleation rate upon temperature, pH, ionic strength, and protein supersaturation. It is found that the nucleation rate increases with increasing temperature and increasing ionic strength. Under condition of fixed temperature, supersaturation, and inionic strength, the nucleation rate has local maxima at low pH, where individual lysozyme macro ions are highly charged, and at pH ? 11, where they have zero average net charge. At both pH values, the nucleus that determines the rate has minimum size. In contrast to standard nucleation theory, which ignores charge, it is found that the size of the nucleus that controls the rate is different from the size of the nucleus that has the lowest concentration. All other conditions being the same, it is predicted that lysozyme crystals should nucleate most rapidly near pH = 2 and near pH = 11.     

Time Relativity in the Dynamics of Open Quantum Systems

Various methods for determining the Coulomb logarithm in the kinetic theory of transport and various variants of the choice of the plasma screening constant, taking into account and disregarding the contribution of the ion component and the boundary value of the electron wavevector are considered. The correlation of ions is taken into account using the Ornstein–Zernike integral equation in the hypernetted-chain approximation. It is found that the effect of ion correlation in a nondegenerate plasma is weak, while in a degenerate plasma, this effect must be taken into account when screening is determined by the electron component alone. The calculated values of the electrical conductivity of a hydrogen plasma are compared with the values determined experimentally in the megabar pressure range. It is shown that the values of the Coulomb logarithm can indeed be smaller than unity. Special experiments are proposed for a more exact determination of the Coulomb logarithm in a magnetic field for extremely high pressures, for which electron scattering by ions prevails.     

Dynamic Screening in Solar and Stellar Nuclear Reactions

In the hot, dense plasma of solar and stellar interiors, Coulomb potentials are screened, resulting in increased nuclear reaction rates. Although Salpeter's approximation for static screening is widely accepted and used in stellar modeling, the question of screening in nuclear reactions was revisited in the 1990s. In particular the issue of dynamic effects was raised by Shaviv and Shaviv, who applied the techniques of molecular dynamics to the conditions in the Sun's core in order to numerically determine the effect of screening. By directly calculating the motion of ions and electrons due to Coulomb interactions, the simulations are used to compute the effect of screening without the mean‐field assumption inherent in Salpeter's approximation. In the last few years, the USC group has first reproduced Shaviv and Shaviv's numerical analysis of the screening energy, showing an effect of dynamic screening. When the consequence for the reaction‐rate was computed, a rather surprising resulted, which is contrary to that from static screening theory. Our calculations showed that dynamic screening does not significantly change the reaction rate from that of the bare Coulomb potential. If this can be independently confirmed, then the effects of dynamic screening are highly relevant and should be included in stellar nuclear reaction rates (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Core polarization effects on the Coulomb form factor

Coulomb form factors for the transitions between single-particle (or -hole) states with LS closed shells are investigated. Core polarization effects are calculated by using microscopic models. Information on the effective interaction which cannot be provided by γ-transition data alone is obtained from the momentum transfer dependence of the form factor. An effective interaction is required not to be repulsive in triplet-odd two-particle states in order to explain the experimental data on ¹⁵N. The bare G-matrix gives a reasonable fit to the data while the phenomenological interaction with Rosenfeld mixture does not. It is also shown that the core polarization effect for the Coulomb form factors with high multipolarity is sensitive to the mixing character of the effective interaction.     

Antiproton-Nucleus Interaction and Coulomb Effect at High Energies

The Coulomb effect in high energy antiproton-nucleus elastic and inelastic scattering from ¹²C and ¹⁶O is studied in the framework of Glauber multiple scattering theory for five kinetic energies ranged from 0.23 to 1.83 GeV. A microscopic shell-model nuclear wave functions, Woods-Saxon single-particle wave functions, and experimental pN amplitudes are used in the calculations. The results show that the Coulomb effect is of paramount importance for filling up the dips of differential cross sections. We claim that the present result for inelastic scattering of antiproton-¹²C is sufficiently reliable to be a guide for measurements in the very near future. We also believe that antiproton nucleus elastic and inelastic scattering may produce new information on both the nuclear structure and the antinucleon-nucleon interaction, in particular the p-neutron interaction.     

Impurity effects in the optical absorption of quantum rings

We study the interplay between impurity scattering and Coulomb interaction effects in the absorption spectrum of neutral bound magnetoexcitons confined in quantum-ring structures. Impurity scattering breaks the rotational symmetry of the ring system, introducing characteristic features in the optical emission. Signatures of the optical Aharonov–Bohm effect are still present for weak scattering and strong Coulomb screening. Furthermore, an impurity-induced modulation of the absorption strength is present even for a strong impurity potential and low screening. This behavior is likely responsible of recent experimental observations in quantum-ring structures.     

Scattering of conduction electrons by interface roughness in semiconductor heterostructures

A fluctuation transport theory is applied to describe the mobility limiting effect of interface roughness scattering in semiconductor heterostructures. As an example we consider a high mobility transistor and compare electron scattering by interface roughness with Coulomb scattering processes by ions and dipole fluctuations. We show that the dynamical resistivity measurement provides detailed information about the autocorrelation of the interface morphology.     

Ground-state energy of beryllium atom with parameter perturbation method

We present a perturbation study of the ground-state energy of the beryllium atom by incorporating double parameters in the atom's Hamiltonian. The eigenvalue of the Hamiltonian is then solved with a double-fold perturbation scheme,where the spin-spin interaction of electrons from different shells of the atom is also considered. Calculations show that the obtained ground-state energy is in satisfactory agreement with experiment. It is found that the Coulomb repulsion of the inner-shell electrons enhances the effective nuclear charge seen by the outer-shell electrons, and the shielding effect of the outer-shell electrons to the nucleus is also notable compared with that of the inner-shell electrons.     

Peculiarities of elastic scattering of intermediate-energy electrons related to their capture at quasi-stationary levels of an atom in a continuous spectrum

A theoretical model of electron scattering on an atom is constructed to study elastic atomic scattering of intermediate-energy electrons. The proposed model is based upon the combined Mensing potential with two spheres of atomic electrons, which admits analytical solutions of the radial Schröbinger equation. A procedure for matching the parameters of this scatterer to an approximate electrostatic potential of an atom in the form of a screened Coulomb potential has been determined. The screening radius of the latter potential has been calculated proceeding from the properties corresponding to the Thomas-Fermi method. A model of a scatterer determined according to the aforementioned procedure can be used to calculate the energy dependence of the cross section of elastic electron scattering on some atoms with s, p, and d shells representing elements neighboring zirconium. The main result is the establishment of factors responsible for the appearance of maxima on the energy dependences of the cross section of elastic electron scattering. These maxima are related to the resonant trapping of impinging electrons by quasi-stationary levels in a continuous spectrum.     

高能聚变产物与燃料粒子间的核加库仑相干散射

在具有较高电子温度的D－^3He聚变等离子体中,强子弹性散射、核加库仑相干散射和核反应产物的传播等效尖变得相对重要,而聚变产生的高能离子与电子的库仑相互作用变弱。部分本底燃料离子被聚变产生的高能离子轰击而成为麦克斯韦分布函数尾部的“超热”燃料离子,从而提高了D-^3He聚变反应。     

On semi-quantal approximations to heavy-ion scattering

The coupled-channel equations for heavy-ion scattering are approximately solved in a closed form, in the context of semi-quantal approach. Our solutions are shown to contain dynamic polarization potentials (arising from two and/or multi-step processes) in a natural way. A closed form treatment, of the effects of dynamic polarization by Coulomb excitation, on the elastic scattering of deformed heavy-ions is also presented. As an example, we compare our results for quadrupole Coulomb excitation of¹⁸⁴W ions by¹⁸O ions at 90 MeV, with those obtained from optical model treatments.     

Equivalent bare optical potentials in heavy-ion inelastic scattering

The equivalent bare optical potentials have been calculated for the inelastic scattering of ¹⁶O and ¹³C by ⁴⁰Ca at 60 and 68 MeV, respectively. The potentials obtained are quite consistent with those found phenomenologically by coupled-channels calculations. The shape of the bare potential is interpreted by showing the significant contribution of the nuclear—Coulomb cross term.     

Combined effects of carrier scattering and Coulomb screening on photoluminescence in InGaN/GaN quantum well structure with high In content

Photoluminescence(PL) spectra of two different green InGaN/GaN multiple quantum well(MQW) samples S1 and S2,respectively with a higher growth temperature and a lower growth temperature of InGaN well layers are analyzed over a wide temperature range of 6 K-3 30 K and an excitation power range of 0.001 mW-75 mW.The excitation power-dependent PL peak energy and linewidth at 6 K show that in an initial excitation power range,the emission process of the MQW is dominated simultaneously by the combined effects of the carrier scattering and Coulomb screening for both the samples,and both the carrier scattering effect and the Coulomb screening effect are stronger for S2 than those for S1;in the highest excitation power range,the emission process of the MQWs is dominated by the filling effect of the high-energy localized states for S1,and by the Coulomb screening effect for S2.The behaviors can be attributed to the fact that sample S2 should have a higher amount of In content in the InGaN well layers than S1 because of the lower growth temperature,and this results in a stronger component fluctuation-induced potential fluctuation and a stronger well/barrier lattice mismatchinduced quantum-confined Stark effect.This explanation is also supported by other relevant measurements of the samples,such as temperature-dependent peak energy and excitation-power-dependent internal quantum efficiency.     

Nuclear and Coulomb deformation parameters of 142Nd

Nuclear and Coulomb deformation parameters have been deduced from DWBA analyses of angular distributions of 67.5 MeV ¹³C ions inelastically scattered from ¹⁴²Nd. Optical model parameters from fits of measured elastic scattering data were used with previously measured B(EL) values to determine initial deformation parameters. Comparison With the experimental data indicates that DWBA calculations can be used to understand the inelastic scattering from the nearly spherical nucleus ¹⁴²Nd.     

Permanent confinement in the compact QED3 with fermionic matter

We argue that the compact three dimensional electrodynamics with massless relativistic fermions is always in the confined phase, in spite of the bare interaction between the magnetic monopoles being rendered logarithmic by fermions. The effect is caused by screening by other dipoles, which transforms the logarithmic back into the Coulomb interaction at large distances. Possible implications for the chiral symmetry breaking for fermions are discussed, and the global phase diagram of the theory is proposed.     

C20离子团簇在氧化物中穿行时库仑爆炸过程的理论研究

研究了C20团簇在几种金属氧化物(Al2O3,SiO2)中穿行时发生的库仑爆炸过程.采用线性介电响应理论,并结合Mermin形式的介电函数,得到了团簇中各组成离子的空间感应势,其中组成团簇中各组成离子的电荷分布情况由Brandt-Kitagawa有效电荷理论模型来描述.通过求解运动方程得到离子团结构随时间的演化过程,并采用Monte Carlo方法模拟了爆炸过程中的多重散射现象.我们发现,尾流效应使团簇的空间结构和电荷分布呈现非对称性.     

Low Energy D(p, p)D Elastic Scattering Including Coulomb Force

The motivation of this paper is to obtain the three-body amplitudes for the Coulomb potential plus a nuclear force in momentum space. Not only the two-body off-shell nuclear amplitude but also the two-body off-shell Coulomb amplitude is important in the three-body calculation. For calculating the Coulomb amplitude, the modified Coulomb potential whose Fourier transformation is analytically equivalent to the pure configuration space Coulomb potential, is introduced. In addition, the decisive screening range parameter is also utilized instead of the screening range. The modified Coulomb potential plus the parameter is called decisive modified Coulomb potential. The three-body proton-deuteron elastic scattering is calculated by using the proper two-body off-shell amplitude for the decisive modified Coulomb potential.     

Modeling of beam ions loss and slowing down with Coulomb collisions in EAST

This paper uses the implicit Monte-Carlo full-orbit-following parallel program ISSDE to calculate the prompt loss and slowing down process of neutral beam injection (NBI)-generated fast ions due to Coulomb collisions in the equilibrium configuration of Experimental Advanced Superconducting Tokamak (EAST). This program is based on the weak equivalence of the Fokker-Planck equation under Rosenbluth MacDonald Judd (RMJ) potential and Stratonovich stochastic differential equation (SDE). The prompt loss with the LCFS boundary and the first wall (FW) boundary of the two co-current neutral injection beams are studied. Simulation results indicate that the loss behavior of fast ions using the FW boundary is very different from that of the LCFS boundary, especially for fast ions with a large gyration radius. According to our calculations, about 5.11% of fast ions generated by perpendicular injection drift out of the LCFS and then return inside the LCFS to be captured by the magnetic field. The prompt loss ratio of fast ions and the ratio of orbital types depend on the initial distribution of fast ions in the P_ζ-$\varLambda$ space. Under the effect of Coulomb collisions, the pitch-angle scattering and stochastic diffusion happens, which will cause more fast ion loss. For short time scales, among the particles lost due to collisions, the fraction of banana ions reaches 92.31% in the perpendicular beam and 58.65% in the tangential beam when the fraction of banana ions in the tangential beam is 3.4% of the total ions, which means that the effect of Coulomb collisions on banana fast ions is more significant. For long time scales, the additional fast ion loss caused by Coulomb collisions of tangential and perpendicular beams accounted for 16.21% and 25.05% of the total particles, respectively. We have also investigated the slowing down process of NBI fast ions.