A Study of a Confined Hydrogen Negative Ion

The ground and three low-excited states of the hydrogen negative ion confined by a spherical harmonic oscillator potential are studied employing the adiabatic hyperspherical approach method. Total energies are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values.     

Energy Spectrum of a Positronium Negative Ion in a Parabolic Quantum Well

The method of few-body physics is applied to calculating the energy levels of low-lying states ofa positro-nium negative ion in a parabolic quantum well. The results show that the energy levels of a positronium negativeion intwo-dimensional case are lower than those in three-dimensional case.     

A Helium Atom Confined by a Spherical Gaussian Potential Well

The helium atom confined by a non-impenetrable spherical box, i.e., a spherical Gaussian potential well which possesses finite height and range, is studied employing the exact diagonalization method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other： in general, the energies of the states decrease and the energy intervals between states increase with the reduction of the space dimensions.     

A Positronium Molecule Confined in a Two-Dimensional Space Under a Magnetic Field

Making use of hyperspherical coordinates, we investigate the qualitative features of the ground and lowlying states of a positronium molecule confined in a two-dimensional (2D) space under a magnetic field. We find that a positronium molecule has more bound states in 2D than in 3D. With the increase of the magnetic field, the second bound state experiences a transition in angular momentum. The result shows that symmetry plays an essential role in the energy spectrum of low-lying states.     

Negative Trions Trapped by a Spherical Parabolic Quantum Dot

In this paper, a negatively charged exciton trapped by a spherical parabolic quantum dot has been investigated. The energy spectra of low-lying states are calculated by means of matrix diagonalization. The important feature of the low-lying states of the negatively charged excitons in a spherical quantum dot is obtained via an analysis of the energy spectra.     

Two-dimensional hydrogen negative ion in a magnetic field

Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of a two-dimensional hydrogen negative ion H^{-} in a magnetic field. The results show that the ground and low-excited states of H^{-} in low-dimensional space are more stable than those in three-dimensional space and there may exist more bound states.     

Lattice Wave of Magnetized Spherical Dust in Radio-Frequency Sheath with Negative Ions

Lattice wave of magnetized spherical dust in radio-frequency sheath with negative ions is investigated. The dispersion relation of two-dimensional hexagonal lattice horizontal wave and the influence of negative ions and magnetic field intensity on the wave are also investigated. The results show that for two-dimensional hexagonal horizontal lattice wave, negative ions reduce the wave frequency at the range of long-wavelength, whereas raising the wave frequency at the range of short-wavelength and magnetic field contributes to dropping the wave frequency a little.     

基于氧负离子PIG源的原子氧产生装置

近地轨道能量为5eV的原子氧对航天器表面影响的地面等效模拟, 是世界各航天国家竟相研究的重要领域. 本文介绍一种基于氧负离子PIG源的原子氧产生装置, 本装置由永磁PIG离子源、两电极引出系统、电子过滤器、单透镜、减速电极和样品架组成. 目前, 这一装置已安装在中国科学院空间科学与应用研究中心小碎片加速器上, 并开展了初步实验. 当离子源放电电流50mA, 在2kV和3kV的引出电压下, 引出的氧负离子分别为200μA和300μA. 并开展了减速实验和kapton膜的溅蚀研究. 由于原子氧装置和小碎片加速器供用同一个靶室. 因此, 这一安排还可以同时开展小碎片和原子氧对空间材料的撞击和侵蚀的研究.     

Positronium annihilation in silica aerogel studied by a positron age-momentum correlation technique

A high-performance positron age-momentum correlation (AMOC) spectrometer was newly developed.The counting rate is increased up to 200 cps much larger than the value 20 cps reported by other international groups.And at the same time,the time resolution still keeps at the international level of 220 ps.Furthermore,positronium (Ps) annihilation in silica aerogel was investigated by AMOC,which indicates:(1) Ps annihilation between the grains dominantly undergoes pick-off process and spin conversion from o-Ps to p-Ps;(2) Annealing below 400 ℃ changes the grain surface conditions,i.e.the desorption of hydrogen and the decrease of the defect centers concentration.     

Positronium annihilation in silica aerogel studied by a positron age-momentum correlation technique

A high-performance positron age-momentum correlation (AMOC) spectrometer was newly developed. The counting rate is increased up to 200 cps much larger than the value 20~cps reported by other international groups. And at the same time, the time resolution still keeps at the international level of 220 ps. Furthermore, positronium (Ps) annihilation in silica aerogel was investigated by AMOC, which indicates: (1) Ps annihilation between the grains dominantly undergoes pick-off process and spin conversion from o-Ps to p-Ps; (2) Annealing below 400 ℃ changes the grain surface conditions, i. e. the desorption of hydrogen and the decrease of the defect centers concentration.     

负离子对等离子体鞘层特性影响的数值研究

构造强电负性等离子体中平板电极处鞘层形成的模型,使用流体动力学方程组研究等离子体鞘层.得到空间电势、空间静电荷分布和鞘层宽度作为距离函数的数值结果.结果表明,强电负性鞘层中,在等离子体区和鞘层区之间几乎没有过渡的预鞘区,在靠近极板附近鞘层里的电子、负离子和正离子的分布形成一个纯正离子鞘区.在靠近鞘边附近,空间静电荷密度分布有一个很尖的峰.发现同电正性情形相比,强电负性鞘层的宽度要窄很多,空间电势下降得快得多.     

Three Charged Bosons Confined in a Harmonic Trap

A system of three charged bosons confined in a harmonic trap has been investigated by an exact diagonalization. We report a calculation for the energy spectrum of the low-lying states of a system of three charged bosons. The important feature of the low-lying states of three charged bosons in a harmonic trap is obtained via an analysis of the energy spectrum.     

Three Charged Bosons Confined in a Harmonic Trap

A system of three charged bosons confined in a harmonic trap has been investigated by an exact diagonalization. We report a calculation for the energy spectrum of the low-lying states of a system of three charged bosons.The important feature of the low-lying states of three charged bosons in a harmonic trap is obtained via an analysis of the energy spectrum.     

Energy Spectrum of Helium Confined to a Two-Dimensional Space

Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of a two-dimensional helium in a magnetic field. The results show that the ground and low-excited states of helium in low-dimensional space are more stable than those in three-dimensional space and there may exist more bound states.     

Re-examining Photodetachment of H~- near a Spherical Surface using Closed-Orbit Theory

Photodeachment of H~-near a reflective spherical surface was studied by Haneef et al.[J.Phys.B:At.Mol.Opt.Phys.44(2011)195004]using a theoretical imaging method.The total cross section displays interesting oscillations.Here we re-examine the total photodetachment cross section of this system by directly applying the standard closed-orbit theory.Our result for the total cross section differs from the result obtained by Haneef et al.The difference between the two results vanishes in the limit of large radius of the reflective sphere.We argue that the theoretical imaging method developed originally for photodetachment near a Hat surface can not be directly applied to the present system.     

相对论性重离子碰撞中负粒子的横动量和赝快度分布

基于三火球模型和强子共振态衰变图象,得到了相对论性重离子碰撞中负粒子的横动量和赝快度分布,并与200和60GeV/N ¹⁶O与An相互作用的有关实验结果作了比较.     

Effect of Parabolic Potential on Bipolaron

We apply a Feynman path-integral variational approach combining with the average for the relative motion to study the stability of bipolaron in a quantum dot. The binding energy is calculated in different parameters. We find that an optimum quantum potential favors the formation of bipolaron. Compared with other methods in literature, the present pproach is better than Laudau-Pekar one in all coupling regime and full path-integral one in the strong coupling regime.     

A Study of Confined Helium Atom

The helium atom confined by a spherical parabolic potential well is studied employing the adiabatic hyperspherical approach method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the energies of a spherical parabolic potential well are in good agreement with those of an impenetrable spherical box for the larger confined potential radius. We find also that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other. We find that the energy difference between states in a two-dimensional parabolic potential is also obviously larger than the corresponding levels for a spherical parabolic potential.     

Effect of Parabolic Potential on Bipolaron

We apply a Feynman path-integral variational approach combining with the average for the relative motion to study the stability of bipolaron in a quantum dot. The binding energy is calculated in different parameters. We find that an optimum quantum potential favors the formation of bipolaron. Compared with other methods in literature, the present approach is better than Laudau Pekar one in all coupling regime and full path-integral one in the strong coupling regime.     

A Study of Confined Helium Atom

The helium atom confined by a spherical parabolic potential well is studied employing the adiabatic hyperspherical approach method. Total energies of the ground and three low-excited states are obtained as a function of the confined potential radii. We find that the energies of a spherical parabolic potential well are in good agreement with those of an impenetrable spherical box for the larger confined potential radius. We find also that the confinement may cause accidental degeneracies between levels with different low-excited states and the inversion of the energy values. The results for the three-dimensional spherical potential well and the two-dimensional disc-like potential well are compared with each other. We find that the energy difference between states in a two-dimensional parabolic potential is also obviously larger than the corresponding levels for a spherical parabolic potential.