Probing proton halo of the exotic nucleus ~(28)S by elastic electron scattering

~~Probing proton halo of the exotic nucleus ~(28)S by elastic electron scattering~~     

Probing proton halo of the exotic nucleus28S by elastic electron scattering

Science China Physics, Mechanics & Astronomy - Elastic electron scattering on the exotic light nucleus28S is investigated in the plane wave Born approximation. The variation of the squared form...     

Differential, elastic integral and moment transfer cross sections for electron scattering from N2 at intermediate- and high-energies

A complex optical model potential modified by incorporating the concept of bonded atom, with the overlapping effect of electron clouds between two atoms in a molecule taken into consideration, is firstly employed to calculate the differential cross sections, elastic integral cross sections, and moment transfer cross sections for electron scattering from molecular nitrogen over the energy range 300—1000eV by using additivity rule model at Hartree—Fock level. The bonded-atom concept is used in the study of the complex optical model potential composed of static, exchange, correlation polarization and absorption contributions. The calculated quantitative molecular differential cross sections, elastic integral cross sections, and moment transfer cross sections are compared with the experimental and theoretical ones wherever available, and they are found to be in good agreement with each other. It is shown that the additivity rule model together with the complex optical model potential modified by incorporating the concept of bonded atom is completely suitable for the calculations of differential cross section, elastic integral cross section and moment transfer cross section over the intermediate- and high-energy ranges.     

BeCl_2分子的低能电子弹性散射研究

基于R矩阵理论方法,通过构建BeCl_2分子的静态交换势模型(SE),静态交换加极化势模型(SEP)和密耦合模型(CC),在0-10 eV能量范围内首次研究了低能电子与BeCl_2分子的散射动力学过程,预测了弹性散射积分截面,并在三种模型中分别发现一个来自B_(2u)和B_(3u)对称性贡献的势形共振态.讨论了这些共振态随着极化效应的变化,获得了收敛的截面和共振态结果.进一步使用POLYDCS程序首次计算了电子与BeCl_2分子的散射微分截面(DCS)以及动量转移截面(MTCS).当前研究结果将为天体物理和等离子体物理提供重要的截面数据.     

中高能电子被O2及CF4分子散射的微分截面、弹性积分截面及动量转移截面

利用可加性规则，使用Roothaan-Hartree-Fock波函数，采用由束缚原子概念修正过的复光 学势，在300—1000eV内若干个能量点处计算了电子被O₂及CF₄分子 散射的微分截面、 弹性积分截面及动量转移截面，并将计算结果与实验结果及其他理论计算结果进行了比较. 比较的结果表明，利用被束缚原子概念修正过的复光学势及可加性规则进行计算，所得微分 散射截面的精度要比利用未修正的复光学势及可加性规则进行计算得到的结果准确得多；同 时，计算得到的弹性积分截面及动量转移截面也比较接近实验值.因此，在复光学势中采用 束缚原子概念可提高电子被分子散射的微分截面、弹性积分截面及动量转移截面的计算准确 度. 关键词： 电子散射 可加性规则 微分截面 弹性积分截面     

中、高能电子被SO2分子散射的微分截面、动量转移截面及弹性积分截面

在考虑分子内成键原子间的电子云重叠效应的基础上, 提出了一种能够准确计算“中、高能电子-分子”散射的微分截面、动量转移截面及弹性积分截面的修正势方法. 利用可加性规则、使用Hartree-Fock波函数并采用被这一方法修正过的复光学势, 在100—1000eV内对电子被SO₂分子散射的微分截面、动量转移截面及弹性积分截面进行了计算, 并将计算结果与实验及其他理论结果进行比较. 结果表明, 利用这一修正过的复光学势及可加性规则获得的微分截面比利用未修正的复光学势及可加性规则得到的结果准 关键词： 可加性规则 微分截面 动量转移截面 电子散射     

Accurate calculation of the elastic scattering properties of ^7Li atoms at ultralow temperatures

The elastic scattering properties for collisions between two ^7Li atoms are investigated in the cold and ultracold regimes separately. Based on recent theoretical and experimental results, we present the improved hybrid potentials for the singlet X^1 ∑g^＋ and triplet a^3 ∑u^＋ ground states of the Li2, Our calculated values for the scattering lengths α and the effective ranges re are compared with previous ones, and found them to be in good agreement. The scattering lengths are 34.6α0 for the singlet state and -27.6α0 for the triplet state. Shape resonances occur in the collisions at low energies. We also calculate the total cross sections and the energy positions of shape resonances for both X^1 ∑g^＋ and a^3 ∑u^＋ states.     

Calculation of scattering parameters for ultracold ~6 Li-~7 Li elastic collisions

This paper theoretically studies the elastic scattering properties in a mixture of 6 Li and 7 Li atoms at cold and ultracold temperatures.Based on the constructed accurate interatomic potential of the triplet state for 6 Li 7 Li mixture by the mass scaling method,it calculates the interspecies s-wave scattering lengths and the p-wave scattering lengths by the variable phase method and the semiclassical method,respectively.The scattering length is in good agreement with the experiment.The partial-wave and total cross sections are also calculated and a rich resonance structure is found.     

Elastic electron scattering with CH2Br2 and CCl2Br2: The role of the polarization effects

We present elastic electron scattering cross sections with holmethane molecules CH₂Br₂ and CCl₂Br₂ in the low-energy region ranging from 0.01 eV to 20 eV. The calculations are performed with the R-matrix method in static-exchange plus polarization (SEP) and close-coupling (CC) approximations. The integral, differential, and momentum transfer cross sections are calculated. The convergence of the obtained cross sections is checked at four different levels of SEP approximation. The predicted positions of the resonances agree well with available results. The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. We find that the polarization has a substantial effect on the cross sections, and this effect becomes even more important for lower impact energies.     

Calculation of the elastic scattering properties for cold and ultracold 39K atoms in a triplet state

The elastic scattering properties for collisions between cold and ultracold 39K atoms in a triplet state are investigated. Based on the recent theoretical and experimental results, the improved hybrid potential is presented for a triplet α3∑u^＋ ground state of K2. Our calculated value of the s-wave scattering length a by using the Numerov method for the triplet state is 79.578α0 and found to be in good agreement with the previous ones. The numbers of bound states are supported by the molecular potential. Pronounced shape resonances appear for the l = 3 partial waves for the α3∑u^＋ state. Furthermore, the s-wave scattering cross section, the total cross section and energy positions of shape resonances for the α3∑u^＋ state are calculated.     

中、高能电子被SO2分子散射的微分截面、动量转移截面及弹性积分截面

在考虑分子内成键原子间的电子云重叠效应的基础上,提出了一种能够准确计算“中、高能电子-分子”散射的微分截面、动量转移截面及弹性积分截面的修正势方法.利用可加性规则、使用Hartree-Fock波函数并采用被这一方法修正过的复光学势,在100—1000eV内对电子被SO2分子散射的微分截面、动量转移截面及弹性积分截面进行了计算,并将计算结果与实验及其他理论结果进行比较.结果表明,利用这一修正过的复光学势及可加性规则获得的微分截面比利用未修正的复光学势及可加性规则得到的结果准确得多,计算得到的动量转移截面及弹性积分截面在入射电子能量不低于200eV时也都比较接近实验值.     

超冷钠原子弹性散射特性的精确计算

基于精确的原子之间相互作用势,系统研究了钠原子在超冷温度下的弹性散射特性,精确计算了钠原子间碰撞时的s波散射长度、有效力程、p波散射长度以及束缚态数目等散射参数.超冷温度下单重态和三重态原子间的弹性散射截面主要为s波贡献,随着碰撞能量的增加散射截面有丰富的形状共振出现,计算发现单重态和三重态散射截面分别存在显著的f波和i波形状共振.应用简并内态近似方法获得了超精细态相互作用时的s波散射长度,所得结果与精确值比较符合.     

乙炔分子的低能电子弹性散射研究

本文采用R矩阵方法研究低能电子与乙炔分子的弹性散射截面及其动力学过程.研究采用静态交换势模型(SE)和静态交换加极化势模型(SEP)两种方法.结果显示当前SEP模型预测的弹性散射截面与已有的实验值和理论结果符合的很好.SE模型预测了一个位于4.75 eV,宽度为3.0 eV的π形状共振态.该共振态在SEP模型中的位置降低为2.65 eV,宽度为1.5 eV.它来自B_(2g)和B_(3g)对称性贡献,理论预测共振态位置与实验值符合的很好.我们讨论了考虑不同的虚轨道对共振态的影响,说明预测精确的共振态的位置需要准确的处理极化效应.基于SEP模型得到的K矩阵元,我们使用POLYDCS代码计算的散射微分截面(DCS),和实验值符合的较好.除此之外,我们还报道了2 eV时转动分辨的态-态微分截面.     

Absolute differential, elastic integrated and moment transfer cross sections for electron--OCS collisions at intermediate and high energies

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between atoms in a molecule, is firstly employed to calculate the absolute differential, elastic integrated and moment transfer cross sections for electron scattering by OCS over the incident energy range from 200 to 1000\,eV using the additivity rule model at Hartree--Fock level. The calculated results are compared with those obtained by experiment and other theories wherever available, and good agreement is obtained over a wide energy range. It is shown that the additivity rule model together with the modified potential is completely suitable for calculating the absolute differential, elastic integrated and moment transfer cross sections of electron scattering by molecules such as OCS.     

超冷温度下钾和铯原子间弹性散射特性的精确计算

本文分别用量子方法和半经典方法计算了超冷钾和铯原子之间弹性碰撞的s波散射长度,有效力程和p波散射长度等散射参数. 超冷温度下³⁹K-¹³³Cs原子间的弹性散射截面主要为s波贡献,随着碰撞能量的增加散射截面有丰富的形状共振出现, 计算发现单重态和三重态截面分别存在显著的g波和d波形状共振.另外,本文应用简并内态近似方法获得了⁴¹K-¹³³Cs 超精细态相互作用时的s波散射长度.     

Recent results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering

The results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering are reported based on a simple hadronic model. The corrections are calculated including the nucleon and △（1232） intermediate states. And the numerical results are also compared with the recent results reported by other group and other methods.     

Recent results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering

The results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering are reported based on a simple hadronic model. The corrections are calculated including the nucleon and △(1232) intermediate states. And the numerical results are also compared with the recent results reported by other group and other methods.     

Total cross sections for electron scattering from fluoromethanes: A revised additivity rule method

The additivity rule for electron-molecule scattering is revised by considering the difference between the free atom and the bound atom in the molecule.The total cross sections for electron scattering from fluoromethanes(CF4,CF3H,CF2H2,and CFH3) are calculated in an energy range from 100 eV to 1500 eV by the revised additivity rule.The present calculations are compared with the original additivity rule results and the available experimental data.Better agreement with each other is obtained.     

Probing the halo and cluster structure of exotic nuclei

The Halo and cluster structure at the ground state of unstable nuclei are among the most exciting phenomena of current nuclear physics. Probing these structures requires a careful selection of reaction tools. In the past twenty years, knockout reactions have been used intensively to investigate spectroscopically the structure of unstable nuclei. In this report we have illustrated the latest development of the knockout reaction tool and have emphasized the recoiled proton tagging method. A quantitative criteria is developed to evaluate the quasi-free feature of the knockout process. The newly discovered "towing mode" reaction tool is also outlined and its applicability at transit energies is discussed.