核介质中核子–核子散射截面的BHF微观计算

在Brueckner-Hartree-Fock(BHF)框架下,计算了核介质中核子-核子(N-N)散射总截面.计算中,N-N相互作用势采用Paris势的可分离表示,单粒子谱采用连续选择.计算结果表明,质子-质子散射及质子-中子散射的总截面随核密度的增加而强烈地减小,特别是对低能散射.对结果作了简单的讨论,并与已有的一些计算结果进行了比较.     

核介质中核子－核子散射截面的BHF微观计算

在Ｂｒｕｅｃｋｎｅｒ－Ｈａｒｔｒｅｅ－Ｆｏｃｋ（ＢＨＦ）框架下，计算了核介质中核子－核子（Ｎ－Ｎ）散射总截面．计算中，Ｎ－Ｎ相互作用势采用Ｐａｒｉｓ势的可分离表示，单粒子谱采用连续选择．计算结果表明，质子－质子散射及质子－中子散射的总截面随核密度的增加而强烈地减小，特别是对低能散射．对结果作了简单的讨论，并与已有的一些计算结果进行了比较．     

高能核子—核子散射的带区近似

最近Chew—Frautchi提出了双重色散关系的带区近似(Strip approximation),由于高能散射存在绕射现象,他们认为对于高能散射带区4μ~2相似文献   

质子滴线核12N在28Si靶上的核反应总截面测量

描述了50.4MeV/u的¹²N和42.3MeV/u的¹³N次级放射性束在²⁸Si靶上引起的核反应总截面σ_r实验研究,结果发现¹²N的反应总截面σ_r比其相邻同位素核¹³N有着异常的增大.这可能是核形变及核子对效应造成的,试验中的测量误差也不可忽视.利用微观Glauber模型计算了¹²N在²⁸Si靶上的核反应总截面,并与实验结果做了比较,发现理论计算与实验结果拟合较好 关键词： 质子晕 反应截面     

核子-核子碰撞截面对同位素标度参数α的介质效应

核子能量在40—60MeV能区范围,对在两对重离子中心碰撞系统⁴⁰Ca+⁴⁸Ca和⁶⁰Ca+⁴⁸Ca以及¹¹²Sn+¹¹²Sn和¹²⁴Sn+¹²⁴Sn 的反应中就同位素标度参数α对于核子-核子碰撞截面σ^med_NN(α_m)的介质 关键词： 同位素标度行为 介质效应 核子-核子碰撞截面 重离子碰撞     

光子-核子散射的双谱函数和γ+p→p+π++π-非弹性截面

本文将带区近似法推广到光子-核子散射过程。由t道弹性么正条件导出了光子-核子散射的带区谱函数和s道散射振幅的吸收部分,由此计算了光生π介子的非弹性截面,并与实验作了比较。     

一种考虑几何屏蔽效应的计算“电子-分子”散射总截面的可加性规则修正方法

在考虑分子内原子间的几何屏蔽效应随电子入射能量变化的基础上, 提出了一种能够在中、高能区准确计算“电子-分子”散射总截面的可加性规则修正方法. 利用这一修正后的可加性规则并使用“电子-C, H, O, N原子”散射总截面的实验数据, 在50—5000 eV内计算了电子被NO, N₂O, NO₂和C₂H₆分子散射的总截面, 且将计算结果与实验结果及其他理论结果进行了比较. 结果表明, 利用这一方法修正过的可加性规则进行计 关键词： 电子散射 可加性规则 总截面 几何屏蔽效应     

核子-核子碰撞截面对同位素标度参数α的同位旋效应

对两对重离子中心碰撞系统⁴⁰C+⁴⁰Ca 和⁶⁰Ca+⁴⁰Ca以及¹¹²Sn+¹¹²Sn和¹²⁴Sn+¹²⁴Sn反应中就同位素标度参数α对于核子-核子碰撞截面的同位旋效应进行了研究.计算结果表明α对同位旋相关核子-核子碰撞截面σ^med_{NN关键词： 同位旋效应 核子-核子截面 机理 同位素标度}     

用角动量投影壳模型研究129La的单准质子带

将角动量投影壳模型应用到¹²⁹La核,对单准质子带理论计算与实验结果进行了比较,与组态为πh_11/2的yrast带和组态为πg_7/2带的拟合令人满意-还确认了一个组态为πg_7/2［νh_11/2］²的扁椭球带- 关键词：     

50—5000 eV电子被C4H8O,C5H10O2, C6H5CH3和C4H8O2散射的总截面

使用电子被C, H和O原子散射总截面的实验数据, 利用修正后的可加性规则计算了能量为50—5000eV的电子被4个复杂大分子C₄H₈O, C₅H₁₀O₂, C₆H₅CH₃和C₄H₈O₂散射的总截面, 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. 结果表明, 即 关键词： 电子散射 可加性规则 总截面 几何屏蔽效应     

高能宇宙线粒子与石蜡核作用的角分布

本文描述一个利用云室研究高能宇宙线粒子与石蜡的核作用中次级粒子角分布的实验。共分析了64个n_s≥4的事例,其平均初能E₀≈70BeV。结果表明,在此能区,次级粒子在CMS中,角分布不是各向同性,而在0°和180°方向呈现极大,且有相当比例(≥20％)事例的角分布形式显示出火球模型给出图象。     

The real part of the amplitude of proton-proton scattering at an energy of 3 GeV

Measurement of the differential cross-sections of proton-proton scattering at an energy of 3 GeV is described. The measurement was performed in the region of angles from 2·4° to 16·2°. Analysis of the experimental data shows that besides the imaginary scattering amplitude a real part is also necessary in order to describe elastic scattering at an energy of 3 GeV; the magnitude of the real part is 24% of the magnitude of the imaginary part.It is the authors' pleasant duty to thank V. Sviridov, V. Nikitin, M. afranova and L. Kirillova from the High Energy Laboratory of the Joint Institute of Nuclear Research in Dubna for their help in irradiating the emulsions and monitoring the primary proton beam, and also to Prof. V. Petrílka for stimulating interest and suport in the work.     

Coupling effects of resonant and discretized non-resonant continuum states in 4He + 6Li scattering at 10 MeV/A

Alpha-particle scattering from the resonant (3 ₁ ⁺ ) and non-resonant continuum states of ⁶Li is studied at incident energy 10 MeV/A. The α + d breakup continuum part within the excitation energy E _ex = 1.475–2.475 MeV is discretized in two energy bins. Unlike the results at higher incident energies, here the coupled-channel calculations show significant breakup continuum coupling effects on the elastic and inelastic scattering. It is shown that even when the continuum-continuum coupling effects are strong, the experimental data of the ground state and the resonant as well as discretized non-resonant continuum states impose stringent constraint on the coupling strengths of the non-resonant continuum states.     

The real part of the amplitude of proton-deuteron scattering at an energy 3 GeV

Measurement of the differential cross-sections of the proton-deuteron scattering at 3 GeV is described. Measurement was performed in the region of angles 2.5° to 11.5°. Analysis of the experimental data shows that besides the imaginary scattering amplitude a real part of the scattering amplitude is also required to describe proton-deuteron scattering at 3 GeV energy; the magnitude of the real part is 28% of the imaginary part.Behová 7, Praha 1, Czechoslovakia.We gratefully acknowledge the assistance of the JINR staff and their valuable services.     

Coupling effects of resonant and discretized non-resonant continuum states in4He +6Li scattering at 10 MeV/A

Alpha- particle scattering from the resonant (3 ₁ ⁺ ) and non-resonant continuum states of⁶Li is studied at incident energy 10 MeV/A. Theα+d breakup continuum part within the excitation energyE _ex=1.475–2.475 MeV is discretized in two energy bins. Unlike the results at higher incident energies, here the coupled-channel calculations show significant breakup continuum coupling effects on the elastic and inelastic scattering. It is shown that even when the continuum-continuum coupling effects are strong, the experimental data of the ground state and the resonant as well as discretized non-resonant continuum states impose stringent constraint on the coupling strengths of the non-resonant continuum states.     

Analysis of experimental data on neutron-proton scattering in the energy range between 0 and 150 keV

Experimental data on neutron-proton scattering in the energy range between 0 and 150 keV are analyzed by using various sets of effective-range parameters. It is shown that, in contrast to the parameters corresponding to the phase shifts of a Nijmegen group, the parameters corresponding to the experimental phase shifts reported by a group from George Washington University (GWU group) lead to very good agreement between the calculated cross sections and their experimental counterparts in the energy region under consideration. On the basis of the experimental value of the cross section for neutron—proton scattering at an energy of 2 keV, the total cross section for neutron-proton scattering at zero energy was found to be σ ₀ = 20.428(16) b, which is in very good agreement with a value of σ ₀ = 20.423(9) b, which was obtained as the weighted mean of the cross sections presented by Houke and Hurst. It is shown that, in the energy region around several tens of keV units, the effective-range parameters matched with Dilg’s cross-section value of σ ₀ = 20.491(14) b lead to calculated cross sections whose values are in excess of their experimental counterparts.     

The use of unitarity bounds for a stable extrapolation of low energy data

The properties of the scattering amplitude allow to define a functionf(z) satisfying the following conditions:

1. f(z) is holomorphic in a simply connected domain , which can be mapped conformally onto the unit disk;
2. |Imf(z)| is bounded by some constantM in ;
3. |Ref(z)| is known not to exceed some constantm on a certain part Γ₁ of the boundary Γ of ;f(z) is continuously extensible onto Γ.

Using these properties, constraints are derived on the real part off(z) valid at any point . The result is used for performing a stable extrapolation of low energy pion-pion scattering data to any finite energy. We derive a bound on energy averaged values of the real part of the scattering amplitude. The bound depends onm, M, on the energy variabless and on the energy average intervals ₂?s ₁. Generalizations of the method are discussed.     

On the hole scattering anisotropy in the PbSb<Subscript>2</Subscript>Te<Subscript>4</Subscript> layered compound from data on the Nernst-Ettingshausen coefficient

Three independent components of the Nernst-Ettingshausen coefficient tensor Q _ikl are experimentally measured for an anisotropic single crystal of the p-PbSb₂Te₄ layered compound. The components Q ₁₂₃ and Q ₁₃₂ are found to be negative, whereas the component Q ₃₂₁ is positive. The experimental data on the anisotropy of the Nernst-Ettingshausen coefficient are discussed together with the available data on the thermopower, the Hall effect, and the electrical conductivity. The analysis demonstrates that the experimental data on the transport effects in p-PbSb₂Te₄ can be explained within a one-band model of the band spectrum and a mixed mechanism of hole scattering under the assumption that scattering from acoustic phonons and scattering from impurity ions are dominant in the cleavage plane and along the c ₃ trigonal axis, respectively.     

<Emphasis Type="Italic">K</Emphasis><Superscript>±</Superscript><Emphasis Type="Italic">p</Emphasis> elastic scattering in the QCD inspired eikonalized model

Based on our previous study of the QCD inspired eikonalized model for describing vector meson photoproduction, pp, and \(\bar p\) p elastic scattering at high energies, we apply the mode to high energy K ^± p elastic scattering. The total cross section σ _tot(s), differential cross section dσ/dt, the ratio of the real part to imaginary part of the forward scattering amplitude ρ(s), and nuclear slope parameter function β(s) are calculated in the model. Our results show that the theoretical prediction for σ _tot(s) is in a good agreement with the experimental data within error bars of the data. For the other theoretical predictions there are no data to test the predictive power of the model. We need the corresponding experimental data to examinate the validity of our QCD inspired eikonalized model. However, our calculations clearly show that the Odderon exchange in the process makes a significant contribution to the observable of ρ(s) and β(s). Therefore, we may conclude that there is a good opportunity to find the QCD Odderon in the K ^± p elastic scattering at high energies.