超子及K介子衰变的分枝比和平均寿命间的比例

本文应用了费曼和盖尔曼所提出的普适费米弱相互作用和同位旋守恒的强相互作用计算了各种超子、K介子衰变的分枝比和平均寿命的比例。在计算时应用了微扰论,并在大动量处将相互作用截断。在应用了查尔斯·瓦纳所给出的相互作用常数和对其余两个常数作了一定的选择之后,得到的分枝比和平均寿命之比大部分和实验结果符合,最坏相差一个因子二。如果选择本文所采用的相互作用常数,可以改进前一篇源文中K⁺介子分枝比计算结果和实验的符合程度。本文计算表明V-A普适弱相互作用确实适用于K分子和超子衰变现象,表明在解释这些现象时,必须考虑到“很强”和“较强”两类强相互作用所分别产生的影响。此外,本文还表明Λ和∑应具有相同的相对宇称,K分子和核子、超子之间的四种强相互作用中必须至少有一对是膺标量耦合。     

各向异性高压物质的电子能谱

本文以高压物质作为一种简单的各向异性金属模型,研究了静晶格场、电子间库仑相互作用和通过声子场的相互作用对单粒子元激发谱的影响。讨论了周期场中电子格林函数的微扰论级数,原则上解决了用微扰论求周期场中费米系统能谱的问题。具体计算了面心立方和体心立方高压物质的费米面和态密度,给出了数值结果。     

变容管的非线性性能及时变参量的分析

在变容管的各种参量应用中,变容管的非线性性能成为最基本的重要资料。提高变容管的非线性度,在应用中可以相应减小注入功率。在研究低注入或其他非正弦波注入应用的特性时,更应对变容管时变参量的基波及谐波分量与变容管非线性度及注入电压比等之间的关系深入研究。本文目的在于分析上述问题,选用合适的非线性性能的表示法,采用图解法求出变容管归一化时变参量的基波及谐波分量的特性,并绘出这些分量与变容管非线性度γ,注入电压比m₁之间的关系曲线。这些通用曲线在分析变容管的各种参量应用中可作为重要参考资料,并举例示出这些曲线的用途。     

6.8GeV/cπ-N非弹性作用下π0介子的产生

利用联合原子核研究所24立升丙烷气泡室照片,对动量为6.8GeV/cπ^-介子与核子非弹性作用产生π⁰介子的问题进行了研究。扫描了约2700对立体照片。在宽度为29.3厘米的有效范围内得到了1275个π^--N非弹性作用事例。在936个π^--p事例和339个π^--n事例中,观察到正电子、负电子对数目分别为240和89。考虑了气泡室对γ光子的探测效率,我们得到每个事例产生的平均π⁰介子数n_(π⁰)=1.00±0.06。γ光子的平均横动量为p_⊥γ=173MeV/c。此外,着重研究了γ光子的能量分布。在γ光子全部是由π⁰介子衰变产生以及π⁰介子和π^±介子具有相同能谱的假设下,利用在相同入射粒子能量的π^--N作用中所产生的次级π^±介子能量分布变换成γ光子的能量分布;将本实验所得的γ光子能量分布和变换得到的分布进行比较,这两个分布在实验误差范围内完全符合。     

Effects of Impurity on the Ground—State Transitions of a Quantum Dot in Strong Magnetic Field

The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field.We show,in this paper,that the implantation of an impurity ion at the center can either enhance or suppress such transitions,depending on whether it is an acceptor or a donor ion.     

Realization of Tip Tilting By 8-Step Line Tilting

By direct calculation of rotation matrices of SO(3), we show how certainspecific sequence of eight consecutive rotations of digital angles can yielda tilting of a facet mirror. We also design a detailed program specificallyto tilt an array of mirrors from planar orientation to the required focusingorientation. We describe how to use the 8-step to realize the focusing ofthe mirror array. We have found, in our designed program, an importantfeature of row-sharing during the rotations for the columns and similarlythe column-sharing during the rotations for the row. This feature can save alot of operating time during the actual realization of the mechanicalmovements.     

A Prediction of a New Dibaryon System (Ω-Ω-)Jπ=o+

The structure of a new dibaryon (ΩΩ)_o+ is studied and predicted in the framework of the chiral SU(3) quark model by solving a resonating group method equation. The binding energy of this dibaryon is around 100 MeV, the mean root square of the distance between two Ωs is 0.84 fm and the preliminary estimated mean lifetime is about two times longer than that of the free Ω. All these interesting properties and also the two negative charge units it carried could make it be easily identified experimentally in the heavy-ion collision process. The production probability of this new dibaryon in 158A GeV Pb+Pb collision is estimated using the thermal model, which is of the order of 10^-6 to 10^-5 per event; And it is expected, that with the increase of temperature, the production rate will also be increased.     

A Discussion of the Question in Connexion with the Expansion of a Divergent Series Encountered in Calculating Nuclear 2υ-2β Decay Matrix Element

It is shown that the expansion and summation of the divergent series occurring in 2υ-2β decay calculation^[1,2] can be well-defined without mathematical flaw.     

Electronic Energy Loss and Straggling of Protons in Metals

By making use of the linear-response dielectric theory and local electron density approximation, we calculate the electronic stopping cross section and energy straggling. of protons in metals. The correlation and exchange interaction of electron gas in metals is taken into consideration by introducing a local-field-correction function.in the dielectric function. The theoretical results are compared with experimental and empirical data, as well as with other previous theoretical results.     

Compression Properties of Finite Nuclear Matter at Zero and Finite Temperatures with the Skyrme Force SKM

By taking into account the finite-size effect rationally in the framework of the Hartree-Fock theory, compression properties at zero and finite temperatures of finite nuclear matter are investigated with the Skyrme force SKM^*. Energies of the isoscalar giant monopole resonance of nuclei at zero temperature calculated are found to be in agreement with experimental and empirical values.