不等质量(1/2—1/2)或(1/2-1/2)电磁束缚系统的近似B.S.波函数

本文求解了不等质量(1/2—1/2)电磁束缚系统的Bethe-Salpeter方程. 给出了这类系统的近似B.S.波函数. 利用复合粒子量子场论的微扰展开, 在精确到O(α)的量级下, 计算了Ξ⁰→(Σ⁺μ^－)+ν_μ的衰变率和分支比, 结果是wΞ⁰→(Σ⁺μ^－)+ν_μ=1.12(1/秒)R=[wΞ⁰→(Σ⁺μ^－)+ν_μ]/[wΞ⁰→(Σ⁺μ^－)+ν_μ]≥4.7×10^－7. 类似地, 还讨论了Λ→(pμ^－)+ν_μ过程.     

立方相Na_(1/2)Bi_(1/2)TiO_3和K_(1/2)Bi_(1/2)TiO_3的电子结构和结构不稳定性的第一性原理比较研究

采用基于密度泛函理论的第一性原理方法比较研究了Na1/2Bi1/2TiO3和K1/2Bi1/2TiO3的电子结构、离子位移势能面和Γ声子等性质.结果表明,Na1/2Bi1/2TiO3和K1/2Bi1/2TiO3的电子结构很相似,价带由O 2p电子态主导并包含部分Ti 3d和Bi 6p电子态,导带低能部分由Ti 3d空轨道构成;K取代Na后其Ti—O和Bi—O键的键强略有增加.两者的离子位移势能面也很接近,O离子的偏心位移对结构不稳定性起主导作用,且K取代Na后其作用增强.Γ声子都存在3个软模,分析表明软模主要来自O6基团的振动,K取代Na后A2u软模发生硬化.     

(1/2+1/2+1)腔型热阴极微波电子枪

 介绍了一种新型的轴耦合热阴极微波电子枪的设计，该枪采用了缩短首腔以及在首腔与主加速腔间插入耦合半腔的设计思想，在不破坏粒子束性能的基础上尽量减小反轰功率，给出了用Superfish 及Pamela软件进行物理设计以及粒子动力学计算的结果，在脉冲宽度为6μs, 重复频率为25Hz时，阴极上平均反轰功率为3.6W,达到设计要求。     

2s_(1/2)—1d_(3/2)壳层原子核能谱的壳模型分析

本文对2s_(1/2)-1d_(3/2)壳层原子核(A=30—40)能谱作了系统分析,计算仅限于由2s_(1/2)和1d_(3/2)支壳层产生的情态,但考虑了它们之间的全部组态混合效应。计算是采用多粒子壳模型的Talmi方法,将二体矩阵元当作参数,其值由实验确定。文中详细分析了Si~(30),Si~(31),P~(30),P~(31),P~(32),S~(32),Ar~(37),Ar~(38),K~(38)等原子核能谱,理论与实验符合颇好。     

不等质量(1/2—■/2)或(1/2-1/2)电磁束缚系统的近似B.S.波函数

本文求解了不等质量(1/2—■/2)电磁束缚系统的Bethe-Salpeter方程。给出了这类系统的近似B. S. 波函数,利用复合粒子量子场论的微扰展开,在精确到O(α)的量级下,计算了■的衰变率和分支比,结果是■(1/秒)■类似地,还讨论了■过程.     

Stark效应诱导的类氢离子2s_(1/2)-1s_(1/2)跃迁几率的理论研究

基于微扰理论研究了静电场Stark效应诱导的类氢离子2s_(1/2)-1s_(1/2)跃迁,给出了Z=1—92类氢离子的Stark混合系数和2s_(1/2)-1s_(1/2)跃迁几率,讨论了Stark效应诱导的类氢离子2s_(1/2)-1s_(1/2)跃迁几率随原子序数的变化规律以及相对论效应对Stark混合系数和诱导跃迁几率的影响.结果表明,给定电场强度时,类氢离子的Stark诱导跃迁几率随着原子序数Z的增大单调减小.另外,相对论效应使得类氢离子的Stark诱导跃迁几率减小,甚至在Z=92时会减小到非相对论近似的55%.     

相互作用能量参数对A(B_(1/2)~1B_(1/2)~2)O_3系统有序畴形成的影响

本文利用有序-无序相变理论讨论了A(B_(1/2)~1B_(1/2)~2)O_3系统中的有序-无序相变,半定量地研究了在A(B_(1/2)~1B_(1/2)~2)O_3系统中相互作用能参数对形成B~1:B~2=1:1有序畴的影响,理论计算结果与实验结果基本一致。     

Phase transitions in the ferroelectrics (Sn1−x In(2/3)x )2P2S6 at high pressures

New ferroelectric solid solutions (Sn_1−x In_(2/3)x )₂P₂S₆ were investigated at high hydrostatic pressures. The range in which the incommensurate structure exists was determined. A dynamic shift of the incommensurate-ferroelectric phase transition temperature with increasing rate of change of temperature and the appearance of “reverse hysteresis” were observed. The characteristic features in the appearance of the latter effect in these crystals are investigated. Fiz. Tverd. Telsa (St. Petersburg) 41, 1276–1278 (July 1999)     

Subsidiary conditions of the general Gel'fand-Yaglom wave equation based on the representation (1/2,3/2)⊕(−1/2,3/2)⊕(1/2,5/2)⊕(−1/2,5/2)⊕ (1/2,3/2)⊕(−1/2,3/2)

A method is given of obtaining the subsidiary conditions of the second kind of the general Gel'fand-Yaglom wave equation based on the representation (1/2, 3/2)(–1/2, 3/2)(1/2, 5/2)(–1/2, 5/2)(1/2, 3/2)(–1/2, 3/2) and in the presence of an external electromagnetic field by reformulating the wave equation in spinor form. The wave equations accepting these subsidiary conditions form a class defined by a set of simultaneous equations that is not empty.     

舰船噪声的1(1/2)维谱特征提取

证明了１（１／２）维谱的几个基本性质，分析了由此产生的几种优良性能：可加强成整数倍谐波信号的基频分量，抑制高斯有色噪声及对称分布的噪声；剔除非二次相位耦合的谐波分量。在此基础上，将１（１／２）维谱应用于舰船噪声的目标特征分析，提出井提取了７个特征量。经过神经网络分类器的分类识别，取得了较高的识别率：Ａ类船的正确识别率为９０％，Ｂ类船的为９１．３％，Ｃ类船的为８５．７％。     

Temperature impedance spectroscopy of (1 − x)Na1/2Bi1/2TiO3-xLaMg1/2Ti1/2O3 solid solutions

The dielectric properties of (1 ? x)Na_1/2Bi_1/2TiO₃-xLaMg_1/2Ti_1/2O₃ solid solutions (0 ≤ x ≤ 0.4) were studied over the temperature range 650–1030 K by measuring the impedance spectra over the frequency range 25–10⁶ Hz. The Curie temperature T _C was determined as a function of the composition of the solid solutions. It is shown that T _C decreases linearly with increasing x. The temperature dependences of the dc component (σ_dc) and the polarization component (σ′_ac) of the real part of the conductivity are found. The activation energy for the conductivity σ_dc is shown to increase abruptly as the temperature increases above approximately 770 K for all solid solution compositions. Over the temperature range corresponding approximately to the region of existence of the tetragonal phase of Na_1/2Bi_1/2TiO₃, the polarization component σ′_ac of the solid solutions, as well as that of the pure compound, is anomalously high at low frequencies, which can be due to structural inhomogeneities.     

AN SU(4)×SU(2)×U(1) UNIFIED MODEL

In this paper we propose an SU(4)×SU(2)×U(1) unified model, in which the stratons and leptons of every generation belong to the same Multiplet, and the leptons will couple to the stratons. But this kind of coupling cannot cause the proton decay, and has only some effects in high energy scatterings. This model predicts the existense of two neutral intermediate bosons, instead of one, and the value of Weinberg angle to be sin²θ_w=0.25. The neutrinos have reasonable masses in the model.     

Strong decays of χcJ(2P) and χcJ(3P)

In the framework of the chiral quark model, the mass spectrum of χ _cJ (J = 0, 1, 2, n = 1, 2, 3) is studied with the Gaussian expansion method. Using the wave functions obtained in the study of mass spectrum, the open charm two-body strong decay widths of these states are calculated by using the ³ P ₀ model. The results show that the masses of χ _cJ (1P) and χ _c2(2P) are consistent with the experimental data. But the strong decay width of χ _c2(2P) is three times that of the experimental value. The decay width of χ _c1(2P) is sensitive to its mass. In the quark-antiquark picture, the width is about 385 MeV. However, if the channel coupling effects shift its mass to 3872 MeV, its decay width will be around 1 MeV. The possibility of assigning the state X(3872) as χ _c1(2P) cannot be excluded. To assign X(3915) as χ _c0(2P) is disfavored, due to the unmatching of decay channel. For the χ _cJ (3P) states, no states have been assigned. The possible candidates of χ _c0(3P) are X(4160) and X(4140). Their masses are close to the theoretical ones. The experimental branching ratio of X(4160), $\Gamma (X(4160) \to D\bar D)/\Gamma (X(4160) \to D*\bar D*) < 0.09$ is compatible with that of χ _c0(3P), 0.07. However the broad decay width of X(4160) cannot be explained by the open charm two-body decay. To assign X(4140) as χ _c0(3P) is also possible, due to the compatibility of the total decay width, the further measurement of decay modes of X(4140) are expected to justify the assignment.     

二维RKKY自旋玻璃的磁化率(n_m~(1/2)I<<1)

本文提出了具有非磁性缺陷(n_ml~(1/2)(?)1)的二维 RKKY 自旋玻璃模型,分别推导出高温区和低温区磁化率的表达式,应用渗流理论说明了转变温区磁化率存在尖拐状峰值的实验事实,并讨论了本模型应用的物理条件.     

基于(P)1-(P)2与a1+a2共同本征态的相干纠缠态表象的构建及性质

利用有序算符乘积内的积分技术(IWOP),建立了一种称之为相干纠缠态的两粒子体系的新表象,研究了这种新表象的性质,从理论上探讨了这种相干纠缠态的产生方法.结果表明:本文建立的这种p1-p2与a1+a2的共同本征态|p,β,既具有相干态的特性,又体现了纠缠态的特征,具有超完备性,完全可以作为一个表象使用. 物理上可以用光分束器来实现|p,β>,让分束器的两个输入端分别输入理想单模压缩态|p=0>2=exp[1-2a+22]|0>2和真空态|0>1,再经过对激光场一定的调制作用即可得到|p,β>态.     

Ferroelectric properties of Pb(Zr1/2Ti1/2)O3–Pb(Zn1/3Nb2/3)O3 ceramics under compressive stress

Effects of compressive stress on the ferroelectric properties of ceramics in PZT–PZN system were investigated. The ceramics with a formula (1−x)Pb(Zr_1/2Ti_1/2)O₃–xPb(Zn_1/3Nb_2/3)O₃ or (1−x)PZT–(x)PZN (x = 0.1–0.5) were prepared by a conventional mixed-oxide method. The ferroelectric properties under the compressive stress of the PZT–PZN ceramics were observed at the stress levels up to 170 MPa using a compressometer in conjunction with a modified Sawyer–Tower circuit. It was found that with increasing compressive stress the area of the ferroelectric hysteresis (P–E) loops, the saturation polarization (P_sat), the remnant polarization (P_r), and the coercive field (E_c) decreased. These results were interpreted through the non-180° ferroelastic domain switching processes.     

Thermal-energy Pooling Collisions in Cesium Vapor 6P_(3/2) 6P_(3/2) →7P_J 6S_(1/2)

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~(206)At的[лh_(1/2)vi_(13/2)~(-1)]10~-同质异能态研究(英文)

利用能量为６０－８０ＭｅＶ的~(１２)Ｃ束流,通过~１９７Ａｎ（~(１２)Ｃ,３ｎ）~２０６Ａｔ反应研究了~２０６Ａｔ核的高自旋能级结构．用７台ＢＧＯ（ＡＣ）ＨＰＧｅ探测器和一台用于探测低能γ射线的平面型ＨＰＧｅ探测器进行了γ射线的激发函数、γ－γ－ｔ符合及γ射线的角分布测量．基于这些测量,首次建立了包括２５条γ跃迁的~２０６Ａｔ高自旋能级纲图．确定了一个半寿命为（９０８±４００）ｎｓ、自旋和宇称为１０的同质异能态．基于较重的双奇核~(２０８,２１０ )Ａｔ能级结构的系统性,对~(２０６)Ａｔ的１０~－同质异能态进行了讨论．