Enhancement of the electric dipole moment of the electron in PbO

The a(1) state of PbO can be used to measure the electric dipole moment of the electron d(e). We discuss a semiempirical model for this state, which yields an estimate of the effective electric field on the valence electrons in PbO. Our final result is a lower limit on the measurable energy shift, which is significantly larger than was anticipated earlier: 2/W(d)/d(e)>or=2.4x10(25) Hz[d(e) divided by e cm].     

Schiff moment of the mercury nucleus and the proton dipole moment

We calculated the contribution of internal nucleon electric dipole moments to the Schiff moment of (199) Hg. The contribution of the proton electric dipole moment was obtained via core polarization effects that were treated in the framework of random phase approximation with effective residual forces. We derived a new upper bound |d(p)|<5.4 x 10(-24)e cm of the proton electric dipole moment.     

New limit on the electron electric dipole moment

We present the result of our most recent search for T violation in 205Tl, which is interpreted in terms of an electric dipole moment of the electron d(e). We find d(e) = (6.9 +/- 7.4)x10(-28)e cm, which yields an upper limit /d(e)/ < or = 1.6x10(-27)e cm with 90% confidence. The present apparatus is a major upgrade of the atomic beam magnetic-resonance device used to set the previous limit on d(e).     

Magnetic resonance imaging of electroconvection in a polar organic solvent

Molecular motion in the polar organic solvent nitrobenzene induced by an electric field is studied by magnetic resonance imaging. Rf pulse sequences that correlate images obtained at two different times under conditions of both continuous and pulsed electric fields are introduced. The resultant image correlation spectra indicate that the time scale of motion in a 9.6 kV/cm electric field is tens of milliseconds. Comparison of the results to an analytic solution for the Fokker-Planck probability function for one-dimensional bounded diffusion yields an electric field dependent effective diffusion coefficient for perdeuterated nitrobenzene of D = 1.08 x 10(-5) cm(2)/s + (3.33 x 10(-3) cm(4)/kV(2)s) E(2) at room temperature. Characteristics of this electroconvection and its consequences for combining multidimensional nuclear magnetic resonance with electrical orientation are also discussed.     

Calculation of P, T-odd effects in 205TlF including electron correlation

A method and codes for two-step correlation calculations of heavy-atom molecules have been developed, employing the generalized relativistic effective core potential (GRECP) and relativistic coupled cluster (RCC) methods at the first step, followed by nonvariational one-center restoration of proper four-component spinors in the heavy cores. Electron correlation is included for the first time in an ab initio calculation of the interaction of the permanent P,T-odd proton electric dipole moments with the internal electromagnetic field in a molecule. Inclusion of electron correlation by GRECP/RCC has a major effect on the P,T-odd parameters of 205TlF, decreasing M by 17% and X by 22%.     

AunPt-阴离子小团簇的量子化学研究

在相对论有效势(RECP)近似下,用基于密度泛函理论(B3LYP)的从头计算方法和LANL2DZ基组,系统研究了阴离子团簇AunPt-(n=1-5)g能的几何构型和电子态,确定了低能量异构体.结果表明.AunPt-团簇的剩余电子改变了中性团簇AunPt的稳定结构,这种影响随团簇体积的增大而减小.     

重复Tesla变压器型相对论电子束加速器的初步试验

研制了一台重复率 Tesla型相对论电子束加速器。空心 Tesla变压器对充油Blumlein传输线充电 ;主开关为自击穿油间隙 ;二极管为平面阴极有箔二极管。试验在重复率为 0 .2 Hz和 1 Hz下分别进行。当重复率为 0 .2 Hz时 ,加速器连续重复放电 70次以上。二极管电压幅值 3 0 0 k V,脉宽 3 0 ns,上升沿约     

带电粒子在电磁场中动态受力平衡条件

导体的电平衡条件为E =0 ,这是静电学中一个重要结论 ,但它显然不是相对论协变的 .由于洛伦兹力公式F =q(E +v×B)为相对论协变式 ,故带电粒子 (包括导体中的自由电子 )在电磁场中动态受力平衡条件即应为E +v×B =0 .这个条件是相对论协变的 ,即它在任何惯性系中均成立 .     

Structural analysis and crystal-field calculations of Nd³⁺ in Gd_x Lu_1-x TaO₄（x = 0.85） polycrytalline

The crystal structural parameters of Nd 3+-doped rare earth orthotantalate Gd x Lu 1 x TaO 4(x = 0.85) are determined by applying the Rietveld refinement to its X-ray diffraction,and its emission and excitation spectra at 77 K are analysed.The relativistic model of ab initio self-consistent DV-Xα method,which is applied to the cluster NdO 8 in Gd x Lu 1 x TaO 4,and the effective Hamiltonian model are used to investigate its spin-orbit and crystal-field parameters.The free-ions and crystal-field parameters are fitted to the experimental energy levels at 77 K with a root-mean-square deviation of 14.92 cm 1.According to the crystal-field calculations,96 levels of Nd 3+ are assigned.Finally,the fitting results of free-ions and crystal-field parameters are compared with those already reported for Nd 3+:YAlO 3.The results indicate that the free-ion parameters are similar to those of the Nd3+ in Gdx Lu1-x TaO4 and YAlO 3 hosts,and the crystal-field interaction of Nd3+ in Gdx Lu1-x TaO4 is stronger than that in YAlO 3.     

Reappraisal of the electric dipole moment enhancement factor for thallium

The electric dipole moment (EDM) enhancement factor of atomic Tl is of considerable interest as it has been used in determining the most accurate limit on the electron EDM to date. However, its value varies from -179 to -1041 in different approximations. In view of the large uncertainties associated with many of these calculations, we perform an accurate calculation employing the relativistic coupled-cluster theory and obtain -466, which in combination with the most accurate measurement of Tl EDM [Phys. Rev. Lett. 88, 071805 (2002)] yields a new limit for the electron EDM: |d(e)| < 2.0 × 10?2?e cm.     

Density Functional Study of Cationic and Anionic Ag_mCu_n (m + n ≤ 5) Clusters

The structural and energetic properties of bimetallic Ag m Cu n clusters (m + n ≤ 5) in the cationic and anionic charged states have been investigated by density functional theory with relativistic effective core potentails.The stable cationic pentamers have three-dimensional structures in contrast to anionic clusters assume planar structures.For the given cluster size the electron affinities decrease as the Cu content increases,while no clear trend can be found in adiabatic ionization potentials.The binding energy per atom also increases with the increasing Cu content and follows the order anion cation.The most probable dissociation channels of the clusters considered are also discussed.     

Shell mix in the compressed core of spherical implosions

The Rayleigh-Taylor instability in its highly nonlinear, turbulent stage causes atomic-scale mixing of the shell material with the fuel in the compressed core of inertial-confinement fusion targets. The density of shell material mixed into the outer core of direct-drive plastic-shell spherical-target implosions on the 60-beam, OMEGA laser system is estimated to be 3.4(+/-1.2) g/cm(3) from time-resolved x-ray spectroscopy, charged-particle spectroscopy, and core x-ray images. The estimated fuel density, 3.6(+/-1) g/cm(3), accounts for only approximately 50% of the neutron-burn-averaged electron density, n(e)=2.2(+/-0.4)x10(24) cm(-3).     

Enhanced electric dipole moment of the muon in the presence of large neutrino mixing

The electric dipole moment (edm) of the muon ( d(e)(&mgr;)) is evaluated in supersymmetric models with nonzero neutrino masses and large neutrino mixing arising from the seesaw mechanism. It is found that if the seesaw mechanism is embedded in the framework of a left-right symmetric gauge structure, the interactions responsible for the right-handed neutrino Majorana masses lead to an enhancement in d(e)(&mgr;) to values as large as 5x10(-23)e cm, with a correlated value of (g-2)(&mgr;) approximately 13x10(-10). This should provide a strong motivation for improving the edm of the muon to the level of 10(-24)e cm as has recently been proposed.     

Measurement of the electron electric dipole moment using YbF molecules

The most sensitive measurements of the electron electric dipole moment d(e) have previously been made using heavy atoms. Heavy polar molecules offer a greater sensitivity to d(e) because the interaction energy to be measured is typically 10(3) times larger than in a heavy atom. We have used YbF to make the first measurement of this kind. Together, the large interaction energy and the strong tensor polarizability of the molecule make our experiment essentially free of the systematic errors that currently limit d(e) measurements in atoms. Our first result d(e) = (-0.2+/-3.2)x10(-26)e cm is less sensitive than the best atom measurement but is limited only by counting statistics and demonstrates the power of the method.     

New limit on the permanent electric dipole moment of 199Hg

We present the first results of a new search for a permanent electric dipole moment of the 199Hg atom using a UV laser. Our measurements give d(199Hg) = -(1.06+/-0.49+/-0.40)x10(-28)e cm. We interpret the result as an upper limit absolute value [d(199Hg)]<2.1x10(-28)e cm (95% C.L.), which sets new constraints on theta bar;(QCD), chromo-EDMs of the quarks, and CP violation in supersymmetric models.     

Theory of electric polarization in multiorbital Mott insulators

The interaction between the electric field E and spins in multiorbital Mott insulators is studied theoretically. We find a generic coupling mechanism, which works for all crystal lattices and which does not involve relativistic effects. It couples E to the "internal" electric field e originating from the dynamical Berry phase. We discuss several effects of this interaction: (i) an unusual electron spin resonance, (ii) the displacement of spin textures in an applied electric field, and (iii) the resonant absorption of circularly polarized light by Skyrmions, magnetic bubbles, and magnetic vortices.     

Relativistic effects in the variable-screening model

The variable-screening model devised for a quantitative treatment of screening effects in slow (quasimolecular) ion-atom collisions is extended to include relativistic effects. Relativistic correction terms corresponding to a relative energy correction of second order in the electron velocity are incorporated into the effective molecular single-electron Hamiltonian. The model is applied to the calculation of relativistic molecular-orbital correlation diagrams for the quasimolecular systems Br+Br, Xe+Xe, and I+Au. A detailed comparison of our results with the results of relativistic calculations for (unscreened) one-electron systems and calculations based on self-consistent field methods is performed. The agreement with Dirac-Fock-Slater results is fairly good, and could be improved further by read-justing the values of the parameters in the atomic potentials used to construct the effective molecular potential.     

Relativistic effects in the variable-screening model

The variable-screening model devised for a quantitative treatment of screening effects in slow (quasimolecular) ion-atom collisions is extended to include relativistic effects. Relativistic correction terms corresponding to a relative energy correction of second order in the electron velocity are incorporated into the effective molecular single-electron Hamiltonian. The model is applied to the calculation of relativistic molecular-orbital correlation diagrams for the quasimolecular systems Br+Br, Xe+Xe, and I+Au. A detailed comparison of our results with the results of relativistic calculations for (unscreened) one-electron systems and calculations based on self-consistent field methods is performed. The agreement with Dirac-Fock-Slater results is fairly good, and could be improved further by read-justing the values of the parameters in the atomic potentials used to construct the effective molecular potential.     

类锂体系激发态1s2 nd(n=3,4,5)精细结构和项能的理论计算

使用全实加关联(fullcorepluscorrelation缩写为FCPC)和里兹(Ritz)变分方法计算了类锂体系(Z=11—20)激发态1s2nd(n=3,4,5)的非相对论能量和波函数;包括动能修正、电子电子接触项、轨道轨道相互作用项以及Darwin项的相对论修正和质量极化项由全实加关联波函数的一阶微扰给出,量子电动力学(quantumelectronicdynamics缩写为QED)修正由有效核电荷方法和类氢公式计算;给出了高电离类锂体系激发态的激发能、精细结构和项能(termenergy),并 关键词： 类锂体系 全实加关联 精细结构 激发能     

Microvascular permeability to macromolecules in human melanoma xenografts assessed by contrast-enhanced MRI--intertumor and intratumor heterogeneity.

Several novel macromolecular anticancer agents have fallen short of expectations owing to inadequate and heterogeneous uptake in tumor tissue. In the present work, contrast-enhanced magnetic resonance imaging was used to measure the intertumor and intratumor heterogeneity in the effective microvascular permeability constant, P(eff), of an 82 kDa macromolecule in an attempt to identify possible causes of the inadequate and heterogeneous uptake. Tumors of two human melanoma xenograft lines (A-07 and R-18) were included in the study. Human serum albumin with 30 gadopentetate dimeglumine units per molecule was used as a model molecule of macromolecular therapeutic agents. P(eff) was measured in manually defined regions of interest, corresponding to a whole tumor (ROI(WHOLE)) or to subregions of a tumor (ROIs(SUB)). The P(eff) of the ROI(WHOLE) of individual tumors ranged from 1.4 x 10(-7) cm/s to 2.8 x 10(-7) cm/s (A-07) and from 7.7 x 10(-8) cm/s to 3.2 x 10(-7) cm/s (R-18). P(eff) decreased with increasing tumor volume in R-18, but was independent of tumor volume in A-07. The intratumor heterogeneity in P(eff) exceeded the intertumor heterogeneity in both tumor lines. Some ROIs(SUB) showed P(eff) values that were similar to or slightly higher than the P(eff) values of albumin in normal tissues. Our observations suggest that inadequate and heterogeneous uptake of macromolecular therapeutic agents in tumor tissue is partly a result of low and heterogeneous microvascular permeability. However, the microvascular wall is probably not the major transport barrier to macromolecules in A-07 and R-18 tumors, as most individual tumors and individual tumor subregions showed high P(eff) values, i.e. values that are up to 10-fold higher than those of normal tissues.