Multi-nucleus IBA calculations in the NπNν scheme

IBA-1 calculations for ～ 100 nuclei in three mass regions from A = 100–200 are carried out according to a recently proposed N_πN_ν parametrization. The calculations use a total of only seven constants consisting of four parameters which are constant for all 100 nuclei and one parameter which takes on a separate value for each of the three regions. The changes in nuclear structure for each region are reproduced and the detailed values of individual energy levels and B(E2) values are reasonably well accounted for. The implications of the extreme economy in parameters are discussed and the usefulness of the present approach for other collective models is pointed out.     

A global IBA calculation with constant parameters and theN p N n scheme

It is shown that the principal features of theN _p N_n scheme can be reproduced with an IBA-2 Hamiltonian with constant parameters.     

A correspondence between IBA-1 and IBA-2 models and electromagnetic transitions in the decay of some erbium isotopes

The interacting boson approximation IBA-1 model space, in which neutron and proton degrees of freedom are not distinguished, can be considered as a subspace of the IBA-2 model space. Using the microscopic background of the IBA-2 model, a correspondence can be established between IBA-1 and IBA-2 model space. Since the space of the IBA-1 model can be regarded as a subspace of the IBA-2 model there is a unique way to ‘Project’ the operators of the IBA-2 model onto those of IBA-1. This projection can be carried out using theF-spin formalism. In the IBA-2 model, the lowest states are indeed fully symmetric, and using the calculations with the help of this projection, we explore the energy levels and the electric quadrupole transition probabilitiesB(E2; {ie393-01}) and γ-ray E2/M1 mixing ratios for selected transitions of^{162, 164, 166, 168, 170}Er. Owing to admixtures of non-fully-symmetric states in IBA-2, we renormalized the parameters (ε) and (κ). This is the first time we show that this projection can be applied to some heavier isotopes and the results obtained for^{162, 164, 166, 168, 170}Er isotopes are reasonably in good agreement with the previous experimental values.     

Optical properties of laser-induced heavily doped Si

An analysis of recently reported experimental studies⁽¹⁾ of the optical properties of laser-induced heavily doped Si layers is presented here. The analysis has been made on the basis of models like those of Penn⁽²⁾ and Breckenridge et al.⁽³⁾ Our calculations show that, in general, N_eff, the effective number of electrons contributing to optically induced electronic transitions, increases as does ε₂(E), the imaginary part of the complex dielectric constant. This reflects an increased absorption coefficient for these As-doped samples. These studies have been carried out on samples of Si heavily doped by ion-implantation followed by a laser-annealing process. The conclusions based on these studies are seen to be in accord with those of Aspnes et al.⁽⁴⁾ and Vina and Cardona.⁽⁵⁾     

Determination of effective atomic number and electron density of heavy metal oxide glasses

The effective atomic number (Z_eff) and effective electron density (N_eff) of eight heavy metal oxide (HMO) glasses have been determined using the Monte Carlo simulation code MCNP for the energy range of 10?keV–10?MeV. The interpolation method was employed to extract Z_eff and N_eff values from the simulation and that calculated with the help of XCOM program. Comparisons are also made with predictions from the Auto-Z_eff software in the same energy region. Wherever possible, the simulated values of Z_eff and N_eff are compared with experimental data. In general, a very good agreement was noticed. It was found that the Z_eff and N_eff vary with photon energy and do not have extended intermediate regions where Compton scattering is truly dominating; only dips slightly above ～1.5?MeV were recorded. Z_eff and N_eff are found to increase with PbO and Bi₂O₃ contents. It was found that the Z_eff value rather than the N_eff value is a better indicator for PbO and/or Bi₂O₃ contents.     

Some nuclear and atomic properties of201Hg determined by conversion electron spectroscopy

Conversion electron measurements with an electrostatic spectrometer proved the existence of the 1,565±6 eV transition in²⁰¹Hg. The conversion intensity ratios,N ₁/N ₂ =1.2±0.2,N ₁/N ₃=1.1±0.2,N ₂/N ₃=0.92±0.15,N ₄/N ₃=0.03± 0.02 andN ₅/N ₃=0.04 ±0.02 were determined. These values agree with our calculations for the M1±E2 multipolarity with theE2/M1 mixing ratioδ ²=(l.l±0.3)xl0^?4 and exclude all pure multipolarities withL≦4. The total conversion coefficient for the aboveM1 +E2 mixture was evaluated to be (4.7±0.7)× 10⁴. The reducedB(M1, 1/2→3/2) probability was derived to be (3.9 ±1.2) × 10^?3 (e?/2Mc)². The natural widths of theN-subshell conversion lines in mercury were found to beΓ(N ₁)=8.3± 1.5,Γ(N ₂) =5.8±1.5 and Γ(N ₃) =6.5±1.0 eV. Monte Carlo calculations of electron scattering in matter yielded the conversion line shapes in qualitative agreement with the experiment.     

Mössbauer spectroscopic studies of spin crossover in tris(N, N′-dialkyldithiocarbamato) iron (III) complexes: effect of alkyl substituents

Spin crossover behavior in tris(N,N′-dialkyldithiocarbamato) iron(III) complexes with varying alkyl groups has been studied by variable temperature magnetic moment and Mössbauer spectral studies. All the complexes may be divided into three broad groups; high spin (μ _eff > 4.8 BM), intermediate spin (μ _eff?=?3.5???4.6 BM) and low spin (μ _eff?< 3.2 B.M). Room temperature (RT) Mössbauer spectra exhibit an asymmetric doublet resolved into two doublets corresponding to high and low spin states. Estimated % contributions of HS and LS states and calculated μ _eff were comparable with the experimentally determined values. It has been shown that some complexes undergo spin crossover, ⁶A₁g→²T₂g whereas others exhibit spin transitions ⁶A₁g →⁴T₁g or ⁴T₁g → ²T₂g. IR spectra show characteristic ν _(Fe???S) bands in the region 208–285 (HS) and 311–380 cm^???1 (LS). Nature of alkyl groups affects the spin state.     

Determination of odd-symmetry crystal-field parameters from optical spectra

We have obtained analytical expressions for effective parameters of the crystal field that acts on spin-orbit multiplets of 4f ^N configurations taking into account admixture to them of 4f ^N?15d excited states and ligand-to-metal charge-transfer states. As an example, we analyze splittings of the ground and excited multiplets of Pr³⁺ and Tm²⁺ ions in some crystals without an inversion center. The effect of mixing of states of different configurations is most strongly pronounced for the ¹ G ₄ and ¹ D ₂ excited multiplets. The interconfigurational contribution to splittings is different for different multiplets. This circumstance makes it possible to estimate the values of the parameters of the odd-symmetry crystal field, which causes mixing of the 4f ^N and 4f ^N?15d states, and the covalence parameters of rare-earth ion-ligand bonds.     

Elastic photoelectron-scattering effects in quantitative X-ray photoelectron spectroscopy

We present improved formulae for the correction parameters Q_x and β_eff that are used to account for elastic scattering of photoelectrons in quantitative X-ray photoelectron spectroscopy (XPS). The new formulae are based on new Monte Carlo simulations for 584 photoelectrons in 39 elemental solids that could be excited by Mg Kα and Al Kα X-rays in 315 different XPS configurations. The new simulations differed from similar earlier calculations in that differential elastic-scattering cross sections calculated from the Dirac–Hartree–Fock potential were utilized rather than those from the Thomas–Fermi–Dirac potential, a smaller analyzer acceptance angle was chosen, and the number of trajectories in each simulation was an order of magnitude larger. New values of Q_x and β_eff were obtained for each photoelectron line, each X-ray source, and each XPS configuration. These Q_x and β_eff values could be fitted to simple two-parameter expressions, each a function of the single-scattering albedo and the photoelectron emission angle. Values of Q_x from the new predictive formula differed from the previous expression by less than 1%. Larger deviations in the values of β_eff, up to 2.5%, were found from the new fit to the β_eff parameter. The new expressions for Q_x and β_eff provide a convenient means for correction of elastic-scattering effects in XPS.     

Supersymmetry and the multi-instanton measure

We propose explicit formulae for the integration measure on the moduli space of charge-n ADHM multi-instantons in N = 1 and N = 2 supersymmetric gauge theories. The form of this measure is fixed by its (super) symmetries as well as the physical requirement of clustering in the limit of large spacetime separation between instantons. We test our proposals against known expressions for n ⩽ 2. Knowledge of the measure for all n allows us to revisit, and strengthen, earlier N = 2 results, chiefly: (1) For any number of flavors N_F, we provide a closed formula for F_n, the n-instanton contribution to the Seiberg-Witten propotential, as a finite-dimensional collective coordinate integral. This amounts to a solution, in quadratures, of the Seiberg-Witten models, without appeal to electric-magnetic duality. (2) In the conformal case N_F = 4, this means reducing to quadratures the previously unknown finite renormalization that relates the microscopic and effective coupling constants, τ_micro and τ_eff. (3) Similar expressions are given for the 4-derivative/8-fermion term in the gradient expansion of N = 2 supersymmetric QCD.     

Effective dynamic moment of inertia of 118Xe and 130Ba

The effective moment of inertia J_eff⁽²⁾ of ¹¹⁸Xe and ¹³⁰Ba has been measured using sum-spectrometer techniques. The data are discussed using arguments based on particle alignments and results of cranking calculations. J_band⁽²⁾ and J_eff⁽²⁾ are compared in order to estimate the contribution of particle alignments to the total increase in angular momentum.     

Effective Mode Volume of Nanoscale Plasmon Cavities

The controlled squeezing of electromagnetic energy into nanometric volumes via surface plasmon-polariton excitations in plasmonic nanoresonators is analyzed using the concept of an effective electromagnetic mode volume V _eff, while taking careful account of the plasmon-polariton dispersion and the electromagnetic energy stored in the metal. Together with the quality factor Q of the cavity resonance, this enables a comparison with dielectric optical cavities, where V _eff is limited by diffraction. For a Fabry–Perot type planar metallic cavity, a one-dimensional analytic model as well as a three-dimensional finite-difference time-domain simulation reveal that V _eff is not bounded by diffraction, and that Q/V _eff increases for decreasing cavity size. In this picture, matter–plasmon interactions can be quantified in terms of Q and V _eff, and a resonant cavity model for the enhancement of spontaneous Raman scattering is presented.     

Solar-neutrino variations: A manifestation of nonzero neutrino mass and magnetic moment, and mixing

Time variations of solar neutrino flux are investigated on the basis of available Homestake experimental data for more than two solar cycles (1970–1994). At first, we determine (with the weight-time function by taking into account ³⁷Ar decay), for each solar neutrino run n, the effective Earth’s heliolatitude L _eff(n), the effective Zurich sunspots number Z _eff(n), the effective latitude of sunspots distribution Λ_eff(n), and the effective surfaces of sunspots in different heliolatitude belts. Then, we consider the correlation of solar-electron-neutrino fluxes with these parameters for different periods of solar activity. It is found that correlation coefficients change sign in different periods of solar activity, so that for total period 1970–1994 the correlation coefficient is very small. The obtained information indicates that a neutrino should have nonzero mass and nonzero magnetic moment.     

Numerical calculation of the fidelity for the Kondo and the Friedel-Anderson impurities

The fidelities of the Kondo and the Friedel-Anderson (FA) impurities are calculated numerically. The ground states of both systems are calculated with the FAIR (Friedel artificially inserted resonance) theory. The ground state in the interacting systems is compared with a nullstate in which the interaction is zero. The different multi-electron states are expressed in terms of Wilson states. The use of N Wilson states simulates the use of a large effective number N _eff of states. A plot of ln(F) versus N ∝ ln(N _eff ) reveals whether one has an Anderson orthogonality catastrophe at zero energy. The results are at first glance surprising. The ln(F) – ln(N _eff ) plot for the Kondo impurity diverges for large N _eff . On the other hand, the corresponding plot for the symmetric FA impurity saturates for large N _eff when the level spacing at the Fermi level is of the order of the singlet-triplet excitation energy. The behavior of the fidelity allows one to determine the phase shift of the electron states in this regime.     

Shear flow of a nematic liquid crystal near a charged surface

The maximum alignment angle θ_eff and the effective rotational viscosity coefficient γ _i ^eff of polar liquid crystals, such as 4-n-octyloxy-4′-cyanobiphenyl (8OCB), are investigated in the vicinity of charged bounding surfaces. The quantities θ_eff and γ ₁ ^eff are calculated in the framework of the Ericksen-Leslie theory. The results of calculations demonstrate that, for a homeotropic alignment of molecules on charged indium tin oxide surfaces, the effective rotational viscosity coefficient γ _i ^eff can increase by 7.8% as compared to the bulk rotational viscosity coefficient γ₁.     

The effect of evolving grain shape and alignment on the coercivity in thermomechanically deformed Nd13.9(Fe0.92Co0.08)80.3B5.3Ga0.5 permanent magnets

A series of samples of nominally identical composition have been melt-quenched and thermomechanically deformed to varying degrees, resulting in a variation in crystallographic alignment. The effect of the alignment on the coercivity has been studied using measurements of the temperature dependence of coercivity. The analysis was performed using a well-known phenomenological model which relates the coercivity to the anisotropy field, through a parameter α, and the saturation magnetization, through an effective demagnetization coefficient N_eff. It was discovered that the trends in α and N_eff as a function of crystallographic grain alignment are the opposite to what is expected and measured previously in analogous sintered samples of varying crystallographic alignment. An explanation for this behavior is proposed in which the evolving grain shape and grain boundary topography caused by deformation becomes the controlling factor in the coercivity rather than the crystallographic alignment of the grains.     

On condensation of the vortex solitons in a 2 + 1 dimensional abelian Higgs model

We study the roles of the vortex solitons in a 2 + 1 dimensional abelian Higgs model. From the effective lagrangian L_eff for the soliton field χ, it is found that the appearance of the solitons reduces the dielectric constant to a value smaller than one. If the Higgs field 〈H〉_vac does not vanish, the vacuum is in the Higgs phase and the solitons are not important. If it does vanish, the solitons become massless and L_eff has an infinite number of classically degenerate vacua. In the quantum theory of L_eff with large coupling constant e, no evidence of 〈χ〉_vac ≠ 0 has been discovered. For this conclusion to hold it is crucial that the free energy of scalar QED monotonically increases with e².