Characteristics of the discrete and continuous spectra of the <Superscript>4</Superscript>He + Λ system

In view of projected experiments on the production of relativistic hypernuclei and the investigation of reactions induced by them, the characteristics of the hypernucleus and low-energy parameters of the _Λ ⁵ He hyperon scattering from ⁴He were calculated. The interaction of the Λ hyperon and the α particle is described by the effective Λα potential in two different forms. The root-mean-square radius of the Λ hyperon in the _Λ ⁵ He hypernucleus, the vertex constant for the _Λ ⁵ He ? ⁴He + Λ process, and the corresponding asymptotic normalization coefficient of the _Λ ⁵ He wave function were calculated by solving the radial Schrödinger equation. The scattering length and the effective radius for the scattering of Λ from ⁴He were calculated by two methods. The calculated characteristics turn out to be sensitive to the form of the Λα potential.     

Parametric Model of the Optical Constant Spectra of Hg1 – xCdxTe and Determination of the Compound Composition

Optics and Spectroscopy - A parametric model describing the spectra of optical constants n(λ) and k(λ) of a Hg1&nbsp;–&nbsp;xCdxTe (MCT) solid solution for the x values in...     

Investigation of the tunnel effect and dielectric parameters of α-LiIO<Subscript>3</Subscript> crystals

Temperature and frequency spectra of tanδ, ε′, and ε″ of laser lithium iodate single crystals are investigated at temperatures in the interval 77–450 K and frequencies in the range 5–10⁸ Hz. An analysis of these spectra and the Cole–Cole diagrams demonstrates tunneling of charge carriers and existence of relaxation oscillators of several types. The temperature interval for the tunnel effect is determined. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 39–42, February, 2009.     

Angular Distributions and Anisotropy of the Fragments from Neutron-Induced Fission of <Superscript>239</Superscript>Pu and <Superscript>nat</Superscript>Pb in the Energy Range of 1–200 MeV

The angular distributions of fragments from the neutron-induced fission of ^natPb and ²³⁹Pu nuclei have been measured in the energy of range 1–200 MeV using the neutron time-of-flight spectrometer GNEIS. Fission fragments have been detected by position sensitive multiwire proportional counters. The results for the anisotropy of fission fragments deduced from the measured angular distributions have been presented. The results have been compared with the experimental data of other authors.     

Self-Consistent Calculations of the Quadrupole Moments of the Lowest 3<Superscript>–</Superscript> States in Sn and Pb Isotopes

self-consistent approach to anharmonic effects based on the quantum many-body theory is for the first time used to calculate the quadrupole moments of the lowest 3^– states in Sn and Pb isotopes, including the ¹⁰⁰Sn, ¹³²Sn, and ²⁰⁸Pb doubly magic ones. The consistency between the mean nuclear field and the effective interaction is maintained using the energy-density-functional method with known parameters of the Fayans functional. Thereby, the quadrupole moments of the lowest 3^– states of isotopes with nucleon pairing are reliably predicted, and the existing data for the ²⁰⁸Pb isotope are reproduced. It has been shown that the new three-quasiparticle correlations are responsible for slightly more than half of the observed effect and the remaining part is due to the quadrupole polarizability of the nucleus.     

Angular distributions and anisotropy of the fragments from neutron-induced fission of <Superscript>233</Superscript>U and <Superscript>209</Superscript>Bi in the intermediate energy range of 1–200 MeV

New results of the neutron-induced fission experiments carried out at the neutron time-of-flight spectrometer GNEIS of the PNPI are given. Angular distributions of fission fragments from the neutron-induced fission of ²³³U and ²⁰⁹Bi nuclei have been measured in the energy range 1–200 MeV using position sensitive multiwire proportional counters as fission fragment detector. The recent improvements of the measurement and data processing procedures are described. The data on anisotropy of fission fragments deduced from the measured angular distributions are presented in comparison with the experimental data of other authors.     

Calculation of the optical and electronic properties of the zinc-blende alloy Zn1 − xMgxSe

In order to clarify the electronic and optical properties of wide-energy gap zinc-blende structures ZnSe, MgSe and their alloys (ZnSe)_1 − x(MgSe)_x, a simple pseudo-potential scheme (EPM) within an effective potential, the virtual crystal approximation (VCA) which incorporates compositional disorder as an effective potential, is presented. Various quantities, including the fundamental band gap, the energies of several optical gaps, charge densities, ionicity character, transverse effective charge, and refractive index are obtained for this alloy.     

Features of the structure and properties of β-FeSi<Subscript>2</Subscript> nanofilms and a β-FeSi<Subscript>2</Subscript>/Si interface

The electronic, geometric, and magnetic structure of nanofilms of the β phase of iron disilicide FeSi₂ with the (001), (100), and (010) surfaces have been simulated through density functional calculations. A substantial reconstruction of the (001) surface terminated with silicon atoms has been observed, which was accompanied by an increase in the surface symmetry and appearance of “squares” of silicon atoms. Analysis of the electron density of states (DOS) and spin DOS projected on the contributions of layers of atoms (LSDOS) indicates that all plates have metallic properties. The main contribution near the Fermi level comes from the surface iron layers and it decreases rapidly with an increase in the distance from the surface of the plate. Analysis of the calculated effective magnetic moments of atoms shows that the surface layers in the plates have a significant magnetic moment, in particular, iron layers on the (001) surface (1.89 μ_B/atom). The moments of atoms decrease rapidly with an increase in their distance from the surface. The electron and geometric regions of a (001)Si/FeSi₂ interface have been studied. Analysis of the LSDOS shows that the surface conducting state mainly determined by the contribution from the near-surface silicide layers is implemented in this region. The possibility of the formation of the perfect and sharp Si/FeSi₂ interface has been demonstrated.     

Using of the χ<Superscript>2</Superscript> criterion to evaluate the quality of the placement of transitions in the level scheme

The results from a statistical analysis of the evaluated nuclear structure data file (ENSDF) are presented. The article deals with the procedures for evaluating of the quality of the placement of transitions in the level scheme.     

Measurement of the Dalitz-decay branching ratio of the π<Superscript>0</Superscript>

The ratio is measured by comparing the production rates of the π⁰ in the two decay channels. The analysis is based on approximately four million hadronic decays of the Z boson recorded by the ALEPH detector in the years 1991 to 1995. The value of is determined to be . A recalculation of the Particle Data Group world average gives rise to a slightly improved error, and moves the world average closer to the theoretical value.     

Small broadening of the Mössbauer gamma line of the isomer <Superscript>109<Emphasis Type="Italic">m</Emphasis></Superscript>Ag as yet another indication of the protracted character of the emission of photons from nuclei and their absorption

Nine experiments performed to date by three research groups in order to observe the Mössbauer effect in the case of gamma rays emitted by the long-lived isomer ^109m Ag yielded results suggesting an anomalously small broadening of the Mössbauer gamma line of this isomer. In turn, this indicates that the emission of photons from nuclei and their resonance absorption cannot proceed within a time interval much shorter than the characteristic time of the change in the energy of hyperfine dipole—dipole interaction, because the photon energy would otherwise be determined by the sum of the instantaneous value of the energy of this interaction and the nuclear-transition energy, in which case the broadening of the Mössbauer gamma line would reach five to six orders of magnitude, as opposed to one to two orders of magnitude broadening observed experimentally.     

The Origin of Phase Transition and the Usual Evolutions of the Unit-Cell Constants of the NASICON Structures of the Solid Solution LiTi2 – xGex(PO4)3

Physics of the Solid State - Ge-doped LiTi2(PO4)3 has been synthesized by a conventional solid-state reaction. Compounds LiM$$_{2}^{{{\text{IV}}}}$$(PO4)3 with LTP-type structure present a...     

Contribution of the π<Superscript>0</Superscript>γ and ηγ intermediate states to vacuum polarization and the muon anomalous magnetic moment

Using new experimental data, we calculated, with a high precision, a contribution to the muon anomalous magnetic moment from the vacuum-polarization intermediate states π⁰γ and ηγ taking into account a correction for the trapezoidal rule: aμ(π⁰γ+aμ(ηγ)=(53.1± 1.5)×10^?11. We also determined a small contribution from the e⁺e^?π⁰, e⁺e^?η, and μ⁺μ^?π⁰ intermediate states, which was found to be equal to 0.5×10^?11.     

Dynamic light scattering and <Superscript>31</Superscript>P NMR study of the self-assembly of deoxyguanosine 5’-monophosphate: the effect of added salt

Self-assembling and dynamical properties of deoxyguanosine 5-monophosphate in isotropic aqueous solutions were studied by ³¹P NMR spectroscopy and dynamic light scattering (DLS). All solutions had the same c = 4 wt% guanosine concentration, while the added KCl molarity ranged from 0 to 1.5 M. ³¹P NMR measurements show that potassium ions strongly enhance the stacking process of guanosine tetramers until a saturation is reached at 0.1 M KCl with more than 70% of the molecules aggregated. Polarized light scattering reveals the presence of a fast relaxation mode that arises from the translational dynamics of the self-assembled stacks. The diffusion coefficient of this mode shows a strong dependence on molarity of added salt, which can be described in terms of the coupled mode and counterion condensation theories for polyelectrolyte solutions. Depolarized light scattering reveals the rotational dynamics of the self-assembled stacks which exhibits a pronounced slowing down with increasing the added salt content.Received: 19 November 2003, Published online: 2 March 2004PACS: 81.16.Dn Self-assembly - 61.30.St Lyotropic phases - 82.35.Rs Polyelectrolytes     

Temporal pulsewidth and the wavelength dependences of the product ions obtained by laser ablation of solid C<Subscript>60</Subscript>

By ablating solid C₆₀ with a laser pulse, we observe various processes such as the prompt- and the delayed-ionization of C₆₀, the fragmentation into molecular ions and the formation of cluster ions. We found these processes show distinct dependences on the temporal pulse width, the power and the wavelength of the ablation laser. From the observations, we could confirm efficient coupling of laser energy to C₆₀ through the molecular absorption even with a laser pulse width less than the electron-phonon coupling time of the C₆₀ molecule.     

Broadening and collisional interference of lines in the ir spectra of ammonia: Self-broadening in the ν<Subscript>2</Subscript> band

The relaxation parameters of lines of the P, Q, and R branches of the ammonia ν₂ band are calculated in the case of self-broadening with the effects of collisional interference of doublet components taken into account. It is shown that the cross-relaxation parameters do not exceed, as a rule, several percent of the values of the self-broadening coefficients and, consequently, the isolated line approximation is applicable in a wide pressure range. The calculated results are compared with experimental data.     

A first principles study of the adsorption and dissociation of CO<Subscript>2</Subscript> on the δ-Pu (111) surface

A complete understanding of the nature of the 5f electrons has been and continues to be a major scientific problem in condensed matter physics. Bulk and surface electronic structure studies of the actinides as also atomic and molecular adsorptions on the actinide surfaces provide a path towards this understanding. In this work, ab initio calculations within the framework of density functional theory have been used to study the adsorption of molecular CO₂ and the corresponding partially dissociated (CO + O) and completely dissociated (C + O + O) products on the δ-Pu (111) surface. The completely dissociated C + O + O configurations exhibit the strongest binding with the surface (7.92 eV), followed by partially dissociated products CO + O (5.08 eV), with molecular CO₂ adsorption having the lowest binding energies (2.35 eV). For all initial vertically upright orientations, the CO₂ molecule physisorbs or do not bind to the surface and the geometry and orientation do not change. For all initial flat lying orientations chemisorption occurs, with the final state corresponding to a bent CO₂ molecule with bond angles of 117°–130° and the elongation of the CO bond. For CO + O co-adsorption, the stable configurations corresponded to CO dipole moment orientations of 100°–172° with respect to the surface normal and the elongation of the CO bond. The most stable chemisorption cases correspond to anomalously large rumpling of the top Pu layer. The interactions of the CO₂ and CO with the Pu surface have been analyzed using the energy density of states and difference charge density distributions. The nature and the behavior of the 5f electrons have also been discussed in detail in the context of this study.