Nuclear longitudinal form factors for axially deformed charge distributions expanded by nonorthogonal basis functions

In this paper,the nuclear longitudinal form factors are systematically studied from the intrinsic charge multipoles.For axially deformed nuclei,two different types of density profiles are used to describe their charge distributions.For the same charge distributions expanded with different basis functions,the corresponding longitudinal form factors are derived and compared with each other.Results show the multipoles C_λ of longitudinal form factors are independent of the basis functions of charge distributions.Further numerical calculations of longitudinal form factors of~(12)C indicates that the C_0 multipole reflects the contributions of spherical components of all nonorthogonal basis functions.For deformed nuclei,their charge RMS radii can also be determined accurately by the C_0 measurement.The studies in this paper examine the model-independent properties of electron scattering,which are useful for interpreting electron scattering experiments on exotic deformed nuclei.     

Spallative ablation of dielectrics by X-ray laser

A short laser pulse in wide range of wavelengths, from infrared to X-ray, disturbs electron–ion equilibrium and increases pressure in a heated layer. The case where the pulse duration τ _L is shorter than acoustic relaxation time t _s is considered in the paper. It is shown that this short pulse may cause thermomechanical phenomena such as spallative ablation regardless of wavelength. While the physics of electron–ion relaxation strongly depends on wavelength and various electron spectra of substances: there are spectra with an energy gap in semiconductors and dielectrics opposed to gapless continuous spectra in metals. The paper describes entire sequence of thermomechanical processes from expansion, nucleation, foaming, and nanostructuring to spallation with particular attention to spallation by X-ray pulse.     

Mixing characterization of mechanically milled Fe75Si15M10 powders using Mössbauer spectroscopy

Iron nitrides are attractive as they show excellent magnetic properties which can be utilized as recording and permanent magnetic materials for potential applications. Due to the high saturation magnetization and chemical stability, γ ^′-Fe₄N compound is widely investigated as a promising high density magnetic recording material. γ ^′-Fe₄N particles were synthesized by conventional gaseous nitriding in a heated atmosphere containing ammonia as a source of nitrogen. X-ray diffraction, ⁵⁷Fe Mössbauer spectroscopy, vibrating sample magnetometer, scanning electron microscopy and transmission electron microscopy are used for the characterization of the as prepared sample.     

Different electronic structures of C6Li and C8K graphite intercalation compounds studied by positron annihilation

The 2λ-angular correlation distributions of the stage 1 Graphite Intercalation Compounds C₆Li and C₈K are found to be very different. For C₈K, the distributions are dominated by a free electron contribution similar to those in pure alkali metals. In contrast, the distributions of C₆Li remain similar to those of graphite. The two materials are classified into s(+ π)-band metals (C₈K) and π-band metals (C₆Li).     

Distribution of electron flows over the cathode surface in a discharge with oscillating electrons

The mechanisms governing the distribution of the longitudinal electron flows over the cathode surface in a discharge with oscillating electrons are studied experimentally. The influence of the discharge gap length on the magnitude and distribution of the electron flows is investigated. It is shown that intense longitudinal electron flows in a tube of diameter d _a =31 mm can form only with short anodes of length l _a =2.5–3.5 cm. The distributions of the electron current over the cathode surface at various discharge conditions are determined.     

Errata

Angular distributions of protons emitted in the (e, e'p) reaction on ⁴⁰Ca at an incident electron energy of 710 MeV and for missing energies e_m = 39 MeV and E_M = 81 MeV are presented. The interpretation of these angular distributions in terms of momentum distributions for the struck protons in the original target nucleus indicates l ≠ 0 protons at E_M = 39 MeV and l = 0 protons at E_M = 81 MeV. Finally (p, 2p) and (e, e'p) results in calcium are compared.     

Aspects of Angular Dependent Auger Spectroscopy (ADAS)

Calculational results are presented which pertain to recent observations that considerable structure exists in the angular distributions of 62 eV M_2,3VV Auger electrons emitted from copper surfaces. A direct interpretation of these results demonstrates that both electron diffraction and anisotropic Auger emission must contribute significantly to the observed angular distributions.     

Preparation and analysis of zirconia doped ceria nanocrystal dispersions

Crystalline and highly dispersible solid solutions with the general formula Ce_1−xZr_xO_2−δ, where δ represents any possible oxygen vacancies, and in the ceria rich region were prepared using an inorganic sol-gel technique. The particle size distributions of the transparent sols were measured using photon correlation spectroscopy and found to be les than 25 nm with narrow distributions. Compositional analysis using EDAX confirmed the correct zirconia doping. Lattice parameters, structural and crystallite size data for the dried sols and heated powders using X-ray diffraction confirmed a cubic structure stable to at least 1000°C with crystallite sizes varying from 34 Å to 55 nm, depending on calcination temperature and composition. Dispersions of the nanocrystals on silica were studied using high resolution TEM/EDAX, the structure and compositions of individual nanocrystals closely matching those of the bulk agglomerated powders, showing exceptional homogeneity.     

The temperature dependence of penning ionization electron energy spectra: He(23S)—ar,N2, NO,O2, N2O,CO2

Using two intense thermal energy He(2³S) sources of different temperatures (≈400 and ≈ 1000 K, resp.) and a transmission-calibrated electron energy analyzer with about 30meV resolution, the dependence of He(2³S) Penning ionization electron spectra on collision energy for the target species Ar, N₂, NO, O₂, N₂O and CO₂ have been studied. The energy shifts of the Penning electron energy distributions and the branching ratios for the population of different electronic states in the molecular ions are determined quantitatively and compared for the two different collision temperatures. These results and the shapes of the observed Penning electron energy distributions are discussed in the light of current models for the Penning procen; the observed temperature dependences are correlated with the nature of the ionized orbitals in cases of only one entrance channel (closed shell targets) and, in addition, to the existence of qualitatively different entrance channels (open shell targets).     

Measurements of the spatially resolved electron temperature and plasma potential in ferrite-core side type Ar/He inductively-coupled plasmas

Spatial distributions of the effective electron temperature (T_eff) and plasma potential were studied from the measurement of an electron energy probability function in a side type ferrite-core inductively coupled plasma with an argon–helium mixture. As the helium gas was diluted at the fixed total gas pressure of 5 mTorr in an argon discharge, the distribution of the plasma density and plasma potential changed from a concave to a flat profile, and finally became a convex profile, while all spatial profiles of T_eff were hollow shapes with helium dilution in the argon discharge. This evolution of the plasma potential with helium gas could be explained by the increased energy relaxation length (λ_ε), indicating the transition of electron kinetics from local to non-local kinetics.     

Charge exchange cross sections of carbon ions

Based on experimental data on the ion charge distributions, the cross sections of single electron loss σ _{i, i + 1} and single electron capture σ _{i, i ? 1} by carbon ions with velocities (2.7–8) × 10⁸ cm/s in different gaseous media (He, N₂, and Ar) have been obtained. Regularities of the cross section variation of the electron capture and loss by carbon ions as a function of the ion velocity, ion charge, and atomic number of the target have been for the first time studied in a wide range of the initial ion charge, from i = 0 to i = 6. A qualitative agreement of the obtained results with the published data has been established for a number of other ions. Theoretical calculations of the cross sections of single electron loss by carbon ions in helium have been carried out.     

In situ electron microscopy investigations of solid-state synthesis in Al/Au thin bilayer films

In situ transmission electron microscopy investigations of solid-state synthesis in Al/Au thin bilayer films are conducted. The samples are heated in the column of a transmission electron microscope. The heating temperature is changed from room temperature to 300°C with a heating rate of up to 120°C min^?1. It is found that solid-phase synthesis starts at ≈100°C. At 140 ± 5°C, two crystal phases, Al₂Au (Fm3m) and AlAu₂ (I4/mmm), are simultaneously observed, while at 235 ± 5°C and higher (up to 300°C) only Al₂Au phase is detected.     

FastJ/Ψ's as a signal for quark-gluon plasma formation

The weak production of a top particle of mass ?35 GeV is seen to be an order of magnitude lower than the most conservative estimate of strong production, and two orders of magnitude lower than the rate required to explain the UA1 single jet electron events. All the kinematic distributions are very similar for the two production mechanisms. Detailed comparison of the rate and kinematic distributions are shown, for the decay electron (muon)p _T cut of 10 and 15 GeV.     

SIMS direct surface imaging of Cu1−xCrx formation

Cu-Cr alloys, irradiated with a low-energy, high-current electron beam, are analyzed by high-resolution secondary ion mass spectrometry. Mass spectra and images of Cu⁺ and Cr⁺ surface distributions finely reveal the regions enriched in Cu and Cr. For electron beam energies above a threshold value, the formation of a non-equilibrium Cu_1−xCr_x solid solution, extending over sub-micrometer areas is highlighted for the first time. A discussion of the process leading to Cu_1−xCr_x formation is given.     

Autosolitons in electron-hole plasma in p-Ge

The self-organization of an electron-hole plasma (EHP) heated by an electric field in pure p-Ge samples at T = 77 K has been studied experimentally. The derived current-voltage characteristics (CVCs) and the distributions of the electric field and IR emission of the hot carriers along the samples show that the segments of a steep rise or the S-shaped segments of the CVCs in samples with n-p junctions are related to the formation of longitudinal thermal-diffusion autosolitons (AS_‖); as a result, thin (d = 2–20 μm in diameter), melted-through current channels appear. Such AS_‖ are formed at high EHP densities (n ≥ 1 × 10¹⁶ cm⁻³), when the electron-hole scattering is dominant, and at electron temperatures T _e = (2–4.5)T ₀ (T ₀ is the lattice temperature). The saturation segments and the N-shaped segments in the CVCs are attributable to the generation of transverse thermal-diffusion high-field autosolitons (AS_⊥) in the form of narrow strata with electric field strengths = 1–20 kV cm⁻¹. High-field AS_⊥ are formed at EHP densities n = 5 × 10¹³−1 × 10¹⁶ cm⁻³, when the electron-phonon scattering is dominant, and at electron temperatures T _e ∼ Θ ≥ 5T ₀ (Θ is the Debye temperature). The generated longitudinal and transverse autosolitons have high temperatures (T _e ≥ 1000 K) and reduced carrier densities and can exist simultaneously in different parts of the sample. Original Russian Text ? M.N. Vinoslavskiĭ, P.A. Belevskii, A.V. Kravchenko, 2006, published in Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2006, Vol. 129, No. 3, pp. 477–492.     

Measurement of the spin-structure function g 2 and the semi-inclusive double-spin asymmetries at HERMES

A measurement of the virtual-photon asymmetry A ₂ and of the spin-structure function g ₂ of the proton are presented for the kinematic range of the HERMES experiment carried out at the HERA electron storage ring at DESY. Semi-inclusive longitudinal double-spin asymmetries provide new insight into the valence quark helicity distributions Δu _v and Δd _v.     

Elimination of the mott interband s-d enhancement of the electrical resistance of nickel and platinum owing to the excitation of electrons by femtosecond laser pulses

The dependence of electrical, σ, and thermal, κ, conductivities of metals on the electron temperature T _e at high (～1 eV) T _e values has been calculated. The two-temperature states for which the temperature T _e of heated electrons exceeds the temperature T _i of ions in the crystal lattice result from the excitation of electrons by femtosecond laser pulses. It is well known that the existence of empty d levels with a high density of states near the Fermi surface (as, e.g., in nickel, platinum, and iron) leads to a pronounced enhancement of the electrical resistance (Mott, 1936). This is due to an increase in the statistical factor related to the electron transitions to the empty states induced by collisions with phonons. It is found that the excitation of the electron subsystem significantly reduces the electron-phonon scattering to unoccupied d states since the chemical potential μ(T _e ) rises above the upper edge of the d band. The decrease in the scattering probability leads to the anomalous behavior of the conductivity σ_el-ph, which increases with the temperature T _e . Such a behavior turns out to be inverse with respect to the usual situation in condensed matter.     

Auger electron spectroscopic measurements of ZnCl2-coal interaction

Two anolomous peaks in the ZnL₃M₂,₃M_4,5 Auger electron spectra of dried and heated samples of ZnCl₂-coal mixtures have been interpreted as indication of a Zn-coal bond formation. The peaks show a decrease from the normal 9.1 eV splitting for ZnCl₂ alone to 4.2 eV for ZnCl₂-coal mixtures. High volatile bituminous coals show this effect to a greater extent than either higher or lower rank coals. It is surmised that the side of this bond formation could coincide with the site of catalytic activity in the catalytic hydrogenation of coal in the presence of ZnCl₂.     

Calogero–Sutherland system with two types interacting spins

The dynamics of low-temperature (T = 5 K) photoluminescence spectra of Si/Si_1-x Ge _x /Si heterostructures (x = 0.045) under the influence of a stream of nonequilibrium phonons (heat pulses) propagating in the structure is investigated. The rapid evaporation of the electron–hole liquid in the quantum well of the structure is observed as the liquid is heated by nonequilibrium phonons. It is established that an increase in the exciton-gas density in the quantum well is caused by the evaporation of the electron–hole liquid and by an increase in the rate of exciton capture by the quantum well. It is shown that the interaction with nonequilibrium phonons results in the dissociation of bound-exciton complexes in the Si layers, which is accompanied by an increase in the exciton concentration and lifetime.