Energy spectra of developed superfluid turbulence

Turbulence spectra in superfluids are modified by the nonlinear energy dissipation caused by the mutual friction between quantized vortices and the normal component of the liquid. We have found a new state of fully developed turbulence, which occurs in some range of two Reynolds parameters characterizing the superfluid flow. This state displays both the Kolmogorov-Obukhov 5/3-scaling law E_k ∝ k^?5/3 and a new “3-scaling law” E_k ∝ k^?3, each in a well-separated range of k.     

Systematization of intermediate-mass fragments

We consider the power law dependence of cross-sections of formation of intermediate-mass fragments on the mass number and atomic number, σ (A _f ) ～ A _f ^?τ and σ (Z _f ) ～ Z _f ^?τ . The values of parameter τ are determined for fragments detected by the ΔE ? E and the induced activity methods. It is shown that in “liquid-gas” phase transition τ varies within the limits of 2–3. A conclusion was drawn that at high beam energies parameter τ does not depend on the detection angle of the fragment. At the increase in the energy τ passes through a minimum at E _i ～ 6–7 GeV which is typical “critical behavior” predicted by models.     

Systematics of the power law parameter and minimum angular momenta for fragment production

The element yield distributionsσ(Z) of intermediate mass fragments from proton, helium, and heavy-ion induced reactions exhibit a universal behaviour as a function of the bombarding energy. The power law parameterτ, obtained from fits withσ(Z)∝σ ^-τ, falls monotonically with increasing projectile energy E_lab and reaches a saturation valueτ?2.0 atE _lab?2GeV. It is suggested that the behaviour at low bombarding energies is caused by a dynamical hindrance of the fragment emission at low angular momentum.     

Nuclear matter approach to the heavy-ion optical potential: (II). Imaginary part

The heavy-ion optical potentials are constructed in a nuclear matter approach, for the ¹⁶O + ¹⁶O, ⁴⁰Ca + ¹⁶O and ⁴⁰Ca + ⁴⁰Ca elastic scattering at the incident energies per nucleon E^lab/A ? 45 MeV. The energy density formalism is employed assuming that the complex energy density of colliding heavy ions is a functional of the nucleon density ?(r), the intrinsic kinetic energy density τ⁽²⁾(r) and the average momentum of relative motion per nucleon K_r(≦ 1.5 fm^?1). The complex energy density is numerically evaluated for the two units of colliding nuclear matter with the same values of ρ, τ⁽²⁾ and K_r. The Bethe-Goldstone equation is solved for the corresponding Fermi distribution in momentum space using the Reid soft-core interaction. The “self-consistent” single-particle potential for unoccupied states which is continuous at the Fermi surface plays a crucial role to produce the imaginary part. It is found that the calculated optical potentials become more attractive and absorptive with increasing incident energy. The elastic scattering and the reaction cross sections are in fair agreement with the experimental data.     

Microwave spectroscopic study of the conformations,relative energies,and dipole moments of ethyl cyanoformate

The microwave spectrum of ethyl cyanoformate displays a-type band spectra from three nearly prolate conformers. High-resolution spectra of the two more stable species have been assigned. One form, designated extended, has rotational constants A″ = 6453.3(4) MHz, B″ = 1500.47(6) MHz, C″ = 1236.36(6) MHz, which are consistent with a syn-anti [τ₁ (OCOC) = 0°, τ₂ (COCC) = 180°] structure. The second form, labeled compact, has rotational constants A″ = 6787.8(7) MHz, B″ = 1549.38(8) MHz, C″ = 1406.80(8) MHz, which are consistent with a syn-gauche [τ₁ (OCOC) = 0°, τ₂ (COCC) ～ 90°] structure. The extended form is marginally more stable, ΔE = 55 ± 27 cm^?1. The extended conformer has dipole moment components μ_a = 4.44(7), μ_b ～ 0 D and the compact conformer has dipole moment components μ_a = 4.25(7), μ_b = 0, μ_c = 1.08(23) D. The third conformer (relative energy 600 ± 140 cm^?1) has the most intense band series even at ?63°C. the bands of this conformer are unresolvable into individual rotational transitions.     

Image potential eigenstates and resonances on the (110) surfaces of noble metals: Energies and lifetimes

The energies and lifetimes of the image potential resonances at the ? point on the Cu(110), Ag(110), and Au(110) surfaces are studied, and the energies of the image potential states on the Pd(110) surface are analyzed. It is shown that every quantum number n corresponds to a pair of image potential states (resonances) n ⁺ and n ^? at the ? point. The average energy of a pair of eigenstates (resonances) at n ≥ 2 is well described by the formula ē _n = (E _n+ + E _n?) = E ₀ ? (0.85 eV)/(n + δ)², where δ is the quantum defect, E ₀ = (1/2m _e )(?π/a)², and a is the lattice parameter. The splitting energy of a pair of eigenstates (resonances) obeys the law ΔE _n = E _n+ — E _n? ∝ n ^?3. The lifetimes τ _n± of image potential resonances are proportional to n ³.     

Energetics of “double” charge transfer and two-to-one charge-transfer adducts

Second-order perturbation theory and Hückel approximation are used to estimate the charge-transfer stabilization energy due to the mixing-in of the following dative configurations into the neutral donor (D) and acceptor (A) systems, (1) A^?D²⁺A^?, (2) D⁺A^2?D⁺, (3) D²⁺A^2?, and (4) D⁺A^?. $\text{General}$ parametric energy formulas are derived in terms of orbital overlap (S_DA), one- and two-electron electron affinities (E_A⁽¹⁾ and E_A⁽²⁾), and Coulomb energy differences (σU_c). These parametric formulas will help the assessment of the occurence and relative importance of the “defect” dative structures necessary for conduction. The specific case of the BZ-I₂ complexes studied show that (1), (2) and (3) exist with stabilization energies of less than 1% of that of (4). (4) is the conventionally known contributor to the usual “single” charge-transfer state.     

Advection of a passive vector field by the Gaussian velocity field with finite correlations in time

Using the field theoretic renormalization group technique the model of a passive vector field advected by an incompressible turbulent flow is investigated up to the second order of the perturbation theory (two-loop approximation). The turbulent environment is given by statistical fluctuations of the velocity field that has a Gaussian distribution with zero mean and defined noise with finite correlations in time. Two-loop analysis of all possible scaling regimes in general d-dimensional space is done in the plane of exponents ? ? η, where ? characterizes the energy spectrum of the velocity field in the inertial range E ∝ k ^{1 ? 2ε}, and η is related to the correlation time at the wave number k which is scaled as k ^{?2 + η}. It is shown that the scaling regimes of the present model of vector advection have essentially different properties than the scaling regimes of the corresponding model of passively advected scalar quantity. The results demonstrate the fact that within the present model of passively advected vector field the internal tensor structure of the advected field can have nontrivial impact on the diffusion processes deep inside in the inertial interval of given turbulent flow.     

Monte Carlo study on dynamical behaviour of spins and spin clusters in the 2D ± J Ising spin-glass

To investigate dynamical (time-dependent) behavior of spins and spin clusters in the two-dimensional ± J Ising spin-glass, we have evaluated the relaxation time τ_i of individual spins by the Monte Carlo simulation. An interesting finding is that, at least in the temperature range $\text{T ? 0.8J}$, most of τ_i are described by $\text{τ}{}_{\mathrm{i}}\text{∝}\text{exp}\text{{}\text{E}{}_{\mathrm{i}}\text{(T ? T}{}_0\text{}}$ with T₀?0.5J (E_i being a constant), which suggests that the system undergoes a glass transition obeying Fulcher's law.     

Microscopic theory of the second- and third-order elastic constants of cobalt in a thermodynamic module

The total potential energy of a crystal is presented as an expansion by irreducible interactions in clusters containing pairs of atomic triplets and quadruplets. The potential energy of the clusters in the adiabatic approximation is a function of vectors \(\vec r_{ik}\) connecting the centers of atoms in the clusters. Arguments (basic functions) affecting the potential energy of clusters are found using the model with allowance for the exchange symmetry of atoms and the irreducibility of the considered energies of doublet, triplet, and quadruplet atoms and interactions. This allows us to present arguments of the potential energy in the form of summed integral numbers (latticed sums) multiplied by a fixed value of the crystal unit cell parameter, and to set the numerical values of the potential energy arguments as a function of vectors \(\vec r_{ik}\). A potential corresponding to the thermodynamic additivity concept of crystal energy is selected as the model potential of pairwise interaction. Secondand third-order moduli of the rigidity of Co crystals with A1, A2, and HCP structures are calculated using this model of multiatom interactions.     

Zero-bias tunneling anomaly in a two-dimensional electron system with disorder

The temperature dependence of a zero-bias anomaly in the tunneling conductance of an Al/δ-GaAs tunneling structure with a two-dimensional electron density in the δ-layer of 3.5 × 10¹² cm^?2 has been investigated. It has been shown that the respective drop Δρ(?, T) in the tunneling density of states ρ near the Fermi level E _F of the two-dimensional electron system depends logarithmically on the energy ? within the range of 2.7kT < |?| < ?/τ, where ? is measured with respect to E _F and τ is the momentum relaxation time of two-dimensional electrons. It has been found that the drop depth Δρ(0, T)/ρ is also proportional to ln(kT/?₀) in the temperature range T = 0.1–20 K and saturates below 0.1 K.     

Mean field for the p+90Zr system in the energy range −60 MeV<E<+65 MeV and single-particle features of proton states in 90Zr from a dispersive optical-model analysis

Data on the scattering of protons with energies 5 MeV<E<65 MeV by ⁹⁰Zr nuclei and data on the energies of proton particle and hole levels in the A+1 and A?1 systems with A=90 are analyzed within the dispersive optical model. The parameters of the mean proton field for ⁹⁰Zr are determined in the energy range ?60 MeV<E<+65 MeV. The predicted single-particle features of the levels (root-mean-square radii of orbits, occupation numbers, spread widths, spectroscopic factors, and spectral functions) comply well with experimental data obtained in (d, ³He), (³He, d), (n, d), and (d, n) reactions for levels near the Fermi surface and in (e, e′p) and (p, 2p) reactions for deep levels.     

Tellurium-related trap levels in silicon

Tellurium-related defects inn-type silicon have been analysed by deep level transient spectroscopy (DLTS). The tellurium doping of the samples was performed by ion implantation or during epitaxy. In all the samples, a level having a thermal activation energy around 0.37 eV is observed. This activation energy is found to be dependent on the electric field. Taking into account the Poole-Frenkel (FP) effect and a temperature dependence proportional toT ^?2 in the capture cross-section, a value ofE _A=0.41eV is obtained. A second Te-related level having an activation energy ofE _A=0.14eV without correction of the FP effect could only be measured in the implanted samples. The same concentration is observed for the two levels in the implanted samples thus indicating that both peaks in the DLTS spectra are caused by the identical Te-related defect.     

The 14N quadrupole coupling constants and barrier to internal rotation of ethylcyanide-d5

The microwave spectrum of ethylcyanide-d₅ has been recorded from 18.0 to 40.0 GHz. Both a-type and b-type transitions were observed and assigned. Also, the R-branch assignments have been made for three excited states of the internal torsional mode and two excited states of the CN inplane bending mode as well as an excited vibrational state involving both of these motions. The barrier to internal rotation was determined to be 3.00 ± 0.15 kcal/mole from the E, A splittings of the third excited state. The quadrupole coupling constants of the¹⁴N nucleus were found to have values of ?3.213, 1.168, and 2.045 MHz for χ_aa, χ_bb, and χ_cc, respectively. These results are compared to those previously obtained on the corresponding hydrogen compound.     

Emission and laser-excitation spectra of rotationally cooled methylcyanodiacetylene cation (A˜2EāX˜2 E) and photoelectron—photon

The A?²EāX?² E band system of rotationally cooled methylcyanodiacetylene cation has been studied by emission and excitation spectroscopies. Spectra were obtained by electron-impact ionisation of a seeded helium supersonic free jet and by Penning ionisation followed by laser excitation. These data enable the vibrational frequencies of most of the A₁ fundamentals to be inferred for the X?²E (to within ±2 cm^?1) andX?²E (to within ±4 cm?1) states. The fluorescence quantum yields and lifetimes of the cation prepared in selected levels of theA?²E andB?²A₁, excited states have been determined by photoelectron—photon coincidence measurements and yield a quantitative insight into the radiationless-decay pathways.     

An effective chiral Lagrangian model for the τ-decay into three charged pions

An effective chiral Lagrangian for the π-ρ-A ₁-system is used to study the decayτ ^±→ν _τπ⁺π^?π^±. Demanding that the hadronic current 〈0|J _μ|3π〉 agrees at the low energy limit with the one obtained from the corresponding pseudoscalar meson Lagrangian ?(π), an ambiguity linked to free parameters in ?(π,ρ,A ₁) is eliminated. The decay spectrum and branching ratio of τ^±→ν _τπ⁺π^?π^± are calculated as functions of theA ₁-mass and compared with the experimental results. So conclusions can be drawn concerning theA ₁-parameters, which are found to be $$m_{A_1 } = (1180 \pm 50)MeV;\Gamma _{A_1 } = (450 \pm 100)MeV.$$ . The mass-value is smaller than recently published ones. This is attributed to the effect of suppressed decay channels not seen in the experiments up to now. A contribution from direct, non-(ρ ⁰π^±) resonanceA ₁-decay is obtained, being about 15%.     

Evidence for the τ → νϱπ decay mode

Annihilation of e⁺e^? into final states with a single electron has been studied with the PLUTO detector at the DORIS storage ring at CMS energies from 3.6 to 5 GeV. In the sample of 4-prong events without any detected photon we observe 21 events which we assign to the reaction e⁺e^? → τ⁺τ^? → ννe + ν?⁰π. We obtain a branching ratio for τ⁺ → ν?⁰π⁺ of 0.050 ± 0.015 with an overall systematic uncertainty of 30%. The data are consistent with the ?π coming from an A₁ meson.     

Temperature dependence of dispersive hopping transport and diffusion in disordered solids

The time- and temperature-dependent drift mobility μ_d for dispersive transients in disordered solids is $\text{μ}{}_{\mathrm{d}}\text{(T,t) =}\text{L}\text{Et}{}_{\mathrm{T}}$ in terms of distance L, field E and transit time t_T. Since current I ∝ tsu?(1?α) for t <_Tand 0<α<1 by Scher-Montroll theory for hopping among localized states, it follows that $\text{μ}{}_{\mathrm{d}}\text{(T) = α[μ}{}_{\mathrm{d}}\text{(T,t)]}{}^{\mathrm{\alpha }}\text{(}\text{L}\text{Eτ}\text{)}{}^{\mathrm{1?\alpha }}$ where τ≈ 10^?13s is estimated. Further $\text{μ}{}_{\mathrm{d}}\text{(T) ∝ exp (}\text{?Δ}{}_0\text{KT}\text{)}$ and the activation energy Δ₀ is time independent. On this basis Δ for the carbazole polymers is ca. zero, that for a-Se is ca. 0.05 eV, and that for a-As₂Se₃ is 0.35 eV rather than 0.5, 0.3 and 0.6 eV respectively on a phenomenological basis for μ_d(T,t). Trap-controlled hopping transport may be excluded. Time-resolved optical studies of excess carrier recombination supplement mobility measurements in a-Si:H and a-As₂Se₃ as well as other systems. Combined results suggest a dielectric response mechanism in which the time-dependent hopping frequency of localized carriers ν ∝ t^α?1 arises from distortion of the medium at localization sites. This is satisfied by Δ(T,t) = Δ₀+(1?α)KTT ln(t/τ) where τ is the mean initial localization time of the carrier, 10^?13?10^?12s, Δio is the height of the barrier at T, and 0<α<l. Consequently ν = ν₀(t/τ)^α?1 exp(frsol|?Δ₀/KT) which applies also to bimolecular recombination.     

Corrections to the Zτ +τ− vertex in topcolor-assisted technicolor theory

We calculate the corrections to the Zτ⁺τ^? vertex in the one-family topcolor-assisted technicolor models without exact custodial symmetry contributed from the exchange of extended technicolor (ETC) sideways and diagonal gauge bosons and the topcolor gauge boson Z′. The precise measurements of the τ asymmetry parameter Aτ give strong constraint on the free parameters in the topcolor-assisted technicolor models.