Spectrum and losses of surface magnetostatic waves in a 1D magnon crystal

The spectrum and propagation losses of a surface magnetostatic wave in a 1D ferrite magnon crystal are experimentally studied as a function of angle φ between the wavevectors of the surface magnetostatic wave and periodic crystal lattice. Variation in the positions of Bragg forbidden bands with angle φ is described. A wide transmission band is discovered near long-wave frequency boundary f ₀ of the surface magnetostatic wave in a narrow interval of angles around φ ≈ 57°. In the interval 70° < φ < 90° and at frequencies below f ₀, there exists a magnetostatic wave with a wavevector that is normal to the bias field.     

The Beam Propagation Factor of Nonparaxial Truncated Flattened Gaussian Beams

By using the second-order moment of the power density, the beam width, far-field divergence angle and M² factor of nonparaxial truncated flattened Gaussian (FG) beams are derived analytically. It is shown that the M² factor of nonparaxial truncated FG beams depends not only on the truncation parameter δ and beam order N, but also on the initial waist-width to wavelength ratio w₀/λ. The far-field divergence angle approaches an asymptotic value of θ_max=63.435° when the truncation parameter δ → 0. For the special cases of N = 0 and δ → ∞ our results reduce to those of nonparaxial truncated Gaussian beams and nonparaxial untruncated FG beams, respectively.     

Wetting behavior of Al–Si–Mg alloys on Si3N4/Si substrates: optimization of processing parameters

The wetting behavior of Al–Si–Mg alloys on Si₃N₄/Si substrates has been investigated using the sessile drop technique. Based on a Taguchi experiment design, the effect of the following processing parameters on the contact angle (θ) and surface tension (σ_LV) was studied: processing time and temperature, atmosphere (Ar and N₂), substrate surface condition (with and without a silicon wafer), as well as the Mg and Si contents in the aluminium alloy. In nitrogen, non-wetting conditions prevail during the isothermal events while in argon a remarkable non-wetting to wetting transition leads to contact angles θ as low as 11±3° and a liquid surface tension σ_LV of 33± 10×10^-5 kJ/m². According to the multiple analysis of variance (Manova), the optimum conditions for minimizing the values of θ and σ_LV are as follows: temperature of 1100 °C, processing time of 90 min, argon atmosphere, no use of a silicon wafer, and the use of the Al-18% Mg-1% Si alloy. A verification test conducted under the optimized conditions resulted in a contact angle of θ=9±3° and a surface tension of σ_LV=29± 9×10^-5 kJ/m², both indicative of excellent wetting. PACS 68.03.Cd; 81.05.Bx; 68.08.Bc; 05.70.-a; 61.10.Nz     

Spectra of high-frequency waves in hot magnetized plasmas

On the basis of numerical solution of the dispersion equation, we obtain the spectra of weakly damped high-frequency waves in a hot magnetized plasma for the case where the electron cyclotron frequency ω_He is below the plasma frequency ω_pe. It is shown that the longitudinal wave propagating at an angle to the magnetic field evolves into the slow extraordinary wave for the refractive index n ≤ 1. For n ≫ 1, the longitudinal-wave frequency increases with the refractive index, and the wave evolves into the wave with anomalous dispersion if the angle θ between the wave vector and the magnetic field is close to 90°. In the same range of θ angles, Bernstein modes appear in the spectrum of plasma eigenmode oscillations. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 258–266, March 2006.     

C2GT: intercepting CERN neutrinos to Gran Sasso in the Gulf of Taranto to measure θ13

Today’s greatest challenge in accelerator-based neutrino physics is to measure the mixing angle θ₁₃ which is known to be much smaller than the solar mixing angle θ₁₂ and the atmospheric mixing angle θ₂₃. A non-zero value of the angle θ₁₃ is a prerequisite for observing CP violation in neutrino mixing. In this paper, we discuss a deep-sea neutrino experiment with 1.5 Mt fiducial target mass in the Gulf of Taranto with the prime objective of measuring θ₁₃. The detector is exposed to the CERN neutrino beam to Gran Sasso in off-axis geometry. Monochromatic muon neutrinos of ≈ 800 MeV energy are the dominant beam component. Neutrinos are detected through quasi-elastic, charged-current reactions in sea water; electrons and muons are detected in a large-surface, ring-imaging Cherenkov detector. The profile of the seabed in the Gulf of Taranto allows for a moveable experiment at variable distances from CERN, starting at 1100 km. From the oscillatory pattern of the disappearance of muon neutrinos, the experiment will measure sin²θ₂₃ and especially Δm² ₂₃ with high precision. The appearance of electron neutrinos will be observed with a sensitivity to P(ν_μ→ν_e) as small as 0.0035 (90% CL) and sin²θ₁₃ as small as 0.0019 (90% CL; for a CP phase angle δ=0° and for normal neutrino mass hierarchy).     

Determination of reference values for optical characteristics in multiwavelength optical detection and ranging (lidar) measurements of atmospheric extinction coefficients

We have studied multiple regressions between the spectral aerosol extinction coefficient ε, backscatter indicatrix g_π, and light-scattering coefficients β_θ at angles of θ = 1–180°, which we used to select the optimal scattering angle for determining the extinction coefficient at the wavelengths 0.350, 0.532, and 1.060 μm. We have estimated the errors in determination of the values of ε and g_π at the given wavelengths for different atmospheric situations with different meteorological parameters. We have shown that it is possible to use the spectral β_θ values at a 33° angle to determine the reference values for ε(λ) and g_π(λ) at λ = 0.350, 0.532, and 1.060 μm in laser detection and ranging (lidar) measurements, and we give examples of recovering the vertical profiles of ε in a slightly turbid atmosphere from the results of simultaneous multiwavelength lidar and nephelometric measurements. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 767–772, November–December, 2007.     

Deviation from tri-bimaximal mixings through flavour twisters in inverted and normal hierarchical neutrino mass models

We explore a novel possibility for lowering the solar mixing angle (θ ₁₂) from tri-bimaximal mixings, without sacrificing the predictions of maximal atmospheric mixing angle (θ ₂₃ = 45°) and zero reactor angle (θ ₁₃ = 0°) in the inverted and normal hierarchical neutrino mass models having 2–3 symmetry. This can be done through the identification of a flavour twister term in the texture of neutrino mass matrix and the variation of such term leads to lowering of solar mixing angle. For the observed ranges of Δm ₂₁² and Δm ₂₃², we calculate the predictions on tan² θ ₁₂ = 0.5, 0.45, 0.35 for different input values of the parameters in the neutrino mass matrix. We also observe a possible transition from inverted hierarchical model having even CP parity (Type-IHA) to inverted hierarchical model having odd CP parity (Type-IHB) in the first two mass eigenvalues, when there is a change in input values of parameters in the same mass matrix. The present work differs from the conventional approaches for the deviations from tri-bimaximal mixing, where the 2–3 symmetry is broken, leading to θ ₂₃ ≠ 45° and θ ₁₃ ≠ 0°.      

Kinematical separation of α-n final-state interaction at 50 MeV incident energy

A kinematically complete experiment has been performed to study the α-n final-state interaction (FSI) in the α + d ↦α + p + n break-up reaction at 50 MeV incident energy for the alpha-particles. For this, we have chosen four pairs of correlation angles for the outgoing alpha and protons. These are ( θ_α = 18^°, θ_p = 42^°), ( θ_α = 20^°, θ_p = 45^°), ( θ_α = 22^°, θ_p = 42^°) and ( θ_α = 22^°, θ_p = 47^°), selected kinematically where the allowed phase spaces are in favor of the α-n final-state interaction. Our experimental data show strong α-n FSI in all the selected configurations. Also, the FSI is found to be stronger at the lower alpha-particle energy when two FSI peaks appear in the same configuration. Received: 17 June 2002 / Accepted: 3 October 2002 / Published online: 4 February 2003 RID="a" ID="a"e-mail: dey_s2001@yahoo.com; Present address: 445 Waupelani Drive, Apt. F3, State College, PA 16801, USA. Communicated by M. Gar?on     

Antivortices due to competing orbital and paramagnetic pair-breaking effects

Thermodynamically stable vortex—antivortex structures in a quasi-twodimensional superconductor in a tilted magnetic field are predicted. For this geometry, both orbital and spin pair-breaking effects exist, with their relative strength depending on the tilt angle θ. The spectrum of possible states contains the ordinary vortex state (for large θ) and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state (for θ = 0) as limits. The quasi-classical equations are solved nearH _c2 for arbitrary θ and it is shown that stable states with co-existing vortices and antivortices exist in a small interval close to θ= 0. The results are compared with recent predictions of antivortices in mesoscopic samples.     

Electron screening in backward elastic scattering

Abstact: The elastic scattering cross sections, σ (E,θ), for the systems He+Ta and He+W have been measured at θ_lab=165° and E _lab=76.1 keV to 3.988 MeV using targets with a thickness of a few atomic layers. The results are smaller than the results given by the Rutherford scattering law, σ_R(E,θ), due to the effects of electron screening and can be described by σ(E,θ)/σ_R(E,θ)=(1+U_e/E)⁻¹, where U _e is an atomic screening potential energy. The deduced average value, U _e=28 ± 3 keV, is consistent with the Moliére- and Lenz-Jensen-models as well as electron binding energies. Received: 25 May 1998     

Magnetoresistivity and acoustoelectronic effects in a tilted magnetic field in <Emphasis Type="Italic">p</Emphasis>-Si/SiGe/Si structures with an anisotropic <Emphasis Type="Italic">g</Emphasis> factor

Magnetoresistivity ρ _xx and ρ _xy and the acoustoelectronic effects are measured in p-Si/SiGe/Si with an impurity concentration p = 1.99 × 10¹¹ cm⁻² in the temperature range 0.3–2.0 K and an tilted magnetic field up to 18 T. The dependence of the effective g factor on the angle of magnetic field tilt θ to the normal to the plane of a two-dimensional p-Si/SiGe/Si channel is determined. A first-order ferromagnet-paramagnet phase transition is observed in the magnetic fields corresponding to a filling factor ν = 2 at θ ≈ 59°–60°.     

High-frequency FeCoNiNbB–SiO2 nano-granular films with high resistivity and adjustable resonance frequency from 1.3 to 7.8?GHz

A series of (FeCoNiNbB) _x –(SiO₂)_1−x nano-granular thin films were fabricated by magnetron sputtering with different oblique incidence angles θ. High-resolution transmission electron micrographs show that the films consist of amorphous CoFeM (M = Ni, Nb, B) alloy particles with diameter about 2 nm surrounded by amorphous SiO₂ matrix. Excellent soft magnetic properties have been achieved with a variable in-plane uniaxial magnetic anisotropy field H _k0, which increases monotonically with θ and x, and decreases with the composition of B in FeCoM. For one typical sample of x=0.63 with θ=30°, H _ch and H _ce are 4.2 Oe and 5.4 Oe, respectively, ρ reaches 12.5 mΩ cm and 4π M _s and H _k0 are 5.70 kG s and 92 Oe, respectively, which lead to a high ferromagnetic resonance frequency f _r of 2.2 GHz. Based on the analysis of experimental results, two sources for the origin of the magnetic anisotropy, namely anisotropic magnetic coupling and orientation order of atomic pairs, are suggested.     

Giant waves in weakly crossing sea states

The formation of rogue waves in sea states with two close spectral maxima near the wave vectors k ₀ ± Δk/2 in the Fourier plane is studied through numerical simulations using a completely nonlinear model for long-crested surface waves [24]. Depending on the angle θ between the vectors k ₀ and Δk, which specifies a typical orientation of the interference stripes in the physical plane, the emerging extreme waves have a different spatial structure. If θ ≲ arctan(1/√2), then typical giant waves are relatively long fragments of essentially two-dimensional ridges separated by wide valleys and composed of alternating oblique crests and troughs. For nearly perpendicular vectors k ₀ and Δk, the interference minima develop into coherent structures similar to the dark solitons of the defocusing nonlinear Schroedinger equation and a two-dimensional killer wave looks much like a one-dimensional giant wave bounded in the transverse direction by two such dark solitons.     

Plastic Versus Glass Support for an Immunoassay on Metal-Coated Surfaces in Optically Dense Samples Utilizing Directional Surface Plasmon-Coupled Emission

We compared plastic (polycarbonate) and high-quality glass support materials for gold-coated slides, when performing a model immunoassay against rabbit IgG using fluorescently labeled (AlexaFluor-647) anti-rabbit IgG, and detecting surface plasmon-coupled emission (SPCE) signals. Both, glass and plastic slides were simultaneously coated with a 48-nm layer of gold and protected with a 10-nm layer of silica. The maximum SPCE signal of AlexaFluor-647 was only two- to three-fold smaller on plastic slides than on glass slides. A small difference in the SPCE angles on glass (θ _F = 55°) and plastic (θ _F = 52.5°) slides was observed and can be explained with a slightly smaller refractive index of the plastic. We have not found any difference in the angle distribution (sharpness of the fluorescence signal at optimal SPCE angle) for the plastic slide compared to the glass slide. The kinetics of binding was monitored on the plastic slide as well as on the glass slide. Optically dense samples, a 4% red blood cell suspension and a 15% hemoglobin solution, are causing a reduction in the immunoassay SPCE signal by approximately 15% and three times, respectively, and the percentage of the reduction is the same for plastic and for glass slides. We believe that plastic substrates can be readily used in any SPCE assay, with only marginally lower total signal compared to high-quality glass slides.     

Peculiarities of the anisotropy of cosmic rays with E0 ≥ 1019 eV from Yakutsk EAS array data

The arrival directions of primary cosmic ray particles with energies E ₀ ≥ 10¹⁹ eV and zenith angles θ ≤ 60° recorded on the Yakutsk array over the period 1974–2009 are analyzed. These events separated by different time intervals are shown to have different global anisotropies.     

Local anisotropy of cosmic rays with <Emphasis Type="Italic">E</Emphasis><Subscript>0</Subscript> ≥ 10<Superscript>17</Superscript> eV from Yakutsk EAS array data

The arrival directions of primary cosmic ray particles with energies E ₀ ≥ 10¹⁷ eV and zenith angles θ ≤ 60° recorded on the Yakutsk array over the period 1974–2009 are analyzed. These events are shown to have different anisotropies in different energy ranges.     

Morphology and electrical properties of pulsed-laser deposited Bi2Sr2CaCu2O8+δ films on vicinal substrates

Thin films of Bi₂Sr₂CaCu₂O_8+δ have been grown on vicinal (001) SrTiO₃ substrates by pulsed-laser deposition. Transmission electron microscopy (TEM) and X-ray diffraction reveal well ordered films with the c axis of the film parallel with the c axis of the substrate for miscut angles up to θ_S≈15°. TEM also reveals the step-like film morphology due to step-flow growth. The in-plane and out-of-plane resistivities are independent of film thickness within the range 20–300 nm and agree quite well with Bi₂Sr₂CaCu₂O_8+δ single-crystal data. Received:15 May 2000 / Accepted:17 May 2000 / Published online: 9 August 2000     

Determination of the 1S0 neutron-neutron scattering length in the nd breakup reaction at energies in the range En = 40?60 MeV

The first results are obtained in a kinematically complete experiment devoted to measuring the n + d → p + n + n reaction yield at energies in the range E _n = 40−60 MeV and various angles of divergence of two neutrons (Δθ = 4°, 6°, and 8°) in the geometry of neutron-neutron final-state interaction. The ¹ S ₀ neutron-neutron scattering length a _nn is determined by comparing the experimental energy dependence of the reaction yield with the results of a simulation in the Watson-Migdal approximation, which depend on a _nn . For E _n = 40 MeV and Δθ = 6° (the best statistics in the experiment), the value a _nn = −17.9 ± 1.0 fm was obtained. A further improvement of the experimental accuracy will make it possible to remove the existing disagreement of the results from different experiments.     

Mixing angles of quarks and leptons in quantum field theory

Arguments coming from Quantum Field Theory are supplemented with a 1-loop perturbative calculation to settle the non-unitarity of mixing matrices linking renormalized mass eigenstates to bare flavor states for non-degenerate coupled fermions. We simultaneously diagonalize the kinetic and mass terms and counterterms in the renormalized Lagrangian. SU(2) _L gauge invariance constrains the mixing matrix in charged currents of renormalized mass states, for example the Cabibbo matrix, to stay unitary. Leaving aside CP violation, we observe that the mixing angles exhibit, within experimental uncertainty, a very simple breaking pattern of SU(2) _f horizontal symmetry linked to the algebra of weak neutral currents, the origin of which presumably lies beyond the Standard Model. It concerns on the one hand the three quark mixing angles; on the other hand a neutrino-like pattern in which θ ₂₃ is maximal and tan (2θ ₁₂)=2. The Cabibbo angle fulfills the condition tan (2θ _c )=1/2 and θ ₁₂ for neutrinos satisfies accordingly the “quark–lepton complementarity condition” θ _c +θ ₁₂=π/4. θ ₁₃=±5.7⋅10⁻³ are the only values obtained for the third neutrino mixing angle that lie within present experimental bounds. Flavor symmetries, their breaking by a non-degenerate mass spectrum, and their entanglement with the gauge symmetry, are scrutinized; the special role of flavor rotations as a very mildly broken symmetry of the Standard Model is outlined.     

Mixing parameters of η and η′ mesons

Mixing angles of η and η′ mesons are obtained in the scheme of octet-singlet mixing θ_η = −15.4°, θ′_η = −17.9°, and in the scheme connected with expansion in the quark basis $ \bar q $ \bar q q − $ \bar s $ \bar s s φ = 39.3°. The constants gV _ηγ, g _η′ V _γ of radiative decays η′ → V _γ and V → ηγ (V ≡ ρ, ω, φ) and the ratios of constants of weak decays of η and η′ mesons are calculated. The numerical values that were found are in agreement with the experimental data.