Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam.

The T2K experiment observes indications of ν(μ) → ν(e) appearance in data accumulated with 1.43×10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Δm(23)(2)| = 2.4×10(-3)  eV(2), sin(2)2θ(23) = 1 and sin(2)2θ(13) = 0, the expected number of such events is 1.5±0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7×10(-3), equivalent to 2.5σ significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2θ(13) < 0.28(0.34) for δ(CP) = 0 and a normal (inverted) hierarchy.

Beam-target double-spin asymmetry A{LT} in charged pion production from deep inelastic scattering on a transversely polarized {3}He target at 1.4

We report the first measurement of the double-spin asymmetry A{LT} for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized {3}He target. The kinematics focused on the valence quark region, 0.16

Properties of InAlN/GaN Heterostructures Prepared by Molecular Beam Epitaxy

InAlN thin films and InAlN/GaN heterostructures have been intensively studied over recent years due to their applications in a variety of devices, including high electron mobility transistors (HEMTs). However, the quality of InAlN remains relatively poor with basic material and structural characteristics remain unclear.

Molecular beam epitaxy (MBE) is used to synthesize the materials for this research, as MBE is a widely used tool for semiconductor growth but has rarely been explored for InAlN growth. X-ray photoelectron spectroscopy (XPS) is used to determine the electronic and chemical characteristics of InAlN surfaces. This tool is used for the first time in application to MBE-grown InAlN and heterostructures for the characterization of surface oxides, the bare surface barrier height (BSBH), and valence band offsets (VBOs).

The surface properties of InAlN are studied in relation to surface oxide characteristics and formation. First, the native oxide compositions are studied. Then, methods enabling the effective removal of the native oxides are found. Finally, annealing is explored for the reliable growth of surface thermal oxides.

The bulk properties of InAlN films are studied. The unintentional compositional grading in InAlN during MBE growth is discovered and found to be affected by strain and relaxation. The optical characterization of InAlN using spectroscopy ellipsometry (SE) is also developed and reveals that a two-phase InAlN model applies to MBE-grown InAlN due to its natural formation of a nanocolumnar microstructure. The insertion of an AlN interlayer is found to mitigate the formation of this microstructure and increases mobility of whole structure by fivefold.

Finally, the synthesis and characterization of InAlN/GaN HEMT device structures are explored. The density and energy distribution of surface states are studied with relationships to surface chemical composition and surface oxide. The determination of the VBOs of InAlN/GaN structures with different In compositions are discussed at last.

Acceptance angle effects on the beam attenuation in the ocean

The beam attenuation serves as a proxy for particulate matter and is a key parameter in visibility algorithms for the aquatic environment. It is well known, however, that the beam attenuation is a function of the acceptance angle of the transmissometer used to measure it. Here we compare eight different transmissometers with four different acceptance angles using four different deployment strategies and sites, and find that their mean attenuation values differ markedly and in a consistent way with instrument acceptance angle: smaller acceptance angles provide higher beam attenuation values. This difference is due to variations in scattered light collected with different acceptance angles and is neither constant nor easy to parameterize. Variability (in space or time) in the ratios of beam attenuations measured by two different instruments correlates, in most cases, with the particle size parameter (as expected from Mie theory), but this correlation is often weak and can be the opposite of expectations based on particle size changes. We recommended careful consideration of acceptance angle in applications of beam transmission data especially when comparing data from different instruments. (C) 2009 Optical Society of America

Modified stiffened panel analysis methods for laser beam and friction stir welded aircraft panels

The introduction of advanced welding methods as an alternative joining process to riveting in the manufacture of primary aircraft structure has the potential to realize reductions in both manufacturing costs and structural weight. Current design and analysis methods for aircraft panels have been developed and validated for riveted fabrication. For welded panels, considering the buckling collapse design philosophy of aircraft stiffened panels, strength prediction methods considering welding process effects for both local-buckling and post-buckling behaviours must be developed and validated. This article reports on the work undertaken to develop analysis methods for the crippling failure of stiffened panels fabricated using laser beam and friction stir welding. The work assesses modifications to conventional analysis methods and finite-element analysis methods for strength prediction. The analysis work is validated experimentally with welded single stiffener crippling specimens. The experimental programme has demonstrated the potential static strength of laser beam and friction stir welded sheet-stiffener joints for post-buckling panel applications. The work undertaken has demonstrated that the crippling behaviour of welded stiffened panels may be analysed considering standard-buckling behaviour. However, stiffened panel buckling analysis procedures must be altered to account for the weld joint geometry and process altered material properties. © IMechE 2006.

Transfer ionization process p+He -> H-0+He2++e(-) with the ejected electron detected in the plane perpendicular to the incident beam direction

A joint experimental and theoretical study of the transfer ionization process p+He&RARR; H-0+He2++e(-) is presented for 630-keV proton impact energy, where the electron is detected in a plane perpendicular to the proton beam direction. With this choice of kinematics we find the triple-differential cross section to be particularly sensitive to angular correlation in the helium target. There is a good agreement between the experimental data and theoretical calculations.

Entanglers: Beam splitters and thermal fields

Entanglement is an important ingredient for quantum information processing. We discuss some sources of entanglement, namely a beam splitter and a thermal field. For the generation of entangled continuous-variable states, we consider a beam splitter and find some conditions for input fields to see entanglement in the output. While a beam splitter is a unitary device to generate an entangled state for a bipartite continuous-variable system, a thermal field is shown to mediate entanglement of two qubits.

Entanglement by a beam splitter: Nonclassicality as a prerequisite for entanglement

A beam splitter is a simple, readily available device which can act to entangle output optical fields. We show that a necessary condition for the fields at the output of the beam splitter to be entangled is that the pure input states exhibit nonclassical behavior. We generalize this proof for arbitrary (pure or impure) Gaussian input states. Specifically, nonclassicality of the input Gaussian fields is a necessary condition for entanglement of the field modes with the help of a beam splitter. We conjecture that this is a general property of beam splitters: Nonclassicality of the inputs is a necessary condition for entangling fields in a beam splitter.

Plasma-based studies with intense X-ray and particle beam sources

The construction of short pulse (

Measurements of temperature dynamics of ions trapped inside an electron beam ion trap and evidence for ionisation heating

A technique is described whereby measurements of ions extracted from an electron beam ion trap can be used to deduce their temperature dynamics. The measured temperature dynamics shows the expected trend as a function of charge and also gives evidence for Landau-Spitzer heating, ionization heating and evaporative cooling.