8,271 research outputs found

    D0D^0 production rate measurement in neutrino interactions and a limit on muon neutrino to tau neutrino oscillations

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    The CHORUS experiment was designed to search for \nu_\mu---> \nu_\tau oscillations. Recently, Phase I analysis has been completed and no \tau candidate is found. The second phase of the CHORUS analysis was recently started with new scanning systems. The big improvements in the scanning system and methods allow the CHORUS experiment to study also charm physics with large statistics. In this work, D^0 production rate in neutrino charged-current interactions has been evaluated using 122 D^0 candidates found in 8028 located \nu_\mu charged-current interactions in the collaboration, as; \sigma(\nu_mu N--> D^0\mu^-X)/sigma(\nu_mu N--> \mu^-X)= 1.998 \pm 0.223%. The achived precision of the production rate exceeds that of the previous experiments

    OPERA neutrino oscillation results

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    The OPERA experiment was designed to perform the first detection of νμ → ντ neutrino oscillations in a direct appearance mode. We present the analysis results of the 2008–2009 statistics corresponding to 4.88 × 1019 p.o.t. In this sample, one ντ candidate event has been observed in the τ → h channel. The statistical significance of this observation is estimated to be 95%

    Colloidal Plasmonic Titanium Nitride Nanoparticles: Properties and Applications

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    Optical properties of colloidal plasmonic titanium nitride nanoparticles are examined with an eye on their photothermal via transmission electron microscopy and optical transmittance measurements. Single crystal titanium nitride cubic nanoparticles with an average size of 50 nm exhibit plasmon resonance in the biological transparency window. With dimensions optimized for efficient cellular uptake, the nanoparticles demonstrate a high photothermal conversion efficiency. A self-passivating native oxide at the surface of the nanoparticles provides an additional degree of freedom for surface functionalization.Comment: 17 pages, 4 figures, 1 abstract figur

    Temperature-dependent optical properties of plasmonic titanium nitride thin films

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    Due to their exceptional plasmonic properties, noble metals such as gold and silver have been the materials of choice for the demonstration of various plasmonic and nanophotonic phenomena. However, noble metals' softness, lack of tailorability and low melting point along with challenges in thin film fabrication and device integration have prevented the realization of real-life plasmonic devices.In the recent years, titanium nitride (TiN) has emerged as a promising plasmonic material with good metallic and refractory (high temperature stable) properties. The refractory nature of TiN could enable practical plasmonic devices operating at elevated temperatures for energy conversion and harsh-environment industries such as gas and oil. Here we report on the temperature dependent dielectric functions of TiN thin films of varying thicknesses in the technologically relevant visible and near-infrared wavelength range from 330 nm to 2000 nm for temperatures up to 900 0C using in-situ high temperature ellipsometry. Our findings show that the complex dielectric function of TiN at elevated temperatures deviates from the optical parameters at room temperature, indicating degradation in plasmonic properties both in the real and imaginary parts of the dielectric constant. However, quite strikingly, the relative changes of the optical properties of TiN are significantly smaller compared to its noble metal counterparts. Using simulations, we demonstrate that incorporating the temperature-induced deviations into the numerical models leads to significant differences in the optical responses of high temperature nanophotonic systems. These studies hold the key for accurate modeling of high temperature TiN based optical elements and nanophotonic systems for energy conversion, harsh-environment sensors and heat-assisted applications.Comment: 23 pages, 9 figures and 5 table

    Ultrasonic Laboratory Study of Full Waveform Acoustic Logs in Boreholes with Fractures

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    A set of ultrasonic experiments was carried out to determine the effects of horizontal and vertical fractures on full waveform acoustic logs. Boreholes of 1 cm diameter were drilled in aluminum blocks. Measurements were made with horizontal fractures of 0.05 mm, 1.0 mm, 2.5 mm, and 4.5 mm width and a vertical fracture of 1.0 mm width. The horizontal fractures of even the smallest thickness significantly attenuate the P, S, and pseudo-Rayleigh waves. The Stoneley waves are the least attenuated, and attenuation increases with increasing fracture width. The vertical fracture attenuates Stoneley waves most significantly. Both scattering and fluid flow playa role in attenuation. The results may qualitatively be extended to inclined open fractures, where we expect strong attenuation of P and S waves and moderate attenuation of Stoneley waves.Massachusetts Institute of Technology. Full Waveform Acoustic Logging Consortiu

    Quasi-coherent thermal emitter based on refractory plasmonic materials

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    The thermal emission of refractory plasmonic metamaterial - a titanium nitride 1D grating - is studied at high operating temperature (540 {\deg}C). By choosing a refractory material, we fabricate thermal gratings with high brightness that are emitting mid-infrared radiation centered around 3 μ\mum. We demonstrate experimentally that the thermal excitation of plasmon-polariton on the surface of the grating produces a well-collimated beam with a spatial coherence length of 32{\lambda} (angular divergence of 1.8{\deg}) which is quasi-monochromatic with a full width at half maximum of 70 nm. These experimental results show good agreement with a numerical model based on a two-dimensional full-wave analysis in frequency domain.Comment: 10 pages, 5 figure

    Fracture Detection And Characterization

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    The effects of fractures on full waveform acoustic logs are studied on the basis of field observations, available theoretical models, and a series of ultrasonic laboratory experiments. Results from diffusion models applicable to fine microfractures and finite difference models of isolated fractures are reviewed. Laboratory experiments are carried out with fine microfractures around the borehole in a Lucite model, and isolated single fractures in aluminum models. Cases of horizontal and inclined (45°) fractures are studied as a function of fracture aperture and frequency of Stoneley waves. A vertical fracture model is also studied. Results indicate that the effect of different fractures are manifested differently on P, S, pseudo-Rayleigh, and Stoneley waves. Micro-fractures surrounding a borehole attenuate Stoneley waves most strongly. Vertical fractures attenuate Stoneley waves more strongly than other phases in the wave train. Horizontal and inclined fractures have a greater effect on P and S waves than on Stoneley waves.Massachusetts Institute of Technology. Full Waveform Acoustic Logging Consortiu
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