Showing papers by "Cristina Riccardi published in 2005"
TL;DR: The shape of the probability distribution function of density fluctuations seems to be well described by an analytical form suggested on the basis of Tsallis generalized statistics.
Abstract: A statistical analysis of density fluctuations in a cylindrical non-fusion device is performed. The experimental setup is implemented in order to reach a turbulent behavior of the linear plasma column. Two different turbulent regimes are obtained corresponding to two selected sets of values for the discharge parameters. The first regime displays a rotating column characterized by the presence of a shear layer separating the plasma bulk from the tenuous plasma in the shadow of the limiter, the latter showing a strong intermittent behavior and superdiffusion. The second regime corresponds to a weakly rotating column in which coherence is lost in the plasma bulk and a standard diffusive process takes place in the shadow region. These findings are supported by the calculation of the Hurst's exponent using wavelet-analysis techniques. Furthermore the intermittent behavior is characterized and related to the diffusive process. Finally the shape of the probability distribution function of density fluctuations seems to be well described by an analytical form suggested on the basis of Tsallis generalized statistics.
84 citations
TL;DR: In this paper, the surface modification of polyethylene terephthalate film (PET) after the exposure to an atmospheric pressure air dielectric barrier discharge (DBD) was analyzed using atomic force microscopy (AFM) and contact angle measurement.
Abstract: Plasma treatments are used to modify surface properties of materials such as adhesivity, hydrophobicity, oleophobicity, hydrophilicity The plasma interaction with the surface produces modifications of its chemical structure and morphology The present work shows the surface modification of polyethylene terephthalate film (PET) after the exposure to an atmospheric pressure air dielectric barrier discharge (DBD) The treated surface has been analyzed using atomic force microscopy (AFM) and contact angle measurement AFM analysis show roughness changes in both amplitude and peaks spacing: surface modifications cause both optical properties changes and adhesivity enhancement to coating and depositions
66 citations
11 Sep 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the authors describe the general experimental set-up, the test procedure and the cosmic muon test results, and the criteria to accept or reject a detector are also given.
Abstract: The CMS Barrel resistive plate chambers quality tests are performed at three different sites (Bari, Pavia and Sofia), where equivalent software and hardware tools are used. Data from the first 210 detectors are available for a comprehensive analysis. The paper describes the general experimental set-up, the test procedure and the cosmic muon test results. The muon trajectory reconstruction algorithm, used for precise studies, is presented. The criteria to accept or reject a detector are also given. The CMS final-design chambers show an average efficiency greater than 95%.
55 citations
TL;DR: In this paper, the structure and bondings in the polyethylene terephthalate (PET) films were studied by means of IR spectroscopy and the thickness of the deposited films was deduced observing images acquired with a focused ion beam (FIB).
Abstract: HMDSO plasma polymer films are known to reduce the resulting surface free energy and the permeation rate of water vapour and oxygen through the treated polymer substrates. In this work, plasma polymer films were deposited from hexamethyldisiloxane (HMDSO) on polyethylene terephthalate surfaces under different operating conditions and the resulting surface properties were investigated. The structure and bondings in the deposited films were studied by means of IR spectroscopy. The thickness of the deposited films was deduced observing images acquired with a focused ion beam (FIB). Hydrophobic performances were investigated by means of water droplet contact angle measurements. Correlation between operating deposition conditions and resulting structure and surface properties of the films were also discussed.
51 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15, University of Wisconsin-Madison16
TL;DR: In this paper, the q 2 dependence of the f + q 2 ) form factor was measured using a large sample of D 0 → K − μ + ν and D 0 to π − μ+ ν decays collected by the FOCUS photoproduction experiment at Fermilab.
50 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, Pontifical Catholic University of Rio de Janeiro12, University of Puerto Rico at Mayagüez13, University of South Carolina14, University of Tennessee15, Vanderbilt University16, University of Wisconsin-Madison17
TL;DR: In this article, the authors search for T violation in charm meson decays using the four-body decay channels D 0 → K − K + π − π +, D + → K S 0 K+ π− π+, and D s → KS 0 K−K+π−π+ +, and find the asymmetry values to be A T viol (D 0 ) = 0.010 ± 0.057 ( stat.
45 citations
TL;DR: In this article, surface modification induced on poly(ethylene terephthalate) (PET) fibers by cold SF6 plasma treatment has been investigated systematically as a function of plasma device parameters.
Abstract: Summary: Surface modification induced on poly(ethylene terephthalate) (PET) fibers by cold SF6 plasma treatment has been investigated systematically as a function of plasma device parameters. The observed wettability modifications of fibers plasma-treated under different operating conditions were correlated to their dyeability modifications and to the changes in surface chemical composition, determined by X-ray Photoelectron Spectroscopy (XPS), and topography, investigated by atomic force microscopy (AFM). Optical emission spectra from the SF6 plasma at different pressures gave information on its content of fluorine atoms. A striking transition was observed between the increased hydrophilicity and high dyeability, imparted by plasma treatment at low pressure (<0.2 mbar), mainly as a consequence of surface etching and surface activation, and the increased hydrophobicity, imparted by plasma treatment in the higher pressure regime (0.2–0.4 mbar), consequent to extended surface fluorination.
Water droplet adsorption time on PET fabrics, plasma-treated at different pressures.
36 citations
TL;DR: In this article, the authors presented a theoretical analysis of air discharges at high pressure which operates in a streamer regime and provided a simplified framework to study the chemical kinetics in the discharge gas phase.
Abstract: We present a theoretical analysis of air discharges at high pressure which operates in a streamer regime. The aim is to provide a simplified framework to study the chemical kinetics in the discharge gas phase. We have tried to model the characteristics of actually existing devices, such as dc and ac discharges in sharp point-plane, point to point, or coaxial cylinder configuration, dielectric barrier discharges. Within such scheme it is possible to perform numerical simulations in order to predict the evolution of the gas-phase chemical composition. As a first application we have chosen to simulate the chemical kinetics induced in a single isolated streamer and the results of this approach are examined within this paper. In particular, we have studied the detailed temporal evolution of the discharge gas phase using reference values for the simulation free parameters. The interplay between different time scale processes is shown. The effect due to charged as well as metastable species on chemical kinetics has been discussed too. Then we have studied the dependence of chemical species density on discharge parameters such as the electron temperature, the electron density, the transverse radius of the streamer, and the streamer formation time. Many results can be proven relevant for a better understanding of the operating conditions during technological sensible processing based on atmospheric pressure plasma.
33 citations
TL;DR: In this article, the type and amount of radicals formed on lignocellulosic fibers obtained from chemical pulp and chemothermomechanical pulp were evaluated by Electron Paramagnetic Resonance (EPR) spectroscopy and the chemical modifications induced on the same fibers by plasma treatment were assessed by Nuclear Magnetic Resonance 13C-NMR and Gel Permeation Chromatography (GPC) analysis.
Abstract: Cold Ar plasma treatments can be used to modify the structure of lignocellulosic fibers for a variety of applications. In order to better understand the effects of such treatments, the type and amount of radicals formed on lignocellulosic fibers obtained from chemical pulp and chemothermomechanical pulp were evaluated by Electron Paramagnetic Resonance (EPR) spectroscopy and the chemical modifications induced on the same fibers by plasma treatment were assessed by Nuclear Magnetic Resonance (13C-NMR) spectroscopy and Gel Permeation Chromatography (GPC) analysis. The obtained results were compared with those obtained after enzymatic treatments of lignocellulosic fibers reported in literature.
33 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15, University of Wisconsin-Madison16
TL;DR: In this paper, the authors present an analysis of the decay D 0 → K + π − based on FOCUS data, and they find a branching ratio of Γ (D 0 → k+ π + ) = ( 0.429 −0.061 + 0.027 ) % under the assumptions of no mixing and no CP violation.
33 citations
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Asheville11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15, University of Wisconsin-Madison16
01 Mar 2005-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the first application of the genetic programming technique to high energy physics data was reported. But the technique was applied to FOCUS data samples, and the method was used to study the doubly Cabibbo suppressed decay relative to its favored counterpart.
Abstract: We review genetic programming principles, their application to FOCUS data samples, and use the method to study the doubly Cabibbo suppressed decay D + → K + π + π - relative to its Cabibbo favored counterpart, D + → K - π + π + . We find that this technique is able to improve upon more traditional analysis methods. To our knowledge, this is the first application of the genetic programming technique to High Energy Physics data.
TL;DR: In this paper, the rotation of a cylindrical plasma column in a magnetic field has been studied in the linear section of the new plasma device Mistral, and the detection and the study of the spatio-temporal evolution of structures in the turbulent regime have been performed by means of a new enhanced conditional sampling technique.
Abstract: The rotation of a cylindrical plasma column in a magnetic field has been studied in the linear section of the new plasma device Mistral. Under suitable conditions we observe a transition to a turbulent regime characterized by strong, bursty fluctuations at the edge of the column. The detection and the study of the spatio-temporal evolution of structures in the turbulent regime have been performed by means of a new enhanced conditional sampling technique. We have collected evidence of the development of a bent tail emanating from the plasma column. The charged particles inside the structure move along a spiral trajectory resulting in a net radial convection of the plasma to the walls. We show experimentally that a poloidal electric field is present inside the structures leading to the observed outwards radial E × B drift, in agreement with the expectations of recent and past theoretical works.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15
TL;DR: In this article, a Kπ mass spectrum analysis of the four-body semileptonic charm decay was presented, where the authors obtained a mass of 895.41±0.35MeV/c2, a width of 47.79± 0.86−1.32MeV, and a Blatt-Weisskopf damping factor parameter of 3.99% with respect to the total D+→K−π+μ+ν decay.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, Pontifical Catholic University of Rio de Janeiro12, University of Puerto Rico13, University of South Carolina14, University of Tennessee15, Vanderbilt University16, University of Wisconsin-Madison17
TL;DR: In this paper, the authors present a search for a charmed pentaquark decaying strongly to D ( ∗ ) − p, finding no evidence for such a state, they set limits on the cross-section times branching ratio relative to D ∗ − and D − under particular assumptions about the production mechanism.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15, University of Wisconsin-Madison16
TL;DR: In this paper, the first measurements for the semileptonic decay D0→K¯0π−μ+ν were made using data collected by the fixed target Fermilab experiment FOCUS.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15, University of Wisconsin-Madison16
TL;DR: In this paper, a new measurement for the Cabibbo-suppressed decay mode D{sup 0} {yields} K{sup +}K{sup -}{pi}{sup +}{pi-sup -}.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, Pontifical Catholic University of Rio de Janeiro12, University of Puerto Rico at Mayagüez13, University of South Carolina14, University of Tennessee15, Vanderbilt University16, University of Wisconsin-Madison17
TL;DR: In this paper, the decay of Λ c + baryons into final states containing a Λ hyperon was studied using data from the FOCUS experiment (FNAL-E831).
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, Pontifical Catholic University of Rio de Janeiro12, University of Puerto Rico at Mayagüez13, University of South Carolina14, University of Tennessee15, Vanderbilt University16, University of Wisconsin-Madison17
TL;DR: This article applied a genetic programming technique to search for the doubly Cabibbo suppressed decays Λ c + → p K + π − and D s + → K + K + −.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15, University of Wisconsin-Madison16
TL;DR: In this article, a new measurement of the branching ratio of the Cabibbo suppressed decay D 0 → π − μ + ν relative to the CSA favored decay D 1 → K − μ+ ν was presented.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, University of Puerto Rico at Mayagüez12, University of South Carolina13, University of Tennessee14, Vanderbilt University15, University of Wisconsin-Madison16
TL;DR: In this paper, the decay of D 0 mesons into final states containing more than one K S 0 was investigated and it was shown that two Cabibbo favored decay modes, D 0 → KS 0 K S, K − π + π+ π −, and D0 → K S S 0 KS, K + ρ − ρ− π−, can be found to be 0.0019 ± 0.0010.
TL;DR: In this paper, the theoretical analysis of an air atmospheric pressure discharge in a streamer regime in order to predict the evolution of the gas-phase chemical composition is presented. But the authors focus on a single isolated streamer and the results of this approach are examined within this paper.
Abstract: The present research concerns the theoretical analysis of an air atmospheric pressure discharge in a streamer regime in order to predict the evolution of the gas-phase chemical composition. Detailed modeling of the discharge development and evolution leads to the identification of a suitable scheme for chemical kinetics simulations. Such scheme has been exploited with the implementation of suitable numerical models of the chemical kinetics considering actually existing devices (DC discharges in point-plane, point to point or coaxial cylinder configuration, dielectric barrier discharges) and used to study the evolution of the discharge composition. As a first application we have chosen to simulate the chemical kinetics induced in a single isolated streamer and the results of this approach are examined within this paper. The interplay between different time scale processes is shown. The model allows also to investigate the dependence of chemical species density as a function of input parameters depending on actual discharge parameters. Many of our observations are directly relevant for a better understanding of the operating conditions during atmospheric pressure plasma processing.
TL;DR: A review of the different experimental results obtained at the research center PlasmaPrometeo on the surface modification of silk by various plasma processing is presented in this paper, where the authors show that silk is a very promising object for cold plasma treatment, which happens at room temperature in absence of solvents.
Abstract: Silk, as most of the natural textile fibres, shows many excellent qualities but also some defects. In particular natural fibres are in general delicate and cannot be treated under extreme conditions, for instance at high temperatures or in reactive solutions. This makes silk a very promising object for cold plasma treatment, which happens at room temperature in absence of solvents. A review of the different experimental results obtained at the research center PlasmaPrometeo on the surface modification of silk by various plasma processing will be presented.
University of California, Davis1, CINVESTAV2, University of Colorado Boulder3, Fermilab4, Universidad de Guanajuato5, University of Illinois at Urbana–Champaign6, Indiana University7, Korea University8, Kyungpook National University9, University of Milan10, University of North Carolina at Chapel Hill11, Pontifical Catholic University of Rio de Janeiro12, University of Puerto Rico at Mayagüez13, University of South Carolina14, University of Tennessee15, Vanderbilt University16, University of Wisconsin-Madison17
TL;DR: A high statistics measurement of the D(s)+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented and the analysis of the two decay modes, D( s)+ --> phi(1020)pi+ and D (s)+ -->K*(892)0K+ is described.
Abstract: A high statistics measurement of the D(s)+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, D(s)+ --> phi(1020)pi+ and D(s)+ -->K*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5(stat) +/- 5.1(syst) fs using 8961 +/- 105 D(s)+ --> phi(1020)pi+ and 4680 +/- 90 D(s)+ --> K*(892)0K+ decays. This is a significant improvement over the present world average.
Journal Article•
TL;DR: The thickness and homogeneity of plasma-assisted deposits by focused ion beam (FIB) is analysed and a novel approach to the edge detection techniques (EDT) in images is developed for a fast evaluation and monitoring of the deposited layer.
Abstract: In this paper, a novel technique is presented for the characterization at the nanoscale of plasma-assisted deposit on polyethylene-terephthalate (PET) polymer films. In previous studies, some microcharacterization and morphology analyses of plasma-assisted deposition were performed by atomic force microscopy (AFM). In the work presented here, we analysed the thickness and homogeneity of plasma-assisted deposits by focused ion beam (FIB). This technique with 5-7 nm resolution requires no sample preparation and relies on a sequence of operations on a relatively fast time scale, so that it is easy to make thorough investigations of the sample. We performed electron and ion imaging of the surface of the material, and a subsequent ionic cutting allowed the study of the morphology of the same sample. We developed a novel approach to the edge detection techniques (EDT) in images for a fast evaluation and monitoring of the deposited layer.
Patent•
24 May 2005TL;DR: In this article, a method for making components for fuel cells comprising at least a step of carrying out a surface treatment based on a plasma technology on at least one component of said fuel cell is presented.
Abstract: A method for making components for fuel cells comprising at least a step of carrying out a surface treatment based on a plasma technology on at least one component of said fuel cell. To provide surface functional properties of different nature on materials used as fuel cell components, thereby allowing to make integrated component fuel cells of less weight and size, high efficiency and operating life.
01 Jan 2005