Search results for "Composite"
showing 10 items of 4584 documents
Ionizing radiation induced curing of epoxy resin for advanced composites matrices
2005
Abstract The radiation curing of an epoxy monomer in the presence of an iodonium salt, as photo initiator, is studied. Systems with different concentrations of photo initiators have been polymerized via both gamma rays and e-beam, at various dose rates. The aim of this work is to investigate how the photo initiator concentration and the irradiation dose rate affect the temperature of the systems during curing and how the different thermal histories influence the dynamic mechanical thermal properties of the obtained materials.
Micro-Raman analysis of the fuel-cladding interface in a high burnup PWR fuel rod
2017
International audience; New insights on the fuel-cladding bonding layer in high burnup nuclear fuel were obtained using micro-Raman spectroscopy. A specimen was specifically prepared from a fuel rod which had been irradiated to an average burnup of 56 GWd.tU-1 in a pressurized water reactor (PWR). Both inner and outer corrosion scale regions were investigated. A 10-15 et956;m thick zirconia bonding layer between fuel and cladding materials which consisted of three distinct regions was observed. Close to the fuel, tetragonal, then monoclinic zirconia was identified as the main phases. Close to the bonding layer-cladding interface, peculiar Raman signals were observed. Similar signals were ob…
Elektronenmikroskopische Untersuchung von Transversalschnitten d�nner Schichten auf festen Unterlagen
1969
A method is described which allows to prepare transverse sections of thin films by means of an ion etching technique so that transmission electron micrographs of the film structure can be carried out. A section through a 6-layered optical film with a total thickness of 0.62 μm is shown as an example.
Fingerprints of heavy scales in electroweak effective Lagrangians
2017
The couplings of the electroweak effective theory contain information on the heavy-mass scales which are no-longer present in the low-energy Lagrangian. We build a general effective Lagrangian, implementing the electroweak chiral symmetry breaking $SU(2)_L\otimes SU(2)_R\to SU(2)_{L+R}$, which couples the known particle fields to heavier states with bosonic quantum numbers $J^P=0^\pm$ and $1^\pm$. We consider colour-singlet heavy fields that are in singlet or triplet representations of the electroweak group. Integrating out these heavy scales, we analyze the pattern of low-energy couplings among the light fields which are generated by the massive states. We adopt a generic non-linear realiz…
A 125 GeV composite Higgs boson versus flavour and electroweak precision tests
2013
A composite Higgs boson of 125 GeV mass, only mildly fine-tuned, requires top partners with a semi-perturbative coupling and a mass not greater than about a TeV. We analyze the strong constraints on such picture arising from flavour and electroweak precision tests in models of partial compositeness. We consider different representations for the composite fermions and compare the case of an anarchic flavour structure to models with a U(3)^3 and U(2)^3 flavour symmetry. Although non trivially, some models emerge that look capable of accommodating a 125 GeV Higgs boson with top partners in an interesting mass range for discovery at the LHC as well as associated flavour signals.
Light baryons and their electromagnetic interactions in the covariant constituent quark model
2012
We extend the confined covariant constituent quark model that was previously developed by us for mesons to the baryon sector. In our numerical calculation we use the same values for the constituent quark masses and the infrared cutoff as have been previously used in the meson sector. In a first application we describe the static properties of the proton and neutron, and the $\Lambda$-hyperon (magnetic moments and charge radii) and the behavior of the nucleon form factors at low momentum transfers. We discuss in some detail the conservation of gauge invariance of the electromagnetic transition matrix elements in the presence of a nonlocal coupling of the baryons to the three constituent quar…
Consistent searches for SMEFT effects in non-resonant dijet events
2018
We investigate the bounds which can be placed on generic new-physics contributions to dijet production at the LHC using the framework of the Standard Model Effective Field Theory, deriving the first consistently-treated EFT bounds from non-resonant high-energy data. We recast an analysis searching for quark compositeness, equivalent to treating the SM with one higher-dimensional operator as a complete UV model. In order to reach consistent, model-independent EFT conclusions, it is necessary to truncate the EFT effects consistently at order $1/\Lambda^2$ and to include the possibility of multiple operators simultaneously contributing to the observables, neither of which has been done in prev…
Cathodoluminescence and IR absorption of oxygen deficient silica – influence of hydrogen treatment
1999
Abstract The cathodoluminescence (CL) and IR absorption of silica samples with normal stoichiometry as well as with an extremely high level of oxygen deficit were studied. Additionally, some samples have been treated in hydrogen at 800°C. Crystalline quartz was used for reference measurements and the CL data have been compared with those of X-ray excited luminescence (XL). The luminescence spectra of silica have a band at 1.85 eV due to non-bridging oxygens and the two bands at 2.7 and 4.4 eV due to twofold-coordinated silicons. The energetic yield for CL is about 0.1%, for XL it approaches 0.15%. Cathodoluminescence of quartz at temperatures >130 K exhibits the self-trapped exciton lumines…
Nucleation kinetics in deionized charged colloidal suspension
2011
A systematic experimental study on the nucleation, crystallization and crystal-growth of one-componentcharged colloidal particles (122 nm diluted in pure water with densities between 0.5 μm−3bnpb5 ...
The structural properties of soda–silicate sols and of the lime–soda–silicate gel formation
1999
Abstract Alkaline silicate solutions were prepared with varying SiO 2 –Na 2 O ratios, Rm=[SiO 2 ]/[Na 2 O]=2 or 3, with a constant silica concentration equal to 1.5 M. The structure and the number fraction of different silicate molecular species present in the solutions were classically determined for molar ratio Rm=2 using 29 Si nuclear magnetic resonance ( 29 Si NMR). In the case of the sample with Rm=3, for which no NMR data was available, we used small-angle X-ray scattering (SAXS) experiments to get this information. The SAXS model was previously tested with Rm=2 silicate solution. When Ca ++ is added to alkaline silicate solutions, a gel is obtained under well-defined conditions. The …