We describe the Hybrid seeding, a stand-alone pattern recognition algorithm aiming at finding charged particle trajectories for the LHCb upgrade. A significant improvement to the charged particle ...reconstruction efficiency is accomplished by exploiting the knowledge of the LHCb magnetic field and the position of energy deposits in the scintillating fibre tracker detector. Moreover, we achieve a low fake rate and a small contribution to the overall timing budget of the LHCb real-time data processing.
Novel fluorescent materials were satisfactorily synthesized. With this aim, an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) was reacted with a laser dye, rhodamine B (RB), to achieve ...an epoxy-based prepolymer. Then, a diamine, m-xylylenediamine (MXDA), was used as hardener with the purpose of obtaining a crosslinked polymer. The curing conditions strongly influence the intended final properties and the optimization of the curing requires a reliable kinetic model. For that reason, this work presents the kinetic study of the polymerization of the epoxy resin by differential scanning calorimetry (DSC) in isothermal mode as well as by Fourier transform infrared spectroscopy (FTIR). DSC data were fitted using a Kamal autocatalytic equation. Conversion as a function of reaction time curves obtained by means of both techniques agreed well. In addition, the synthesized epoxy-based materials were characterized by proton nuclear magnetic resonance spectroscopy (
1H NMR) and their fluorescent properties were also analysed.
The OPE treatment that has been so successful in describing inclusive B̄→lν̄Xc decays yields sum rules (in particular the Uraltsev sum rule and its higher moments) implying the dominance of the P ...wave jq=3/2 charm states in Xc over their jq=1/2 counterparts. This prediction is supported by other general arguments as well as quark model calculations, which illustrate the OPE results, and by preliminary lattice findings. Its failure would indicate a significant limitation in our theoretical understanding of B̄→lν̄Xc. Some experimental issues have been clarified since a preliminary version of this note had appeared; yet, the verdict on the composition of the final states beyond D, D* and the two narrow jq=3/2 resonances remains unsettled. Establishing which hadronic configurations – D/D*+π,D/D*+2π,... – contribute, what their quantum numbers are, and their mass distributions will require considerable experimental effort. We explain the theoretical issues involved and why a better understanding of them will be of considerable value. Having significant contributions from a mass continuum distribution below 2.5 GeV raises serious theoretical questions for which we have no good answer. Two lists are given, one with measurements that need to be done and one with items of theoretical homework. Some of the latter can be done by employing existing theoretical tools, whereas others need new ideas.
A push–pull azo dye (DO3) was used as photosensitive substance to satisfactorily synthesize new epoxy polymers containing azo groups covalently linked. Three different amines BA, TA and MXDA were ...used as hardeners. Materials with different chemical structure and azo group concentration were prepared. The polymerization kinetics was followed using SEC, FTIR and DSC. It was observed that polymerization rate increases with the azo chromophore incorporation and with the photosensitive component concentration in the reaction precursors. The photoinduced birefringence of the obtained films has been analyzed. A completely reversible optical orientation was reached.
Reactions taking place in a homogeneous solution of an epoxy monomer based on the diglycidyl ether of bisphenol A (DGEBA) and palmitic acid (PA), in the presence of benzyldimethylamine (BDMA), were ...investigated using Fourier‐transformed infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). In the stoichiometric formulations prepared with equal molar ratios of epoxy (E) to carboxyl groups, E/PA = 1, the main reaction was the carboxyl addition to the epoxy giving a β‐hydroxy ester. This reaction was followed by transesterification that occurred to a very small extent. In the formulations prepared with an epoxy excess, E/PA > 1, the transesterification reactions were very significant as well as the homopolymerization of the epoxy excess that took place to an almost complete conversion. Reaction products synthesized in the range of 1 < E/PA < 2 were solids at room temperature due to the crystallization of a fraction of fatty acid chains. Above the melting temperature, reaction products recovered the liquid state. The formulation synthesized with E/PA = 2 exhibited a good behavior as a hot‐melt adhesive of steel sheets with a single lap‐shear strength of 2.5 MPa and an interfacial‐cohesive failure. For E/PA > 3, the gelation took place leading to the networks exhibiting a single glass transition temperature (Tg) without any evidence of crystallization or phase separation. Tg varied from 90 °C for the neat epoxy to 0 °C for the formulation with E/PA = 3.
Single lap‐shear strength values of hot‐melt adhesives corresponding to reaction products synthesized with E/PA = 1.6, 1.8, and 2.
Two series of crosslinked fluorinated epoxy-based materials containing variable fluorine contents (from 0 to 6
wt.% F) were prepared using formulations based on a fluorinated acid (FA), epoxy monomer ...and a diamine. The epoxy monomer was based on diglycidyl ether of bisphenol A (DGEBA) while the curing agent was propyleneoxide diamine (Jeffamine D-230). The selected FA were: 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptanoic acid (FA1), perfluoro-heptanoic acid (FA2), and perfluoro-nonanoic acid (FA3). One of the series synthesized, FA–DGEBA/Jeffamine, is characterized by covalent attachment of the FA to the polymer by an ester bond. The other series, FA–Jeffamine/DGEBA, is characterized by ionic interaction between FA and polymer chains. The influence on thermal and surface properties of the architecture and chain-length of FA, and the nature of the linkage between FA and network precursors, was analyzed and discussed. It was found that both series showed high oleophobicity, but depending on the linkage between the fluorinated acid and the network, it was possible to develop hydrophobic or hydrophilic materials. The fluorine enrichment with the perfluoroalkyl substitutions was proved by XPS. By this technique it was possible also to analyze the concentration of ammonium groups at the surface.
New photosensitive materials containing photochromic azobenzene moieties were synthesized. For this purpose, an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) was reacted with an ...azobenzene chromophore (disperse orange 3, AZ) to satisfactorily synthesize an azo-modified prepolymer, which was then used to generate series of epoxy-based polymers containing azo groups. Three different amines were used as hardeners, with the aim of obtaining materials with different chemical structures. Understanding the epoxy resin polymerization kinetics is essential for intelligent processing of materials. Near-IR (NIR) spectral analysis was used to follow the polymerization kinetics. The quality of the NIR spectra enables concentrations of individual chemical species to be measured in real time. Conversion of epoxy and primary amine groups, as well as the concentration of different groups, as a function of reaction time was therefore calculated by this spectroscopic technique. Samples containing azo units were compared to the pure DGEBA/amine systems. Results showed that the azo-prepolymer incorporation has an accelerating effect on polymerization rate.
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