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Search Results: 1 - 10 of 401182 matches for " M. Morlet "
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Projectile $Δ$ and target-Roper excitation in the p (d, d')X reaction
S. Hirenzaki,E. Oset,C. Djalali,M. Morlet
Physics , 2000, DOI: 10.1103/PhysRevC.61.044605
Abstract: In this paper we compare a model that contains the mechanisms of $\Delta$ excitation in the projectile and Roper excitation in the target with experimental data from two (d, d') experiments on a proton target. The agreement of the theory with the experiment is fair for the data taken at T_d = 2.3 GeV. The $\Delta$ excitation in the projectile is predicted close to the observed energy with the correct width. The theory, however, underpredicts by about 40% the cross sections measured at T_d = 1.6 GeV at angles where the cross section has fallen by about two orders of magnitude. The analysis done here allows to extract an approximate strength for the excitation of the Roper [N^*(1440)] excitation and a qualitative agreement with the theoretical predictions is also found.
Realtime calibration of the A4 electromagnetic lead fluoride calorimeter
S. Baunack,D. Balaguer Ríos,L. Capozza,J. Diefenbach,R. Frascaria,B. Gl?ser,D. v. Harrach,Y. Imai,R. Kothe,R. Kunne,J. H. Lee,F. E. Maas,M. C. Mora Espí,M. Morlet,S. Ong,E. Schilling,J. van de Wiele,C. Weinrich
Physics , 2011, DOI: 10.1016/j.nima.2011.02.099
Abstract: Sufficient energy resolution is the key issue for the calorimetry in particle and nuclear physics. The calorimeter of the A4 parity violation experiment at MAMI is a segmented calorimeter where the energy of an event is determined by summing the signals of neighbouring channels. In this case the precise matching of the individual modules is crucial to obtain a good energy resolution. We have developped a calibration procedure for our total absorbing electromagnetic calorimeter which consists of 1022 lead fluoride (PbF_2) crystals. This procedure reconstructs the the single-module contributions to the events by solving a linear system of equations, involving the inversion of a 1022 x 1022-matrix. The system has shown its functionality at beam energies between 300 and 1500 MeV and represents a new and fast method to keep the calorimeter permanently in a well-calibrated state.
Photogenerating Silver Nanoparticles and Polymer Nanocomposites by Direct Activation in the Near Infrared
Lavinia Balan,Raphael Schneider,Colette Turck,Daniel Lougnot,Fabrice Morlet-Savary
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/512579
Abstract: This work reports on an improvement of the photochemically assisted synthesis of silver nanoparticles by direct photoreduction of AgNO3 with a laser source emitting in the near infrared range (NIR). For this, polymethine dyes were used as the photoactive agents. Both the effects of central chain structure and activation intensity were investigated. The reduction kinetics was followed up by UV-Vis spectroscopy, and the particles size was evaluated by transmission electron microscopy. The results showed that light intensity affects both the average size and size distribution of Ag nanoparticles generated through this process. The particles can also be generated in situ in a photopolymerizable formulation so that metal/polymer nanocomposites become available through a one-step photoassisted process on the basis of NIR activation. The process described herein is very fast (seconds to a few minutes), and it readily lends itself to automatization for mass production of micro-optical elements implemented directly onto integrated NIR sources.
Dyes as Photoinitiators or Photosensitizers of Polymerization Reactions
Jean-Pierre Fouassier,Fabrice Morlet-Savary,Jacques Lalevée,Xavier Allonas,Christian Ley
Materials , 2010, DOI: 10.3390/ma3125130
Abstract: A short but up-to-date review on the role of dyes in the photoinitiation processes of polymerization reactions is presented. Radical and cationic reactions are largely encountered in the radiation curing and the imaging areas for use in traditional coating applications as well as in high tech sectors such as nanofabrication, computer-to-plate processing, laser direct imaging, manufacture of optical elements, etc. Recent promising developments concerned with the introduction of the silyl radical chemistry that enhances the polymerization efficiency are also discussed.
Manejo del Paciente Psicótico en el Servicio de Urgencias de un Hospital General
Arturo Morlet-Barjau,Ernesto Ortiz-Maldonado,Manuel Moscoso-López
Salud en Tabasco , 2008,
Abstract: Las psicosis son situaciones clínicas prevalentes tanto en los servicios de hospitalización como en urgencias. Es importante que los médicos estén familiarizados con los datos clínicos y el manejo farmacológico para evitar con ello complicaciones posteriores. Aunque los problemas psicóticos son situaciones clínicas difíciles que muchos médicos intentan evitar, es importante conocer los aspectos generales y prácticos del abordaje de estos pacientes. Esta revisión práctica de la literatura intenta proporcionar lineamientos básicos para la identificación y tratamiento de emergencia de los cuadros psicóticos que se presentan en un servicio de urgencias de un Hospital General.
Photochemistry and Radical Chemistry under Low Intensity Visible Light Sources: Application to Photopolymerization Reactions
Jacques Lalevée,Fabrice Morlet-Savary,Céline Dietlin,Bernadette Graff,Jean-Pierre Fouassier
Molecules , 2014, DOI: 10.3390/molecules190915026
Abstract: The search for radical initiators able to work under soft conditions is a great challenge, driven by the fact that the use of safe and cheap light sources is very attractive. In the present paper, a review of some recently reported photoinitiating systems for polymerization under soft conditions is provided. Different approaches based on multi-component systems (e.g., photoredox catalysis) or light harvesting photoinitiators are described and discussed. The chemical mechanisms associated with the production of free radicals usable as initiating species or mediators of cations are reported.
Measurement of Strange Quark Contributions to the Vector Form Factors of the Proton at Q**2=0.22 (GeV/c)**2
S. Baunack,K. Aulenbacher,D. Balaguer Ríos,L. Capozza,J. Diefenbach,B. Gl?ser,D. v. Harrach,Y. Imai,E. M. Kabu?,R. Kothe,J. H. Lee,H. Merkel,M. C. Mora Espí,U. Müller,E. Schilling,G. Stephan,C. Weinrich,J. Arvieux,M. A. El-Yakoubi,R. Kunne,F. E. Maas,M. Morlet,S. Ong,J. van de Wiele,S. Kowalski,Y. Prok,S. Taylor
Physics , 2009, DOI: 10.1103/PhysRevLett.102.151803
Abstract: A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q^2=0.22 (GeV/c)^2 is reported here. The measured asymmetry is A_LR=(-17.23 +- 0.82_stat +-0.89_syst) ppm. The Standard Model prediction assuming no strangeness is A_0=(-15.87 +- 1.22) ppm. In combination with previous results from measurements at forward angles, it it possible to disentangle for the first time the strange electric and magnetic form factors at this momentum transfer, G_E^s(0.22)=0.050 +- 0.038 +- 0.019 and G_M^s(0.22)=-0.14 +- 0.11 +- 0.11.
Evidence for Strange Quark Contributions to the Nucleon's Form Factors at $Q^2$ = 0.108 (GeV/c)$^2$
F. E. Maas,K. Aulenbacher,S. Baunack,L. Capozza,J. Diefenbach,B. Gl?ser,T. Hammel,D. von Harrach,Y. Imai,E. -M. Kabu?,R. Kothe,J. H. Lee,A. Lorente,E. Schilling,D. Schwaab,M. Sikora,G. Stephan,G. Weber,C. Weinrich,I. Altarev,J. Arvieux,M. El-Yakoubi,R. Frascaria,R. Kunne,M. Morlet,S. Ong,J. van de Wiele,S. Kowalski,B. Plaster,R. Suleiman,S. Taylor
Physics , 2004, DOI: 10.1103/PhysRevLett.94.152001
Abstract: We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of $Q^2$ = \Qsquare (GeV/c)$^2$ and at a forward electron scattering angle of 30$^\circ < \theta_e < 40^\circ$. The measured asymmetry is $A_{LR}(\vec{e}p)$ = (\Aphys $\pm$ \Deltastat$_{stat}$ $\pm$ \Deltasyst$_{syst}$) $\times$ 10$^{-6}$. The expectation from the Standard Model assuming no strangeness contribution to the vector current is A$_0$ = (\Azero $\pm$ \DeltaAzero) $\times$ 10$^{-6}$. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher $Q^2$. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be $G_E^s$ + \FakGMs $G_M^s$ = \GEsGMs $\pm $ \DeltaGEsGMs at $Q^2$ = \Qsquare (GeV/c)$^2$. As in our previous measurement at higher momentum transfer for $G_E^s$ + 0.230 $G_M^s$, we again find the value for $G_E^s$ + \FakGMs $G_M^s$ to be positive, this time at an improved significance level of 2 $\sigma$.
Measurement of the Transverse Beam Spin Asymmetry in Elastic Electron Proton Scattering and the Inelastic Contribution to the Imaginary Part of the Two-Photon Exchange Amplitude
F. E. Maas,K. Aulenbacher,S. Baunack,L. Capozza,J. Diefenbach,B. Gl?ser,Y. Imai,T. Hammel,D. von Harrach,E. -M. Kabub,R. Kothe,J. H. Lee,A. Sanchez-Lorente,E. Schilling,D. Schwaab,G. Stephan,G. Weber,C. Weinrich,I. Altarev,J. Arvieux,M. Elyakoubi,R. Frascaria,R. Kunne,M. Morlet,S. Ong,J. Vandewiele,S. Kowalski,R. Suleiman,S. Taylor
Physics , 2004, DOI: 10.1103/PhysRevLett.94.082001
Abstract: We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A$_\perp$, at two Q$^2$ values of \qsquaredaveragedlow (GeV/c)$^2$ and \qsquaredaveragedhighII (GeV/c)$^2$ and a scattering angle of $30^\circ < \theta_e < 40^\circ$. The measured transverse asymmetries are A$_{\perp}$(Q$^2$ = \qsquaredaveragedlow (GeV/c)$^2$) = (\experimentalasymmetry alulowcorr $\pm$ \statisticalerrorlow$_{\rm stat}$ $\pm$ \combinedsyspolerrorlowalucor$_{\rm sys}$) $\times$ 10$^{-6}$ and A$_{\perp}$(Q$^2$ = \qsquaredaveragedhighII (GeV/c)$^2$) = (\experimentalasymme tryaluhighcorr $\pm$ \statisticalerrorhigh$_{\rm stat}$ $\pm$ \combinedsyspolerrorhighalucor$_{\rm sys}$) $\times$ 10$^{-6}$. The first errors denotes the statistical error and the second the systematic uncertainties. A$_\perp$ arises from the imaginary part of the two-photon exchange amplitude and is zero in the one-photon exchange approximation. From comparison with theoretical estimates of A$_\perp$ we conclude that $\pi$N-intermediate states give a substantial contribution to the imaginary part of the two-photon amplitude. The contribution from the ground state proton to the imaginary part of the two-photon exchange can be neglected. There is no obvious reason why this should be different for the real part of the two-photon amplitude, which enters into the radiative corrections for the Rosenbluth separation measurements of the electric form factor of the proton.
Measurement of Strange Quark Contributions to the Nucleon's Form Factors at Q^2=0.230 (GeV/c)^2
A4 Collaboration,F. E. Maas,P. Achenbach,K. Aulenbacher,S. Baunack,L. Capozza,J. Diefenbach,K. Grimm,Y. Imai,T. Hammel,D. von Harrach,E. -M. Kabuss,R. Kothe,J. H. Lee,A. Lorente,A. Lopes Ginja,L. Nungesser,E. Schilling,G. Stephan,C. Weinrich,I. Altarev,J. Arvieux,B. Collin,R. Frascaria,M. Guidal,R. Kunne,D. Marchand,M. Morlet,S. Ong,J. van de Wiele,S. Kowalski,B. Plaster,R. Suleiman,S. Taylor
Physics , 2004, DOI: 10.1103/PhysRevLett.93.022002
Abstract: We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a $Q^2$ of 0.230 (GeV/c)^2 and a scattering angle of \theta_e = 30^o - 40^o. Using a large acceptance fast PbF_2 calorimeter with a solid angle of \Delta\Omega = 0.62 sr the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A_{phys} =(-5.44 +- 0.54_{stat} +- 0.27_{\rm sys}) 10^{-6}. The Standard Model expectation assuming no strangeness contributions to the vector form factors is $A_0=(-6.30 +- 0.43) 10^{-6}$. The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is G^s_E + 0.225 G^s_M = 0.039 +- 0.034 or F^s_1 + 0.130 F^s_2 = 0.032 +- 0.028.
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