352 research outputs found

    LES PROGRAMMES EXPERIMENTAUX AUPRES DU SYNCHROCYCLOTRON D'ORSAY

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    Les programmes expérimentaux auprÚs du S.C. d'Orsay ont commencé il y a un an environ. L'accélérateur est une machine stable mais présentant quelques défauts de jeunesse. De nombreuses voies de recherches amorcées avec un certain succÚs sont décrites ci-dessous

    Observation of coherent π0\pi^0 electroproduction on deuterons at large momentum transfer

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    The first experimental results for coherent π0\pi^0-electroproduction on the deuteron, e+d→e+d+π0e+d\to e+d +\pi^0, at large momentum transfer, are reported. The experiment was performed at Jefferson Laboratory at an incident electron energy of 4.05 GeV. A large pion production yield has been observed in a kinematical region for 1.1<Q2<<Q^2<1.8 GeV2^2, from threshold to 200 MeV excitation energy in the dπ0d\pi^0 system. The Q2Q^2-dependence is compared with theoretical predictions.Comment: 26 page

    Phenomenological insight into JLab proton polarization data puzzle by deuteron impulse approximation

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    The non-relativistic impulse approximation of deuteron electromagnetic form factors is used to investigate the space-like region behavior of the proton electric form factor in regard of the two contradictory experimental results extracted either from Rosenbluth separation method or from recoil proton JLab polarization data.Comment: Revtex, 6 pages, 7 figure

    RÉACTION DE PRODUCTION DE PIONS PRÈS DU SEUIL

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    La distribution angulaire de la section efficace diffĂ©rentielle de la rĂ©action 40Ca(p, π+)41Ca (Ă©tat fondamental) a Ă©tĂ© mesurĂ©e. L'Ă©tude de la dĂ©pendance en Ă©nergie de la production de pions prĂšs du seuil a Ă©tĂ© faite Ă  transfert de moment constant. La section efficace dĂ©croĂźt d'un facteur 7 pour des Ă©nergies de protons variant de 154 Ă  149 MeV (Eπ varie de 17,4 Ă  12,4 MeV). L'interprĂ©tation des rĂ©sultats est faite dans le cadre d'un mĂ©canisme Ă  un nuclĂ©on

    Audio source separation with a single sensor

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    G0^0 Electronics and Data Acquisition (Forward-Angle Measurements)

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    The G0^0 parity-violation experiment at Jefferson Lab (Newport News, VA) is designed to determine the contribution of strange/anti-strange quark pairs to the intrinsic properties of the proton. In the forward-angle part of the experiment, the asymmetry in the cross section was measured for e⃗p\vec{e}p elastic scattering by counting the recoil protons corresponding to the two beam-helicity states. Due to the high accuracy required on the asymmetry, the G0^0 experiment was based on a custom experimental setup with its own associated electronics and data acquisition (DAQ) system. Highly specialized time-encoding electronics provided time-of-flight spectra for each detector for each helicity state. More conventional electronics was used for monitoring (mainly FastBus). The time-encoding electronics and the DAQ system have been designed to handle events at a mean rate of 2 MHz per detector with low deadtime and to minimize helicity-correlated systematic errors. In this paper, we outline the general architecture and the main features of the electronics and the DAQ system dedicated to G0^0 forward-angle measurements.Comment: 35 pages. 17 figures. This article is to be submitted to NIM section A. It has been written with Latex using \documentclass{elsart}. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment In Press (2007

    Phenomenology of the Deuteron Electromagnetic Form Factors

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    A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm^-1. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.Comment: 18 pages (LaTeX), 2 figures Feb. 25: minor changes of content and in Table

    A SIGNATURE FOR ISOSCALAR-SPIN TRANSITIONS IN ([d,d) SCATTERING

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    Three different signatures for isoscalar spin transitions in nuclei have been tested in the 12C(d,d)12C reaction at 400 MeV. These signatures have values close to zero for the natural parity states, and ranging from 0.22 to 0.50 for the ΔS=1 ΔT=0, 12.7 MeV state

    Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment

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    We have measured parity-violating asymmetries in elastic electron-proton and quasi-elastic electron-deuteron scattering at Q^2 = 0.22 and 0.63 GeV^2. They are sensitive to strange quark contributions to currents in the nucleon, and to the nucleon axial current. The results indicate strange quark contributions of < 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial current at these four-momentum transfers.Comment: 5 pages, 2 figures, changed references, typo, and conten
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