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David Anez Saint Mary’s/Dalhousie University June 9, 2011

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Measurement of the Coulomb quadrupole amplitude in the γ * p → Δ (1232) reaction in the low momentum transfer region. David Anez Saint Mary’s/Dalhousie University June 9, 2011. Introduction. Took measurements of the p ( e , e ′ p ) π 0 (pion electroproduction) reaction - PowerPoint PPT Presentation

Text of David Anez Saint Mary’s/Dalhousie University June 9, 2011

  • Measurement of the Coulomb quadrupole amplitude in the *p(1232) reaction in the low momentum transfer regionDavid AnezSaint Marys/Dalhousie UniversityJune 9, 2011

  • IntroductionTook measurements of the p(e,ep)0 (pion electroproduction) reactionIn the low Q2 region where the pion cloud is expected to dominateWith center-of-mass energies near the resonance to look at the transition amplitudes between the nucleon and the deltaTo better understand the Coulomb quadrupole transition amplitude behavior in this region and how it affects nucleon deformationDavid Anez June 9th, 2011*/19

  • Motivation: Constituent Quark ModelWave functions created David Anez June 9th, 2011*/19

  • Motivation: Constituent Quark ModelMagnetic Dipole (M1 / ) Spin-flipDominantDavid Anez June 9th, 2011*/19

  • Motivation: Constituent Quark ModelElectric quadrupole (E2 / )Coulomb quadrupole (C2 / )Only with virtual photons

    David Anez June 9th, 2011*/19

  • Multipole AmplitudesDavid Anez June 9th, 2011*/19

  • Multipole AmplitudesE1+ and S1+ at same magnitude as background amplitudesMeasure ratio to dominant M1+

    EMR =

    CMR = David Anez June 9th, 2011*/19

  • World Data and ModelsDavid Anez June 9th, 2011*/19

  • World Data and ModelsDavid Anez June 9th, 2011*/19

  • World Data and ModelsQ2 = 0.045 (GeV/c)2New lowest CMR valuee = 12.5Q2 = 0.125 (GeV/c)2Validate previous measurementsQ2 = 0.090 (GeV/c)2Bridge previous measurementsDavid Anez June 9th, 2011*/19

  • The ExperimentJefferson Lab, Hall AFebruary 27th March 8th, 20111160 MeV e beam4 & 15 cm LH2 targetTwo high resolution spectrometersHRSe and HRShDavid Anez June 9th, 2011*/19

  • High Resolution SpectrometersVertical drift chambersParticle trackingScintillatorsTiming informationTriggering DAQGas Cerenkov detectorsParticle identificationLead glass showersParticle identificationDavid Anez June 9th, 2011*/19

  • Original Kinematic SettingsDavid Anez June 9th, 2011*/19

  • Revised Kinematic SettingsDavid Anez June 9th, 2011*/19

  • Actual Kinematic Settings85%85%*/19David Anez June 9th, 2011

  • Response FunctionsUnpolarized cross section made up of four independent partial cross sections

    David Anez June 9th, 2011*/19

  • Response Functions

    David Anez June 9th, 2011*/19

  • Response Functions Truncated Multipole Expansion Model Dependent ExtractionFit theoretical model to existing dataInsert model values for background amplitudesDavid Anez June 9th, 2011*/19

  • Work Still to DoCalibration Analysis: May 2011Data Analysis: January 2012Doctoral Thesis: December 2012Published Paper: 2014?David Anez June 9th, 2011*/19

  • Motivation: Constituent Quark ModelOne-body interactions

    Two-body interactions

    David Anez June 9th, 2011

  • Motivation: Constituent Quark ModelPion CloudDavid Anez June 9th, 2011

  • Kinematics Electronic VertexIncoming electronEnergy EMomentum kiScattered electronEnergy EMomentum kfAngle eVirtual photonEnergy Momentum qAngle qDavid Anez June 9th, 2011

  • Kinematics Electronic VertexMomentum transfer, Q2

    David Anez June 9th, 2011

  • Kinematics Hadronic VertexRecoil protonEnergy EpMomentum pp Angle pqRecoil pionEnergy EMomentum pAngle Not detectedDavid Anez June 9th, 2011

  • Kinematics PlanesScattering plane ki and kfRecoil plane pp and pAzimuthal angle pqDavid Anez June 9th, 2011

  • Multipole AmplitudesGeneral form of N Multipoles: X type of excitation (M, E, S)I isospin of excited intermediate state J = 12Magnetic dipole M1 / Electric quadrupole E2 / Coulomb quadrupole C2 /

    David Anez June 9th, 2011

  • Response FunctionsUnpolarized cross section made up of four independent partial cross sections

    David Anez June 9th, 2011

  • Response FunctionsUnpolarized cross section made up of four independent partial cross sections

    David Anez June 9th, 2011

  • Original Phase Space PlotsQ2 = 0.041 (GeV/c)2 (pq* = 30)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

  • Original Phase Space PlotsQ2 = 0.090 (GeV/c)2 (pq* = 40)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

  • Original Phase Space PlotsQ2 = 0.125 (GeV/c)2 (pq* = 30)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

  • Original Phase Space PlotsQ2 = 0.125 (GeV/c)2 (pq* = 55)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

  • Revised Phase Space PlotsQ2 = 0.045 (GeV/c)2 (pq* = 33)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

  • Revised Phase Space PlotsQ2 = 0.090 (GeV/c)2 (pq* = 45)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

  • Revised Phase Space PlotsQ2 = 0.125 (GeV/c)2 (pq* = 30)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

  • Revised Phase Space PlotsQ2 = 0.125 (GeV/c)2 (pq* = 55)W vs pq*W vs Q2Q2 vs pq*Q2 vs pq*W 5MeV

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