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Data Analysis (ODU) and Simulations (J. Udias, Madrid)

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Outline Introduction – Hall A and Electron Scattering Experiment – Goals and Kinematics Setup Data Analysis – Good Runs, Target Foils, TOF, Acceptance – Comparing to Previous Work – R-Function and Results Summary and Whats Next?

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Mom Resolution Mom Accpt 1 x 10 -4 ± 4.5% Solid Angle 6 msr Angular Range (in degree) 12.5 – 150 (L) 12.5 – 130 (R) Angular Accpt± 30 mr (ver) ± 60 mr (hor) Angular Resolution 1 mr ( ver) 0.5 mr (hor) TOF Resolution1 ns FWHM

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Electron-Nucleus Interactions Three cases: Low q –Photon wavelength larger than the nucleon size (R N ) Medium q: 0.2 < q < 1 GeV/c – ~ R N –Nucleons resolvable High q: q > 1 GeV/c – < R N –Nucleon structure resolvable Select spatial resolution and excitation energy independently Photon energy determines excitation energy Photon momentum q determines spatial resolution hbar/q Energy vs Spatial Resolution

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Diagram of A(e,ep) Missing Energy: Missing Momentum: E m = - T p – T R p m = q – p 4-vector transferred mom: Invariant : Q 2 = 4E i E f sin 2 ( e / 2 )

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Outline Introduction –Hall A and Electron Scattering Experiment –Goals and Kinematics Setup Data Analysis – Good Runs, Target Foils, TOF, Acceptance – Comparing to Previous Work – R-Function and Results Summary and Whats Next?

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Goals of E00102 Measurement of cross-section, R LT and A LT for the 16 O(e,ep) reaction with higher precision and to higher missing momentum than in E89003. Determine the limit of validity of the single- particle model of valence proton knock-out. Determine effects of relativity and spinor distortion on valence proton knock-out using the diffractive character of the A LT symmetry. Determine bound-state wave function and spectroscopic factors for valence proton knockout.

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Kin Settings 9 Negative Kins 11 Positive Kins 1 Parallel Kin Statistics Total : 1743 runs Good (77%) Fixable (4%) Calibration (6%) Bad Runs (13%) E00102 Kinematics +

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mm 28 o – 96 o

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Introduction –Hall A and Electron Scattering Experiment –Goals and Kinematics Setup Data Analysis – Good Runs, Target Foils, TOF, Acceptance – Comparing to Previous Work – R-Function and Results Summary and Whats Next? Outline

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Good Runs coll open coll 6msr Fixable Bad Runs T1/T3 RUNNO T1 = Proton Rates T3 = Electron Rates Determining Good Runs For Kin AA+

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Uncut CTOF cut How We Handle Targets Kin AA+ Foil 1 Foil 2 Foil 3

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Time of Flight : Kin AA- (1531) 1 3 2 Region A

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Missing Energy Spectra : Kin AA- (1531) True = Real – 2 Accidental ( 1+ 3) Events 1P 1/2 1P 3/2 Mistiming factor

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1P 1/2 Relative Cross Section Comparing to Previous Results* Determination of 1P 1/2 cross section relative to H(e,e) * M. Anderson, Licentiate Thesis October 2005 Previous WorkThis Work Pm Range0 < Pm < 350 MeVSame KinsA+, C+, D+, E+, F+A± and D± Bin SizePm: 2 MeV/c (A-D) 4MeV/c (E-F) Pm: 2 MeV/c Em: 0.5 MeV Accpt cuts : ±50 mr, : ±50 mr : ±3.5% : ±50 mr, : ±25 mr : ±3.5% Unc.7% (stat) and 5%(syst)7% (stat) Only used central target foils !

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Relative Cross Section Cross Section : 16 O(e,ep) : H(e,e) : Relative Cross Section : No L !

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Data Replayed good runs Implemented energy loss correction Studied CTOF, zreact, acceptances, Emiss, Pmiss, mistiming factor correction, etc. Applied angular cuts : (±50 mr) and (±25 mr) Applied momentum cuts : (±3.5%) Applied background subtraction.

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Simulation Bound states physics models – calculated by Madrid Group. Spectrometer models – ON, radiative effects – ON, and energy loss correction – OFF Use the same acceptance values (,,and ) as in data. Use target configuration that built into the MCEEP.

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Recipe relative for 1P 1/2 1.Apply cuts on tg, tg, zreact, CTOF (Region A), and Emiss. 2.Subtract CTOF background bin-by- bin. 3.Apply mistiming correction factor 4.Normalize to 1 H(e,e)luminosity 5.Normalize to MC phase-space 6.Divide each data point by pmiss bin width

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relative for 1P 1/2 (Central Foils) Pmiss (MeV/c) dhfkjklll Previous Work

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Pmiss (MeV/c) AA+ DD+ AA- DD- relative for 1P 1/2 (Central Foils) This Work

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R-Function Maximize Event Acceptance Determine nominal acceptance boundaries ( tg, tg, ) for each HRS. R-function measures distance (+/-) to boundary of each trajectory : 1. R < 0.0 outside 2. R >= 0.0 inside Choose cut to make on R a. where we understand the acceptance b. Maximize it tg R-arm Kin AA- (1531)

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R-Functions of Kin AA+ (1315) Red (Data) and Blue (Simulation) L-Arm R-Arm

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Where to R-Function Cuts? (Kin AA+) L-Arm R-Arm

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Value of R-Function Cuts Next plots four different conditions of R-cut are used: 1. No R-cut (uncut) 2. R > 0.0 3. R > 0.005 4. R > 0.01

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Uncut R > 0.0R > 0.005R > 0.01 L-Arm Acceptance with 3-foils : Kin AA+

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R-Arm Acceptance with 3-foils : Kin AA+ Uncut R > 0.0R > 0.005R > 0.01

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Missing Momentum : Kin DD+ (1497) R > 0.005 R > 0.01 R > 0.005 R > 0.0Uncut

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Outline Introduction –Hall A and Electron Scattering Experiment –Goals and Kinematics Setup Data Analysis – Good Runs, Target Foils, TOF, Acceptance – Comparing to Previous Work – R-Function and Results Summary and Whats Next?

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Intensive studies to understand both data and simulation has been performed. Treatment for both data and simulation is better understood. All three foils cut would be used (previous work only used the central foils). R-function is now better understood and will be implemented as the acceptance cut for both data and simulations. Ready to replay to all different sets of kinematics and ready to fix/save runs (to gain better statistics). Plan to perform the reduced cross section and make plots of red versus pmiss for available replayed runs in each kinematics.

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THANK YOU, ANY QUESTION ?

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