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Elastic Electron Scattering off He and He (E04-018) Elena Khrosinkova Kent State University Hall A Collaboration Meeting Jefferson Lab, June 2008 34
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Objective Elastic scattering off helium's stable isotopes at large momentum transfers Extraction of He3 charge and magnetic and He4 charge form factors Jefferson Lab, June 2008 2/17
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Experimental Apparatus Coincidence experiment using TOF method 20 cm helium cells Jefferson Lab, June 2008 3/17
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Elastic Electron-Helium Scattering He charge and magnetic form factors:, He charge form factor: AB const A B Jefferson Lab, June 2008 4/17
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Data range Jefferson Lab, June 2008 5/17
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Data range Jefferson Lab, June 2008 6/16
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Data range Jefferson Lab, June 2008 7/17
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Analysis projects Current Calibration 2 current calibrations Normalization of the current at the injector cavity to the Faraday cup Cross-check with the Unser current Jefferson Lab, June 2008 8/17
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Normalization of the two BCM cavities to the calibrated injector cavity Analysis projects Current Calibration Jefferson Lab, June 2008 9/17
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Normalization of the scalers frequency (right, left) to the average value of the calibrated injector cavity current Analysis projects Current Calibration Jefferson Lab, June 2008 10/17
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Analysis projects Calorimeter calibration 6x6 blocks calibration MC simulation for energy deposited in first and second layers 1222 – 1273 runs ep elastic, 2.13 GeV E/p vs E E/p Counts Jefferson Lab, June 2008 11/17
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Cerenkov sum corrected Analysis projects Cerenkov Gain Equalization With cuts on >99% of total light in one particular tube Number of photoelectrons > 6 Cerenkov efficiency close to 100% 1222 – 1273 runs ep elastic, 2.13 GeV L.cer.a_p[4] L.cer.a_p[5] Counts Jefferson Lab, June 2008 12/17
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Analysis projects Timing Offsets Correction 1232 – 1233 runs, ep elastic 2.34 GeV Jefferson Lab, June 2008 13/17 tof, uncorrected tof, corrected Counts
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Analysis projects Scintillators ADC Equalization L.s1.ra_p[3] L.s1.ra_p[2] L.s1.la_p[3] L.s1.la_p[2] L.s1.la_c[*] + L.s1.ra_c[*] Jefferson Lab, June 2008 14/17 1222 – 1273 runs ep elastic, 2.13 GeV
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Analysis projects Event Display Jefferson Lab, June 2008 15/17 3D event display For all tracks from the analyzer LHRS and RHRS Cuts for fired blocks In progress
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Elastic stripe = 40 fm, e He Jefferson Lab, June 2008 16/17 Left, m Right, m
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Summary Finalization of the detector calibrations Improving tracking routine Ready for mass analysis Jefferson Lab, June 2008 17/17
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