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Inclusive Scattering of Polarized Electrons from Polarized Protons in the - Excitation Region with BLAST. Octavian Florin Filoti

Inclusive Scattering of Polarized Electrons from Polarized Protons in the - Excitation Region with BLAST BY Octavian Florin Filoti M.S. in Physics, University of Bucharest, 996 Diploma of Eng. in Engineering
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Inclusive Scattering of Polarized Electrons from Polarized Protons in the - Excitation Region with BLAST BY Octavian Florin Filoti M.S. in Physics, University of Bucharest, 996 Diploma of Eng. in Engineering Physics, University of Bucharest, Romania, 995 B.S. in Physics, University of Bucharest, Romania, 995 DISSERTATION Submitted to the University of New Hampshire in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics April 7 This dissertation has been examined and approved. Director, J. R. Calarco Professor of Physics W. F. Hersman Professor of Physics J. F. Dawson Professor of Physics J. M. Ryan Professor of Physics T. W. Donnelly Senior Research Scientist (MIT) M. Kohl Research Scientist (MIT) Date Dedication To my parents. iii Acknowledgments I want to thank my advisor Prof. John Calarco for his support, patience and guidance during my Ph.D. program. I like to thank Prof. Apostol Stefan who opened the physics door for me. I would like to thank my Professors from the University of Bucharest for teaching me modern physics. After College, I worked for three years at the Institute for Nuclear Research, Pitesti, Romania: thank you all for everything. I also like to thank my Professors from the University of New Hampshire for expanding my horizon in physics. I would also like to thank to MIT-Bates Laboratory staff for the nice environment and for making BLAST possible. I thank my doctoral committee members for their encouragements. To all graduate students working at BLAST: I could not make it without you guys, thanks a lot. To Alexander Ilyichev (Sasha): thank you for teaching me radiative corrections. To George Caia: thanks for explaining me the pion production theory. Many thanks to the BLAST collaboration for a job well done. To all my friends and my family for your love and support: I love you. iv Table of Contents Dedication Acknowledgments iii iv ABSTRACT xxviii Introduction. History Motivation Theoretical Framework. Formalism Multipole Decomposition Nucleon Models Phenomenological Models Constituent Quark Models Bag Models Skyrme Models Experimental Setup 3 3. The MIT-Bates Linear Accelerator The Polarized Source The Bates South Hall Ring Compton Polarimeter Polarized Internal Target v 3.. Atomic Beam Source Target Cell and Scattering Chamber BLAST Detector BLAST Toroid Magnet Drift Chambers Čerenkov Counters Time-of-Flight Scintillators Neutron Detectors Data Acquisition First Level Trigger Trigger Types Second Level Trigger Data Acquisition Software Data Analysis Inclusive Scattering Events Event Reconstruction Standard Cuts Trigger Selection Momentum Corrections Observables Background Contributions Beam blow-up Factor False Asymmetries Radiative Corrections Introduction Radiative Effects in Elastic Electron-Proton Scattering vi 4.3.3 Radiative Effects in Inelastic Electron-Proton Scattering Generation of Radiative Events Monte Carlo Simulations Results and Discussion 5. Asymmetry Extraction Spin Correlation Parameters Electric and Coulomb Quadrupole Strength Extraction Spin Structure Functions Systematic Uncertainties Reconstruction Uncertainty Target Spin Angle Uncertainty False Asymmetries Beam and Target Polarization Uncertainty Background Uncertainty Normalization and Radiative Corrections Uncertainty Results Discussion Discussion of the Correlation Parameters Results Discussion of the Spin-Structure Function Results Conclusion REFERENCES 63 APPENDICES 68 APPENDIX A 68 APPENDIX B 7 APPENDIX C 74 vii APPENDIX D 75 APPENDIX E 97 viii List of Figures - The total photo-absorption cross section of the proton and its decomposition into exclusive channels as a function of the photon energy [GeV ] in the center of mass frame. Figure taken from [] Predictions of E/M (left) and C/M (right). MAID model is the solid line, SL is the short dashed curve; long dashed [], dot-dashed [3] and dotted only left [4] represent different constituent quark models; dotted line only in the right [5] is a Skyrme model. Figure from [6] E/M and C/M world data. The predictions from Figure - are added for comparison. Figure from [6] Sensitivity of the longitudinal and perpendicular spin asymmetries to the E (left) and C (right) amplitudes in the MAID model. The bands correspond to E/M and C/M rates of ±.4%. Figure from [6] Spin-correlation parameters A TT and A TL. Top (bottom) figures are MAID (SL) model predictions for standard strengths (solid line) and for zero strength (dashed line), for a momentum transfer Q =. GeV and beam energy E e = 7 MeV. Figure from [6] Feynman diagram for electron-proton scattering in the one photon exchange approximation Scattering plane conventions Sato and Lee: resonant pion production term (left) and non-resonant followed by resonant pion rescattering term (right) ix -4 MAID first-order diagrams for pion production Two-body scattering equation: schematic form Overview of the MIT-Bates Linear Accelerator Center Integrated charge delivered to the BLAST experiment over the course of the 4-5 running period Beam current and lifetime LIGIT Pressure vs Time Compton polarimeter beam polarization data vs. time Yield and asymmetry results of the Compton polarimeter BLAST ABS and target storage cell Hydrogen Atomic Fraction versus Flow Rate and Nozzle Temperature Hyperfine states of hydrogen Hydrogen target polarization for fall 4 data BLAST Detector BLAST laboratory frame Magnetic coils in BLAST Magnetic field map of BLAST One sector drift chambers Top-view of the drift chambers Cell wires Drift lines in a cell without (left) and with (right) magnetic field Steps of reconstruction Čerenkov radiation A Čerenkov box (middle size box) A simulated Čerenkov ADC x 3-3 Čerenkov counters efficiency as a function of TOF number. Red square shows the right sector and blue diamond the left sector counters Čerenkov counters efficiencies along the box vs. TOF paddle. The left sector counters are on top, and the right sector on the bottom. The most forward TOF starts from View of BLAST Right Sector TOFs BLAST Trigger Electronics Steps of reconstruction BLAST detector front/rear view (schematic). In the case of p( e,e ) reaction, an electron is detected in one sector (green), while the other reaction products could be anywhere (red) Electron (lepton) vertex: momentum conservation Lepton and hadron vertices notation Distribution of E e [GeV ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right Distribution of θ e [ ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right Distribution of φ e [ ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right Distribution of θ q [ ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right Distribution of θ [ ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right Distribution of Z target [cm] for ABS hydrogen data. Left sector is on top, right sector on the bottom xi 4- Q [GeV ] vs. W [GeV ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right Q [GeV ] vs. θ q [ ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right Q [GeV ] vs. θ [ ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right W [GeV ] vs. E e [GeV ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right W [GeV ] vs. θ [ ] for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right W [GeV ] vs. x for each trigger type (,, 3, 7) for ABS hydrogen data. Left sector is on the left, right sector on the right x = sin θ cos φ for all trigger types (,, 3, 7) for ABS hydrogen data, and for each Q bin starting at Q =.8GeV (left) and ending at Q =.38GeV (right) in steps of.6gev over the region, when the electron is scattered in the left sector (θ 9 ) x = sin θ cos φ for all trigger types (,, 3, 7) for ABS hydrogen data, and for each Q bin starting at Q =.8GeV (left) and ending at Q =.38GeV (right) in steps of.6gev over the region, when the electron is scattered in the right sector (θ ) z = cos θ for all trigger types (,, 3, 7) for ABS hydrogen data, and for each Q bin starting at Q =.8GeV (left) and ending at Q =.38GeV (right) in steps of.6gev over the region, when the electron is scattered in the left sector (θ 9 ) xii 4- z = cos θ for all trigger types (,, 3, 7) for ABS hydrogen data, and for each Q bin starting at Q =.8GeV (left) and ending at Q =.38GeV (right) in steps of.6gev over the region, when the electron is scattered in the right sector (θ ) Rates of W [GeV ] for each trigger type (,, 3, 7) and for Q [.5,.35]GeV. Data runs are in blue, empty runs in green. Left sector is on the left, right sector on the right Rates of Q [GeV ] for each trigger type (,, 3, 7). Data runs are in blue, empty runs in green. Left sector is on the left, right sector on the right Rates of Q [GeV ] for each trigger type (,, 3, 7) in the region (. W .4(GeV )). Data runs are in blue, empty runs in green. Left sector is on the left, right sector on the right Rates of x for each trigger type (,, 3, 7) in the region (. W .4(GeV )). Data runs are in blue, empty runs in green. Left sector is on the left, right sector on the right Distribution of E e [GeV ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right Distribution of θ e [ ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right Distribution of φ e [ ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right Distribution of θ q [ ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right Distribution of Z target [cm] for empty target data. Left sector is on top, right sector on the bottom Q [GeV ] vs. W [GeV ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right xiii 4-3 Q [GeV ] vs. θ q [ ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right Q [GeV ] vs. Z target [cm] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right W [GeV ] vs. E e [GeV ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right W [GeV ] vs. θ [ ] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right W [GeV ] vs. Z target [cm] for each trigger type (,, 3, 7) for empty target data. Left sector is on the left, right sector on the right Beam asymmetry for left (left) and right (right) sectors Target asymmetry for left (left) and right (right) sectors Feynman diagrams contributing to the observed cross section in elastic electron-proton scattering Feynman diagrams contributing to the observed cross section in inelastic electron-proton scattering BLAST invariant mass (red dots), W (GeV ), for left (left) and right (right) sectors and Monte Carlo simulations of radiative effects (green line) using unpolarized ELRADGEN and Hoehler form factors model, Q [.8,.38]GeV The polarization vectors for initial electron (ξ) and proton (η) in the laboratory frame Normalized yields as a function of the invariant mass, W(GeV ) over.8 Q .38GeV. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the solid line represents the Monte Carlo simulations with radiative effects (polarized ELRADGEN). Left sector is on the left, right sector on the right xiv 5- Normalized yields as a function of the invariant mass, W(GeV ) over.8 Q .38GeV, for the radiative simulations obtained with the polarized ELRADGEN code, for all the electron-target spin states. Left sector is on the left, right sector on the right Normalized yields as a function of the invariant mass, W, for Q =.3GeV. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the solid line represents the Monte Carlo simulations with radiative effects (polarized ELRADGEN). Left sector is on the left, right sector on the right Normalized yields as a function of the invariant mass, W, for Q =.75GeV. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the solid line represents the Monte Carlo simulations with radiative effects (polarized ELRADGEN). Left sector is on the left, right sector on the right Normalized yields as a function of the invariant mass, W, for Q =.4GeV. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the solid line represents the Monte Carlo simulations with radiative effects (polarized ELRADGEN). Left sector is on the left, right sector on the right Normalized yields as a function of the invariant mass, W for Q =.3GeV. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the solid line represents the Monte Carlo simulations with radiative effects (polarized ELRADGEN). Left sector is on the left, right sector on the right The effect of the radiative contributions to the asymmetry. The left (left) and right (right) asymmetries are shown with (red dots) and without (black squares) radiative corrections (RC),.8 Q .38GeV xv 5-8 Extracted asymmetry, A, for left (left) and right (right) sectors as a function of invariant mass, W, and for Q =.3GeV Extracted asymmetry, A, for left (left) and right (right) sectors as a function of invariant mass, W, and for Q =.75GeV Extracted asymmetry, A, for left (left) and right (right) sectors as a function of invariant mass, W, and for Q =.4GeV Extracted asymmetry, A, for left (left) and right (right) sectors as a function of invariant mass, W, and for Q =.3GeV Spin correlation parameters, A TT, A TL, as a function of invariant mass, W, and for Q =.3GeV Spin correlation parameters, A TT, A TL, as a function of invariant mass, W, and for Q =.75GeV Spin correlation parameters, A TT, A TL, as a function of invariant mass, W, and for Q =.4GeV Spin correlation parameters, A TT, A TL, as a function of invariant mass, W, and for Q =.3GeV The ratios σ TT /σ, σ TL /σ, as a function of invariant mass, W, and for Q =.3GeV The ratios σ TT /σ, σ TL /σ, as a function of invariant mass, W, and for Q =.75GeV The ratios σ TT /σ, σ TL /σ, as a function of invariant mass, W, and for Q =.4GeV The ratios σ TT /σ, σ TL /σ, as a function of invariant mass, W, and for Q =.3GeV Dependence of the spin-correlation parameters, A TL and A TT, on the E quadrupole strength for Q =.3GeV, in the MAID model xvi 5- Dependence of the spin-correlation parameters, A TL and A TT, on the E quadrupole strength for Q =.75GeV, in the MAID model Dependence of the spin-correlation parameters, A TL and A TT, on the E quadrupole strength for Q =.4GeV, in the MAID model Dependence of the spin-correlation parameters, A TL and A TT, on the E quadrupole strength for Q =.3GeV, in the MAID model Dependence of the spin-correlation parameters, A TL and A TT, on the C quadrupole strength for Q =.3GeV, in the MAID model Dependence of the spin-correlation parameters, A TL and A TT, on the C quadrupole strength for Q =.75GeV, in the MAID model Dependence of the spin-correlation parameters, A TL and A TT, on the C quadrupole strength for Q =.4GeV, in the MAID model Dependence of the spin-correlation parameters, A TL and A TT, on the C quadrupole strength for Q =.3GeV, in the MAID model Extracted E quadrupole strength as a function of Q [(GeV/c) ], using the MAID model Extracted C quadrupole strength as a function of Q [(GeV/c) ], using the MAID model Normalized yields as a function of the momentum transfer squared Q in the region (. W .36GeV ), and for x [.8,.48]. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the line shows the Monte Carlo radiative effects. Left sector is on the left, right sector on the right xvii 5-3 Normalized yields as a function of the momentum transfer squared Q in the region (. W .36GeV ), and for x [.8,.8]. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the line shows the Monte Carlo radiative effects. Left sector is on the left, right sector on the right Normalized yields as a function of the momentum transfer squared Q in the region (. W .36GeV ), and for x [.8,.48]. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the line shows the Monte Carlo radiative effects. Left sector is on the left, right sector on the right Normalized yields as a function of the Bjorken scaling variable x in the region (. W .36GeV ), and for Q [.8,.8]GeV. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the line shows the Monte Carlo radiative effects. Left sector is on the left, right sector on the right Normalized yields as a function of the Bjorken scaling variable x in the region (. W .36GeV ), and for Q [.8,.38]GeV. The dots show the BLAST ABS hydrogen data corrected for the background contributions, and the line shows the Monte Carlo radiative effects. Left sector is on the left, right sector on the right Extracted asymmetry, A, for left (left) and right (right) sectors as a function of Q [GeV ] in the region (. W .36GeV ) and for x [.8,.48] Extracted asymmetry, A, for left (left) and right (right) sectors as a function of Q [GeV ] in the region (. W .36GeV ) and for x [.8,.8] Extracted asymmetry, A, for left (left) and right (right) sectors as a function of Q [GeV ] in the region (. W .36GeV ) and for x [.8,.48]. 35 xviii 5-38 Extracted asymmetry, A, for left (left) and right (right) sectors as a function of x, in the region (. W .36GeV ), and for Q [.8,.8]GeV Extracted asymmetry, A, for left (left) and right (right) sectors as a function of x, in the region (. W .36GeV ), and for Q [.8,.38]GeV The spin-structure functions, g /σ and g /σ as a function of Q [GeV ] in the region (. W .36GeV ), and for x [.8,.48], x =., using Hand s convention The spin-structure functions, g /σ and g /σ as a function of Q [GeV ] in the region (. W .36GeV ), and for x [.8,.8], x =.85, using Hand s convention The spin-structure functions, g /σ and g /σ as a function of Q [GeV ] in the region (. W .36GeV ), and for x [.8,.48], x =.3, using Hand s convention The spin-structure functions, g /σ and g /σ as a function of x in the region (. W .36GeV ), and for.8 Q .8GeV, Q =.9[GeV ], using Hand s convention The spin-structure functions, g /σ and g /σ as a function of x in the region (. W .4GeV ), and for.8 Q .38GeV, Q =.5[GeV ], using Hand s convention Best θ e versus θ p for the left (left) and right (right) sectors for the elastic electron-proton scattering Beam Energy corrections using E e and θ e (left), and P p and θ p (right) as a function of the polar angle( ) Target spin angle map as a function of the target cell length Beam only asymmetry for left (left) and right (right) sectors as a function of invariant mass, W, at Q =.3GeV xix 5-49 Target only asymmetry for left (left) and right (right) sectors as a function of invariant mass, W, at Q =.3GeV Beam only asymmetry for left (left) and right (right) sectors as a function of invariant mass, W, at Q =.75GeV Target only asymmetry for left (left) and right (right) sectors as a function of invariant mass, W, at Q =.75GeV Beam only asymmetry for left (left) and right (right) sectors as a function of invariant mass, W, at Q =.4GeV Target only asymmetry for left (left) and right (right) sectors as a function of invaria
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