Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 186
Book Description
The overarching goal of this analysis, and many like it, is to develop our understanding of the strong force interactions within the nucleon by examining the nature of their excitation spectra. As the resonances of these spectra have very short lifetimes (tau = 1x10-23 s) and often have very similar masses, it is often impossible to directly observe resonances in the excitation spectra of nucleons. Polarization observables allow us to study the resonances by looking at how they affect the spin state of final state particles. The beam asymmetry is a polarization observable that allows us to detect the sensitivity of these resonances, and other transition mechanisms, to the electric vector orientation of incident photons. Presented in this thesis are first measurements of the beam asymmetries in the resonant region for the reaction channel pgamma p --> p [pi]+ [pi]-focusing on the intermediate mesonic states rho^0 and f^0, and the final state pions. The analysis used data from the g8b experiment undertaken at the Thomas Jefferson National Accelerator Facility (JLab), the first experiment at JLab to use a linearly polarized photon beam. Using the coherent Bremsstrahlung facility and the CLAS detector of Hall B at JLab allowed for many multi-channel reactions to be detected and the first measurements of many polarization observables including those presented here. A brief overview of the theoretical framework used to undertake this analysis is given, followed by a description of the experimental details of the facilities used, then a description of the calibration of the Bremsstrahlung tagging facility which the author undertook, and finally the analysis is presented and the resulting measurements.
Beam Spin Asymmetry Measurements for Two Pion Photoproduction at CLAS.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 186
Book Description
The overarching goal of this analysis, and many like it, is to develop our understanding of the strong force interactions within the nucleon by examining the nature of their excitation spectra. As the resonances of these spectra have very short lifetimes (tau = 1x10-23 s) and often have very similar masses, it is often impossible to directly observe resonances in the excitation spectra of nucleons. Polarization observables allow us to study the resonances by looking at how they affect the spin state of final state particles. The beam asymmetry is a polarization observable that allows us to detect the sensitivity of these resonances, and other transition mechanisms, to the electric vector orientation of incident photons. Presented in this thesis are first measurements of the beam asymmetries in the resonant region for the reaction channel pgamma p --> p [pi]+ [pi]-focusing on the intermediate mesonic states rho^0 and f^0, and the final state pions. The analysis used data from the g8b experiment undertaken at the Thomas Jefferson National Accelerator Facility (JLab), the first experiment at JLab to use a linearly polarized photon beam. Using the coherent Bremsstrahlung facility and the CLAS detector of Hall B at JLab allowed for many multi-channel reactions to be detected and the first measurements of many polarization observables including those presented here. A brief overview of the theoretical framework used to undertake this analysis is given, followed by a description of the experimental details of the facilities used, then a description of the calibration of the Bremsstrahlung tagging facility which the author undertook, and finally the analysis is presented and the resulting measurements.
Publisher:
ISBN:
Category :
Languages : en
Pages : 186
Book Description
The overarching goal of this analysis, and many like it, is to develop our understanding of the strong force interactions within the nucleon by examining the nature of their excitation spectra. As the resonances of these spectra have very short lifetimes (tau = 1x10-23 s) and often have very similar masses, it is often impossible to directly observe resonances in the excitation spectra of nucleons. Polarization observables allow us to study the resonances by looking at how they affect the spin state of final state particles. The beam asymmetry is a polarization observable that allows us to detect the sensitivity of these resonances, and other transition mechanisms, to the electric vector orientation of incident photons. Presented in this thesis are first measurements of the beam asymmetries in the resonant region for the reaction channel pgamma p --> p [pi]+ [pi]-focusing on the intermediate mesonic states rho^0 and f^0, and the final state pions. The analysis used data from the g8b experiment undertaken at the Thomas Jefferson National Accelerator Facility (JLab), the first experiment at JLab to use a linearly polarized photon beam. Using the coherent Bremsstrahlung facility and the CLAS detector of Hall B at JLab allowed for many multi-channel reactions to be detected and the first measurements of many polarization observables including those presented here. A brief overview of the theoretical framework used to undertake this analysis is given, followed by a description of the experimental details of the facilities used, then a description of the calibration of the Bremsstrahlung tagging facility which the author undertook, and finally the analysis is presented and the resulting measurements.
Beam Spin Asymmetry Measurements for Two Pion Photoproduction at CLAS
Author: Mark David Anderson
Publisher:
ISBN:
Category : Hadron spectroscopy
Languages : en
Pages : 173
Book Description
Publisher:
ISBN:
Category : Hadron spectroscopy
Languages : en
Pages : 173
Book Description
Beam-spin Asymmetries from Semi-inclusive Pion Electroproduction
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
Book Description
We have measured the moment A{sup sin?}{sub LU} corresponding to the polarized electron beam-spin asymmetry in SIDIS. A{sup sin?}{sub LU} is a twist-3 quantity providing information about quark-gluon correlations. Data were taken with the CLAS Spectrometer at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target. All three pion channels (pi, pi° and pi−) were measured simultaneously over a large range of kinematics within the virtuality range Q2 ̃1.0-4.5 GeV2. The observable was measured with good statistical precision over a large range of z, P{sub T}, x{sub B}, and Q2, which permits comparison with several reaction models. The discussed measurements provide an upgrade in statistics over previous measurements, and serve as the first evidence for the negative sign of the?− sin? Moment.
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
Book Description
We have measured the moment A{sup sin?}{sub LU} corresponding to the polarized electron beam-spin asymmetry in SIDIS. A{sup sin?}{sub LU} is a twist-3 quantity providing information about quark-gluon correlations. Data were taken with the CLAS Spectrometer at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target. All three pion channels (pi, pi° and pi−) were measured simultaneously over a large range of kinematics within the virtuality range Q2 ̃1.0-4.5 GeV2. The observable was measured with good statistical precision over a large range of z, P{sub T}, x{sub B}, and Q2, which permits comparison with several reaction models. The discussed measurements provide an upgrade in statistics over previous measurements, and serve as the first evidence for the negative sign of the?− sin? Moment.
A Measurement of the Beam Asymmetry Parameter [sigma] for Neutral Pion Photoproduction in the Energy Range 1.26-2.00 GeV.
Author: Peter Waller
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A Measurement of the Beam Asymmetry Parameter [sigma] for Neutral Pion Photoproduction in the Energy Range 1.26-2.00 GeV.
Author: Peter Waller
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Beam-Target Double Spin Asymmetry A[sub]LT[/sub] in Charged Pion Production from Deep Inelastic Scattering on a Transversely Polarized [sup]3[/sup]He Target at 1.4[Q[sup]2[/sup][2.7 GeV[sup]2[/sup].
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
Book Description
We report the first measurement of the double-spin asymmetry ALT for charged pion electroproduction in semi-inclusive deep inelastic electron scattering on a transversely polarized 3He target. The kinematics focused on the valence quark region, 0.16 x 0.35 with 1.4 Qsup2/sup 2.7 GeVsup2/sup. The corresponding neutron AsubLT/sub asymmetries were extracted from the measured sup3/supHe asymmetries and proton/sup3/supHe cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function gsub 1T/subsupq/sup and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for?sup-
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
Book Description
We report the first measurement of the double-spin asymmetry ALT for charged pion electroproduction in semi-inclusive deep inelastic electron scattering on a transversely polarized 3He target. The kinematics focused on the valence quark region, 0.16 x 0.35 with 1.4 Qsup2/sup 2.7 GeVsup2/sup. The corresponding neutron AsubLT/sub asymmetries were extracted from the measured sup3/supHe asymmetries and proton/sup3/supHe cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function gsub 1T/subsupq/sup and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for?sup-
Measurement of Beam-Spin Asymmetries for Deep Inelastic Pi Electroproduction
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
We report the first evidence for a non-zero beam-spin azimuthal asymmetry in the electroproduction of positive pions in the deep-inelastic region. Data have been obtained using a polarized electron beam of 4.3 GeV and with the CLAS detector at the Thomas Jefferson National Accelerator Facility (JLab). The amplitude of the sin phi modulation increases with the momentum of the pion relative to the virtual photon, z, with an average amplitude of 0.038+/-0.005+/-0.003 for 0.5
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
We report the first evidence for a non-zero beam-spin azimuthal asymmetry in the electroproduction of positive pions in the deep-inelastic region. Data have been obtained using a polarized electron beam of 4.3 GeV and with the CLAS detector at the Thomas Jefferson National Accelerator Facility (JLab). The amplitude of the sin phi modulation increases with the momentum of the pion relative to the virtual photon, z, with an average amplitude of 0.038+/-0.005+/-0.003 for 0.5
Simultaneous Measurements of Positive Pion Photoproduction Cross Sections and Beam Asymmetries with Linearly Polarized Photons in the Delta-region
Author: Lino Miceli
Publisher:
ISBN:
Category :
Languages : en
Pages : 446
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 446
Book Description
A Measurement of the Beam Asymmetry Parameter Sigma for Neutral Pion Photoproduction in the Energy Range 1.2. GeV - 2.8 GeV
Author: P. J. Bussey
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
Book Description
CLAS
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Beam-helicity asymmetries for the gamma+p -> pi+ + pi- + p reaction have been measured for center-of-mass energies between 1.35 GeV and 2.30 GeV at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons. The beam-helicity asymmetries vary with kinematics and exhibit strong sensitivity to the dynamics of the reaction, as demonstrated in the comparison of the data with results of various phenomenological model calculations. These models currently do not provide an adequate description of the data over the entire kinematic range covered in this experiment. Additional polarization observables are accessible in an upcoming experiment at Jefferson Lab with polarized beam and target.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Beam-helicity asymmetries for the gamma+p -> pi+ + pi- + p reaction have been measured for center-of-mass energies between 1.35 GeV and 2.30 GeV at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons. The beam-helicity asymmetries vary with kinematics and exhibit strong sensitivity to the dynamics of the reaction, as demonstrated in the comparison of the data with results of various phenomenological model calculations. These models currently do not provide an adequate description of the data over the entire kinematic range covered in this experiment. Additional polarization observables are accessible in an upcoming experiment at Jefferson Lab with polarized beam and target.