Author: Oliver Zaudtke
Publisher:
ISBN:
Category :
Languages : en
Pages : 238
Book Description
Measurement of Direct Photon Production and Neutral Pion Double Helicity Asymmetry in Ultra Relativistic P+p Collisions
Neutral Pion Double Helicity Asymmetry in Polarized Proton-Proton Collisions at [the Square Root of Sigma]
Author: William Axel Leight
Publisher:
ISBN:
Category :
Languages : en
Pages : 112
Book Description
One of the primary goals of the spin physics program at the STAR experiment is to constrain the polarized gluon distribution function, [delta]g(X,Q2), by measuring the double longitudinal spin asymmetry, ALL, of various final-state channels. Neutral pions provide a potentially powerful final state because they are copiously produced in p+p collisions and have few backgrounds. In 2009, STAR took 14 pb-1 of integrated luminosity of 200 GeV p+p collisions, with average beam longitudinal polarization of 59%. Neutral pions produced in these collisions can be identified using STAR's large-acceptance electromagnetic calorimeter, with help from tracking from the STAR Time Projection Chamber. This work presents a measurement of the inclusive neutral pion ALL from this data, based on a new [pi]0 reconstruction algorithm. A comparison to theoretical predictions and other experimental results suggests that the current best-fit value of AG, the gluon contribution to the proton spin, is too small and that [delta]G is actually comparable in magnitude to the quark contribution to the proton spin [delta][sigma].
Publisher:
ISBN:
Category :
Languages : en
Pages : 112
Book Description
One of the primary goals of the spin physics program at the STAR experiment is to constrain the polarized gluon distribution function, [delta]g(X,Q2), by measuring the double longitudinal spin asymmetry, ALL, of various final-state channels. Neutral pions provide a potentially powerful final state because they are copiously produced in p+p collisions and have few backgrounds. In 2009, STAR took 14 pb-1 of integrated luminosity of 200 GeV p+p collisions, with average beam longitudinal polarization of 59%. Neutral pions produced in these collisions can be identified using STAR's large-acceptance electromagnetic calorimeter, with help from tracking from the STAR Time Projection Chamber. This work presents a measurement of the inclusive neutral pion ALL from this data, based on a new [pi]0 reconstruction algorithm. A comparison to theoretical predictions and other experimental results suggests that the current best-fit value of AG, the gluon contribution to the proton spin, is too small and that [delta]G is actually comparable in magnitude to the quark contribution to the proton spin [delta][sigma].
Measurement of Neutral Pions and Direct Photons in Copper + Copper Collisions at 62.4 GeV Center of Mass Energy
Author: Timothy James Hester
Publisher:
ISBN:
Category : Quantum chromodynamics
Languages : en
Pages : 112
Book Description
Publisher:
ISBN:
Category : Quantum chromodynamics
Languages : en
Pages : 112
Book Description
Measurements of the Double Helicity Asymmetry in Pion Production in Proton Collisions at [square Root Of]
Measurement of Double Longitudinal Spin Asymmetry of Jet-[pi] +/- Correlations in Polarized Proton-proton Collisions at [square Root Of] S
Author: James Prewitt Hays-Wehle
Publisher:
ISBN:
Category :
Languages : en
Pages : 83
Book Description
Inclusive measurements from polarized proton-proton collisions at RHIC have constrained [Delta]g, the polarized gluon distribution function of the proton. Correlation observables, such as this pion+jet measurement, allow for reconstruction of initial parton kinematics and are thus sensitive to the x dependence of [Delta]g. By measuring charged pions opposite a jet, this particular measurement can be sensitive to the flavor of the struck parton. This measurement, which is dominated by the quark-gluon subprocess, can be divided into terms proportional to [Delta]u[Delta]g and [Delta]d[Delta]g. The relatively larger quark polarization amplifies the measured asymmetry thereby enhancing the statistical power. This thesis presents the result of the mid-rapidity pion+jet longitudinal double spin asymmetry analysis from 10.6 pb-1 of luminosity collected in the 2009 200 GeV p+p run.
Publisher:
ISBN:
Category :
Languages : en
Pages : 83
Book Description
Inclusive measurements from polarized proton-proton collisions at RHIC have constrained [Delta]g, the polarized gluon distribution function of the proton. Correlation observables, such as this pion+jet measurement, allow for reconstruction of initial parton kinematics and are thus sensitive to the x dependence of [Delta]g. By measuring charged pions opposite a jet, this particular measurement can be sensitive to the flavor of the struck parton. This measurement, which is dominated by the quark-gluon subprocess, can be divided into terms proportional to [Delta]u[Delta]g and [Delta]d[Delta]g. The relatively larger quark polarization amplifies the measured asymmetry thereby enhancing the statistical power. This thesis presents the result of the mid-rapidity pion+jet longitudinal double spin asymmetry analysis from 10.6 pb-1 of luminosity collected in the 2009 200 GeV p+p run.
MEASUREMENT OF SINGLE TRANSVERSE-SPIN ASYMMETRY IN FORWARD PRODUCTION OF PHOTONS AND NEUTRONS IN PP COLLSION AT SQUARE ROOT
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5
Book Description
The Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory (BNL) was commissioned for polarized proton-proton collisions, at the center of mass energy (square root)s = 200 GeV during the run in 2001-2002. The authors have measured the single transverse-spin asymmetry A{sub N} for production of photons, neutral pions, and neutrons at the very forward angle. The asymmetries for the photon and neutral pion sample were consistent with zero within the experimental uncertainties. In contrast, the neutron sample exhibited an unexpectedly large asymmetry. This large asymmetry will be used for the non-destructive polarimeter for polarized proton beams at the collision points in the RHIC interaction region.
Publisher:
ISBN:
Category :
Languages : en
Pages : 5
Book Description
The Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory (BNL) was commissioned for polarized proton-proton collisions, at the center of mass energy (square root)s = 200 GeV during the run in 2001-2002. The authors have measured the single transverse-spin asymmetry A{sub N} for production of photons, neutral pions, and neutrons at the very forward angle. The asymmetries for the photon and neutral pion sample were consistent with zero within the experimental uncertainties. In contrast, the neutron sample exhibited an unexpectedly large asymmetry. This large asymmetry will be used for the non-destructive polarimeter for polarized proton beams at the collision points in the RHIC interaction region.
Longitudinal Double-spin Asymmetry and Cross Section for Inclusive Neutral Pion Production in Polarized Proton Collisions at [the Square Root of Sigma]
Author: Alan Michael Hoffman
Publisher:
ISBN:
Category :
Languages : en
Pages : 126
Book Description
Twenty years of polarized lepton-nucleon scattering experiments have found that the contribution from quark spins (1/2[delta] [sigma]) to the spin of the proton is only ~ 35%. This has lead researchers to look elsewhere, specifically to gluon spin ([delta sigma]) for a large contribution to proton spin. [delta sigma] has been only loosely constrained in polarized DIS and SIDIS experiments. Polarized proton-proton collisions at RHIC provide sensitivity to [delta sigma] through measurements of the longitudinal double-spin asymmetry, ALL. This work presents a measurement of ALL for inclusive 7ro production in polarized proton-proton collisions using the STAR detector and data from RHIC Run 6. 7r0s are abundantly produced at mid-rapidity in proton-proton collisions, making them natural candidates for studies of [delta] [sigma]. Novel techniques for reconstructing 7ros at STAR are discussed, and a measurement of the unpolarized cross section presented. Finally, the measured ALL is compared to perturbative QCD predictions and from this comparison constraints are placed on [delta] [sigma].
Publisher:
ISBN:
Category :
Languages : en
Pages : 126
Book Description
Twenty years of polarized lepton-nucleon scattering experiments have found that the contribution from quark spins (1/2[delta] [sigma]) to the spin of the proton is only ~ 35%. This has lead researchers to look elsewhere, specifically to gluon spin ([delta sigma]) for a large contribution to proton spin. [delta sigma] has been only loosely constrained in polarized DIS and SIDIS experiments. Polarized proton-proton collisions at RHIC provide sensitivity to [delta sigma] through measurements of the longitudinal double-spin asymmetry, ALL. This work presents a measurement of ALL for inclusive 7ro production in polarized proton-proton collisions using the STAR detector and data from RHIC Run 6. 7r0s are abundantly produced at mid-rapidity in proton-proton collisions, making them natural candidates for studies of [delta] [sigma]. Novel techniques for reconstructing 7ros at STAR are discussed, and a measurement of the unpolarized cross section presented. Finally, the measured ALL is compared to perturbative QCD predictions and from this comparison constraints are placed on [delta] [sigma].
Production of Direct Photons and Neutral Pions in Relativistic Au+Au Collisions
Author: Tadaaki Isobe
Publisher:
ISBN:
Category : Heavy ion collisions
Languages : en
Pages : 216
Book Description
Publisher:
ISBN:
Category : Heavy ion collisions
Languages : en
Pages : 216
Book Description
Measurement of Double-helicity Asymmetry and Search for Open Charm in Single-muon Production in Polarized Proton-proton Collisions
Author: Mikhail Stepanov
Publisher:
ISBN:
Category : Muons
Languages : en
Pages : 424
Book Description
Publisher:
ISBN:
Category : Muons
Languages : en
Pages : 424
Book Description