Forward Neutral Pion Transverse Single Spin Asymmetries In P P Collisions At Sqrt S
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Forward Neutral Pion Transverse Single Spin Asymmetries In P P Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2008
Forward Neutral Pion Transverse Single Spin Asymmetries In P P Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
We report precision measurements of the Feynman-x (x{sub F}) dependence, and first measurements of the transverse momentum (p{sub T}) dependence, of transverse single spin asymmetries for the production of [pi]° mesons from polarized proton collisions at √s = 200 GeV. The x{sub F} dependence of the results are in fair agreement with perturbative QCD (pQCD) model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the p{sub T} dependence at fixed x{sub F} are not consistent with these same pQCD-based calculations.
Cross Sections And Transverse Single Spin Asymmetries In Forward Neutral Pion Production From Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2003
Cross Sections And Transverse Single Spin Asymmetries In Forward Neutral Pion Production From Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
Spin 2002
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Author : Yousef I. Makdisi
language : en
Publisher: American Institute of Physics
Release Date : 2003-09-04
Spin 2002 written by Yousef I. Makdisi and has been published by American Institute of Physics this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-09-04 with Science categories.
The SPIN 2002 Proceedings describe the recent advances in the field of spin physics. The topics cover research in high energy and nuclear physics and the study of the nuclear spin structure. The symposium also covers advances in polarized proton and electron acceleration and storage as well as polarized ion sources and targets. The first measurement of spin physics observables in pp collisions at center of mass energy of 200 Gev was announced at this symposium.
Measurement Of Single Transverse Spin Asymmetry In Forward Production Of Photons And Neutrons In Pp Collsion At Square Root
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Author :
language : en
Publisher:
Release Date : 2002
Measurement Of Single Transverse Spin Asymmetry In Forward Production Of Photons And Neutrons In Pp Collsion At Square Root written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
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.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1992
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Aeronautics categories.
Government Reports Annual Index
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Author :
language : en
Publisher:
Release Date : 1992
Government Reports Annual Index written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Government publications categories.
Forward Di Hadron Asymmetries From P P At 8 S
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Author : James Lucas Drachenberg
language : en
Publisher:
Release Date : 2012
Forward Di Hadron Asymmetries From P P At 8 S written by James Lucas Drachenberg and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
One unresolved question in hadronic physics is the origin of large transverse single-spin asymmetries, AN, observed in hadron production from high-energy polarized-proton collisions. Collinear perturbative Quantum Chromodynamics (pQCD) predicts that AN should scale with the quark mass, however, experiments have since reported large AN for inclusive hadron production. Recent measurements from RHIC experiments show examples of these asymmetries at forward angles in a kinematic region where pQCD cross-section calculations reasonably agree with measured cross-sections. Disentangling dynamical contributions to AN from hadro-production requires moving beyond inclusive measurements. One possibility is to investigate asymmetries in two-particle correlations due to Interference Fragmentation Functions (IFF) and the Sivers effect. In 2008, RHIC dedicated a portion of the run to transversely polarized proton collisions at sqrt(s) = 200 GeV. STAR was equipped with a Foward Meson Spectrometer (FMS) and a Forward Time Projection Chamber (FTPC), overlapping in the pseudorapidity range of 2.5 eta & lt; 4. By analyzing neutral pions with the FMS correlated with charged particles from the FTPC, correlation asymmetries can be measured at kinematics where large inclusive asymmetries have been measured. Correlations are measured for pi^0's with 2 & lt; pT, pi^0 & lt; 5 GeV/c and associated charged particles in two ranges of transverse momentum: 1 & lt; pT, ch & lt; 2 GeV/c and 0.5 & lt; pT, ch & lt; 1 GeV/c. IFF and Sivers asymmetries manifest themselves through the correlation of two particles from the same jet. These events are selected through a cut on the pair radius, delta R. Gain non-uniformities and electronics failures have resulted in large holes in trigger acceptance and associated particle acceptance, respectively. This non-uniform acceptance allows the Sivers and IFF effects to mix and distort the raw asymmetries. Techniques are developed to measure this leak-through by means of unpolarized yields and event weighting. They result in small corrections to the asymmetries. IFF and Sivers asymmetries both for xF 0 and for xF & lt; 0 are reported for forward-angle pi^0-charged particle correlations from polarized-proton collisions at sqrt(s) = 200 GeV. Asymmetries are shown corrected for full underlying-event and pileup backgrounds, as well as corrected only for pile-up contributions. It appears the asymmetries are less sensitive to delta R when corrected for the full underlying-event background. Unfortunately, statistics limitations preclude a firm conclusion.
Longitudinal Double Spin Asymmetry And Cross Section For Inclusive Neutral Pion Production In Polarized Proton Collisions At The Square Root Of Sigma
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Author : Alan Michael Hoffman
language : en
Publisher:
Release Date : 2009
Longitudinal Double Spin Asymmetry And Cross Section For Inclusive Neutral Pion Production In Polarized Proton Collisions At The Square Root Of Sigma written by Alan Michael Hoffman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
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].
Measurement Of Transverse Single Spin Asymmetries For Di Jetproduction In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2007
Measurement Of Transverse Single Spin Asymmetries For Di Jetproduction In Proton Proton Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
We report the first measurement of the opening angledistribution between pairs of jets produced in high-energy collisions oftransversely polarized protons. The measurement probes (Sivers)correlations between the transverse spin orientation of a proton and thetransverse momentum directions of its partons. With both beams polarized, the wide pseudorapidity ( -1 leq eta leq +2) coverage for jets permitsseparation of Sivers functions for the valence and sea regions. Theresulting asymmetries are all consistent with zero and considerablysmaller than Sivers effects observed in semi-inclusive deep inelasticscattering (SIDIS). We discuss theoretical attempts to reconcile the newresults with the sizable transverse spin effects seen in SIDIS andforward hadron production in pp collisions.
Neutral Pion Double Helicity Asymmetry In Polarized Proton Proton Collisions At The Square Root Of Sigma
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Author : William Axel Leight
language : en
Publisher:
Release Date : 2012
Neutral Pion Double Helicity Asymmetry In Polarized Proton Proton Collisions At The Square Root Of Sigma written by William Axel Leight and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
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].