Download or read book Measuring the Spin Structure of the Proton with the STAR Detector at RHIC written by and published by . This book was released on 1996 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unique aspect of RHIC is the ability to collide beams of polarized protons at (square root)s = 200 and 500 GeV. The STAR experiment will measure the spin structure functions for the sea quarks and gluons by measuring spin asymmetries in {ital W} and {ital Z} direct photon and jet productions. Sensitivity expectations are presented.

Download or read book Studying the Spin Structure of the Proton Using the Solenoidal Tracker at RHIC written by and published by . This book was released on 1998 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary goal of RHIC is to produce nuclear matter under extremes of temperature and density sufficient to excite the QCD vacuum, resulting in the creation of a deconfined plasma of quarks and gluons. A second goal central to the RHIC scientific program is to advance the study of the spin structure of the proton significantly beyond what has been learned from deep inelastic scattering (DIS) measurements by studying spin asymmetries in strong processes involving the partonic constituents of polarized protons. After decades of being regarded as an inessential complication to the strong interaction at high energy, spin has again become a topic of considerable experimental and theoretical interest. This is largely due to the observation from DIS that the net contribution to the proton spin from the quark constituents ((approximately) 30%) is smaller than expected relative to the momentum carried in this sector. The RHIC accelerator will provide an unprecedented opportunity to fully explore the spin structure of the proton with high precision studies focused on measuring the spin-dependent parton distributions (valence quark, sea quark, gluon) of the proton. It is designed to operate both with high luminosity (1031--1032 cm−2 sec−1) and high polarization ((approximately) 70%). In addition, the energy range at RHIC ((square root)s = 200--500 GeV) is sufficiently high that spin effects in polarized proton interactions should be calculable once the spin structure of the proton is sufficiently understood. The experimental results will therefore provide a rigorous test of QCD. A further focus of the RHIC spin physics program will be to search for physics beyond the standard model. The increased sensitivity afforded by using polarized protons to study parity violation in inclusive jet production at high p{sub t} makes this exploration competitive with respect to ongoing searches using unpolarized beams.

Download or read book The Spin Structure of the Proton written by Steven D. Bass and published by World Scientific. This book was released on 2008 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the main challenges in nuclear and particle physics in the last 20 years has been to understand how the proton''s spin is built up from its quark and gluon constituents. Quark models generally predict that about 60% of the proton''s spin should be carried by the spin of the quarks inside, whereas high energy scattering experiments have shown that the quark spin contribution is small OCo only about 30%. This result has been the underlying motivation for about 1000 theoretical papers and a global program of dedicated spin experiments at BNL, CERN, DESY and Jefferson Laboratory to map the individual quark and gluon angular momentum contributions to the proton''s spin, which are now yielding exciting results. This book gives an overview of the present status of the field: what is new in the data and what can be expected in the next few years. The emphasis is on the main physical ideas and the interpretation of spin data. The interface between QCD spin physics and the famous axial U(1) problem of QCD (eta and etaprime meson physics) is also highlighted. Sample Chapter(s). Chapter 1: Introduction (159 KB). Contents: Spin Experiments and Data; Dispersion Relations and Spin Sum Rules; g 1 Spin Sum Rules; Fixed Poles; The Axial Anomaly, Gluon topology and g (0) A; Chiral Symmetry and Axial U(1) Dynamics; QCD Inspired Models of the Proton Spin Problem; The Spin-Flavour Structure of the Proton; QCD Fits to g 1 Data; Polarized Quark Distributions; Polarized Glue o g(x, Q 2 ); Transversity; Deeply Virtual Compton Scattering and Exclusive Processes; Polarized Photon Structure Functions; Conclusions and Open Questions: How Does the Proton Spin?. Readership: Academics, as well as physicists working on particle and nuclear physics at the interface of theory and experiment.

Download or read book The Radiance of the Gluon Spin written by Michael Joseph Betancourt and published by . This book was released on 2012 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although fundamental to the observable universe, the proton is not elementary. Rather the particle is a bound state of three valence quarks and the QCD vacuum that condenses around them, its properties an amalgamation of those underlying degrees of freedom. Naive expectations presume that contributions from the valence quarks dominate these properties, but the deep inelastic scattering (DIS) experiments which first investigated the proton structure in detail revealed the importance of the vacuum. In particular, polarized DIS measurements uncovered a surprisingly inadequate quark polarization, necessitating significant contributions to the proton spin from elsewhere. The total spin of the gluon field confining the quarks is one possibility, but a contribution only weakly constrained by the electromagnetic probes of DIS. An observable far more sensitive to contributions from the gluon field can be found in the collision of two polarized protons. By correlating the incident proton helicities with final-states originating from an initial-state gluon, the double-helicity asymmetry directly probes the underlying gluon polarization and provides much stronger experimental constraints. Asymmetries measured with hadronic final-states have already improved the understanding of the proton spin structure significantly, but with accumulating statistics these measurements will eventually be limited by systematic uncertainties. Although direct photons are rare in the hadronic environment, the simplicity of the resulting asymmetry ultimately promises a more precise probe of the gluon polarization. Located at the Relativistic Heavy Ion Collider (RHIC), the only facility in the world capable of accelerating and colliding polarized proton beams, the Solenoidal Tracker at RHIC (STAR) provides the large acceptance electromagnetic calorimetry and charged particle tracking critical for measuring direct photons and, subsequently, their asymmetry. Utilizing data from the 2009 running period with intricate simulation, state-of-the-art statistical methods have been developed to tease out the rare photon signal from an overwhelming hadronic background to enable the first direct photon measurements at STAR. This thesis details the construction of the unpolarized cross section and an initial double-helicity asymmetry, proving the feasibility of the direct photon program at the experiment.

Download or read book The Spin Structure of the Proton and Polarized Collider Physics written by Steven D. Bass and published by . This book was released on 2002 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spin 96 Proceedings Of The 12th International Symposium On High energy Spin Physics written by J E J Oberski and published by World Scientific. This book was released on 1997-04-15 with total page 906 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments using highly polarized intense beams and targets, and theoretical studies of spin and polarization phenomena, are now providing us with numerous additional details of the electroweak and strong interactions and the structure of matter. The spin structure of the nucleon has been measured over wide ranges of kinematic variables, and the cross sections have been calculated to several orders in perturbative field theory. At present, the influence of the higher twist contributions, the gluon spin, and the quark orbital angular momentum are under scrutiny. Quantum chromodynamics (QCD) captures a lot of our experimental knowledge of hard polarized scattering processes. Can our understanding of such processes within QCD be further improved?Hyperons produced in high energy reactions show how puzzling strong interactions between hadrons still are. Spin observables in experiments at intermediate energy are used to test parity and charge symmetries. Will they also reveal, at low energy, a violation of time reversal symmetry? We are on the verge of using parity violation measurements at intermediate electron scattering energies to determine the amount of strange quark contributions to the neutral weak form factor of the nucleon. The polarization of the sea quarks is expected to be measured soon in W± decays produced in high energy polarized proton interactions. Will the jets in polarized Z⁰ decays show a definite handedness? These and many other topics are discussed in these proceedings.

Download or read book Trends In Collider Spin Physics Proceedings Of The Adriatico Research Conference written by Yasar Onel and published by World Scientific. This book was released on 1997-03-10 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volume presents an up-to-date survey of spin physics at the very high energies of present and future colliders. Topics discussed include the theory of high-energy spin physics, deep-inelastic scattering, polarization experiments at colliders, the production of high-energy polarized electron and proton beams, the construction of intense polarized sources and high-energy polarimeters. It will represent a significant reference in the field and an informative text for non-specialists as well, with rather complete keynote overview reports by some physicists who have contributed most to the subject. In addition, it will document the character of frontier research symposium of the Conference, with specialized reports of leading experts in the various items of the field.

Download or read book Measurement of the Proton and Deuteron Spin Structure Functions G1 and G2 written by William Alexander Tobias and published by . This book was released on 2001 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Spin Structure Function G1 x Q2 of the Proton in the Resonance Region written by Yelena Alexandrovna Prok and published by . This book was released on 2004 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spin 2004 Proceedings Of The 16th International Spin Physics Symposium And Workshop On Polarized Electron Sources And Polarimeters With Cd rom written by Franco Bradamante and published by World Scientific. This book was released on 2005-08-02 with total page 1065 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive volume covers the most recent advances in the field of spin physics, including the latest research in high energy and nuclear physics and the study of nuclear spin structure. The comprehensive coverage also includes polarized proton and electron acceleration and storage as well as polarized ion sources and targets. Many significant new results and achievements on the different topics considered at the symposium are presented in this book for the first time.

Download or read book 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 published by . This book was released on 2009 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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].

Download or read book Proceedings of the XXV DAE BRNS High Energy Physics HEP Symposium 2022 12 16 December Mohali India written by Satyajit Jena and published by Springer Nature. This book was released on with total page 1353 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Precision Measurement of the Spin Structure of the Proton and the Deuteron written by Frank R. Wesselmann and published by . This book was released on 2000 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 108 1 Hearings Energy and Water Development Appropriations For 2004 Part 4 2003 written by and published by . This book was released on 2003 with total page 3122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Proton A 1 and A 2 Spin Asymmetries Probing Color Forces written by and published by . This book was released on 2015 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Longitudinal Double Spin Asymmetry of Electrons from Heavy Flavor Decays in Polarized p p Collisions at s 200 GeV written by Katsuro Nakamura and published by Springer. This book was released on 2014-05-21 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the measurement of double-spin asymmetry for electron production from heavy flavor decays was performed in a Relativistic Heavy Ion Collider (RHIC) in the PHENIX experiment at Brookhaven National Laboratory to measure the polarized parton distribution function of gluon in the small Bjorken x region (x~0.01). For this experiment, for the first time a Hadron Blind Detector (HBD), which is a position-sensitive gas Cherenkov counter with Gas Electron Multiplier whose surface is evaporated by CsI, was employed. This HBD contributes to reducing the background from electron pairs produced by real and virtual photon conversion. Furthermore, the author develops a new analysis method for the background reduction, and the signal-to-background ratio is improved by a factor of roughly 2.0. Using the combination of the HBD and a new analysis method, the double-spin asymmetry of the electron production with transverse momentum ranging 0.5 pT 3.0 GeV/c is measured and confirmed to be zero-consistent within the limit of the statistical uncertainty of about 1%. This result identifies the constraint of the gluon polarization in the small Bjorken

Download or read book Understanding the Composition of Nucleon Spin with the PHENIX Detector at RHIC written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has just finished 14 years of operation. A significant fraction of these operating years were with polarized proton collisions at 62.4, 200, and 500 GeV center of mass, investigating various aspects of nucleon spin through longitudinal and transversely polarized collisions. These data have helped to address some of the most puzzling and fundamental questions in quantum chromodynamics including: what fraction of the nucleon's spin originates in the gluon's helicity contribution?, how polarized are the sea quarks?, and what if any, is the evidence for transverse motion of quarks in polarized protons? These questions have been addressed by the PHENIX detector collaboration. We present in this review highlights of the PHENIX results and discuss their impact.