Spin Dependence in Polarized Proton-Proton Elastic Scattering at RHIC

<p>The STAR (Solenoidal Tracker At RHIC - Relativistic Heavy Ion Collider) experiment is equipped with Roman Pots, insertion devices that allow detectors to be moved close to the beam for the measurement of high energy protons scattered at very small angles. This setup, together with the unique capability of RHIC to collide spin-polarized proton beams, allows STAR to study both the dynamics and the spin-dependence of the proton-proton (<em> pp</em>) elastic scattering process. Silicon strip detectors, installed inside the Roman Pots, measure tracks of protons scattered diffractively at very small angles. In a dedicated run with special beam optics during the 2009 RHIC run, the collaboration collected about 20 million elastic events with transversely polarized proton beams at the center of mass energy √s= 200 GeV and four momentum transfer squared (<em>t</em>) range of 0.003 ≤ |<em>t</em>| ≤ 0.035 (GeV/<em>c</em>)², where, due to the Coulomb Nuclear Interference (CNI), a measurable single spin asymmetry arises. While the electromagnetic interaction can be determined in QED, the description of the hadronic interaction at small<em> -t</em> scattering requires the use of nonperturbative techniques in QCD, and, phenomenological models, rather than pQCD, are used to describe the exchange mechanism. High energy diffractive scattering at small<em>-t</em> is dominated by the Pomeron exchange, treated in pQCD as a color singlet combination of two gluons carrying quantum numbers of the vacuum (<em>J^PC</em> = 0⁺⁺). In this dissertation, I report on a high precision measurement of the transverse single spin asymmetry <em>A</em>_N at √s= 200 GeV in <em>pp</em> elastic scattering at RHIC. The measured <em>A</em>N and its <em>t-</em>dependence are consistent with the absence of a hadronic spin-flip amplitude. The major contribution to the uncertainty in <em>A</em>N comes from the uncertainty in the beam polarization measurement. The presented results provide a precise measurement in the non-perturbative QCD regime, where experimental data are indispensable, and, a significant constraint on the spin-flip component of the Pomeron.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date.available

2013

Author dc:creator

• Plyku, Donika

Contributors dc:contributor

• Stephen Bültmann
• Gail Dodge
• Leposava Vuskovic
• J. Wallace Van Orden
• Richard Zimmerman

• Elastic scattering
• Proton-proton collisions
• Relativistic heavy ion collider
• Roman pots
• Single-spin asymmetry
• Spin dependence
• Nuclear

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9781303080098

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:physics_etds-1073