Measurement of the Longitudinal Double-spin Asymmetry for Neutral Pion Production in Polarized Proton Collisions at √s = 510 GeV

Author

Taegyun Kim, Valparaiso University

Date of Award

5-13-2017

Project Type

Departmental Honors Paper/Project

Department

Department of Physics & Astronomy

First Advisor

Adam Gibson-Even

Abstract

Beyond the valence quarks' spin contribution to the total spin of a proton, gluon and sea quark contributions are becoming clear as well. For proton+proton collisions at a center of mass energy of 510 GeV , neutral pion production is dominated by gluon-gluon and gluon-quark scattering. An avenue to constrain the gluon polarization is the asymmetry, A_LL, in the production of neutral pions from collisions of longitudinally spin-polarized proton beams. Our experiment was performed with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), unique for its ability to collide spin-polarized proton beams. The Endcap Electromagnetic Calorimeter (EEMC) of the STAR detector with its pseudo-rapidity (η) range between 1.09 and 2.00 and full azimuthal coverage measures energies of photons from π⁰ decays. We consider the invariant mass of all photon pairs in the EEMC as we identify π⁰ candidates. We will present the current status of the analysis of the π⁰ A_LL as measured by the EEMC at STAR in 2012 data with center-of-mass energy of 510 GeV.

Recommended Citation

Kim, Taegyun, "Measurement of the Longitudinal Double-spin Asymmetry for Neutral Pion Production in Polarized Proton Collisions at √s = 510 GeV" (2017). Undergraduate Honors Papers. 1.
https://scholar.valpo.edu/undergrad_capstones/1