Analysis of Neutral Pion Helicity Asymmetry with the STAR Detector

Faculty Sponsor

Adam Gibson-Even


Arts and Sciences


Physics and Astronomy

Document Type

Poster Presentation

Symposium Date

Summer 7-31-2017


Analysis of Neutral Pion Helicity Asymmetry with the STAR Detector

Alec Hauck and Noah Strand, Valparaiso University

for the STAR Collaboration

The gluon contribution to the spin of a proton is poorly constrained in comparison to the quark contribution. In order to further constrain this gluon contribution, part of the STAR collaboration at RHIC analyzes the asymmetry in neutral pion (πœ‹0) production as a function of spin alignment in longitudinally polarized proton beam collisions. These πœ‹0s most commonly decay into photon pairs, some of which are then identified in the Endcap Electromagnetic Calorimeter (EEMC) within the STAR detector. The EEMC covers a pseudorapidity range of 1 < Ξ· < 2 with full azimuthal coverage. The EEMC’s Shower Max Detector (SMD) is particularly useful in determining the positions of photon showers; a first step in photon identification is reconstructing clusters of energy in each layer of the SMD. Knowing the position and energy of these photons allows us to reconstruct the πœ‹0s they decayed from. From these reconstructed πœ‹0s, a corrected count is determined by fitting signal and background templates from Monte Carlo simulation to the πœ‹0 invariant mass distributions. We will describe the current state of this analysis on the 510 GeV dataset from 2012 (82 pb-1) including cluster identification, Monte Carlo simulation, and data. We will also give a first glimpse of the 2013 dataset (300 pb-1).

Biographical Information about Author(s)

Alec Hauck and Noah Strand are currently pursuing a bachelor's degree in physics. Noah aims to get certification to become a pastor after graduating. He hopes his background in physics will provide him with a unique perspective for his career as a pastor. Alec plans on going onto grad school after he graduates. He hopes that this summer research will provide some insight into what a future in nuclear physics would entail.

This document is currently not available here.