Analysis of Neutral Pion Asymmetry with the STAR Detector

Faculty Sponsor

Shirvel Stanislaus


Arts and Sciences


The Department of Physics and Astronomy

Presentation Type

Poster Presentation

Symposium Date

Spring 5-3-2018


Although the quark contribution to the proton’s spin is well known, the gluon contribution to the spin is relatively poorly constrained. In order to further constrain this gluon contribution, part of the Solenoidal Tracker at the Relativistic Heavy Ion Collider (RHIC) (STAR) collaboration analyzes collisions between different alignments of longitudinally spin-polarized proton beams. These collisions produce varying amounts of neutral pions which most commonly decay into photon pairs, some of which are then identified in the Endcap Electro Magnetic Calorimeter (EEMC) within the STAR detector. The EEMC makes measurements in a pseudorapidity range of 1 < η ≤ 2 with full azimuthal coverage. The Shower Maximum Detector (SMD) is particularly useful in determining the positions of energy readings in the EEMC which we label as clusters. These clusters, caused by photons, are then used to reconstruct the neutral pions. From these reconstructed pions, a corrected number of pions is determined by fitting templates from Monte Carlo simulation to the pion mass distribution data. We will describe the current state of the analysis including cluster identification and neutral pion data and simulation.

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