Probing the Gluon’s Contribution to the Proton’s Spin using the STAR Endcap Electromagnetic Calorimeter: Data Reconstruction and Quality Assurance

Faculty Sponsor

Dr. Gibson-Even


Arts and Sciences


Physics and Astronomy

Presentation Type

Poster Presentation

Symposium Date

Summer 7-29-2023


Measuring the gluon’s contribution to the proton’s spin is an important goal of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). Our group is aiding this effort by studying the 2013 data from √s = 510 GeV longitudinally polarized proton-proton collisions. Our data are gathered using the Endcap Electromagnetic Calorimeter (EEMC) which is stationed at a pseudorapidity range of 1.1 < η < 2.0 and detects photons from the decays of neutral pions (π0). We reconstruct STAR data and store the results in a series of three ROOT trees, containing C++ objects, for each STAR run. We previously reconstructed pi0s from 1583 runs of the 2013 data, but many were incomplete due to the partial availability of data on disk. Recently, we executed a new reconstruction campaign to add additional files to many runs, and complete the set of runs. After reconstruction, we assessed the quality of the data including a consideration of the mean invariant π0 mass, number of towers hit, and signal fraction. Eventually, the data will be used to calculate the spin-dependent asymmetry of π0 production (ALL), sensitive to the gluon’s contribution to the proton’s spin. I will present the process and impact of the reconstruction campaign and quality assurance effort.

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