STAR Experiment and Forward Upgrade at RHIC

Authors

Claire Kovarik, Valparaiso UniversityFollow
Andrew Edwards, Valparaiso UniversityFollow
JD Snaidauf, Valparaiso UniversityFollow

College

Arts and Sciences

Department/Program

Physics and Astronomy

Presentation Type

Poster Presentation

Symposium Date

Summer 7-29-2019

Abstract

The Solenoidal Tracker at RHIC (STAR) located at Brookhaven National Laboratory in New York uses longitudinally polarized proton-proton collisions to determine the gluon contribution to the spin of the proton. One analysis of the 2012 data set, at a proton-proton center of mass energy of 510 GeV, studies the production of neutral pions (𝜋⁰) which immediately (~10^-16s) decay into two photons. The neutral pion asymmetry, A_LL, can be determined through data collected by the Endcap Electromagnetic Calorimeter (EEMC). The EEMC, positioned in an intermediate pseudorapidity range of 1 < η < 2, is able to measure the energy and position of each photon’s electromagnetic shower. By using this information as well as the angle between the photons, the two-photon invariant mass can be reconstructed. The invariant mass spectra are fitted using a skewed Gaussian plus a background function to determine the total number of 𝜋⁰s present. The 𝜋⁰ asymmetry is calculated from the number of 𝜋⁰s in collisions with different polarization directions of the colliding proton beams. The status of the measurement of A_LL of the 𝜋⁰s as a function of the transverse momentum, p_T, of the 𝜋⁰ will be presented.

Recommended Citation

Kovarik, Claire; Edwards, Andrew; and Snaidauf, JD, "STAR Experiment and Forward Upgrade at RHIC" (2019). Summer Interdisciplinary Research Symposium. 65.
https://scholar.valpo.edu/sires/65