Gluon Contribution to Proton Spin and the Connection to Forward Calorimetry at STAR
Arts and Sciences
The proton has an intrinsic spin quality that is derived from its quark and gluon components. While the quark contribution to the spin of the proton is relatively well known, the gluon contribution is comparatively poorly constrained. The STAR (Solenoidal Tracker at RHIC (Relativistic Heavy Ion Collider)) collaboration is working to clear this ambiguity by analyzing collisions of spin-polarized protons. One analysis uses neutral pion (𝛑0s) detected by the Endcap Electromagnetic Calorimeter (1 < η < 2). We measure the number of 𝛑0s resulting from varied spin-aligned collisions and calculate the production asymmetry, which is related to the gluon contribution. We are beginning to analyze the dataset from 2013 (integrated luminosity 300 pb-1), which is about three times the size of the dataset from 2012 (82 pb-1), whose analysis is more mature. Currently at Brookhaven National Laboratory, the Forward Meson Spectrometer (FMS, 2.5 < η < 4.0), which is responsible for the measurement of forward 𝛑0s, is being deconstructed in preparation of a new Forward Calorimeter System (FCS, 2.5 < η < 4.0) which will feature electromagnetic and hadronic calorimetry. I will discuss the 𝛑0 asymmetry analysis with a glimpse at the 2013 data, the FMS deconstruction, and the proposed FCS.
Bailey, Miya, "Gluon Contribution to Proton Spin and the Connection to Forward Calorimetry at STAR" (2018). Summer Interdisciplinary Research Symposium. 31.