Calibrating the STAR Endcap Calorimiter for 2012 Data and Optimizing the Tower Gains for 2009 Data
Arts and Sciences
The Solenoidal Tracker at RHIC (STAR), based at Brookhaven National Laboratory, uses polarized p+p collisions to investigate sea quark and gluon contributions to the proton spin. The STAR detector’s Endcap Electromagnetic Calorimeter (EEMC) is of particular interest in these experiments because it covers a kinematic region of the detector which is sensitive to gluons carrying a low fraction of the proton momentum, where the gluon spin is almost entirely unconstrained. The EEMC is located in the intermediate pseudorapidity range 1<eta<2, and measures the energy of particles produced in the collisions using a spatially segmented lead-scintillator sampling calorimeter. Each segment, or tower, is energy-calibrated using minimum ionizing particles. Scintillator light is converted to an electric pulse whose height is proportional to the energy deposited in the tower. A gain factor that converts the pulse height to energy deposited in GeV is determined separately for each tower. An independent energy calibration method was used to fine tune the tower gains and attempt to address other potential sources of systematic uncertainty, such as pseudorapidity-dependence in the reconstructed pi0 mass. Calibration of the detector for 2012 data using minimum ionizing particles has been started. Results from the 2009 and 2012 calibrations will be presented.
Langholz, Erik, "Calibrating the STAR Endcap Calorimiter for 2012 Data and Optimizing the Tower Gains for 2009 Data" (2014). Symposium on Undergraduate Research and Creative Expression (SOURCE). 377.