Characterizing Readout Electronics of the Time Projection Chamber in the sPHENIX Experiment

Quark-Gluon Plasma is a hot, dense medium of quarks and gluons formed in heavy ion collisions, such as those at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab. The sPHENIX experiment, which completed installation at RHIC in 2023, is designed to measure the QGP properties using a diverse set of high energy probes. The sPHENIX detector consists of a multitude of different sub-detectors, including a Time Projection Chamber (TPC) used as its main particle tracking device. The TPC is a gaseous drift detector that measures the momentum of charged particles which pass through it. During heavy ion collisions, particles are produced at the collision point, traverse the TPC gas, and ionize it. The electrons from the ionization drift towards the ends of the TPC, where they are amplified by gaseous electron multiplier (GEM) foils, and then read out as analog signals. These signals are amplified, digitized, and shaped by a system of 624 Front End Electronics (FEE) cards. We present a measurement of the overall efficiency of the FEE cards, quantifying the sPHENIX TPC live readout area from measurements made during the 2023 data taking period. This measurement is critical for the commissioning of the TPC and for determining its tracking performance.