Status of the Forward Calorimeter System (FCS) Upgrade at STAR

The Forward Calorimeter System (FCS), together with the Forward Silicon Tracker (FST) and small-strip Thin Gap Chambers (sTGC), are the most recent upgrades of the STAR detector at RHIC, BNL. This upgrade in the forward \( 2.5 < \eta < 4\) rapidity region is motivated to explore QCD physics in the low region of x as those related to revealing the nucleon spin structure. The FCS consists of the refurbished PHENIX Shashlyk Lead Scinitillator (Pb/Sc) Electromagnetic Calorimeter (EMCal) followed by an iron - scintillator (Fe/Sc) sampling Hadronic Calorimeter (HCal), with silicon photomultipliers (SiPMs) as readout. The construction of the FCS was completed towards the end of 2020 and started taking data during the 2022 Run Period. This talk will cover the construction and calibration of the FCS with a focus on the radiation damage of the front end electronics, as well as the gain correction factor for each ECal tower for reconstructing neutral pions using the pp Run23 \(\sqrt{s}\) = 510 GeV data.