Construction of the Vessel for the Proximity-Focusing RICH for the ePIC Experiment

We will present an overview of the proximity-focusing Ring Imaging Cherenkov (pfRICH) detector for the ePIC experiment at the Electron-Ion Collider (EIC) at Brookhaven National Lab. As a key particle identification (PID) subsystem in the backward region, the pfRICH provides momentum coverage up to 7 GeV/c for pions, kaons, and protons, aiding in Deep Inelastic Scattering (DIS) measurements. The pfRICH uses a 25mm thick aerogel radiator with = 1.040, forming photon rings on the sensor plane without focusing. The sensor plane which is composed of HRPPD photosensors by Incom Inc., spans a pseudorapidity range of -3.5 ≤ η ≤ -1.5, with mirrors enhancing acceptance. The vessel, made of robust carbon fiber composite plastic (CFRP) with an aramid honeycomb core, supports all components, ensures gas and light containment, and minimizes the material budget, using construction techniques from the sPHENIX TPC field cages.