epic-TN-TC-2025-002: Barrel Imaging Calorimeter Light Guide Simulations

The goal of these tests is to estimate the transmission efficiency (the percentage of thrown photons that reach the sensitive volume of the SiPM) and degree of light mixing (some measure of how uniformly the light illuminates the SiPM surface) for Barrel Imaging Calorimeter (BIC) light guides of various designs and lengths. Since space in the ePIC detector is extremely limited, knowing how short the light guides can reasonably be is important. In the past, Elton Smith had done these studies for the GlueX light guides using Geant3, results we wish to verify using Geant4 and extend to BIC light guides.