Electro-optical interface design for CMS HCAL

The CMS detector at the CERN Large Hadron Collider is being built to study particle physics at the energy frontier. An important detector subsystem of CMS is the hadron calorimeter (HCAL), used for the measurement of particle and jet energies and to identify and measure missing transverse energy in collision events. This paper provides details of the electro-optical interfaces for the barrel and endcap regions of the HCAL called readout boxes (RBX). These system elements are located "on detector" and operate in regions of very high magnetic field, converting scintillation signals for megatile sampling layers to tower geometry for energy measurement.