Front-end electro-optical interfaces for CMS HCAL

The CMS experiment is a complex instrument to study particle physicsat the energy frontier. An important detector subsystem within CMS is the hadron calorimeteror HCAL, consisting of four subsystems that cover the kinematic region |/spl eta/|<5. This paper provides details of the electro-optical interfaces for the central barrel subsystem that operates in a region of high magnetic field and converts scintillation signals from megatile sampling layers to lower geometry for energy measurement.