Overview of the backing calorimeter after the ZEUS detector upgrade

New hardware and software developments on the Backing Calorimeter (BAC) for the ZEUS detector are presented. The modernization of the detector was related to the recent luminosity upgrade of the HERA accelerator. The role and place of the BAC detector in the ZEUS experiment is described with special emphasis on the new BAC muon trigger and its diagnostic and monitoring system. This overview introduces a series of detailed articles following in this chapter of the SPIE proceedings.